M05.749
BillableRheumatoid arthritis with rheumatoid factor of unspecified hand without organ or systems involvement
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is M05.749 an HCC code?
Yes. M05.749 maps to Rheumatoid Arthritis and Inflammatory Connective Tissue Disease under the CMS-HCC V28 risk adjustment model (and Rheumatoid Arthritis and Inflammatory Connective Tissue Disease 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 M05.749
For M05.749to 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 M05.749 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
M05.749 is the ICD-10-CM diagnosis code for rheumatoid arthritis with rheumatoid factor of unspecified hand without organ or systems involvement. Rheumatoid arthritis affecting the hand with a positive rheumatoid factor blood test when the specific side is not documented, without involvement of other organs or body systems. M05.749 sits in the ICD-10-CM chapter for diseases of the musculoskeletal system and connective tissue (m00-m99), within the section covering inflammatory polyarthropathies (m05-m14).
Under the CMS-HCC V28 risk adjustment model, M05.749 maps to Rheumatoid Arthritis and Inflammatory Connective Tissue Disease (HCC 93) with a community, non-dual, aged base RAF weight of 0.175. Under the older V24 model, M05.749 mapped to the same category but with a base RAF weight of 0.307 — V28 recalibrated weights across the entire model. 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.
Use only when laterality of hand involvement is not specified in the documentation. Because M05.749 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 M05.749 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Use only when laterality of hand involvement is not specified in the documentation
- •Query provider for clarification on which hand is affected to allow for more specific coding
Clinical Significance
This code captures seropositive rheumatoid arthritis affecting unspecified hand without systemic involvement, representing localized inflammatory disease when laterality cannot be determined. Hand involvement significantly impacts daily functioning regardless of which hand is affected, requiring ongoing management despite non-systemic nature.
Documentation Requirements
- ✓Confirmation of rheumatoid arthritis diagnosis affecting hand joints
- ✓Positive rheumatoid factor laboratory test result
- ✓Documentation that hand laterality cannot be determined from records
- ✓Confirmation that no organ or system involvement is present
- ✓Clinical evidence of inflammatory arthritis in hand
- ✓Exclusion of extra-articular manifestations
- ✓Assessment of disease activity and functional impact on hand use
Commonly Confused Codes
- •M05749 vs M05741/M05742 — Use specific laterality when hand side is documented
- •M05749 vs M19.049 — M19.049 is unspecified osteoarthritis of hand
- •M05749 vs M25.549 — M25.549 is pain in unspecified hand
- •M05749 vs M65.849 — M65.849 is tenosynovitis of unspecified hand
- •M05749 vs M05.649 — M05.649 includes organ involvement