Table 1. Case numbers for patients with CKF requiring dialysis together with sociodemographic and clinical characteristics according to different definitions in claims data.

Definition		Criteria*1			12-Month prevalence		6-Month incidence *2		Women, n (%)	Age, M (SD)	Prior AKI*4, n (%)
					Cases, n	Standardized*3, % [95% CI]	Cases, n	Standardized*3, % [95% CI]
a)	Gandjour et al., 2020 (10)	1.	ICD-10-GM N18.5 “and”		1466	0.58 [0.55; 0.61]	190	0.081 [0.071; 0.093]	67 (35.3)	80.8 (6.2)	86 (45.3)
		2.	ICD-10-GM Z49*, Z99.2
b)	Kolbrink et al., 2023 (3)	1.	ICD-10-GM N18.5 “and”		1447	0.57 [0.54; 0.60]	178	0.073 [0.063; 0.084]	60 (33.7)	81.2 (6.5)	110 (61.8)
		2.	Either
			2.1.	OPS 8-854.2–5, 8-855, 8-857 “or”
			2.2.	GOP 13610, 13611
c)	Lonnemann et al., 2017 (13)	1.	ICD-10-GM N18.5 “and”		1547	0.61 [0.58; 0.64]	213	0.089 [0.078; 0.101]	79 (37.1)	81.2 (6.2)	104 (48.8)
		2.	Either
			2.1.	ICD-10-GM Z49*, Z99.2 “or”
			2.2.	GOP 40800–8, 40812–3, 40820–3 “or”
			2.3.	OPS 8-854
d)	Schellartz et al., 2021 (14)	1.	ICD-10-GM N18.5 “and”		1262	0.50 [0.47; 0.53]	241	0.100 [0.088; 0.113]	81 (33.6)	81.0 (6.5)	120 (49.8)
		2.	Either
			2.1.	GOP 13611, 40823–7, 40837–8 “or”
			2.2.	OPS 8-853, 8-854, 8-855, 8-857
e)	Billing rationale	1.	Outpatient dialysis:		832	0.33 [0.31; 0.35]	134	0.058 [0.050; 0.069]	40 (29.9)	80.3 (6.0)	37 (27.6)
			1.1.	ICD-10-GM Z49.1–2 “and”
			1.2.	ICD-10-GM Z99.2 “and“
			1.3.	GOP 13610, 13611
		“or”
		2.	Day-care dialysis:
			2.1.	ICD-10-GM Z49.1–2 “and”
			2.2.	OPS 8-853, 8-854, 8-855, 8-857

*¹ Only individuals fulfilling all criteria with the Boolean operator “and” were included in the analyses. The first date on which all criteria were fulfilled was defined as the index date. Commas and hyphens represent an “or” condition. Unless otherwise stated, both outpatient and inpatient codes were used.

*² Incidence was determined as the proportion of all prevalent cases in the 2nd or 3rd quarter of an individual year out of all persons at risk (neither prevalent nor deceased in the respective 1st quarter).

*³ Prevalence and incidence are standardized for individuals aged ≥ 70 years. We used year-, age-, and gender-specific DESTASTIS weights for individuals aged ≥ 70 years from Berlin, Brandenburg, and Mecklenburg-Western Pomerania.

*⁴ Number of cases with acute kidney injury (AKI; ICD-10-GM N17*) within 3 months before or on the index date.

CKF, chronic kidney failure; GOP, fee schedule items (Gebührenordnungspositionen) in the German Uniform Value Scale (Einheitlicher Bewertungsmaßstab, EBM); ICD-10-GM, International statistical classification of diseases and related health problems, 10th revision, German Modification. Only “confirmed” outpatient and “main” and “secondary” (partial) inpatient diagnoses were used; M, mean; 95% CI, 95% confidence interval; OPS, German “Operations and Procedures Code”; a list and description of all codes used can be found in the eSupplement.