We thus designed a large-scale population-based retrospective matchedcohort study to answer this question. The severe CVDs included malignant hypertension, hypertensive nephropathy, myocardial infarction, or any form of congestive heart failure,MM-206 as well as a coronary artery bypass surgery or percutaneous transluminal coronary angioplasty. In addition, subjects with intracerebral hemorrhage, intracranial hemorrhage, occlusion/stenosis of pre-cerebral arteries, and occlusion of cerebral arteries were also excluded. The detailed list of the corresponding ICD-9-CM codes can be found in our previously published article. By excluding this group of patients, we ensured that the study would not contain patients with pre-existing severe cardiovascular and/or cerebrovascular comorbidities and, therefore, with a high pre-existing risk of a cardiovascular outcome. The study population was divided into two groups: those who received allopurinol treatment and those who did not. The allopurinol group consisted of 12,563 patients and the nonallopurinol group consisted of 11,466 patients. We then performed one-to-one matching by age at accrual, gender, index date of subjects in the allopurinol group, diabetes mellitus, hypertension, hyperlipidemia, and atrial fibrillation. After matching, we finalized two matched study group, an allopurinol group and a nonallopurinol group,UPCDC30245 each containing 2483 patients. Follow-up continued until the occurrence of a primary cardiovascular outcome, death, or the end of 2008. Demographic data such as age and gender, as well as medical comorbidities including hypertension, diabetes mellitus, hyperlipidemia, atrial fibrillation, uric acid nephrolithiasis, acute kidney injury, hepatitis, contact dermatitis and other eczema, CKD, uremia, and gastric ulcer were collected for baseline evaluation. The Charlson comorbidity index was also calculated for each case in the two groups. Comorbid medical conditions, identified using their standard ICD-9-CM codes, were used to calculate cumulatively the CCI score for each individual. The established CCI, adapted from the Charlson index for use with ICD-9-CM coded administrative databases, contains 17 weighted categories related to chronic concomitant diseases and is able to predict the subsequent 1-year mortality among inpatients.