Ten-year trends in CD4 cell counts at HIV and AIDS diagnosis in a London HIV clinic

Objective: To examine temporal trends (1986-1996) in the CD4 cell count at first HIV-1 positive test and initial AIDS diagnosis, and the influence of selected patient characteristics and treatment factors on these trends. Design: A retrospective clinic-based study. Setting: Three hospital-based clinics in West London. Patients: A group of 5921 adult HIV-1-seropositive persons and 2835 reported patients with AIDS over a 10-year period from 1 January 1986 to 1 October 1996. Methods: The CD4 cell count at HIV diagnosis (CD4HIV) was defined as the ne arest CD4 cell count to within 2 months of HIV diagnosis; and the CD4 cell count at AIDS diagnosis (CD4AIDS) as the last CD4 cell count in the two mon ths prior to the development of AIDS. Simple and multiple linear regression analysis were used to examine the influence of selected covariates on CD4H IV and CD4AIDS. Results: The percentage of patients with an available CD4HIV and CD4AIDS in creased from less than 5% in 1987 to 53% and 40%, respectively, in 1990, an d 79% and 48%, respectively, in 1996. Patients with a missing CD4HIV or CD4 AIDS were younger and less likely to have received antiretroviral therapy o r prophylaxis for Pneumocystis carinii pneumonia (PCP). There was no signif icant change in CD4HIV over a 10-year period (median 334 x 10(6) cells/l), but a lower CD4HIV was associated with older age at presentation and inject ing drug use. There was a delay in the onset of clinical AIDS, with a fall in the median CD4AIDS value from 99 x 10(6) cells/l prior to 1987, to 58 x 10(6) cells/l in 1990, 68 x 10(6) cells/l in 1994 and 60 x 10(6) cells/l in 1996; this decline in onset was seen for PCP as well as for cytomegaloviru s and atypical mycobacterial infections. At all time periods, a lower CD4AI DS was associated with combined use of antiretroviral therapy and PCP proph ylaxis. After adjustment for use of antiretroviral therapy and PCP prophyla xis prior to AIDS diagnosis, year of diagnosis was no longer associated wit h CD4AIDS. There was a significant trend towards an improved survival follo wing AIDS diagnosis from 20.1 months prior to 1988, to 20.3 months (1989-19 90), 21.0 months (1991-1992) and 22.1 (1993-1994) (P < 0.0005). Conclusions: The observed decline in CD4AIDS value was related to the intro duction of antiretroviral therapy in 1988, and PCP prophylaxis in 1989. Tem poral changes in the CD4 cell count at HIV and AIDS diagnosis among differe nt demographic groups can provide insights into the changing natural histor y of the HIV epidemic and access to medical care. We recommend monitoring o f the CD4 cell count at new HIV and AIDS diagnosis and at initiation of ant iretroviral therapy as additional measures in national HIV/AIDS surveillanc e. (C) 2000 Lippincott Williams & Wilkins.