Methods Cross-sectional data, based on self-reports, were derived from national health interview surveys from 19 European countries (N = 127 018; age range = 25–44 years). Height and weight data were used to calculate the body mass index (BMI). Multivariate regression analysis was employed to measure educational inequalities in overweight and obesity, based on BMI. Gross domestic product (GDP) per capita was used as a measure of level of socio-economic development.

Results Inverse educational gradients in overweight and obesity (i.e. higher education, less overweight and obesity) are a generalized phenomenon among European men and even more so among women. Baltic and eastern European men were the exceptions, with weak positive associations between education and overweight and obesity. Educational inequalities in overweight and obesity were largest in Mediterranean women. A 10 000-euro increase in GDP was related to a 3% increase in overweight and obesity for low-educated men, but a 4% decrease for high-educated men. No associations with GDP were observed for women.

Conclusion In most European countries, people of lower educational attainment are now most likely to be overweight or obese. An increasing level of socio-economic development was associated with an emergence of inequalities among men, and a persistence of these inequalities among women.

Methods A population-based birth cohort study in Japan (2001–02), the ‘Longitudinal Survey of Babies Born in 21st Century’, was used (n = 42 144). The impact of paternal involvement in childcare of 6-month-old infants (feeding, diaper change, bathing, putting the child to sleep, playing, taking a walk) on the incidence of young childhood injury (fall, near-drowning, accidental ingestion or burn) until 18 months of age was analysed by multiple logistic regression.

Results Infants who received a high degree of paternal involvement in childcare at 6 months were less likely to suffer from all unintentional injuries at 18 months than those who received a low degree of paternal involvement in childcare (adjusted odds ratio 0.91, 95% confidence interval 0.85–0.98). Taking the child for a walk by the father strongly prevented all unintentional injuries, and there were dose–effect relationships (P_trend < 0.001).

Conclusions Paternal involvement in childcare at 6 months of age prevented childhood injury at 18 months of age. Paternal involvement in childcare might be a useful indicator for predicting childhood injury.

Methods A total of 6640 men and women, aged 25–84 years, were included in a 10-year mortality follow-up: 345 subjects with a diagnosed AAA and 6295 subjects with a non-aneurismal aorta. Non-aneurismal aortic diameter and prevalent AAAs were categorized into seven groups.

Results In subjects without an AAA, an aortic diameter ≥30 mm increased age- and sex-adjusted total mortality [mortality rate ratio (MRR) = 3.73, 95% confidence interval (CI) 1.77–7.89] and CVD mortality (MRR = 9.24, 95% CI 4.07–20.97) compared with subjects with aortic diameter of 21–23 mm. An AAA at screening was strongly associated with deaths from aortic aneurysm and was associated with total (MRR = 1.60, 95% CI 1.31–1.96) and CVD mortality (MRR = 2.41, 95% CI 1.81–3.21). This was not explained by deaths due to an AAA. Adjustments for CVD risk factors could fully explain the increased total, but not CVD mortality in subjects with an AAA.

Conclusions An AAA increases total and CVD mortality. In the large majority of subjects with a non-aneurysmal aorta, the diameter does not influence total or CVD mortality. However, in individuals with a maximal diameter >26 mm (2% of the population), a positive relationship is found.

Methods From 1988 to 1990, a total of 67 129 Japanese non-workers or daytime workers (27 755 men and 39 374 women) aged 40–79 years, without a history of stroke, heart disease or cancer, completed a lifestyle questionnaire. They were followed for mortality until the end of 2003.

Results During the 879 244 person-year follow-up, 9643 deaths (2852 from CVD, 3643 from cancer, 2392 from other internal causes, 738 from external causes and 18 from unspecified causes) were observed. After adjustment for possible confounders, subjects with a daytime napping habit had elevated hazard ratios (HRs) for mortality from all causes [HR 1.19, 95% confidence interval (CI) 1.14–1.24, P < 0.001], CVD (HR 1.31, 95% CI 1.22–1.42, P < 0.001), non-cardiovascular/non-cancer internal diseases (HR 1.26, 95% CI 1.16–1.37, P < 0.001) and external causes (HR 1.28, 95% CI 1.10–1.50, P = 0.001), but not for cancer death (HR 1.03, 95% CI 0.96–1.10, P = 0.400). The risk of CVD mortality associated with daytime napping was diminished among overweight subjects, but pronounced in those with weight loss after age 20 years, with non-regular employment, with lower education level and with a follow-up period <5 years.

Conclusions Daytime napping is associated with elevated risk of CVD mortality as well as non-cardiovascular/non-cancer and external deaths. Daytime napping may elevate risk of CVD death through some biological effects but, to a larger extent, some comorbid disorders causing weight loss or associated with non-regular employment and low education level could explain this association.

Methods Data are from participants (60% women, mean age 38 years) in a cohort of university graduates in Spain (1999–2008). Among other exposures and outcomes, they self report on frequency of participation in several physical activities over 1 year, and on incidence of sports-related injuries after 2, 4 or 6 years follow-up. Participation in 17 physical activities was categorized as a dichotomous variable (yes/no) and also according to average time per week spent in each one. Proportional hazards regression was used to estimate the adjusted relative risks [hazard ratios (HRs)] of incident injury associated with each specific physical activity or with total weekly energy expenditure in leisure-time activity [metabolic equivalents (METs)-h/week]. Statistical analyses were stratified by sex.

Results We identified 1658 incident sports-related injuries among 14 356 participants after a median follow-up of 4.6 years. When we adjusted for overall energy expenditure (METs-h/week) in other activities, age and body mass index (BMI), a higher risk of injury was associated with participation in soccer, other team sports, skiing, tennis, running and athletics (HRs ranging from 1.50 to 1.86) among men. With the exception of soccer (rarely practiced by women in Spain), similar results were found for women (HRs ranging from 1.61 to 2.04). Walking, gymnastics, swimming, mountain hiking and gardening were associated with a low injury risk.

Conclusions Despite the healthy effects of physical activity, we consider that the higher risk for injuries related to soccer, team sports, skiing, tennis, running or athletics should be taken into consideration when advice for more physical activity is given to the general population. Daily routine physical activities such as walking or gardening should be encouraged.

