Mediation effect of herpes zoster derived by statin use on cardiovascular disease risk

Background/Aims Although statins are widely used to reduce the risk of cardiovascular disease (CVD) including stroke and myocardial infarction (MI), it is reported that statin use increases the incidence of herpes zoster (HZ) that is associated with increased risk of CVD. So, we evaluated the mediation effect of HZ caused by statin use on CVD. Methods We analyzed a prospective cohort from the National Health Insurance Service-database of South Korea. All individuals received a medical check-up and were followed-up from 2002 to 2013. Results A total of 275,382 individuals > 40 years old were followed up for 11 years from 2003. Of these, 11,415 people (4%) were classified as statin users and 263,967 (96%) as non-statin users. Those who used statins had significantly lower risks of cardiovascular events, stroke, and MI compared with non-statin users; the adjusted hazard ratios in the multivariate analysis were 0.90 (95% confidence interval [CI], 0.82 to 0.98), 0.88 (95% CI, 0.80 to 0.98), and 0.91 (95% CI, 0.79 to 1.07), respectively. When we calculated the mediating effect of cardiovascular events by statin use through HZ, 11.6% of the total beneficial effect of cardiovascular events by statin use was mitigated through the occurrence of HZ caused by statin use. This mediating effect was higher in the younger age group (< 60 years). Conclusions This study showed that statin use reduced CVD by 10%, but the protective effect of statin use against CVD was mitigated by approximately 10% through the development of HZ caused by statin use.