Increased risk of multiple sclerosis following herpes zoster: a nationwide, population-based study.

UNLABELLED (See the editorial commentary by Corona and Flores, on pages 177-8.) OBJECTIVE  Varicella zoster virus (VZV) has been proposed to be involved in the pathogenesis of multiple sclerosis (MS). However, the epidemiological data regarding the MS occurrence rate following herpes zoster are still scanty. The goal of this study is to investigate the frequency and risk for MS following occurrence of herpes zoster. METHODS  This study used the Taiwan National Health Insurance Research Database. A total of 315,550 patients with herpes zoster were included as the study group, and the control group consisted of 946,650 randomly selected subjects. The stratified Cox proportional hazard regression was performed to calculate the 1-year MS-free survival rate. RESULTS  Of 1,262,200 sampled patients, 29 from the study group (.009%) and 24 from the control group (.003%) had MS during the 1-year follow-up period. After adjusting for monthly income and geographic region, the hazard of MS was 3.96 times greater (95% CI = 2.22-7.07, p < 0.001) for the study group than controls. CONCLUSIONS  Our findings support the notion that occurrence of MS could be associated with herpes zoster attack. We found a significantly higher risk for MS within 1 year of herpes zoster attack compared with the control population.