International Journal of Epidemiology, Vol 26, 1115-1120, Copyright © 1997 by International Epidemiological Association
Risk factors for the development of non-response to first-line treatment for tuberculosis in southern Vietnam
VP Keane, N de Klerk, T Krieng, G Hammond and AW Musk
International Organisation for Migration, Harare, Zimbabwe.
BACKGROUND: Acquired resistance to standard chemotherapy for tuberculosis
(TB) is an increasing problem worldwide. Vietnam has one of the highest
incidences of TB and also has a large population of potential migrants to
other countries. Since 1979 the International Organisation for Migration
(IOM) has been running a supervised programme of TB treatment for intending
migrants from Vietnam where few facilities for bacteriological culture and
sensitivity testing exist. This study aimed to assess the most important
factors for predicting non-response to first-line treatment as treatment
starts and whether any further indicators occur during the course of
treatment which may enable more accurate prediction of non-response.
METHODS: In all, 130 subjects failing to respond to first-line therapy
(cases) between 1990 and 1995 were compared with 673 subjects who responded
to therapy (controls) on various demographic and clinical characteristics
using logistic regression to create a prognostic index. Variables analysed
included the patient history of past TB treatment, weight, age, sex and
radiological and bacteriological findings. All subjects also tested
negative for HIV status. RESULTS: The chief markers of successful response
were x-ray signs and degree of sputum smear positivity. These markers
provided a prognostic index with an optimal cutoff providing about 70%
sensitivity and 80% specificity. Incorporating further measures obtained
through the first 3 months of treatment improved the sensitivity to 80%.
CONCLUSION: While this study enabled prediction of the majority of subjects
failing to respond to first-line therapy, other factors need to be assessed
before recommendations for altering treatment regimens can be made. The
prognostic index could be useful in assessing subjects for closer
supervision.