© 1992 Oxford University Press
other |
Predictors of Poliomyelitis Case Confirmation at Initial Clinical Evaluation: Implications for Poliomyelitis Eradication in the Americas
*Expanded Program on Immunization, Pan American Health organization Maxico
Direction of Information and Epidemiologic Emergencies, General Directorate of Epidemiology, Secretariat of Health Mexico
Reprint requests to: Information Services, Center for Prevention Services, Mailstop E-07, Centers for Disease Control, Atlanta, GA 30333, USA
Dietz V (Expanded Program on Immunization, Pan American Health Organization, Mexico), Lezana M, Garcia Sancho C and Montessno R. Predictors of poliomyelitis case confirmation at initial clinical evaluation: Implications for poliomyelitis eradication in the Americas. International Journal of Epidemiology 1992; 2l: 800–806.
In 1985, the Pan American Health Organization adopted tha goal of eradication of poliomyelitis from the Americas by 1990. Strategies to accomplish this included high vaccination coverage, aggressive outbreek control, and active surveillance for acute flaccid paratysis (AFP). Although the sensitivity of AFP surveillance for detecting paralytic poliomyelitis casas is high, studies have shown the specificity to be low. In 1990, 2497 notifid cases of AFP were investigated in the Americas of which 2146 had stool specimens collected. However, only 18 were confirmed as poliomyelitis by isolation of wild poliovirus from stool specimens, 71 were classified as being compatible with poliomyelitis. Cases of AFP due to causes other than poliomyelitis result in extensive but unnecessary outbreak control measures. To predict, at initial clinical evaluation, the likelihood of future confirmation as a case of poliomyelitis, likelihood ratios (LR) were calculated for different combinations of clinical characteristics of AFP cases (249) from Mexico in 1989 and 1990. The best predictors in a child with AFP were proximal muscle involvement which progressed '4 days together with fever at onset of paralysis, and proximal and unilateral involvement with either fever at onset or paralysis which progresed '4 days. The odds would increase by 12 that the child would eventually be confirmed as poliomyelitis (19), based on a stool culture positive for wild poliovirus (95% confidence interval (CI) 2.6–55.9). A guide for use in the field is proposed whereby local health officials, often with little training in neurological evaluation, can predict at initial clinical examination the likelihood that an AFP case will subsequently be confirmed as poliomyelitis. Such a guide can aid in both the rapid determination of appropriate outbreak control measures and in prioritizing limited national resources.
Received 1 February 1992