“…Because comorbidities may be associated with both herpes zoster and SS, they are considered as potential confounders for the association between herpes zoster and the risk of SS. We used the Charlson Comorbidity Index (CCI) as the general comorbidity index25 26 after excluding connective tissue disease (CTD) to examine the presence of comorbidities including diabetes with diabetic complications, myocardial infarction, congestive heart failure, peripheral vascular disease,27 28 chronic pulmonary disease,29–31 ulcer disease,32 mild liver disease,33 34 moderate or severe liver disease, hemiplegia, moderate or severe renal disease, tumour35 and solid metastatic tumour. Patients were considered to have any comorbidity when they had at least three outpatient visits or one hospitalisation with the corresponding ICD-9-CM code within 1 year before the index date.…”