Methods In a 2002 postal questionnaire, 21 522 members of same-sex pairs in the Danish Twin Registry born between 1931 and 1982 reported physical health in the 12-item Short Form Health Survey. We used quantitative genetic models to examine how genetic and environmental variance in physical health differed with level of education, adjusting for birth-year effects.

Results and Conclusions As expected, greater education was associated with better physical health. Greater education was also associated with smaller variance in health status. In both sexes, 2 standard deviations (SDs) above mean educational level, variance in physical health was only about half that among those 2 SDs below. This was because fewer highly educated people reported poor health. There was less total variance in health primarily because there was less genetic variance. Education apparently reduced expression of genetic susceptibilities to poor health. The patterns of genetic and environmental correlations suggested that this might take place because more educated people manage their environments to protect their health. If so, fostering the personal charactieristics associated with educational attainment could be important in reducing the education–health gradient.

Methods We estimated relative survival for 29 563 colorectal cancer patients who were diagnosed between 1997 and 2004 and registered in the North West Cancer Intelligence Service. The method of multiple imputation (MI) was applied to account for the common example of incomplete stage at diagnosis, under the missing at random (MAR) assumption. Multivariable regression with a generalized linear model and Poisson error structure was then used to estimate the excess hazard of death of the colorectal cancer patients, over and above the background mortality, adjusting for significant predictors of mortality.

Results Incomplete information on stage, morphology and grade meant that only 55% of the data could be included in the ‘complete-case’ analysis. All cases could be included after indicator method (IM) or MI method. Handling missing data by MI produced a significantly lower estimate of the excess mortality for stage, morphology and grade, with the largest reductions occurring for late-stage and high-grade tumours, when compared with the results of complete-case analysis.

Conclusion In complete-case analysis, almost 50% of the information could not be included, and with the IM, all records with missing values for stage were combined into a single ‘missing’ category. We show that MI methods greatly improved the results by exploiting all the information in the incomplete records. This method also helped to ensure efficient inferences about survival were made from the multivariate regression analyses.

Methods This article presents a method for correcting the bias in FR estimates from such misclassification of family history, using a simple formula that depends on the prevalence and sensitivity of the observed family history. The sensitivity is estimated by using the R package poplab to create realistic populations of related individuals and then imposing the start-up effect of disease registration.

Results For a range of FRs, the truncation of family history is demonstrated to result in non-differential misclassification, and sensitivity that has little or no dependence on the FR. The bias is most pronounced for high FRs and for registers with a short life span, and increases with the age of the study cohort. In all the situations studied, the bias-corrected estimates are in excellent agreement with the true values.

Conclusions In summary, our method can correct the inevitable bias in FRs induced by using electronic population data, and is a feasible alternative to the use of validation samples.

Methods Eligible studies were identified using a search strategy that included a computerized literature search and a manual search of each article's reference list, up to June 2008. A total of 23 studies were included (10 cohort, 5 case–control and 8 cross-sectional). Each study was summarized and rated for methodological quality. Pooled odds ratio (OR) estimates and 95% confidence intervals (CIs) were calculated using fixed-effects (FE) or random-effects (RE) models; if heterogeneity was present, the latter was used. Three indicators of BCG exposure were considered including BCG vaccination, tuberculin response and scar diameter.

Results The pooled estimate of association for 23 studies reporting on any of the three indicators suggested a protective effect of BCG exposure on childhood asthma occurrence. The studies were heterogeneous, especially when tuberculin response was considered. Restriction to a subgroup of 16 studies that considered BCG vaccination indicated a protective effect with no evidence of heterogeneity. The overall pooled OR using an FE model was 0.86 (95% CI 0.79–0.93). Exclusion of three studies with the lowest quality scores showed a similar association.

Conclusion These results strengthen the epidemiological evidence in support of the hypothesis that exposure to the BCG vaccine in early life prevents asthma, possibly through a modulation of the immune maturation process.

Methods A systematic literature review was carried out to identify cohort studies that collected data on weight and height at baseline and that used a diagnosis of active TB as the study outcome. Weight-for-height measures used in the original studies were transformed into body mass index (BMI). Exponential trend lines were fitted to each data set.

Results Six studies were included. In all of them, there was a log-linear inverse relationship between TB incidence and BMI, within the BMI range 18.5–30 kg/m². The average slope gave a reduction in TB incidence of 13.8% [95% confidence interval 13.4–14.2] per unit increase in BMI. The dose–response relationship was less certain at BMI <18.5 and >30 kg/m².

Conclusion There is a strong and consistent log-linear relationship between TB incidence and BMI across a variety of settings with different levels of TB burden. More research is required to test the relationship at very low and very high BMI levels, to establish the biological mechanism linking BMI with risk of TB and to establish the potential impact on the global TB epidemic of changing nutritional status of populations.

Methods Eligible patients were enrolled in prospective cohort studies participating in the ART Cohort Collaboration. We calculated the ratio of observed to expected deaths from all causes [standardized mortality ratio (SMR)], measuring time from 6 months after starting ART, according to risk group, clinical stage at the start of ART and CD4 cell count and viral load at 6 months. Expected numbers of deaths were obtained from age-, sex- and country-specific mortality rates.

Results Among 29 935 eligible patients, 1134 deaths were recorded in 131 510 person-years of follow-up. The median age was 37 years, 8162 (27%) patients were females, 4400 (15%) were injecting drug users (IDUs) and 6738 (23%) had AIDS when starting ART. At 6 months, 23 539 patients (79%) had viral load measurements ≤500 copies/ml. The lowest SMR, 1.05 [95% confidence interval (CI) 0.82–1.35] was found for men who have sex with men (MSM) who started ART free of AIDS, reached a CD4 cell count of ≥350 cells/µL and suppressed viral replication to ≤500 copies/ml by the sixth month. In contrast, the SMR was 73.7 (95% CI 46.4–116.9) in IDUs who failed to suppress viral replication and had CD4 cell counts <50 cells/µL at 6 months. The percentage of patients with SMRs <2 was 46% for MSM, 42% for heterosexually infected patients and 0% for patients with a history of injection drug use. Corresponding percentages for SMRs >10 were 4, 14 and 47%.

