Incidence of pneumocystosis among patients exposed to immunosuppression.

Abstract

The decision to administer prophylaxis to patients receiving immunosuppression against pneumocystosis remains a dilemma. To determine overall and age-specific 5-year pneumocystosis incidence within a population exposed to immunosuppressants. Retrospective cohort analysis identifying incident pneumocystosis cases among adults without HIV, AIDS, or cancer exposed to immunosuppressant, corticosteroid therapy, or both. We identified 406 new cases among patients prescribed an immunosuppressant, corticosteroid, or both. Overall incidence of pneumocystosis was 0.012% (406/3,366,086). Incidence was highest in those exposed to immunosuppressant and corticosteroid medications (0.199%), followed by those exposed to immunosuppressant alone (0.012%), corticosteroid alone (0.008%), and neither medication (0.001%) (P < .001). The greatest risk differences were noted between groups exposed to immunosuppressant and corticosteroid compared with neither (0.198%, 95% confidence interval [CI] 0.166%-0.230%) or immunosuppressant alone (0.188%, 95% CI 0.155%-0.221%). The greatest relative risks (RRs) were noted among those receiving immunosuppressant and corticosteroid compared with those exposed to neither (RR 122.5, 95% CI 100.9-148.8) or immunosuppressant alone (RR 16.5, 95% CI 7.3-37.4). We could not confirm dose and duration of exposures. Incidence of pneumocystosis among patients exposed to immunosuppressants is very low. Prophylaxis for patients receiving combination immunosuppressant and corticosteroid therapy, the group at highest risk, might be warranted.