Tips for capturing chronic kidney disease documentation
By Doreen V. Bentley
To understand how to appropriately assign codes for chronic kidney disease (CKD) and acute kidney injury (AKI), instead of just reporting the codes that correspond with each and every note in the record, coders need to take a closer look at the clinical picture. Generally speaking, people with AKI are more likely to develop CKD in later years, and people with CKD are more likely to develop AKI.
“A lot of this relationship is modified by the severity of AKI, the stage of CKD, the duration of AKI, and the number of episodes,” says Garry L. Huff, MD, CCS, CCDS, AHIMA-approved ICD-10-CM/PCS trainer and president of Enjoin, formerly Huff DRG Review, in Eads, Tennessee.
This may start to sound like alphabet soup if coders don’t take the time to investigate what is actually going on with the patient and query the physician when necessary.
Whether the documentation notes decreased kidney function, the presence of radiographic or biochemical evidence of kidney damage, or a glomerular filtration rate (GFR) of less than 60 ml/min/1.73m2, CKD is established only when this abnormality persists for at least three months.
There are seven stages of CKD (0 through 5 and end stage renal disease), and these are determined by the GFR:
- Stage 0: GFR greater than or equal to 90 with CKD risk factors, no kidney damage
- Stage 1: GFR greater than or equal to 90 with kidney damage
- Stage 2: GFR of 60–89
- Stage 3: GFR of 30–59
- Stage 4: GFR of 15–29 (a CC)
- Stage 5: GFR less than 15 (a CC)
- End-stage renal disease (ESRD): Patient has CKD and is on continuous dialysis (an MCC)
Note that once a patient is placed on dialysis, even if the documentation states CKD stage 4, coding professionals should automatically assign the code for ESRD, he says.
“Even if it’s not a CC or an MCC, you still need to specify if the patient has CKD because that’s a comorbid condition that does affect morbidity and mortality statistics and risk adjustments,” Huff says.
Clinical example
A patient with CKD is admitted for dehydration. The serum creatinine on admission was 2.4 mg% with an estimated GFR of 27 ml/min. After hydration, the serum creatinine decreased to 1.7 mg% with a GFR of 42 ml/min. The patient is not on dialysis. For this example, the patient is Stage 3 CKD.
“It’s very important to remember, when you’re establishing the CKD level, you use the best GFR that’s available in the record because that’s their true baseline,” Huff says. “This patient dropped down to a lower stage 27 [ml/min], but that was due to AKI, and it came back up once they reestablished their hydration to their baseline.”
When querying physicians to ask them for the stage, coders should provide the criteria for the various stages and not simply give them the diagnosis and the list of stages. “A lot of doctors may not know how the stages correlate, so to help facilitate their answer, give them the table, and then let them make their own calculation,” Huff says.
CKD and sequencing
Because CKD is a chronic condition, it will typically not be used as the principal diagnosis for people who are admitted as inpatients. Rather, they will typically be admitted for an acute or intermediary complication, such as volume overload, congestive heart failure (CHF), hyperkalemia, or uremia.
Uremia, which is a clinical syndrome that develops due to byproducts of metabolism, is more often associated with CKD than it is with a temporary AKI.
“Most often, the reason for the acute admission is perhaps an associated condition of CKD or end-stage renal disease, such as CHF or the volume overload issue and not the kidney disease itself,” says Brandy Kline, RHIA, CCS, CCS-P, CCDS, AHIMA-approved ICD-10-CM/PCS trainer and coordinator of training and quality assurance for Enjoin.
One situation for which it would be appropriate to assign CKD as the principal diagnosis is if it is an initial diagnosis of CKD and the cause is unknown, Kline says. Also, CKD may be coded as the principal diagnosis if the admission is for acute uremic symptoms or diagnoses such as pericarditis and neuropathy and encephalopathy.
Pericarditis and neuropathy have specific subterm entries for “uremic” in both ICD-9-CM and ICD-10-CM, with bracketed codes providing direction to use the CKD code first followed by a secondary code for the associated condition. Uremic encephalopathy indicates the need for an emergent dialysis session, but there is no specific indexing for uremic encephalopathy as there is for pericarditis and neuropathy, Kline says. However the CKD code category in ICD-9-CM (585) has an instructional note to use an additional code to identify the manifestation of the uremia.
“We don’t believe that the very small list included there is all-inclusive but rather an example of the types of conditions that should be used as a code-also condition,” Kline says. “And we believe that encephalopathy falls into that arena.”
Coding Clinic, Fourth Quarter 2013, p. 124, provided the directive that the reason for the dialysis would be reported as the principal diagnosis. Note that CKD and ESRD will be used more frequently with the implementation of ICD-10-CM since there’s no code for an admission for dialysis as there is in ICD-9-CM (V56.0).
Both Official Guidelines for Coding and Reporting state that patients with CKD may also suffer from other serious conditions and that the sequencing of the CKD code in relationship to the codes for other contributing conditions is based on the conventions in the tabular list (e.g., anemia, post renal transplant, diabetes, hypertension.
Physicians do not need to specifically link hypertension and CKD before assigning the combination code for hypertensive renal disease. The hypertensive renal disease code is assigned followed by the specific code to identify the stage of CKD. However, this is not the case with hypertension and CHF, which the physician does need to specifically document as a cause-effect association. Follow this guideline unless the physician specifically documents “renal disease is not due to hypertension.”
In contrast, physicians must specifically note a cause-and-effect association to report a code for diabetes with renal manifestation. If an association is documented, sequencing guidance states that the diabetic renal complication code would be reported first followed by the stage of CKD if documented, along with any associated pathology.
Clinical example
A patient is admitted for accelerated hypertension and diabetes out of control. The patient is placed in the intensive care unit, administered IV vasodilators, and placed on an IV insulin drip. The physician documents that the patient has AKI, which improved with treatment of BP and diabetes. The final diagnosis is accelerated hypertension emergency with AKI, and we know the GFR after treatment was 37 ml/min. With an appropriate query and based on the focus of care, one could consider reporting the following:
- Diabetic renal complication code as the principal diagnosis
- Hypertensive renal disease code because of the assumed association as the principal diagnosis
- AKI as a secondary diagnosis
- CKD as a secondary diagnosis
Based on the GFR, you could query the physician for further specificity of the stage. Coding Clinic, First Quarter 2003, pp. 20-21, directed the use of both the diabetic renal disease code as well as the hypertensive renal disease code, but without any sequencing guidance.
“So we would determine the principal based on the focus of care,” Kline says. “Again, this is because of that assumed relationship in the absence of any specific disassociation by the provider of the hypertension and the CKD.”
Because CKD is a chronic disease, the reason for admission and the scope of care (i.e., principal diagnosis) will often be to address a metabolic complication or a complication of the treatment of CKD itself (CHF and volume overload not due to CHF are the most common).
Editor's Note: Bentley is a freelance writer and editor with more than a dozen years' experience in the field. This article was originally published in JustCoding Inpatient.