eAPPENDIX 1. ICD-9 CODES USED FOR CLASSIFICATION OF COMORBIDITIES
Diabetes included both type I and type II and was defined as any occurrence of International Classification of Diseases, Ninth Edition (ICD-9) diagnosis codes 250.xx, 357.2, 362.0x, or 366.41; glycated hemoglobin ≥6.5%; or any outpatient prescription for an anti-diabetes medication.
Heart failure was identified as any occurrence of ICD-9 diagnosis codes 398.91, 402.x1, 404.x3, 425.xx, 428.xx, or V42.1; or a left ventricular ejection fraction less than 40%.
Chronic Kidney Disease
CKD Stage 2: ICD-9 code 585.2 or single estimated glomerular filtration rate (eGFR) 60-89
CKD Stage 3a: single eGFR 45-59
CKD Stage 3b: single eGFR 30-44
CKD Stage 4: ICD-9 code 585.4 or single eGFR 15-29
CKD Stage 5: ICD-9 code 585.5 or single eGFR <15
ESRD (as an exclusion or an outcome) was defined as ICD-9 code 585.6, single eGFR ≤10, or the initiation of chronic dialysis (defined as first calendar month including a dialysis procedure on 4 separate dates).
Acute Kidney Injury (exclusion) was defined as ICD-9 diagnosis codes 584.5-584.9.