Table 1.

ICD-9-CM codes used to define disease subgroups^*

Diagnosis groups	ICD-9-CM diagnosis and procedure codes
SLE	710.0
SLE + KI
Diagnosis codes
Nephritis	580.0, 580.4, 580.8, 580.81, 580.89, 580.9, 581.0, 581.1, 581.2, 581.3, 581.8, 581.81, 581.89, 581.9, 582.0, 582.1, 582.2, 582.4, 582.8, 582.81, 582.89, 582.9, 583.0, 583.1, 583.2, 583.4, 583.6, 583.7, 583.8, 583.81, 583.89, 583.9
Chronic kidney disease	585, 585.1, 585.2, 585.3, 585.4, 283.11, 403.00, 403.10, 403.90, 404.00, 404.10, 404.90, 404.01, 404.11, 404.91, 587, 588.8, 588.9, 642.1, 642.2, 794.4
Dialysis	v56.0, v56.8, v45.11, v56.1, v56.2, v56.3, v45.12, 792.5, v45.1, v56.31, v56.32
Kidney transplant	v42.0, 996.81
AKF	584, 584.5, 584.6, 584.7, 584.8, 584.9
ESKD	585.5, 585.6, 585.9, 586, 403.01, 403.11, 403.91, 404.02, 404.12, 404.92, 404.03, 404.13, 404.93
Procedure codes
Dialysis	39.95, 54.98, 39.93, 39.94, 39.42, 39.27
Kidney transplant	55.69, 55.53, 55.52, 55.51, 55.54
Kidney biopsy	55.23, 55.24, 55.39, 55.21
SLE – KI	Any 710.0 patient not included in SLE + KI
Kidney failure groups
SLE with transplant	All kidney transplant diagnosis or procedure codes
SLE with ESKD	All ESKD codes except those with a transplant code
	All dialysis codes and/or dialysis procedure codes except those with transplant
SLE with AKF	All AKF codes except those with transplant or ESKD codes

^*ICD-9-CM = International Classification of Diseases, Ninth Revision, Clinical Modification; SLE = systemic lupus erythematosus; SLE + KI = SLE with kidney involvement; AKF = acute kidney failure; ESKD = end-stage kidney disease; SLE – KI = SLE without kidney involvement.