Objective: Quantify and study cofactors of long-term survival without AIDS in HIV-1-infected individuals with CD4+ cell counts < 200 x 10(6)/l.
Design: Comparison of 579 participants who could be longitudinally evaluated for at least 3 years after the earliest date of first reaching a CD4+ cell count < 200 x 10(6)/l or an AIDS-defining illness (1987 Centers for Disease Control and Prevention definition).
Setting: Ongoing 9-year cohort study with data collected at 6-month intervals.
Patients: HIV-1-infected homosexual men.
Measurements and main results: Of the men, 20% did not develop an AIDS illness within 3 years following a confirmed CD4+ cell count < 200 x 10(6)/l; 29 and 28% were diagnosed with a first clinical AIDS illness from 1-3 and < 1 years, respectively, beyond their first CD4+ cell count < 200 x 10(6)/l; 23% were diagnosed with a clinical AIDS illness prior to their first CD4+ cell count < 200 x 10(6)/l. Slower decline of CD4+ cell count (P < 0.001) and presence of higher body-mass index during the period prior to the first CD4+ cell count < 200 x 10(6)/l (P < 0.001) predicted longer time to an AIDS illness once this threshold was reached. Most men had rapid loss of CD4+ cells, total T cells, and hemoglobin during the period after CD4+ cells declined below 200 x 10(6)/l. However, those remaining free of AIDS illnesses the longest arrested their decline in CD4+ cell counts and hemoglobin levels and increased total T cells during this period. Although antiretroviral therapy and Pneumocystis carinii prophylaxis extend AIDS-free survival, 45% of the group who were AIDS-free > or = 3 years after CD4+ cells fell below 200 x 10(6)/l had not used these treatments.
Conclusions: Significant numbers of individuals remain free of illnesses and AIDS symptoms > or = 3 years after CD4+ cell counts drop below 200 x 10(6)/l. This occurs even in the absence of treatment. The associations seen here suggest that host and viral factors play important roles. Thus, further studies are needed to determine the biological basis of long-term survival without AIDS illnesses in HIV-1-immunosuppressed patients.