Pharmacoeconomics of Pneumocystis carinii pneumonia in HIV-infected and HIV-noninfected patients.

Despite the proven effectiveness of Pneumocystis carinii pneumonia (PCP) prophylaxis in both HIV-infected and HIV-noninfected patients, PCP remains an important cause of serious pulmonary infection. Because PCP is a frequent event requiring inpatient admission at our institution, we conducted a study to define the pharmacoeconomics of this infection and the incidence of adverse events associated with anti-PCP therapy. In a retrospective review, 133 patients (101 HIV-positive, 32 HIV-negative) with documented PCP were identified. Significant differences in age, initial arterial oxygen tension (paO2), intensive care unit admission and mortality were evident between HIV-infected and non-HIV-infected patients; however, there were no differences in the duration of hospitalisation or the duration of anti-PCP therapy. The incidence of biochemical abnormalities was similar between the groups. Leucopenia occurred at an incidence of 52 and 31%, while thrombocytopenia occurred at a rate of 7 and 44%, in HIV-positive and HIV-negative patients, respectively. Drug toxicity or treatment failure necessitated a change of therapy in 43% of HIV-positive and 59% of HIV-negative patients. PCP treatment cost, pharmacy cost, hospital cost and net loss (i.e. the difference between hospital cost and reimbursement) were all significantly greater in HIV-negative than in HIV-positive patients. The duration of anti-PCP therapy and the hospital cost for cotrimoxazole (trimethoprim-sulfamethoxazole)- and pentamidine-treated patients were similar, although the treatment cost and pharmacy cost were statistically different in favour of cotrimoxazole. Overall, cotrimoxazole is an inexpensive treatment option. However, the high incidence of adverse events attributed to this agent often necessitates a change to a more costly therapy.