Table 1 Chronic kidney disease definitions and codes

Chronic kidney disease (using administrative data)

Defined as an adult with the following diagnoses from physician claims and hospital records, and drug prescriptions:

• Two or more physician claims with diagnoses for hypertensive chronic kidney disease, hypertensive heart and chronic kidney disease, acute glomerulonephritis, nephrotic syndrome, chronic glomerulonephritis, nephritis and nephropathy not specified as acute or chronic, chronic kidney disease, renal failure (unspecified), renal sclerosis (unspecified), disorders resulting from impaired renal function, hydronephrosis, other disorders of kidney and ureter, congenital anomalies of urinary system (ICD-9-CM: 403, 404, 580, 581, 582, 583, 585, 586, 587, 588, 591, 593, 753), or

• One or more hospital episodes with diagnoses for diabetes with renal manifestations, hypertensive chronic kidney disease, hypertensive heart and chronic kidney disease, acute glomerulonephritis, nephrotic syndrome, chronic glomerulonephritis, nephritis and nephropathy not specified as acute or chronic, chronic kidney disease, renal failure (unspecified), renal sclerosis (unspecified), disorders resulting from impaired renal function, hydronephrosis, unspecified disorder of kidney and ureter, congenital anomalies of urinary system (ICD-9-CM: 250.4, 403, 404, 580, 581, 582, 583, 585,586, 587, 588, 591, 593.9, 753; ICD-10-CA: E10.2, E11.2, I12, I13, N18, N19, N00–16, N25, N26, N28.82, N39.1, Q60–64), or

• One or more filled drug prescriptions used in CKD management:

 ○ generic names: Epoetin Alfa, Darbepoetin Alfa, Peginesatide, Sodium Polystyrene Sulfonate, Calcium Polystyrene sulphonate, Polystyrene Sod Sulfonate 454, Sevelamer HCL, Cinacalcet HCL, Lanthanum;

 ○ Anatomical Therapeutic Chemical (ATC) codes: B03XA01, B03XA02, B03XA04, V03AE01, V03AE02, H05BX01, V03AE03.

Chronic kidney disease (using laboratory data)

Defined as an adult with:

1) Two abnormal estimated Glomerular Filtration Rate (eGFR) tests at least 90 days apart using the following equation:

Modification of Diet in Renal Disease (MDRD) equation [14]

Men: (175 x (S_cr/88.4)^-1.154)) x (AGE)^-0.203)

Women: multiply results by 0.74). OR

2) Two abnormal tests for proteinuria (either Protein-Creatinine Ratio (PCR), Albumin-Creatinine Ratio (ACR) or dipstick protein urinalysis) at least 90 days apart.

Abnormal test values were defined as:

 • eGFR values < 60 ml/min/1.73m²

 • PCR > =15 mg/mmol or ACR > =3 mg/mmol [14]

 • Dipstick Protein Urinalysis gives a categorical measurement of urine protein (0 to 4) which is less precise than a Urine Protein test*. A dipstick protein level greater than or equal to 0.3 g/L is considered abnormally high.

* Note: A comparison of same-day Dipstick and Urine Protein test results showed moderate agreement (kappa = 0.48):

• Dipstick Protein = 0 comparable to Urine Protein < 15 mg/mmol

• Dipstick Protein = 1 comparable to Urine Protein 15–50 mg/mmol

• Dipstick Protein = 2–4 comparable to Urine Protein > 50 mg/mmol