Conclusions In industrialized countries, the mortality experience of HIV-infected patients who start ART and survive the first 6 months continues to be higher than in the general population, but for many patients excess mortality is moderate and comparable with patients having other chronic conditions. Much of the excess mortality might be prevented by earlier diagnosis of HIV followed by timely initiation of ART.

Methods The 2323 cases were categorized as ‘ever screened’ if they had had at least one smear prior to 6 months before diagnosis, and as ‘regular screening’ if they had had no more than 36 months between any two smears in the period 6–114 months before diagnosis. Logistic regression was used to estimate the associations of screening history, ethnicity, SES and urban/rural residence with stage at diagnosis.

Results The percentages ‘ever screened’ were 43.3% overall, 24.8% in Pacific, 30.5% in Asian, 40.6% in Maori and 46.1% in ‘Other’ women. The corresponding estimates for ‘regular screening’ were 14.0, 5.7, 7.8, 12.5 and 15.3%. Women with ‘regular screening’ had a lower risk of late stage diagnosis [odds ratio (OR) 0.16, 95% confidence interval (CI) 0.10–0.26], and the effect was greater for squamous cell carcinoma (OR 0.12, 95% CI 0.07–0.23) than for adenocarcinoma (OR 0.32, 95% CI 0.13–0.82). The increased risk of late-stage diagnosis (OR 2.72, 95% CI 1.99–3.72) in Maori (compared with ‘Other’) women decreased only slightly when adjusted for screening history (OR 2.45, 95% CI 1.77–3.39).

Conclusions Over half of cases had not been ‘ever screened’. Regular screening substantially lowered the risk of being diagnosed at a late stage. However, screening history does not appear to explain the ethnic differences in stage at diagnosis.

Methods In the French nationwide Mortalité 2000 and 2005 surveys, physicians reported causes of deaths in HIV-infected adults in 2000 and 2005, using a standardized questionnaire. We used multivariate logistic regression models to study the association between gender and AIDS-defining causes of death, adjusting for other characteristics.

Results Of the 1013 HIV-infected adults who died in 2005, 247 (24%) were women. Half of women were infected through heterosexual contacts, compared with 25% men. In 2005, the proportion of AIDS-defining causes of death was higher in women than in men (43 vs 34%; P = 0.01), whereas it had been the same in 2000 (47% in women and men). In 2005, women died less frequently than men from respiratory malignancies (lung, ear/nose/throat) and cardiovascular disease (9% of all causes of death in women compared with 16% in men; P = 0.004), and suicides or accidents (4 vs 9%; P = 0.02). Socio-economic precariousness, younger age, less alcohol and tobacco consumption and lack of prior ART explained the higher proportion of deaths from AIDS in women compared with men.

Conclusions The higher proportion of AIDS-related deaths in women is probably explained by two factors: (i) some HIV-infected women, especially migrants in poor socio-economic conditions, may not have access to optimal care; and (ii) a lower prevalence of risk factors for respiratory, cardiovascular and violent deaths means that the risk of dying from non-AIDS causes may be lower in women.

Methods We pooled individual-level data from case–control studies in the International Head and Neck Cancer Epidemiology Consortium. Data were available from 13 studies on drinking cessation (9167 cases and 12 593 controls), and from 17 studies on smoking cessation (12 040 cases and 16 884 controls). We estimated the effect of quitting smoking and drinking on the risk of head and neck cancer and its subsites, by calculating odds ratios (ORs) using logistic regression models.

Results Quitting tobacco smoking for 1–4 years resulted in a head and neck cancer risk reduction [OR 0.70, confidence interval (CI) 0.61–0.81 compared with current smoking], with the risk reduction due to smoking cessation after ≥20 years (OR 0.23, CI 0.18–0.31), reaching the level of never smokers. For alcohol use, a beneficial effect on the risk of head and neck cancer was only observed after ≥20 years of quitting (OR 0.60, CI 0.40–0.89 compared with current drinking), reaching the level of never drinkers.

Conclusions Our results support that cessation of tobacco smoking and cessation of alcohol drinking protect against the development of head and neck cancer.

Methods We performed a detailed analysis of one 15q single nucleotide polymorphism (SNP) (rs16969968) with smoking behaviour and cancer risk in a total of 17 300 subjects from five LC studies and four upper aerodigestive tract (UADT) cancer studies.

Results Subjects with one minor allele smoked on average 0.3 cigarettes per day (CPD) more, whereas subjects with the homozygous minor AA genotype smoked on average 1.2 CPD more than subjects with a GG genotype (P < 0.001). The variant was associated with heavy smoking (>20 CPD) [odds ratio (OR) = 1.13, 95% confidence interval (CI) 0.96–1.34, P = 0.13 for heterozygotes and 1.81, 95% CI 1.39–2.35 for homozygotes, P < 0.0001]. The strong association between the variant and LC risk (OR = 1.30, 95% CI 1.23–1.38, P = 1 x 10^–18), was virtually unchanged after adjusting for this smoking association (smoking adjusted OR = 1.27, 95% CI 1.19–1.35, P = 5 x 10^–13). Furthermore, we found an association between the variant allele and an earlier age of LC onset (P = 0.02). The association was also noted in UADT cancers (OR = 1.08, 95% CI 1.01–1.15, P = 0.02). Genome wide association (GWA) analysis of over 300 000 SNPs on 11 219 subjects did not identify any additional variants related to smoking behaviour.

Conclusions This study confirms the strong association between 15q gene variants and LC and shows an independent association with smoking quantity, as well as an association with UADT cancers.

Methods EMBASE, PubMed, Scopus and Web of Science databases were searched using sensitive search strategies. Meta-analysis was undertaken using STATA 10.

Results A total of 5865 references were retrieved, of which 67 met the inclusion criteria and contributed data to at least one perinatal analysis. Random effects meta-analysis found maternal bleeding during pregnancy [odds ratio (OR) 1.33, 95% confidence interval (CI) 1.02–1.73], birth order (primiparous vs not, 1.08, 95% CI 1.01–1.16; second vs first, OR 0.94, 95% CI 0.88–0.99; third vs first, OR 0.91, 95% CI 0.83–1.01; fourth vs first, OR 0.80, 95% CI 0.69–0.94) and sibship size (2 vs 1, OR 0.93, 95% CI 0.75–1.15; 3 vs 1, OR 0.89, 95% CI 0.74–1.07; 4 vs 1, OR 0.75, 95% CI 0.62–0.90) to be associated with testicular cancer risk. Meta-analyses that produced summary estimates which indicated no association included maternal age, maternal nausea, maternal hypertension, pre-eclampsia, breech delivery and caesarean section. Meta-regression provided evidence that continent of study is important in the relationship between caesarean section and testicular cancer (P = 0.035), and a meta-analysis restricted to the three studies from the USA was suggestive of association (OR 1.67, 95% CI 1.07–2.56).

