CLINICS 2011;66(7):1177-1182 CLINICAL SCIENCE DOI:10.1590/S1807-59322011000700009 Risk of herpes zoster in patients with systemic lupus erythematosus: a three-year follow-up study using a nationwide population-based cohort Hsin-Hua Chen,I,II,IV Yi-Ming Chen,I,II Tzeng-Ji Chen,II,III Joung-Liang Lan,I,II,IV,V Ching-Heng Lin,VI Der-Yuan ChenI,II,IV,V I Division of Allergy, Immunology and Rheumatology, Department of Internal Medicine, Taichung Veterans General Hospital, Taichung, Taiwan. II School of Medicine, National Yang-Ming University, Taipei, Taiwan. III Department of Family Medicine, Taipei Veterans General Hospital, Taipei, Taiwan. IV School of Medicine, Chung-Shan Medical University, Taichung, Taiwan. V Institute of Biomedical Science, Chung-Hsing University, Taichung, Taiwan. VI Department of Medical Research, Taichung Veterans General Hospital, Taichung, Taiwan. OBJECTIVE: The goal of the present study was to estimate the risk ratio of herpes zoster among systemic lupus erythematosus patients after disease onset compared with a cohort of patients without systemic lupus erythematosus over a three-year period. METHODS: A nationwide population-based cohort study using the National Health Insurance Research Database identified 10,337 new cases of systemic lupus erythematosus as the study cohort. In addition, 62,022 patients without systemic lupus erythematosus, who were matched for age, gender, and date of systemic lupus erythematosus diagnosis, were used as the comparison cohort. These cohorts were followed-up for three years. A Cox proportional hazard regression was performed to estimate the risk ratio of herpes zoster, with adjustments for age, gender, level of insurance, urbanization level, geographic region, comorbid medical conditions, average daily dosage of corticosteroids, and the use of immune-modulation agents. RESULTS: Compared to patients without systemic lupus erythematosus, the crude risk ratio and adjusted risk ratio of herpes zoster among systemic lupus erythematosus patients were 7.37 (95% confidence interval 6.75-8.04) and 2.45 (95% confidence interval 1.77-3.40), respectively. Stratified by gender, the adjusted risk ratio of herpes zoster was 2.10 (95% confidence interval 1.45-2.99) in women and 7.51 (95% confidence interval 2.89-19.52) in men. Stratified by age, the adjusted risk ratio peaked in systemic lupus erythematosus patients who were aged 18 to 24 years (risk ratio 8.78, 95% confidence interval 3.08-24.97). CONCLUSION: Based on nationwide population-based data, there is an increased risk of herpes zoster in systemic lupus erythematosus patients compared with non-systemic lupus erythematosus patients, particularly among males and patients aged 18 to 24 years. Further research on the associated risk factors for herpes zoster in systemic lupus erythematosus patients is needed. KEYWORDS: Herpes Zoster; Risk; Systemic Lupus Erythematosus; Population-Based Cohort Study; Database. Chen HH, Chen YM, Chen TJ, Lan JL, Lin CH, Chen DY. Risk of herpes zoster in patients with systemic lupus erythematosus: a three-year follow-up study using a nationwide population-based cohort. Clinics. 2011;66(7):1177-1182. Received for publication on January 26, 2011; First review completed on February 25, 2011; Accepted for publication on May 21, 2011 E-mail: dychen@vghtc.gov.tw Tel.: 886-4-23592525 ext 3336 INTRODUCTION Herpes zoster (HZ) is characterized by debilitating painful vesicular eruptions in a dermatomal distribution that are caused by the reactivation of a latent varicella zoster virus (VZV) infection.1 This disease is commonly observed in the elderly, in immuno-compromised hosts, and in patients with systemic lupus erythematosus (SLE).2-5 Copyright 2011 CLINICS – This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http:// creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non- commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Cutaneous vesicles can be complicated by a bacterial super-infection, and the dissemination of HZ may be life- threatening.3 Post-herpetic neuralgia in the affected areas is the most common complication, which can persist for months or years. The incidence of HZ in the general population is 1.2 to 4.9 cases per 1000 person-years, depending on the ethnic group.6-7 The reported incidence of HZ in SLE patients is significantly greater than the incidence in the general population, ranging from 16 to 22 cases per 1000 patient-years in large cohort studies.2-3,8 The greater incidence of HZ infection in SLE has been shown to be related to abnormal T-cell-mediated cytotoxi- city that is aggravated by the concomitant use of glucocor- ticoids and immuno-suppressants.4,9-10 Disease activity, 1177