The T cell in HIV infection and disease: Clinical scienceThe CD4 lymphocyte count and risk of clinical progressionPhillips, Andrew Na; Lundgren, Jens DbAuthor Information aRoyal Free Centre for HIV Medicine and Department of Primary Care and Population Sciences, Royal Free and University College Medical School, London, UK bCopenhagen HIV Program, Hvidovre Hospital, Copenhagen, Denmark Correspondence to Andrew N. Phillips, Royal Free Centre for HIV Medicine and Department of Primary Care and Population Sciences, Royal Free and University College Medical School, Rowland Hill Street, London NW3 2PF, UK Tel' +44 (0)20 7288 4238; e-mail: [email protected] Current Opinion in HIV and AIDS: January 2006 - Volume 1 - Issue 1 - p 43-49 doi: 10.1097/01.COH.0000194106.12816.b1 Buy Metrics Abstract Purpose of review The CD4 lymphocyte count was identified as a key predictor of risk of AIDS defining diseases almost 20 years ago, early in the HIV epidemic. Several issues concerning its use to predict AIDS have arisen since. These include the difference between short and long-term prediction, the use of CD4 percentage compared with absolute counts, the impact of antiretroviral therapy on the predictive value of the CD4 count, the role relative to other markers such as viral load, the derivation of scores to predict AIDS diseases, the use of CD4 count as a surrogate endpoint, the role of the CD4 count nadir compared with the current value and the differential ability to predict different AIDS diseases. Recent findings All the above issues have been clarified further and this process has continued through 2004 and 2005. These developments are briefly described in this review. Summary The CD4 count remains the strongest short-term predictor of risk of AIDS so far identified in both treated and untreated patients and should continue to be a mainstay of monitoring for both untreated and treated patients. © 2006 Lippincott Williams & Wilkins, Inc.