Hospitalization for the Initiation of Ketogenic Diet — CPB 0226 | AETNA Coverage Update

Aetna modified CPB 0226 for hospitalization to initiate a ketogenic diet, effective September 26, 2025. Here's what billing teams need to act on now.

Aetna, a CVS Health company, updated its coverage policy for inpatient ketogenic diet initiation under CPB 0226 in the Aetna ketogenic diet coverage policy. The policy governs when a hospital admission is medically necessary to start this high-fat, carbohydrate-restricted diet in pediatric patients with intractable seizures—and in patients with specific metabolic disorders at any age. Billing teams working with CPT codes 97802, 97803, and 97804 for medical nutrition therapy, as well as urinalysis codes 81000–81003, should review how this coverage policy applies to their patient population before September 26, 2025.

Quick-Reference Table

Aetna Ketogenic Diet Hospitalization Coverage Criteria and Medical Necessity Requirements 2025

Aetna considers inpatient hospitalization for ketogenic diet initiation medically necessary under two distinct pathways. The first covers intractable seizures, including Doose syndrome (epilepsy with myoclonic atonic seizures) and Lennox-Gastaut syndrome. The second covers patients with glucose transporter protein type 1 (GLUT1) deficiency or pyruvate dehydrogenase complex (PDC) deficiency—and notably, this second pathway carries no age restriction.

For the intractable seizures pathway, all four of the following criteria must be met simultaneously. Meeting three out of four is not enough. Aetna will deny the claim.

Criterion 1 — Drug failure: The member must have failed anti-convulsant medications in both monotherapy and polytherapy, or be intolerant to them. The trial must be adequate: correct medications, correct dosage, careful monitoring of treatment effects, and documented patient compliance for at least one year. This is the single most common point of claim denial under this policy. If your documentation shows only six months of drug therapy, you don't meet the threshold.

Criterion 2 — Age: The member must be younger than 18 years old. There is no flexibility here. This pathway does not apply to adults, regardless of seizure severity.

Criterion 3 — Family compliance: Parents or family members must demonstrate willingness and dedication to support strict dietary compliance. Aetna treats adherence as tantamount to the diet's effectiveness. Vague language in the clinical notes won't hold up. Your documentation needs to show the family specifically understands and accepts the regimen.

Criterion 4 — Outpatient inadequacy: There must be a documented clinical reason why outpatient initiation of the fasting and dehydration period will not work. If your clinicians can't articulate why this patient needs inpatient management rather than outpatient initiation, that's a gap prior authorization reviewers will flag.

For GLUT1 deficiency (ICD-10 E88.09) and pyruvate dehydrogenase complex deficiency (ICD-10 E74.4), the coverage policy is more straightforward. Hospitalization for ketogenic diet initiation is medically necessary. The four seizure-pathway criteria do not apply. If you're billing for these diagnoses, document the confirmed diagnosis clearly and move forward.

Ketogenic diet billing for inpatient initiation is not a routine admission. Prior authorization is required before hospitalization in nearly all cases. Build that prior auth request around documented drug-failure history for seizure patients, or confirmed metabolic diagnosis for GLUT1/PDC patients. Incomplete auth requests—especially those missing the one-year drug trial detail—are returned or denied at high rates.

Aetna Ketogenic Diet Hospitalization Exclusions and Non-Covered Indications

The ICD-10 code list appended to CPB 0226 is expansive—155 codes spanning conditions well beyond intractable seizures and metabolic disorders. Codes for Type 2 diabetes (E11.0–E11.9), schizophrenia (F20.0–F20.9), bipolar disorder (F31.0–F31.9), major depressive disorder (F32.0–F39), Parkinson's disease (G20.A1–G20.C), Alzheimer's disease (G30.0–G30.2), autism spectrum and pervasive developmental disorders (F84.0–F84.9), glioblastoma and malignant neoplasms (C00.0–C96.9), and mitochondrial metabolism disorders (E88.40–E88.49) all appear in the code set.

This is worth pausing on. These codes appear in the policy document as related codes—not as covered indications for inpatient hospitalization. Aetna's stated covered indications are limited to intractable seizures with the four-criterion gate and the two specific metabolic disorders. The presence of a code in the policy's code list does not mean Aetna covers hospitalization for that condition.

