Main outcome and comorbidities
Graves’ disease was the primary end point in this study. We defined Graves’ disease patients as patients with two or more outpatient visit, or one in-patient records of ICD code 242.0. The following comorbidities developed before the index date were considered as confounders: anxiety (ICD-9-CM 309.2-309.4), asthma (ICD-9-CM 493), coronary artery disease (CAD) (ICD-9-CM 410–413, 414.01–414.05, 414.8, and 414.9), cancer (ICD-9-CM 140-208), chronic obstructive pulmonary disease (COPD) (ICD-9-CM 490-496), congestive heart failure (CHF) (ICD-9-CM 398.91, 402.01, 402.11, 402.91, and 428), chronic liver diseases (CLD) (ICD-9-CM 571.4), diabetes mellitus (DM) (ICD-9-CM 250), depression (ICD-9-CM 296.2, 296.3, 296.5, 296.82, 300.4, 309.0-309.1 and 311), hypertension (ICD-9-CM 401-405), hyperlipidemia (ICD-9-CM 272), stroke (ICD-9-CM 430-438) and sleep apnea (ICD-9-CM 327.2, 780.51, 780.53, 780.57).