Early antiretroviral therapy: the role of cohortsSabin, Caroline ACurrent Opinion in HIV & AIDS: May 2009 - Volume 4 - Issue 3 - p 200–205 doi: 10.1097/COH.0b013e32832c06ad Early treatment: Edited by Sean Emery and Andrew Phillips Abstract Author Information Purpose of review: To review the data that contribute to the debate on the optimal time to initiate highly active antiretroviral therapy in HIV-infected individuals, with a focus on the information that is available from cohort studies. Recent findings: The findings from cohort studies generally support initiation of highly active antiretroviral therapy at CD4 cell counts more than 350 cells/μl. In particular, the findings that death rates among treated HIV-infected individuals are higher than those in the general population, and that the risks of AIDS and serious non-AIDS events are higher in those with lower CD4 cell counts (even when the count remains >350 cells/μl), suggest that earlier initiation of highly active antiretroviral therapy may prevent some excess morbidity and mortality. However, given the lack of adjustment for lead-time bias in many analyses, the potential for residual confounding and the possible incomplete ascertainment of relevant outcomes in cohorts, it cannot be concluded that the benefits of highly active antiretroviral therapy when started at higher CD4 cell counts will outweigh the possible detrimental effects. Summary: Whereas the data from cohort studies currently support initiation of highly active antiretroviral therapy at CD4 cell counts more than 350 cells/μl, there is an urgent need for data from randomized trials to inform this decision. Research Department of Infection and Population Health, Division of Population Health, UCL Medical School, London, UK Correspondence to Professor Caroline A. Sabin, PhD, Research Department of Infection and Population Health, Division of Population Health, UCL Medical School, Royal Free Campus, Rowland Hill Street, London NW3 2PF, UK Tel: +44 20 7830 2239 ext. 34752; fax: +44 20 7794 1224; e-mail: email@example.com © 2009 Lippincott Williams & Wilkins, Inc.