Do not assume a glioblastoma diagnosis (C71.x), an autism diagnosis (F84.0), or a bipolar disorder diagnosis (F31.x) makes an inpatient ketogenic diet admission billable under CPB 0226. Those diagnoses may appear in the clinical record alongside a covered indication, but they don't independently qualify a claim. If your billing team sees these codes and assumes coverage, expect denial.

If you have patients where emerging evidence supports ketogenic diet for conditions like Alzheimer's or Parkinson's, Aetna has not designated those as covered indications under this policy. Talk to your compliance officer before submitting claims for inpatient initiation under those diagnoses.

Coverage Indications at a Glance

Aetna Ketogenic Diet Hospitalization Billing Guidelines and Action Items 2025

1. Audit your drug-failure documentation now—before September 26, 2025.
For every active patient on the intractable seizures pathway, pull the medication history. You need documented evidence of at least one year of compliant therapy using correct anti-convulsants at correct dosages with monitoring records. If a chart shows less than 12 months, the prior auth request will likely be denied. Correct documentation gaps before the effective date.

2. Update your prior authorization workflows to flag all four seizure-pathway criteria.
Build a checklist into your PA request template: (1) drug failure documented ≥1 year, (2) patient age <18, (3) family compliance statement in the record, (4) clinical rationale for why outpatient initiation is not appropriate. If any of the four is missing, hold the request until it's complete.

3. Separate your metabolic disorder pathway from your seizure pathway in charge capture.
GLUT1 deficiency (E88.09) and PDC deficiency (E74.4) have a cleaner path to coverage. Flag these diagnoses in your charge capture system so billing staff don't apply the four-criterion seizure checklist to these patients. Mixing the two pathways wastes time and creates documentation errors.

4. Train billing staff on the distinction between code list inclusion and covered indications.
The 155 ICD-10 codes in CPB 0226 create a real risk of misinterpretation. Someone sees F84.0 (autism) or G30.1 (Alzheimer's) in the code list and assumes it's a billable indication. It is not. Run a brief training session for your billing team before September 26, 2025, and make this distinction explicit.

5. Build family compliance documentation into your pre-admission process.
Aetna requires that parents or family members be "willing and dedicated" to support dietary compliance. This needs to appear in clinical notes—not as boilerplate, but as specific language documenting that the family was counseled on the regimen's demands and agreed to support it. Work with your clinical team to make this a standard pre-admission documentation step.

6. Bill medical nutrition therapy codes correctly alongside the admission.
CPT 97802 (medical nutrition therapy, initial assessment), 97803 (reassessment and intervention), and 97804 (group medical nutrition therapy) are the primary billing codes for dietitian services. These codes support the inpatient stay—they don't stand alone as the basis for the admission. Make sure your charge capture links these codes to the correct diagnosis and that you're not billing them in place of the appropriate facility codes for the admission itself.

7. Use urinalysis codes 81000–81003 and HCPCS A4250 accurately.
These codes (urinalysis by dipstick or tablet reagent for ketones, glucose, bilirubin, hemoglobin, leukocytes, and other analytes) are directly relevant to ketogenic diet monitoring. HCPCS A4250 covers urine test strips (100 strips/tablets). Bill these when services are rendered and documented—not prophylactically or on a routine basis without clinical justification.

8. Account for vitamin and mineral supplementation billing.
Ketogenic diets require supplementation. HCPCS A9152 (single vitamin/mineral/trace element, oral, per dose) and A9153 (multiple vitamins with or without minerals, oral, per dose) are in the CPB 0226 code set. If your facility supplies these during the admission, check whether your reimbursement structure captures them correctly. Also review S9470 (nutritional counseling, dietitian visit) if outpatient follow-up is part of the discharge plan.

CPT, HCPCS, and ICD-10 Codes for Ketogenic Diet Hospitalization Under CPB 0226

CPT Codes — Medical Nutrition Therapy and Monitoring

HCPCS Codes — Supplies and Nutritional Counseling

Key ICD-10-CM Diagnosis Codes

The full ICD-10 code list in CPB 0226 contains 155 codes. The codes above represent the primary covered indications and the most commonly misinterpreted non-covered codes. Access the complete list at app.payerpolicy.org/p/aetna/0226.