Effect of antiretroviral therapy on the incidence of bacterial pneumonia in patients with advanced HIV infection.

To determine the relationship of combination antiretroviral therapy and bacterial pneumonia, we assessed incidence of and risk factors for bacterial pneumonia in 1,898 human immunodeficiency virus (HIV)-infected patients with CD4 cell counts < 200/mm(3) followed in the Johns Hopkins HIV clinic between 1993 and 1998. A total of 352 episodes of bacterial pneumonia occurred during 2,310 patient-years of follow-up. Incidence of bacterial pneumonia decreased from 22.7 episodes/100 person-years (py) in the first half of 1993 to 12.3 episodes/100 py in the first half of 1996, reaching a nadir of 9.1 episodes/100 py in the second half of 1997 (p < 0.05). The use of protease inhibitor-containing regimens was associated with a decreased risk of bacterial pneumonia (risk ratio [RR] 0.55, 95% CI 0.31 to 0.94). Lower CD4 cell counts (RR 2.22, 95% CI 1.54 to 3.18), injection drug use as HIV transmission category (RR2.0, 95% CI 1.43 to 2.76), and prior Pneumocystis carinii pneumonia (RR 3.88, 95% CI 1.65 to 9.16) were also significantly associated with bacterial pneumonia. Trimethoprim-sulfamethoxazole and macrolide use were not significantly associated with risk of bacterial pneumonia. There has been a dramatic decline in the incidence of bacterial pneumonia resulting from the use of combination antiretroviral therapy containing protease inhibitors.