Patient Demographics and Clinical Characteristics
We documented demographic variables upon cohort entry and determined the associated morbidities from the inpatient and outpatient ICD-9 and ICD-10 diagnostic codes recorded in the three years preceding the cohort entry.30-32 Next, we used the patients’ characteristics and associated comorbidities to calculate the CHADS2 score (Supplementary Tables S2 and S3) and the modified HAS-BLED score (Supplementary Tables S2 and S4). The comorbidity burden was scored with the Charlson-Deyo Comorbidity Index.34,35 A frailty score was also calculated from the modified Elders Risk Assessment in the two years preceding cohort entry.36,37 Lastly, we assessed all drug prescriptions filled in the two weeks preceding the cohort entry.