Discontinuation of primary prophylaxis against Pneumocystis carinii pneumonia in HIV-1-infected adults treated with combination antiretroviral therapy

Background It is unclear whether primary prophylaxis against Pneumocystis c arinii pneumonia can be discontinued in patients infected with the human im munodeficiency virus (HIV) who are successfully treated with combination an tiretroviral therapy. We prospectively studied the safety of stopping proph ylaxis among patients in the Swiss HIV Cohort Study. Methods Patients were eligible for our study if their CD4 counts had increa sed to at least 200 cells per cubic millimeter and 14 percent of total lymp hocytes while they were receiving combination antiretroviral therapy, with these levels sustained for at least 12 weeks. Prophylaxis was stopped at st udy entry, and patients were examined every three months thereafter. The de velopment of P. carinii pneumonia was the primary end point, and the develo pment of toxoplasmic encephalitis the secondary end point. Results Of the 262 patients included in our analysis, 121 (46.2 percent) we re positive for IgG antibodies to Toxoplasma gondii at base line. The media n CD4 count at study entry was 325 per cubic millimeter (range, 210 to 806) ; the median nadir CD4 count was 110 per cubic millimeter (range, 0 to 240) . During a median follow-up of 11.3 months (range, 3.0 to 18.8), prophylaxi s was resumed in nine patients, and two patients died. There were no cases of P. carinii pneumonia or toxoplasmic encephalitis. The one-sided upper 99 percent confidence limit for the incidence of P. carinii pneumonia was 1.9 cases per 100 patient-years (based on 238 patient-years of followup). The corresponding figure for toxoplasmic encephalitis was 4.2 per 100 patient-y ears (based on 110 patient-years of follow-up). Conclusions Stopping primary prophylaxis against Fl carinii pneumonia appea rs to be safe in HIV-infected patients who are receiving combination antire troviral treatment and who have had a sustained increase in their CD4 count s to at least 200 cells per cubic millimeter and to at least 14 percent of total lymphocytes. (N Engl J Med 1999;340:1301-6.) (C)1999, Massachusetts M edical Society.