Extended criteria (experimental). This is the broader ten-condition engine, kept as a secondary area. It shows ICD-10-CM codes and illustrative grouping effects for CDI staff. The primary surface is Before you sign (kidney, measurement only). All extended pages.

Chronic kidney disease stage (eGFR, CKD-EPI 2021)

Rule ckd version 2026.11-1 · condition: Chronic kidney disease

Published source

KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease (2024). Chapter 1, Table 1 (definition: abnormality for a minimum of 3 months) and Table 2 (GFR categories). https://kdigo.org/wp-content/uploads/2024/03/KDIGO-2024-CKD-Guideline.pdf · public page checked 2026-11-14

G1 >=90, G2 60-89, G3a 45-59, G3b 30-44, G4 15-29, G5 <15. G1 and G2 are CKD only with markers of kidney damage.

Also: National Kidney Foundation: CKD-EPI Creatinine Equation (2021) (2021). Race-free equation: 142 x min(Scr/k,1)^a x max(Scr/k,1)^-1.200 x 0.9938^age x 1.012 [female]; k 0.7/0.9; a -0.241/-0.302. link

Inputs

egfr_n: Number of pre-admission eGFR values within 2 years (inpatient values during acute illness are not used)
egfr_span_days: Days between the earliest and latest pre-admission eGFR values
egfr_early: Earliest pre-admission eGFR (mL/min/1.73 m2, CKD-EPI 2021)
egfr_late: Latest pre-admission eGFR (mL/min/1.73 m2, CKD-EPI 2021)

Thresholds

t.chronic_days: 90
t.g2: 60
t.g3a: 45
t.g3b: 30
t.g4: 15

Derived values

Evaluated in order
Name	Expression
chronic	`egfr_n >= 2 and egfr_span_days >= t.chronic_days`
staging_egfr	`max(egfr_early, egfr_late)`
both_below_60	`egfr_early < t.g2 and egfr_late < t.g2`
category	`case(staging_egfr >= t.g2, 'G1-G2', staging_egfr >= t.g3a, 'G3a', staging_egfr >= t.g3b, 'G3b', staging_egfr >= t.g4, 'G4', 'G5')`

Outcomes

First true outcome wins; an unknown input makes an outcome unknown
Outcome	When	Status	Supports
duration_not_shown Fewer than two pre-admission eGFR values at least 90 days apart	`not chronic`	insufficient	—
straddles_60 Pre-admission eGFR values fall on both sides of 60	`not both_below_60 and min(egfr_early, egfr_late) < t.g2`	judgement	—
g1_g2 eGFR 60 or above; CKD G1-G2 requires markers of kidney damage, which are not assessed here	`staging_egfr >= t.g2`	judgement	—
g3a Two eGFR values >=90 days apart, both below 60; staging value {staging_egfr} (G3a)	`category == 'G3a'`	supported	N18.31 Chronic kidney disease stage 3a
g3b Two eGFR values >=90 days apart, both below 60; staging value {staging_egfr} (G3b)	`category == 'G3b'`	supported	N18.32 Chronic kidney disease stage 3b
g4 Two eGFR values >=90 days apart; staging value {staging_egfr} (G4)	`category == 'G4'`	supported	N18.4 Chronic kidney disease stage 4
g5 Two eGFR values >=90 days apart; staging value {staging_egfr} (G5)	`category == 'G5'`	supported	N18.5 Chronic kidney disease stage 5 Dialysis dependence (end-stage renal disease, N18.6) is a clinical statement the rule does not infer.

ICD-10-CM specificity ladder (FY2026 CC/MCC status as a secondary diagnosis)

N18.9 Chronic kidney disease, unspecified · non-CC
N18.30 Chronic kidney disease stage 3, unspecified · non-CC (refines N18.9)
N18.31 Chronic kidney disease stage 3a · non-CC (refines N18.30)
N18.32 Chronic kidney disease stage 3b · non-CC (refines N18.30)
N18.4 Chronic kidney disease stage 4 · CC (refines N18.9)
N18.5 Chronic kidney disease stage 5 · CC (refines N18.9)

Query topic: chronic kidney documentation · prompts for an undocumented diagnosis: yes

Where clinical judgement is required

Staging uses the higher of the two qualifying values (conservative); a clinician may weigh trends differently.
Albuminuria categories (A1-A3) are not assessed, so G1-G2 cannot be concluded.

Coding notes

Hypertensive CKD combination codes (I12/I13) are outside this subset.