Benefits on infectious outcomes may be explained by “healthy user” effect

Statins reduce the risk of vascular events and are also cost effective.1 In recent years, non-randomised studies have linked statins with a list of biologically diverse actions, indicating that statins have pleiotropic effects.2 3 For severe infections—such as pneumonia, sepsis, or bacteraemia—at least six studies have linked statin use with decreased (to one third or less in some reports) risks of severe sepsis or death; this has caused great excitement among infectious disease and intensive care physicians.4 5

In this issue of the BMJ, Majumdar and colleagues report outcomes in 3415 Canadian patients with community acquired pneumonia.6 They found that statins slightly reduced the risk of in-hospital mortality or admission to intensive care (crude relative risk 0.80). However, statin users may be “healthy users,” because younger, healthier, better educated, and socioeconomically more privileged people may be more likely to receive preventive treatments than less privileged frail people.7 After controlling for measures of the “healthy user” effect (including up to date immunisations, quitting smoking, and …