“…Comorbidities potentially related to ischemic cerebrovascular disease before index date were identified as follows: alcohol-related disease, atrial fibrillation, chronic kidney disease, chronic obstructive pulmonary disease, coronary artery disease, hyperlipidemia, and hypertension. Based on the ICD-9 codes, the diagnosis validity of comorbidities was discussed in previous studies ( Lai et al, 2017a , b , c , d , e , f ; Liao et al, 2017e ; Lin et al, 2017b , c ).…”