D57.451
BillableSickle-cell thalassemia beta plus with acute chest syndrome
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is D57.451 an HCC code?
Yes. D57.451 maps to Sickle Cell Disorders and Thalassemia under the CMS-HCC V28 risk adjustment model (and Severe Hematological Disorders under V24).
HCC Category Mapping
RAF weights shown are the community, non-dual, aged base weights from the CMS risk adjustment model file. Actual per-patient RAF contribution depends on member segment, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains in use during the transition and for historical data.
MEAT Criteria for D57.451
For D57.451 to count as a valid HCC diagnosis in a given encounter, the provider's documentation must show MEAT: Monitor, Evaluate, Assess, or Treat. A diagnosis from a prior year does not carry forward automatically — it has to be re-documented and supported each calendar year.
- MMonitor: signs, symptoms, disease progression, or lab trending documented in the note
- EEvaluate: test results, medication response, or physical findings reviewed by the provider
- AAssess: explicit mention in the assessment or plan with acknowledgment of status
- TTreat: medication, referral, procedure, therapy, or counseling tied to the diagnosis
Only one of M/E/A/T is required to support the code, but the documentation must be specific enough to show that the provider actually addressed D57.451 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
D57.451 is the ICD-10-CM diagnosis code for sickle-cell thalassemia beta plus with acute chest syndrome. A combination blood disorder with sickle-cell and thalassemia beta-plus that causes acute chest syndrome, a serious lung complication with chest pain and breathing difficulty. D57.451 sits in the ICD-10-CM chapter for diseases of the blood and blood-forming organs and certain disorders involving the immune mechanism (d50-d89), within the section covering hemolytic anemias (d55-d59).
Under the CMS-HCC V28 risk adjustment model, D57.451 maps to Sickle Cell Disorders and Thalassemia (HCC 108) with a community, non-dual, aged base RAF weight of 0.607. Under the older CMS-HCC V24 model, D57.451 maps to Severe Hematological Disorders (HCC 46) with a community, non-dual, aged base RAF weight of 0.666. V28 is the CMS-HCC risk adjustment model that reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition.
Acute chest syndrome is a medical emergency; document respiratory symptoms, fever, chest pain, and imaging findings (chest X-ray or CT). Because D57.451 maps to a payment HCC, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's Medicare Advantage risk adjustment score. When documentation is ambiguous, coders should issue a provider query rather than assume the highest-specificity variant.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for D57.451 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Acute chest syndrome is a medical emergency; document respiratory symptoms, fever, chest pain, and imaging findings (chest X-ray or CT)
- •Distinguish from D57.431 by confirming beta-plus (not beta-zero) thalassemia is documented
Clinical Significance
Acute chest syndrome in sickle-cell thalassemia beta plus is the same life-threatening pulmonary complication seen in other sickle cell genotypes, though it may occur less frequently in beta-plus patients due to the milder overall disease phenotype. Despite the generally milder course, acute chest syndrome can still be severe and potentially fatal, requiring the same aggressive management with exchange transfusion, antibiotics, and respiratory support.
Documentation Requirements
- ✓Documentation must confirm the sickle-cell thalassemia beta plus genotype and the explicit diagnosis of acute chest syndrome with new pulmonary infiltrate and respiratory symptoms (chest pain, dyspnea, cough, fever, hypoxia).
- ✓Record oxygen saturation, imaging results, treatment protocol, and clinical course.
- ✓The provider must document 'acute chest syndrome' as the diagnosis.