Conclusions This systematic review and meta-analysis has found evidence for associations of maternal bleeding, birth order, sibship size and possibly caesarean section with risk of testicular cancer.

Methods We conducted a retrospective cohort study of 473 358 Korean men aged 30–64 years, who had undergone health examinations in both 1992 and 1998 and were followed up during 1998–2004. Cox proportional hazards for cause-specific 7-year mortality in relation to BMI changes after stratification of baseline BMI status were analysed.

Results Mortality from cardiovascular disease (CVD) was associated with BMI in both 1992 and 1998. Non-CVD mortality was inversely associated with BMI in both 1992 and 1998. We cross-classified participants into groups based on their baseline BMI levels and percent BMI changes during follow-up; men with the lowest BMI level at baseline (BMI in 1992 <21 kg/m²) and stable BMI during follow-up (percent change in BMI <5%) were included in the reference category. Compared with the reference group, CVD mortality was higher in initially obese men (BMI in 1992 ≥25 kg/m²) with any increase of BMI, and in initially lean men (BMI in 1992 <21 kg/m²) or initially overweight men (BMI in 1992 23–24.9 kg/m²) with BMI increases of ≥10%. BMI increases of 5.0–9.9% in men with baseline BMI <25 kg/m² and stable BMI in men with baseline BMI ≥21 kg/m² appeared to lower the risk for non-CVD or all-cause mortality, to below the levels seen in the reference group.

Conclusions Among middle-aged Korean men, obesity or severe weight gain was detrimental to CVD mortality. An increase in BMI appeared to have a predictive value for CVD mortality, especially when used in combination with baseline BMI level. In contrast, moderate weight gain in non-obese men seemed to protect against non-CVD and all-cause mortality.

Methods We retrieved studies by systematically searching Medline and other computerized databases, and by manually examining the references of the original articles and monographs retrieved. We also contacted international researchers working on this or similar topics to complete our search. We included 247 studies reporting relative risk (RR) estimates of hairdresser occupation and cancer of different sites.

Results Study-specific RRs were weighted by the inverse of their variance to obtain fixed and random effects pooled estimates. The pooled RR of occupational exposure as a hairdresser was 1.27 (95% CI 1.15–1.41) for lung cancer, 1.52 [95% confidence interval (CI) 1.11–2.08] for larynx cancer, 1.30 (95% CI 1.20–1.42) for bladder cancer and 1.62 (95% CI 1.22–2.14) for multiple myeloma. Data for other anatomic sites showed increases of smaller magnitude. The results restricted to those studies carried out before the ban of two major carcinogens from hair dyes in the mid-1970s were similar to the general results.

Conclusions Hairdressers have a higher risk of cancer than the general population. Improvement of the ventilation system in the hairdresser salons and implementation of hygiene measures aimed at mitigating exposure to potential carcinogens at work may reduce the risk.

Methods A meta-analysis of previous epidemiologic studies may help to clarify the potential association. We identified 38 cohort studies and 58 case–control studies in a systematic literature search for studies on liver cancer and cigarette smoking. The meta-relative risk (mRR) of liver cancer and dose–response trends were calculated. Tests for heterogeneity, publication bias assessment and influence analyses were performed.

Results Compared with never smokers, the adjusted mRR was 1.51 [95% confidence interval (CI) 1.37–1.67] for current smokers and 1.12 (95% CI 0.78–1.60) for former smokers. The increased liver cancer risk among current smokers appeared to be consistent in strata of different regions, study designs, study sample sizes and publication periods.

Conclusion The results of our meta-analysis show that tobacco smoking is associated with liver cancer development, which supports the conclusion by the IARC Monograph. This conclusion has an important public health message for areas with high smoking prevalence and high liver cancer incidence such as China.

Methods All children born in Pelotas, Brazil, in 2004, were recruited to a birth cohort study. These children were assessed at birth and at 3, 12 and 24 months of age. In this last assessment involving 3869 children, detailed information on socio-economic and health characteristics was collected. Child development was assessed using the screening version of Battelle's Development Inventory. Five markers of cognitive stimulation and social interaction were recorded and summed to form a score ranging from 0–5. The outcomes studied were mean development score and low performance (less than 10th percentile of the sample).

Results Child development was strongly associated with socio-economic position, maternal schooling and stimulation. Having been told a story and owning a book were the least frequent markers among children with score 1. These children were 8.3 times more likely to present low performance than those who scored 5. The effect of stimulation was much stronger among children from mothers with a low level of schooling—one additional point added 1.7 on the child's development for children of low-schooling mothers, whereas only 0.6 was added for children of high-schooling mothers.

Conclusions Our stimulation markers cannot be directly translated into intervention strategies, but strongly suggest that suitably designed cognitive stimulation can have an important effect on children, especially those from mothers with low schooling.

Methods We used multivariable linear regression to examine the prospective adjusted associations of breastfeeding with body mass index (BMI), height and weight z-scores at 7 years of age relative to the 2007 World Health Organization (WHO) growth reference, in a large (n = 8327), population-representative Hong Kong Chinese birth cohort, recruited between April and May 1997 with high follow-up (n = 7026).

Results Low socio-economic position (SEP) was associated with never breastfeeding and with exclusive breastfeeding for ≥3 months. We did not find any association between breastfeeding and BMI [z-score mean difference 0.07, 95% confidence interval (CI) –0.05 to 0.19], height (0.02, 95% CI –0.07 to 0.11) or weight (0.07, 95% CI –0.05 to 0.18), adjusted for sex, birth weight, gestational age, SEP, second-hand smoke (SHS) exposure, parity, mother's age at birth, mother's place of birth and serious infant morbidity.

Conclusions In a non-European setting, breastfeeding was not associated with child adiposity, suggesting that observed protective effects may be due to socially patterned confounding by SEP, maternal adiposity and maternal smoking.

