The effect of pneumonia on mortality among patients hospitalized for acute stroke

Abstract

Objective: To determine the effect of pneumonia on 30-day mortality in patients hospitalized for acute stroke. Methods: Subjects in the initial cohort were 14,293 Medicare patients admitted for stroke to 29 greater Cleveland hospitals between 1991 and 1997. The relative risk (RR) of pneumonia for 30-day mortality was determined in a final cohort (n = 11,286) that excluded patients dying or having a do not resuscitate order within 3 days of admission. Clinical data were obtained from chart abstraction and were merged with Medicare Provider Analysis and Review files to obtain deaths within 30 days. A predicted-mortality model (c-statistic = 0.78) and propensity score for pneumonia (c-statistic = 0.83) were used for risk adjustment in logistic regression analyses. Results: Pneumonia was identified in 6.9% (n = 985) of all patients and in 5.6% (n = 635) of the final cohort. The rates of pneumonia were higher in patients with greater stroke severity and features indicating general frailty. Unadjusted 30-day mortality rates were six times higher for patients with pneumonia than for those without (26.9% vs 4.4%, p < 0.001). After adjusting for admission severity and propensity for pneumonia, RR of pneumonia for 30-day death was 2.99 (95% CI 2.44 to 3.66), and population attributable risk was 10.0%. Conclusion: In this large community-wide study of stroke outcomes, pneumonia conferred a threefold increased risk of 30-day death, adding impetus to efforts to identify and reduce the risk of pneumonia in patients with stroke.