Decreased efficacy of inhaled pentamidine in the prevention of Pneumocystis carinii pneumonia among HIV-infected patients with severe immunodeficiency.

STUDY OBJECTIVE To determine the relationship between the degree of immune deficiency and the risk of Pneumocystis carinii pneumonia (PCP) among HIV-infected patients receiving inhaled pentamidine prophylaxis. DESIGN Retrospective chart review. SETTING AIDS clinic of inner-city hospital. PATIENTS Patients attending inhaled pentamidine clinic between 1989 and 1991. INTERVENTION Review of medical records of patients receiving inhaled pentamidine, 300 mg/month, via nebulizer (Respirgard II) as primary or secondary prophylaxis of PCP. Statistical analysis of lymphocyte subset results and selected clinical data. RESULTS Ten of 57 patients developed PCP during the period of analysis. Patients with CD4 counts less than 60/mm3 were significantly more likely to develop PCP (p = 0.01; Fisher's exact test) with a relative risk of 7.55 compared to patients with CD4 lymphocyte counts greater than 60/mm3. CONCLUSION Failure of inhaled pentamidine prophylaxis is seen almost exclusively among patients with CD4 lymphocyte counts below 60/mm3.