A review of statistical methods for estimating the risk of vertical human immunodeficiency virus transmission

Background Estimation of the risk of vertical transmission of human immunod eficiency virus (HIV) has been complicated by the lack of a reliable diagno stic test for paediatric HIV infection. Methods A literature search was conducted to identify all statistical metho ds that have been used to estimate HIV vertical transmission risk. Although the focus of this article is the analysis of birth cohort studies, ad hoc studies are also reviewed. Conclusions The standard method for estimating HIV vertical transmission ri sk is biased and inefficient. Various alternative analytical approaches hav e been proposed but all involve simplifying assumptions and some are diffic ult to implement. However, early diagnosis/exclusion of infection is now po ssible because of improvements in polymerase chain reaction technology and complex estimation methods should no longer be required. The best way to an alyse studies conducted in breastfeeding populations is still unclear and d eserves attention in view of the many intervention studies being planned or conducted in developing countries.