SAN FRANCISCO, CA—After adjusting for potential confounders, no difference in length of stay was observed between adults with and without statin exposure who were hospitalized for community-acquired pneumonia, results from the Centers for Disease Control and Prevention’s Etiology of Pneumonia in the Community (EPIC) study reported at IDWeek 2013.
“Statins have anti-inflammatory and immunomodulatory effects, and some retrospective studies suggest that statins might be beneficial for treatment of severe infections, including community-acquired pneumonia,” noted Fiona Havers, MD, MHS, of the Centers for Disease Control and Prevention in Atlanta, GA, and colleagues.
In addition, the effect of statins on community-acquired pneumonia remains unclear. Often, statin users have different co-morbid conditions than non-users (eg, confounding by indication). They may also be more likely to engage in health-promoting behaviors than non-users of similar health status (eg, healthy-user bias).
The investigators analyzed 2,192 adults admitted with clinical and radiographic community-acquired pneumonia to five hospitals in Chicago and Nashville between January 2010 and June 2012.
“Adults on statins prior to admission and who continued on statins during hospitalization (statin group) were compared with those who never took statins (control group),” Dr. Havers noted. “Adults who started or stopped statins in the hospital were excluded from this analysis.” The primary outcome of the trial was hospital length of stay. Length of stay was used as a surrogate for clinical outcome.
Investigators used a Multivariable Cox proportional hazards regression model to examine the association between statin use and hospital length of stay that was adjusted for potential confounders, including demographics and co-morbidities. Also compared were outcomes between propensity score matched groups (eg, the propensity to receive statins).
Exposure groups were matched by propensity score by age, race, gender, study hospital, insurance status, level of education, home oxygen use, smoking status, body mass index, angiotensin-converting enzyme (ACE) inhibitor use, influenza vaccination status, and history of the following co-morbidities: coronary artery disease, diabetes, chronic obstructive pulmonary disease, asthma, kidney disease, heart disease, stroke, and liver disease.
Of the adults enrolled, 88% were included in the analysis, 571 (26%) in the statin group and 1,621 (74%) in the control group. “Statin users were older, had more co-morbid conditions, were better educated, more likely to have health insurance, and more likely to have received influenza vaccination than controls,” she reported.
Statin users had a longer median length of stay, 92 hours (inter-quartile range [IQR] 55–166) vs. 75 hours for the control group (IQR 48–127; P<0.010). Among 1,974 adults with complete co-variate data for the proportional hazards regression model, statin users and controls had similar lengths of stay (adjusted HR 0.98; 95% CI 0.86–1.1; P=0.93). Propensity score matching retained 346 patients in each group and showed comparable lengths of stay (aHR 0.93; 95% CI 0.8–1.1; P=0.86), they concluded.
Substantial confounding affected length of stay due to baseline differences between the statin group and control group. “Further studies, particularly randomized controlled trials, are needed to evaluate the effect of statins on community-acquired pneumonia,” noted Dr. Havers.