Background: Community-acquired pneumonia (CAP) is a major cause of morbidity and mortality worldwide. Clinical practice guidelines for empirical CAP treatment, formulated jointly by the Infectious Diseases Society of America (IDSA) and American Thoracic Society (ATS), remain controversial and inconsistently applied. We evaluated the impact of guideline-concordant therapy on in-hospital survival and other outcomes using a large database including adults treated for CAP in both community and tertiary care hospitals.

Methods: We evaluated the association between in-hospital survival and guideline-concordant therapy using logistic regression models. Time until discharge from hospital and discontinuation of parenteral therapy were evaluated using survival analysis.

Results: Of 54 619 non-intensive care unit inpatients with CAP hospitalized at 113 community hospitals and tertiary care centers, 35 477 (65%) received initial guideline-concordant therapy. After adjustment for severity of illness and other confounders, guideline-concordant therapy was associated with decreased in-hospital mortality (odds ratio [OR], 0.70; 95% confidence interval [CI], 0.63-0.77), sepsis (OR, 0.83; 95% CI, 0.72-0.96), and renal failure (OR, 0.79; 95% CI, 0.67-0.94), and reduced both length of stay and duration of parenteral therapy by approximately 0.6 days (P < .001 for both comparisons). These findings were robust with alternate definitions of "concordance" and were linked to treatment with fluoroquinolone or macrolide agents.

Conclusions: Guideline-concordant therapy for CAP is associated with improved health outcomes and diminished resource use in adults. The mechanisms underlying this finding remain speculative and warrant further study, but our findings nonetheless support compliance with CAP clinical practice guidelines as a benchmark of quality of care.