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 favour 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 of age or older between April 1, 1997 and March 31, 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 thirteen 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 versus 11.71 per 1000 person-years, respectively; hazard ratio 1.13, 95% confidence interval 1.10 to 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 (hazard ratio 1.18, 95% confidence interval 1.09 to 1.27). As expected, we found no association between statin use and knee arthroplasty (hazard ratio 1.04, 95% confidence interval 0.99 to 1.09).

Conclusions — Among older patients, treatment with statins is associated with a small but significantly increased risk of herpes zoster.