Methods We calculate the odds of anti-HIV therapy naiveté in 45 HIV-infected men as a function of measured log₁₀ plasma HIV RNA viral load using five approaches including ad hoc methods as well as a maximum likelihood estimate (MLE). We also generated simulations of a binary outcome with 10% incidence and a 1.5-fold increased odds per log increase in a log-normally distributed exposure with 25, 50 and 75% of exposure data below LOD. Simulated data were analysed using the same five methods, as well as the full data.

Results In the example, the estimated odds ratio (OR) varied by 1.22-fold across methods, from 1.45 to 1.77 per log₁₀ copies of viral load and the standard error for the log OR varied by 1.52-fold across methods, from 0.31 to 0.47. In the simulations, use of full data or the MLE was unbiased with appropriate confidence interval (CI) coverage. However, as the proportion of exposure below LOD increased, substituting LOD, LOD/2 or LOD/2 was increasingly biased with increasingly inappropriate CI coverage. Finally, exclusion of values below LOD was unbiased but imprecise.

Conclusions In this example and the settings explored by simulation, and among methods readily available to investigators (i.e. sans full data), the MLE provided an unbiased and appropriately precise estimate of the exposure–outcome OR.

Methods We compared RTL in 510 sample pairs from the longitudinal population-based Bruneck Study, which were collected in 1995 and recollected in 2005, and additionally determined RTL from 159 participants who died during follow-up. RTL were determined by a high-throughput real-time PCR assay and by applying a mathematical model.

Results The telomeres shortened, on average, by 455 bp over 10 years. The RTL shortening rate was highly correlated with baseline RTL (r = 0.674, P < 0.001). Participants who died within the observed period had considerably shorter telomeres than those who survived (median RTL of 0.98 vs 1.49; P < 0.001). In contrast to previous studies, smoking behaviour had no influence on RTL and on telomere shortening.

Conclusion This is the first comprehensive longitudinal study of individuals who were, on average, 60 at baseline, and who were re-evaluated 10 years later. Our methodology proved to be a reliable tool for a rapid, accurate and cost-efficient determination of RTL with a low amount of DNA.

Methods In the baseline examination of ESTHER, a study conducted in Saarland, serological measurements of pepsinogen I and II and H. pylori antibodies were taken in 9444 participants aged 50–74 years. Information on potential risk factors and medical history were obtained by self-administered standardized questionnaire.

Results A strong dose–response relationship between sibship size and H. pylori seroprevalence was observed (P < 0.01). Adjusted odds ratios (ORs) 95% confidence interval (CI) for H. pylori seropositivity for subjects with 4, 5, 6 and 7 or more siblings compared with subjects without siblings were 1.45 (1.20–1.77), 1.83 (1.50–2.22) and 1.84 (1.47–2.31), respectively. A large sibship size was also associated with an increased risk of CAG with an adjusted OR of 1.42 (1.01–2.01) for 7 or more compared with less than or equal to 2 siblings. This association was attenuated but not entirely eliminated after additional adjustment for H. pylori infection. Notably, a significant association between large sibship size and CAG was also found among H. pylori-negative subjects.

Conclusions Our results suggest that large sibship size is associated with increased H. pylori prevalence and CAG risk. The association with CAG risk may be mediated at least in part by H. pylori infection. However, mechanisms other than H. pylori infection may contribute to the ‘sibling effect’ as well.

Methods Proportional hazards Cox models were fitted to estimate rate ratios (RRs) for the separate and joint effects of entry and follow-up Coulter variables.

Results Entry RBC, PCV and Hgb were significant risk factors for CHD mortality after adjustment for gender but only PCV remained significant after adjustment for potential confounders [RR per 1 standard deviation (SD) increase = 1.17, 95% confidence interval (CI) 1.00–1.37]. This effect was partly reduced when the values of 6 years were analysed (RR per 1 SD increase = 1.10, 95% CI 0.93–1.30). No significant gender, smoking or age/time interactions were identified. PCV was the only significant predictor when all Coulter variables were studied jointly.

Conclusion PCV was found to predict CHD mortality even after controlling for classical risk factors. This may give some insight into possible mechanisms, such as an influence on thrombin production.

Methods The study included all 510 communes of the Central Highlands region (with a total population of ~4 million) where 95% of incidence of plague cases in Vietnam had been reported from 1997 through 2002. Plague was clinically ascertained by using a standard protocol by WHO. Data on domestic fleas and rodents were obtained by using traps and periodic surveillance in accordance with the WHO guidelines. Temperature, duration of sunshine, rainfall and humidity were recorded as monthly averages by local meteorological stations. The association between these ecological factors and plague was assessed by using the Poisson regression model.

Results From 1997 through 2002, 472 cases of plague were reported, of whom 24 (5.1%) died. The incidence of plague peaked during the dry season, with ~63% of cases occurring from February through April. The risk of plague occurrence was associated with an increased monthly flea index (RR and 95% CI: 1.93; 1.61–2.33 for months with the flea index >1) and increased rodent density (RR 1.23; 1.15–1.32 per each 3% increase in density). Moreover, the risk of plague increased during the dry season (RR 2.07; 1.64–2.62), when rainfall fell <10 mm (RR 1.44; 1.17–1.77).

Conclusions These data suggest that the flea index, rodent density and rainfall could be used as ecological indicators of plague risk in Vietnam. The data also suggest that the occurrence of plague in Vietnam's Central Highlands is likely resulted from multiple causes that remain to be delineated.

Methods We present an extension of previously published design (propensity score matching) and analysis (targeted maximum likelihood estimation) methods to evaluate the behavioural and health impacts of a pre-existing but non-randomized intervention (a 3-year, combined household water treatment and handwashing campaign in rural Guatemala). Six months after the intervention, we conducted a cross-sectional cohort study in 30 villages (15 intervention and 15 control) that included 600 households, and 929 children <5 years of age.

Results The study design created a sample of intervention and control villages that were comparable across more than 30 potentially confounding characteristics. The intervention led to modest gains in confirmed water treatment behaviour [risk difference = 0.05, 95% confidence interval (CI) 0.02–0.09]. We found, however, no difference between the intervention and control villages in self-reported handwashing behaviour, spot-check hygiene conditions, or the prevalence of child diarrhoea, clinical acute lower respiratory infections or child growth.

