The impact of statin use on pneumonia risk and outcome: a combined population-based case-control and cohort study

INTRODUCTION: The impact of statin use on pneumonia risk and outcome remains unclear. We therefore examined this risk in a population-based case-control study and did a 5-year update of our previous 30-day mortality analyses. METHODS: We identified 70,953 adults with a first-time hospitalization for pneumonia between 1997 and 2009 in Northern Denmark. Ten age- and sex-matched population controls were selected for each pneumonia patient. To control for potential confounders, we retrieved individual-level data on other medications, comorbidities, recent surgery, socioeconomic indicators, influenza vaccination, and other markers of frailty or health awareness from medical databases. We followed all pneumonia patients for 30 days after hospital admission. RESULTS: A total of 7,223 pneumonia cases (10.2%) and 64 523 controls (9.1%) were statin users before admission, corresponding to an age- and sex-matched odds ratio (OR) of 1.17 (95% confidence interval [CI]: 1.14-1.21). After controlling for higher comorbidity and a wide range of other potential confounders, the adjusted OR for pneumonia associated with current statin use dropped to 0.80 (95% CI: 0.77-0.83). Previous statin use was not associated with decreased pneumonia risk (adjusted OR = 0.97, 95% CI: 0.91-1.02). Decreased risk remained significant after further adjustment for frailty and health awareness markers. The prevalence of statin use among Danish pneumonia patients increased from 1% in 1997 to 24% in 2009. Thirty-day mortality following pneumonia hospitalization was 11.3% among statin users versus 15.1% among nonusers. This corresponded to a 27% reduced mortality rate (adjusted hazard ratio = 0.73, 95% CI: 0.67-0.79), corroborating our earlier findings. CONCLUSIONS: Current statin use was associated with both a decreased risk of hospitalization for pneumonia and lower 30-day mortality following pneumonia.