An evidence based approach to testing for antibody to herpes simplex virus type 2

Objectives: To establish whether a simple risk scoring system, based on limited information, can reflect the variation in HSV-2 prevalence in a population, and whether a common system can be used across settings. To establish whether knowledge of a patient's score can aid the interpretation of the result from one of the commercial type specific assays. Methods: Four previous cross sectional studies are considered, with HSV-2 antibody results by western blot or type specific ELISA tests. The clinical settings were a blood donor centre (1359 participants) and STD clinic (808 participants), London, United Kingdom, an antenatal clinic, Sydney, Australia (2317 participants), and a family medical centre, Seattle, United States (478 participants). We determined the factors associated with HSV-2 prevalence, the similarity of associations across settings, and the variation in HSV-2 prevalence by risk score. Results: A simple scoring captured much variation in HSV-2 prevalence in each population-for example, for London blood donors, scoring based on sex, age, and number of lifetime partners, prevalence varied from 0.7% (95% CI 0.1 to 2.0) to 47.3% (37.9 to 56.6) across five risk groups. For number of lifetime partners, and sex, the association with HSV-2 varied significantly across studies. Conclusions: A scoring system can aid test interpretation-for example, in London blood donors the post-test probability of infection following a positive result varies from around 25% to 98% across risk groups for a typical type specific assay. Further work could address whether this theoretical benefit can be realised in practice. A common risk scoring probably could not be used across settings.