Risk factors for breakthrough PCP in HIV-infected patients receiving aerosol pentamidine

Objective: To identify the risk factors for breakthrough PCP (BPCP) in HIV-infected adult patients receiving aerosol pentamidine (AP) for PCP prophylaxis. Introduction: A large scale community based AP program has been available in Ontario, Canada since May, 1989. Patients receive either 60 mg AP via Fisoneb q 2 weeks or 300 mg via Respirgard. Physicians complete a baseline enrollment forms and provide clinical follow-up at 3 month intervals. All data is entered into a centralized database at the HIV Project Centre in Toronto and provides the opportunity to estimate the time to and risk factors for BPCP. Methods: Kaplan-Meier survival analysis was performed using time from AP initiation to PCP stratified by absolute CD4 count at enrollment. Cox regression analysis was performed using gender, age, CD4 count and year of enrollment as covariates. Results: To May 1996, 2674 patients have been enrolled in the program, 66% for primary and 34% for secondary prophylaxis. 96% were male and the primary risk factor for HIV infection was male homosexual. The median CD4 at initiation of AP was 109 cell/mm3. The mean follow-up time was 23 months. Kaplan-Meier survival analysis found that the median time to PCP following AP initiation was 56 months and 37 months for persons starting primary and secondary prophylaxis respectively. Multivariate Cox models found that only prior PCP and CD4 strata were independent predictors of PCP. Conclusion: For HIV patients the risk of PCP increases with decreasing absolute CD4 counts and prior episodes of PCP. Although TMP/SMX remains the gold standard for PCP prophylaxis, a large number of patients continue to receive AP in Ontario. Time to PCP from AP enrollment (Graph Presented).