Conclusions To our knowledge this is the first post-intervention follow-up study of a combined household water treatment and handwashing behaviour change intervention, and the first post-intervention follow-up of either intervention type to include child health measurement. The lack of child health impacts is consistent with unsustained behaviour adoption. Our findings highlight the difficulty of implementing behaviour-based household water treatment and handwashing outside of intensive efficacy trials.

Methods Using linear regression we described the relationship between estimated ambient-erythemal ultraviolet (eUV) exposure in Oxford (1990–95) and total hours of sunshine and month in order to forecast eUV in nearby regions, whilst adjusting for regional variations in weather. The forecast was validated with empirical data collected from Cornwall and then predicted for the Avon region. Total 98-day prenatal ambient-eUV was then predicted in 355 expectant mothers in the Avon Longitudinal Study of Parents and Children (ALSPAC) cohort and its relationship with maternal vitamin D status was determined.

Results Estimated ambient-eUV was strongly associated with measured ambient-eUV (r² = 0.989) with a near 1:1 prediction for the validation data set [β = 0.99, 95% confidence interval (CI) 0.913, 1.067 r² = 0.980]; strong seasonal associations were observed between eUV in the last trimester of pregnancy and maternal serum 25-(OH)D concentrations (r² = 0.40).

Conclusion This technique of prediction could be applied to existing cohorts allowing the relationship between maternal vitamin D status and the health of the offspring to be studied via instrumental variable analysis.

Methods A follow-up study was conducted for 16 828 men and 8368 women aged 30–59 years and apparently healthy at baseline. Incident DM was identified by ‘fasting serum glucose ≥7.00 mmol/l (126 mg/dl)’ or/and ‘under medical treatment for DM’. Using Cox proportional hazard models, hazard ratio (HR) for incident DM were estimated according to the quartiles of heart rate, systolic or diastolic BP (SBP, DBP), and its linear trends were checked by computing the three indices as continuous variables. Subsequently, interactive effects of slow/fast heart rate (dichotomized by the median) and low/high SBP or DBP (dichotomized by the median) on HR were examined. Baseline age, body mass index, smoking, drinking, exercise and education were computed as conventional confounders.

Results During the follow-up of 125 106 person-years for men and 59 616 person-years for women, 869 men and 224 women developed DM. The multivariate-adjusted HR for incident DM increased across quartiles of heart rate, SBP and DBP in both sexes (linear trend P<0.001 for all). Neither sex showed any significant interactive effects of heart rate and SBP or DBP on HR.

Conclusions Resting heart rate and BP proportionally raise the risk for DM in middle-aged healthy men and women. Moreover, the adverse effects of fast heart rate and high BP are independent of each other as well as of the influences of conventional confounders.

Methods This study was a population-based cohort study in a Japanese urban area. Study subjects were comprised of 5026 initially healthy Japanese (2370 men and 2656 women, mean age: 54.5 years) without a history of MI or stroke. They were followed-up for 11.8 years on average, and 103 MIs (definite: 45; probable: 58) and 168 strokes (definite: 126; probable: 42) were observed. There was no subject who developed MI just at baseline (the follow-up period among those with definite MI was, at earliest, 0.20 years).

Results The adjusted hazard ratio for definite MI was 4.18 (95% confidence interval 1.66–10.53) with s-CK levels of ≥200 IU/l, compared with the reference category (s-CK levels of ≤99 IU/l), whereas no relationship was observed between s-CK levels and the risk for stroke. With regard to definite MI, an interaction between s-CK levels and dyslipidaemia was observed. Among subjects with hypercholesterolaemia, the hazard ratio linearly elevated with increased s-CK levels. On the other hand, no linear elevation was observed among subjects without hypercholesterolaemia (P for interaction = 0.011).

Conclusions The present study suggested that screening for elevated s-CK levels in initially healthy Japanese subjects was useful to predict first-ever MI in the future, especially in subjects with dyslipidaemia.

Methods Spatial accessibility, as measured by network travel times, to 457 grocery stores located in 205 neighbourhoods in four environmental settings (island, rural, small town and urban) in Scotland was calculated using Geographical Information Systems. The distribution of accessibility by neighbourhood deprivation in each of these four settings was investigated.

Results Overall, the most deprived neighbourhoods had the best access to grocery stores and grocery stores selling fresh produce. Stratified analysis by environmental setting suggests that the least deprived compared with the most deprived urban neighbourhoods have greater accessibility to grocery stores than their counterparts in island, rural and small town locations. Access to fresh produce is better in more deprived compared with less deprived urban and small town neighbourhoods, but poorest in the most affluent island communities with mixed results for rural settings.

Conclusions The results presented here suggest that the assumption of a universal ‘deprivation amplification’ hypothesis in studies of the neighbourhood food environment may be misguided. Associations between neighbourhood deprivation and grocery store accessibility vary by environmental setting. Theories and policies aimed at understanding and rectifying spatial inequalities in the distribution of neighbourhood exposures for poor diet need to be context specific.

Methods A cross-sectional survey with face-to-face interviews of rural and urban residents in northern China. Before providing any information, we asked the residents whether they would accept drug treatment if they had hypertension and also asked them to estimate the 5-year cardiovascular risk in untreated hypertension and the benefits from anti-hypertensive drugs. We then informed the participants of necessary information and asked them above what benefit they would be willing to pay the current cost, and how much they would be willing to pay for the actual benefit, for anti-hypertensive drugs out of pocket.

Results Eight hundred and eighty-seven rural residents and 921 urban residents were interviewed with a response rate of 97%. Ninety-five percent [95% confidence interval (CI) 94–96%] of the residents said they would take anti-hypertensive drugs if they had hypertension, although 91% (95% CI 89–92%) said they did not have sufficient knowledge to make a decision. Seventy-eight percent (95% CI 76–80%) believed that anti-hypertensive drugs were primarily to lower blood pressure or relieve symptoms. They over-estimated the cardiovascular risk of untreated hypertension by approximately 12 times and the absolute benefit of drug treatment by 20 times. Given the actual absolute benefit of the drugs, only 23% (95% CI 21–25%) were willing to pay the current annual cost of $500 Ren Min Bi (US$73.3, 54.8 as of 8 May 2009) for these drugs. Given the current cost, they were, on average, willing to pay for the drugs only when the 5-year cardiovascular disease risk was as high as 35% (95% CI 31–38%) or even higher.

