Risk of herpes zoster in SLE Chen HH et al. CLINICS 2011;66(7):1177-1182 Table 2 - Comparison of co-morbidities and prescription medications between the SLE patients and the non-SLE controls. Pd equivalent (mg/day) CCI SLE Patients Non-SLE Patients Variables Co-morbid medical conditions Diabetes Lymphoma Leukemia Breast cancer Liver cancer HIV/AIDS Charlson co-morbidity index, mean ¡ SD Prescription medication Systemic corticosteroid Prednisolone equivalent dose (mg/day) No use 0-10 10-20 .20 Azathioprine Cyclophosphamide Methotrexate Cyclosporin Hydroxychloroquine Values are the number of patients (percentage), unless otherwise indicated. HZ.14 Consistent with data from previous studies, the incidence rate among patients without SLE is greatest in subjects who are older than 64 years of age and lowest in subjects who are younger than 18 years of age. However, the current study reveals that the incident rate for HZ is greater in groups of younger SLE patients. Possible explanations for this finding include an increase in the SLE disease severity, larger doses of corticosteroids and/or immuno-suppressive agents, or a larger number of co-morbid conditions in younger SLE patients. Given the positive correlation between age and CCI in the current study, the last explanation is less likely to be the the cause of increased rate of HZ among younger SLE patients. The elderly lupus population has been reported to exhibit a greater number of benign disease courses,15-16 and physicians may prescribe lower doses of corticosteroid for elderly SLE patients because of a lower level of disease activity or a higher risk of drug-related complications, such as steroid-induced diabetes, atherosclerosis, or immuno-suppressive related infection. Thus, the first two reasons are more likely than the Table 3 - Average daily prednisolone (Pd) equivalent dose and Charlson co-morbidity index (CCI) for the SLE patients and non-SLE controls, as stratified by age. Age, years ,18 18-24 25-34 35-44 45-54 55-64 .64 SLE Patients 13.53 10.44 9.26 7.21 6.49 5.41 5.54 Non-SLE Patients SLE Patients Non-SLE Patients 0.05 0.06 0.07 0.08 0.13 0.20 0.16 7.89 7.76 7.70 7.72 7.94 8.20 8.48 0.04 0.06 0.09 0.21 0.46 0.66 1.01 Values are the means of the groups. *Values are the means of the groups. SLE Patients (n = 10337) 218 (2.1) 22 (0.2) 9 (0.1) 17 (0.2) 11 (0.1) 0 (0.0) 7.83 ¡ 1.22 9695 (93.8) 648 (6.3) 6588 (63.7) 2300 (22.3) 801 (7.7) 3661 (35.4) 2287 (22.1) 859 (8.3) 250 (2.4) 8179 (79.1) Non-SLE Patients (n = 62022) 1565 (2.5) 18 (0.0) 10 (0.0) 154 (0.3) 18 (0.0) 2 (0.0) 0.23 ¡ 0.81 30254 (48.8) 32046 (51.7) 29946 (48.3) 26 (0.0) 4 (0.0) 29 (0.0) 106 (0.2) 140 (0.2) 28 (0.0) 199 (0.3) p-value 0.012 ,0.001 ,0.001 0.104 ,0.001 0.564 ,0.001 ,0.001 ,0.001 ,0.001 ,0.001 ,0.001 ,0.001 ,0.001 last one to lead to the larger incident rates that have been observed in younger SLE patients. The crude RR for HZ is greater in young SLE patients and peaks in the youngest group of these patients. However, after an adjustment for the presence of prescription medication and co-morbid conditions, this trend seems to disappear. The adjusted RR for HZ is greatest in the SLE patients who are aged 18 to 24 years and lowest in those aged 45 to 54 years. It is not known whether this finding is related to SLE severity. Previous studies have demonstrated that men have a lower incidence rate of HZ than women.12 However, the present study indicates that the incidence rate for HZ in male SLE patients is not lower than that in female SLE patients (39.2 cases per 1000 patient-years vs. 37.6 cases per 1000 patient- years). Compared with non-SLE patients, the adjusted RR for an HZ infection in male SLE patients (RR 7.51, 95% CI 2.89- 19.52, p,0.001) is also greater than that in female SLE patients (RR 2.10, 95% CI 1.48-2.99, p,0.001). Despite these conflicting Table 4 - Incidence rates (number of cases per 1000 patient-years) of herpes zoster in the SLE patients and non-SLE controls, stratified by age and gender during the three-year follow-up period*. All Female Male Female Male All 5.1 2.2 3.2 2.9 4.8 10.1 10.0 12.8 5.2 2.4 3.3 2.8 4.9 10.5 10.0 13.0 4.7 1.3 2.5 3.8 3.9 7.0 9.7 12.0 1180 Age, years All ,18 18-24 25-34 35-44 45-54 55-64 .64 37.7 58.1 37.5 30.0 37.7 42.5 34.1 46.9 37.6 57.8 38.8 29.5 35.4 43.7 32.1 45.1 39.2 59.8 27.6 35.4 39.2 31.0 49.2 53.8