Adverse events from drug therapy for human immunodeficiency virus disease

Drug therapies for patients with human immunodeficiency virus (HIV) infection are associated with adverse events that can potentially limit their effectiveness. We sought to quantify the incidence of these events in clinical practice and determine whether there were demographic and clinical differences in adverse event rates for these drugs.

We calculated specific and overall adverse event rates from use of zidovudine, didanosine, zalcitabine, cotrimoxazole, and dapsone in an observational urban cohort of 1,450 HIV-infected patients with a CD4+ count of 500 cells/mm3 or less. We compared adverse event rates by gender, race, age, injecting drug use, and CD4+ count.

Overall adverse event rates in order of incidence were dapsone, 16.2 per 100 person-years (PY); didanosine, 24.1 per 100 PY; zidovudine, 26.3 per 100 PY; cotrimoxazole, 26.3 per 100 PY; and zalcitabine, 37.0 per 100 PY. Rates increased significantly with decline in CD4+ count from > 200 to < 100 cells/mm3 for all drugs but dapsone. In addition, women were more likely than men to have an adverse event for didanosine (relative risk [RR] = 2.7, P = 0.03) and from cotrimoxazole (RR 1.5; P = 0.05). Whites were at greater risk than blacks for adverse events from cotrimoxazole (RR = 1.6, P = 0.03). Only 22 of 357 total events (6%) required hospitalization, and there were no deaths.

Adverse events from antiretroviral drugs and Pneumocystis carinii pneumonia prophylaxis that interrupt therapy are relatively common, although serious events requiring hospitalization are rare. Adverse event rates increase progressively with decline in CD4+ count. The gender and race of the patient modify the risk of adverse events for some drugs.