Changes in AIDS-defining illnesses in a London clinic, 1987-1998

Objectives: To describe the incidence of AIDS-defining illnesses within a s ingle large clinic setting, to describe temporal changes over a 10-year per iod in the overall incidence and of individual AIDS-defining illnesses and to investigate the impact of HIV treatment regimen on the incidence of AIDS -defining illnesses. Subjects and Methods: A person-years analysis was used to determine the inc idence of AIDS-defining illnesses according to calendar year and stratifica tion by CD4 lymphocyte count and treatment regimen in 1806 patients from th e Royal Free Centre for HIV Medicine with at least one CD4 lymphocyte count and follow-up visit. Results: Prior to 1992, the incidence of all AIDS-defining illnesses was 27 .4/100 person-years of follow-up (PYFU; 95% confidence interval ICI, 22.8-3 2.0) and during 1997 this incidence had dropped to 6.9/100 PYFU (95% CI, 4. 7-9.1; p < .0001, test for trend). The decline in incidence over time occur red in esophageal candidiasis, cytomegalovirus disease (including retinitis ), Kaposi's sarcoma, lymphoma, wasting syndrome, and Pneumocystis carinii p neumonia (p < .05, test for trend), but there was no evidence of a decline in AIDS dementia or in Mycobacterium avium complex. In 1997, among patients with CD4 lymphocyte counts of less than or equal to 200 cells/mm(3), the i ncidence rates for any AIDS-defining illness was 51.1/100 PYFU for patients taking no therapy (95% CI, 27.9-85.7), 34.5 among patients on monotherapy (95% CI, 4.2-124.6), 13.2 among patients taking dual combination therapy (9 5% CI, 3.6-33.8) and 6.1 among patients taking triple therapy or more compl ex regimens (95% CI, 0.7-22.0; p < .0001, test for trend). Conclusions: There was a considerable decline in AIDS-defining illnesses du ring 1996 and 1997, coinciding with the rapid development of new antiretrov iral treatments and combinations of treatment. Further follow-up of large o bservational cohorts is essential to monitor the incidence of diagnoses les s common than we were able to consider, such as tuberculosis, cryptosporidi osis, and cryptococcosis, and also to investigate whether the incidence of disease continues to fall, or whether it starts to rise again, as toxicitie s, compliance, drug resistance, and long-term side effects begin to appear.