Conclusion The public in China are significantly misinformed and considerably over estimate the risk of hypertension and the benefit of treatment. The public's willingness to pay for anti-hypertensive drugs is much lower than the current guidelines implicitly assume. The willingness to pay should be considered, along with other factors, when prescribing anti-hypertensive drugs to an individual patient or making hypertension guidelines for a population.

Methods We analysed data from ART-naïve, TB disease-free children enrolled between December 2004 and April 2008 into an HIV care program in Kinshasa, Democratic Republic of Congo. To estimate the effect of ART on TB incidence while accounting for time-dependent confounders affected by exposure, a Cox proportional hazards marginal structural model was used.

Results 364 children contributed 596.0 person-years of follow-up. At baseline, the median age was 6.9 years; 163 (44.8%) were in HIV clinical stage 3 or 4. During follow-up, 242 (66.5%) children initiated ART and 81 (22.3%) developed TB. At TB diagnosis, 41 (50.6%) were receiving ART. The TB incidence rate in those receiving ART was 10.2 per 100 person-years [95% confidence interval (CI) 7.4–13.9] compared with 20.4 per 100 person-years (95% CI 14.6–27.8) in those receiving only primary HIV care. TB incidence decreased with time on ART, from 18.9 per 100 person-years in the first 6 months to 5.3 per 100 person-years after 12 months of ART. The model-estimated TB hazard ratio for ART was 0.51 (95% CI 0.27–0.94).

Conclusions For HIV-infected children in TB-endemic areas, ART reduces the hazard of developing TB by 50%.

Methods Stepwise regression of annual data was applied to model incidence, calculated based on 91 cases, from lagged variables: antecedent precipitation, air temperature, soil water storage, absolute and relative air humidity, and Southern Oscillation Index (SOI).

Results Multiple regression analyses resulted in a model, which explains 49% of the incidence variance, taking into account the absolute air humidity in the year of exposure, soil water storage and SOI of the previous 2 years.

Conclusions The correlations may reflect enhanced fungal growth after increase in soil water storage in the longer term and greater spore release with increase in absolute air humidity in the short term.

Methods This study included 832 children who were members of the Collaborative Perinatal Project. Maternal serum collected between 1959 and 1966 during the third trimester of pregnancy was analysed for free cortisol. We investigated the relationship between maternal cortisol in quintiles and full, verbal and performance scale scores on the Wechsler Intelligence Scale for Children at age 7 years, adjusting for prenatal and family characteristics. We repeated this analysis among 74 discordant sibling pairs using a fixed effects approach, which adjusts for shared family characteristics.

Results Maternal cortisol levels were negatively related to full-scale IQ, an effect driven by verbal IQ scores. Compared with those in the lowest quintile of cortisol exposure, the verbal IQ of children in the highest quintile of exposure was 3.83 points lower [95% confidence interval (CI): –6.44 to –1.22]. Within sibling pairs, being in the highest quintile of exposure was associated with verbal IQ scores 5.5 points lower (95% CI: –11.24 to 0.31) compared with the other quintiles.

Conclusion These findings are consistent with prior human and animal studies, and suggest that exposure to high levels of maternal cortisol during pregnancy may be negatively related to offspring cognitive skills independently of family attributes that characterize the postnatal environment.

Methods Seventy-eight independent retrospective cohort (incidence between 1984 and 2000, followed until 2006) outcomes were synthesized. Fixed effects meta-regression models compared women with breast cancer in low-income areas of Canada and the USA.

Results Low-income Canadian women were advantaged on survival [rate ratio (RR) = 1.14; 95% confidence interval (CI) 1.13–1.15] and their advantage was even larger among women <65 years of age who are not yet eligible for Medicare coverage in the USA (RR = 1.21, 95% CI 1.18–1.24). Canadian advantages were also larger for node positive breast cancer, which may present with greater clinical and managerial discretion (RR = 1.40, 95% CI 1.30–1.50), and smaller when Hawaii, the state providing the most Canadian-like access, was the US comparator (RR = 1.12, 95% CI 1.01–1.20).

Conclusions More inclusive health care insurance coverage in Canada vs the USA, particularly among each country's relatively poor people, seems the most plausible explanation for such Canadian advantages. Provision of health care for all Americans would likely prevent countless early deaths, particularly among the relatively poor.

Methods This was a prospective cohort study. Participants consisted of 13 621 men and women from the Aerobics Center Longitudinal Study (ACLS). Participants completed a clinical exam and 3-day diet record between 1987 and 1999. Participants were followed for mortality until 2003. Reduced rank regression (RRR) was used to identify dietary patterns that predicted unfavourable total and high-density lipoprotein-cholesterol, triglyceride, glucose, blood pressure, uric acid, white blood cell and body mass index values.

Results One primary dietary pattern emerged and was labelled the Unhealthy Eating Index. This pattern was characterized by elevated consumption of processed and red meat, white potato products, non-whole grains, added fat and reduced consumption of non-citrus fruits. The hazard ratio for all-cause mortality in the fifth vs the first quintile of the Unhealthy Eating Index was 1.40 (1.02–1.91). This risk estimate was reduced by 13.5 and 55.0% after controlling for self-reported physical activity and fitness, respectively.

Conclusion In this study the association between diet and overall mortality was, in large part, confounded by fitness.

Methods Methodological review to address the concept of external validity.

Results External validity refers to the question whether results are generalizable to persons other than the population in the original study. The only formal way to establish the external validity would be to repeat the study for that specific target population. We propose a three-way approach for assessing the external validity for specified target populations. (i) The study population might not be representative for the eligibility criteria that were intended. It should be addressed whether the study population differs from the intended source population with respect to characteristics that influence outcome. (ii) The target population will, by definition, differ from the study population with respect to geographical, temporal and ethnical conditions. Pondering external validity means asking the question whether these differences may influence study results. (iii) It should be assessed whether the study's conclusions can be generalized to target populations that do not meet all the eligibility criteria.

