Statins and the Risk of Herpes Zoster: A Population-Based Cohort Study

BACKGROUND Statins are widely used lipid-lowering drugs with immunomodulatory properties that may favor reactivation of latent varicella-zoster virus infection. However, whether statins increase the risk of herpes zoster is unknown. METHODS We conducted a population-based retrospective cohort study of Ontario residents aged ≥ 66 years between 1 April 1997 and 31 March 2010 to examine the association between statin use and incidence of herpes zoster. We used propensity score matching to ensure similarity between users and nonusers of statins, and Cox proportional hazard models to assess differences in outcomes between study groups. To test the specificity of our findings, we examined the association between statin exposure and knee arthroplasty. RESULTS During the 13-year study period, we matched 494 651 individuals treated with a statin to an equal number of untreated individuals. In the main analysis, the rate of herpes zoster was higher among users of statins relative to nonusers of these drugs (13.25 vs 11.71 per 1000 person-years, respectively; hazard ratio [HR], 1.13; 95% confidence interval [CI], 1.10-1.17). The attributable fraction of exposed individuals was 11.6%. In a prespecified analysis, we found a similar risk of herpes zoster among statin users in the subgroup of patients with diabetes (HR, 1.18; 95% CI, 1.09-1.27). As expected, we found no association between statin use and knee arthroplasty (HR, 1.04; 95% CI, .99-1.09). CONCLUSIONS Among older patients, treatment with statins is associated with a small but significantly increased risk of herpes zoster.