CDI Solutions • Tips & Friendly Reminders • Chronic Kidney Disease

Chronic Kidney Disease

Definition

A persistent and usually progressive, irreversible loss of kidney function.

Duration Criteria

Abnormalities are usually present > 3 months per KDIGO.

Often associated with

Diabetes
HTN
Urinary obstruction
Autoimmune diseases
Recurrent UTIs
Prior episodes of AKI

⚠ Medication note: Medications such as ASA, acetaminophen, NSAIDS and some antibiotics can cause renal damage and lead to CKD.

Diagnostic Criteria

The diagnostic criteria for CKD is the presence of either of the following for > 3 months:

Decreased GFR <60 ml/min, OR
Objective measure of kidney damage-significant persistent albuminuria, hematuria, structural abnormalities noted on imaging.
CKD stages 1 or 2 require the presence of one or more markers of kidney damage. A GFR >/= 60 is not CKD if there are no markers noted.
CKD stages 3-5 are based on GFR alone.

CKD Stages & Coding

Stage
1

GFR
>/= 90

N18.1

Stage
2

GFR
60-89

N18.2

Stage
3a

GFR
45-59

N18.31

Stage
3b

GFR
30-44

N18.32

Stage
4

GFR
15-29

N18.4

Stage
5

GFR
< 15

N18.5

Stage
ESRD-dialysis

GFR

N18.6
+ Z99.2

Coding & CDI Considerations

Principal diagnosis tip: When a patient is admitted primarily for fluid overload necessitating emergent dialysis, assign E87.70 (fluid overload) as the principal diagnosis.

There is an assumed relationship between:

HypertensionCKD

HypertensionHeart failureCKD

DiabetesCKD

‘CKD5 requiring chronic dialysis’ codes to N18.6 (ESRD) per Excludes1 note.
Patients receiving dialysis for ESRD should be assigned both N18.6 (ESRD) and Z99.2 (dependence on dialysis).

📚 References to Consider
Official Coding Guidelines
I. C.14.a.2

AHA Coding Clinic · 2023 Q1, p. 19
ESRD and Fluid Overload

Additional considerations

The stage of CKD should not be assigned until glomerular filtration rate (GFR) and/or creatinine (Cr) levels have stabilized. This is especially important in cases of acute kidney injury (AKI) superimposed on CKD, where staging may not be reliable until renal function has returned to baseline. In such scenarios, it is not appropriate to query for CKD staging.
All patients with a history of kidney transplantation meet the definition of CKD, regardless of current GFR. However, CKD alone does not indicate a transplant complication and should not be coded as such unless explicitly documented.
For patients with end-stage renal disease (ESRD) on dialysis, a diagnosis of AKI should not be assigned, as renal function is already non-recoverable.
When applying Sepsis-3 criteria (SOFA score) in patients with CKD, always consider the patient’s baseline creatinine to avoid misclassification of organ dysfunction.
The terms “chronic renal insufficiency,” “chronic renal failure,” and “chronic renal disease” are clinically acceptable and may be used interchangeably with CKD for coding purposes.

Comorbidity and Risk Adjustment

CC Classification
CKD Stages 4 and 5 are classified as Complications or Comorbidities (CCs).

HCC Classification
CKD Stages 3–5 and ESRD are recognized Hierarchical Condition Categories (HCCs) under CMS-HCCs 326–329.

Query Opportunity

1
When documentation reflects “CKD 3/4,” a clarification query should be initiated to specify either Stage 3 (a or b), or Stage 4 CKD. Historical laboratory values may be referenced to support staging.

2
Providers may continue to document ESRD in patients who are post–kidney transplant (s/p transplant). However, if the patient is no longer dialysis-dependent, the code N18.6 (ESRD) should not be assigned. Instead, review for the current CKD stage, querying as necessary and include Z94.0 (kidney transplant status).

3
When CKD is documented, review clinical indicators and query for a stage, as appropriate.

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