Diagnostic Tests: Understanding Results, Assessing Utility, and Predicting Performance

[...]a process is elegantly described by Laeyendecker and associates for a commercial herpes simplex type 2 enzyme-linked immunosorbent assay developed in a Western setting, but intended for use in an epidemiologic study in Uganda.\n Altman and Bland published some useful formulae for the calculation of PPV and NPV under any estimated prevalence, illustrating how, under conditions of extremely low prevalence, the likelihood of false positives (Figure 1, (b)) will be high, despite excellent sensitivity and specificity of the test being used:16[Formula omitted. Many excellent reviews of diagnostic tests provide more detail on the above topics, including guidance for the design and conduct of studies to assess diagnostic test accuracy.10,18-19 Alain B. Labrique is an Assistant Professor in Global Disease Epidemiology and Control in the Departments of International Health and Epidemiology (Joint) at the Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland.