Risk for preventable opportunistic infections in persons with AIDS after antiretroviral therapy increases CD4+ T lymphocyte counts above prophylaxis thresholds.

To determine incidence and risk for preventable opportunistic infections (Pneumocystis carinii pneumonia [PCP] and disseminated Mycobacterium avium-complex [MAC] infection) in persons whose CD4(+) T lymphocyte counts had increased by >/=100 cells/microL to exceed the threshold of risk and in persons whose CD4(+) counts had never dropped below the threshold of risk, we analyzed data collected during the period 1990-1998 in the Adult/Adolescent Spectrum of HIV (Human Immunodeficiency Virus) Disease Project. Using a counting-process formulation of the Cox model, we analyzed observation time in these 2 groups for persons who were prescribed antiretroviral therapy but not prophylaxis. The incidences of the infections were low for patients whose CD4(+) count rose above the threshold of risk (PCP, 0.6 cases per 100 person-years [PY]; MAC, 1. 0 cases per 100 PY) and not higher than in persons whose CD4(+) counts had not decreased below these thresholds, which suggests that discontinuation of primary prophylaxis for opportunistic infections may be considered for some patients.