Conclusion Judging the external validity of study results cannot be done by applying given eligibility criteria to a single target population. Rather, it is a complex reflection in which prior knowledge, statistical considerations, biological plausibility and eligibility criteria all have place.

Methods A systematic review was conducted to explore the relationship between fatigue, chronic fatigue (CF—fatigue lasting for 6 months), CFS and ethnicity. Studies were population-based and health service-based. Meta-analysis was also conducted to examine the population prevalence of CF and CFS across ethnic groups.

Results Meta-analysis showed that compared with the White American majority, African Americans and Native Americans have a higher risk of CFS [Odds Ratio (OR) 2.95, 95% confidence interval (CI): 0.69–10.4; OR = 11.5, CI: 1.1–56.4, respectively] and CF (OR = 1.56, CI: 1.03–2.24; OR = 3.28, CI: 1.63–5.88, respectively). Minority ethnic groups with CF and CFS experience more severe symptoms and may be more likely to use religion, denial and behavioural disengagement to cope with their condition compared with the White majority.

Conclusions Although available studies and data are limited, it does appear that some ethnic minority groups are more likely to suffer from CF and CFS compared with White people. Ethnic minority status alone is insufficient to explain ethnic variation of prevalence. Psychosocial risk factors found in high-risk groups and ethnicity warrant further investigation to improve our understanding of aetiology and the management of this complex condition.

Methods Abridged period lifetables for Maori and non-Maori from 1951 to 2006 were constructed using standard demographic methods. Absolute [standardized rate difference (SRD)] and relative [standardized rate ratio (SRR)] mortality inequalities for Maori compared with European/Other ethnic groups (aged 1–74 years) were measured using the New Zealand Census-Mortality Study (an ongoing data linkage study that links mortality to census records) from 1981–84 to 2001–04. The SRDs were decomposed into their contributions from major causes of death. Poisson regression modelling was used to estimate the extent of socio-economic mediation of the ethnic mortality inequality over time.

Results Life expectancy gaps and relative inequalities in mortality rates (aged 1–74 years) widened and then narrowed again, in tandem with the trends in social inequalities (allowing for a short lag). Among females, the contribution of cardiovascular disease to absolute mortality inequalities steadily decreased, but was partly offset by an increasing contribution from cancer. Among males, the contribution of CVD increased from the early 1980s to the 1990s, then decreased again. The extent of socio-economic mediation of the ethnic mortality inequality peaked in 1991–94, again more notably among males.

Conclusion Our results are consistent with a causal association between changing economic inequalities and changing health inequalities between ethnic groups. However, causality cannot be established from a historical analysis alone. Three lessons nevertheless emerge from the New Zealand experience: the lag between changes in ethnic social inequality and ethnic health inequality may be short (<5 years); both changes in the distribution of the social determinants of health and an appropriate health system response may be required to address ethnic health inequalities; and timely monitoring of ethnic health inequalities, based on high-quality ethnicity data, may help to sustain political commitment to pro-equity health and social policies.

Methods A generalized linear Poisson regression model was used to regress a time-series of daily mortality for all-cause and selected causes against temperature, controlling for seasonal and interannual variations, day of week and public holidays. A total of 13 270 all-cause deaths excluding external causes for residents under demographic surveillance in Matlab, Bangladesh were available between January 1994 and December 2002.

Results There was a marked increase in all-cause deaths and deaths due to cardiovascular, respiratory and perinatal causes at low temperatures over a lag of 0–13 days. Every 1°C decrease in mean temperature was associated with a 3.2% (95% CI 0.9–5.5) increase in all-cause mortality. However, there was no clear heat effect on all-cause mortality for any of the lags examined.

Conclusions This study found that daily mortality increased with low temperatures in the preceding weeks, while there was no association found between high temperatures and daily mortality in rural Bangladesh. Preventive measures during low temperatures should be considered especially for young infants.

Methods Using linear regression models that account for serial correlation between months, monthly rotavirus incidence was significantly negatively correlated with temperature, rainfall and relative humidity in 65%, 55% and 60% of studies, respectively. We carried out pooled analyses using a generalized estimating equation (GEE) that accounts for correlation from between-study variation and serial correlation between months within a given study.

Results For every 1°C (1.8°F) increase in mean temperature, 1 cm (0.39 in.) increase in mean monthly rainfall, and 1% increase in relative humidity (22%) this analysis showed reductions in rotavirus incidence of 10% (95% CI: 6–13%), 1% (95% CI: 0–1%), and 3% (95% CI:0–5%), respectively.

Conclusions On the basis of the evidence, we conclude that rotavirus responds to changes in climate in the tropics, with the highest number of infections found at the colder and drier times of the year.

Background A better understanding of behavioural factors associated with the interruption of human immunodeficiency virus (HIV) dynamics in Uganda are fundamental for guiding HIV prevention strategies. A comparative analysis of population level HIV surveillance and behavioural data in Uganda and countries with similar epidemic dynamics offers a framework to identify distinctive elements of the Ugandan success.

Methods We analysed HIV prevalence among pregnant women attending antenatal surveillance sites between 1990-1998 in Uganda, Kenya, Zambia, and Malawi, and AIDS behavioural data collected in Uganda (1989, 1995), Kenya (1998), Zambia, and Malawi (1996).

Results In Uganda between 1991 and 1998, HIV prevalence rates fell 54% overall, with 75% and 57% declines among 15-19 and 20-24 age groups in urban areas, respectively. HIV declines were associated with a 60% reduction in multiple sexual partners between 1989 and 1995, as well as increased condom use and sexual abstinence. The lack of comparable HIV declines in comparison countries with similar rates of abstinence and condom use, but with multiple sexual partnership rates similar to Uganda in 1989, suggests that partner reduction is paramount in interrupting sexual HIV dynamics. Comparatively, Ugandans were more likely to acknowledge people with AIDS and communicate about HIV through personal networks. Modelling suggests an 80% reduction in incidence among youth early in the 1990s, suggesting a preceding behavioural process during the late 1980s, which reduced HIV risk.

Conclusion The distinctive element explaining declines in HIV prevalence in Uganda is sexual partner reduction. The Ugandan response to AIDS involved a primary HIV intervention whose key outcome was risk avoidance through partner reduction. This focus for HIV prevention could prove more effective than other widely advocated strategies in sub-Saharan Africa.