Effects of inhaled corticosteroids on pneumonia severity and antimicrobial resistance.

BACKGROUND Limited information is available regarding the impact of prior use of inhaled corticosteroids (ICS) in patients subsequently developing community-acquired pneumonia (CAP). We assessed the effects of prior ICS use on severity of illness and microbiology in CAP hospitalized patients. METHODS A retrospective cohort study of subjects with CAP (by the International Classification of Diseases, 9th Revision, Clinical Modification) was conducted over a 4-year period at 2 tertiary teaching hospitals. Subjects were considered to be ICS users if they received ICS prior to admission. Primary outcomes were severity of illness and microbiology at admission. RESULTS Data were abstracted on 664 subjects: 89 prior ICS users (13.4%) and 575 non-users (86.6%). Prior ICS users had higher severity of illness at admission: mean ± SD Pneumonia Severity Index 100.8 ± 31.4 vs 68.8 ± 33.4, P = .001, and CURB-65 (confusion, urea nitrogen, respiratory rate, blood pressure, ≥ 65 years of age) score 1.56 ± 1.02 vs 1.19 ± 1.02, P = .002. Prior ICS use was independently associated with antimicrobial-resistant pathogens: 11.2% vs 5.9%, odds ratio 2.6, 95% CI 1.1-6.1, P = .04. CONCLUSIONS Prior ICS use was associated with higher severity of illness at admission and higher incidence of antimicrobial-resistant pathogens in CAP hospitalized patients.