M05.70 ICD-10-CM Code: Rheumatoid arthritis with rheumatoid factor of unspecified site without organ or systems involvement
HCC Buddy Code Card
Digital ICD-10 code-book layout with official code detail, always-visible risk models, Code Trumping, and Buddy coding guidance.
FY 2026 Apr update / Diseases of the musculoskeletal system and connective tissue (M00-M99) / Inflammatory polyarthropathies (M05-M14)
M05.70
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceRheumatoid arthritis with rheumatoid factor of unspecified site without organ or systems involvement
Rheumatoid arthritis with positive rheumatoid factor affecting an unspecified location, without involvement of other organs or systems.
Buddy Insight
This code represents rheumatoid arthritis with positive rheumatoid factor at an unspecified location without systemic involvement, indicating localized inflammatory arthritis.
CMS-HCC V28
MappedHCC 93
RAF 0.175
CMS-HCC V24
MappedHCC 40
RAF 0.307
ACA/HHS
00
RAF 0
ESRD/PACE
MappedHCC 40
RAF 0.0
RXHCC
MappedHCC 83
RAF 0.0
Code Trumping
Basket needed
Code Book Path
Inclusion Terms
OfficialICD-10-CM does not list inclusion terms for M05.70 in this effective period.
Excludes 2
OfficialICD-10-CM does not list Excludes 2 notes for M05.70 in this effective period.
Related Child Codes
Includes
OfficialICD-10-CM does not list Includes notes for M05.70 in this effective period.
Excludes 1
OfficialICD-10-CM does not list Excludes 1 notes for M05.70 in this effective period.
Code First
OfficialICD-10-CM does not list Code First sequencing instructions for M05.70 in this effective period.
Use Additional
OfficialICD-10-CM does not list Use Additional Code instructions for M05.70 in this effective period.
Code Also
OfficialICD-10-CM does not list Code Also instructions for M05.70 in this effective period.
Buddy Documentation Tip
MEAT Support
Audit Caution
Common Mistakes
Last updated: FY2026 ICD-10-CM Apr update, Apr 1, 2026 through Sep 30, 2026. CMS-HCC V28 is 100% phased in for payment year 2026.
Is M05.70 an HCC code?
Yes. M05.70 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 M05.70
For M05.70to 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 M05.70 during that encounter, not just copy-forwarded from a problem list.
What This Code Means
M05.70 is the ICD-10-CM diagnosis code for rheumatoid arthritis with rheumatoid factor of unspecified site without organ or systems involvement. Rheumatoid arthritis with positive rheumatoid factor affecting an unspecified location, without involvement of other organs or systems. M05.70 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, M05.70 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, M05.70 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 this code when the specific joint location is not documented; request clarification on affected site for more specific coding. Because M05.70 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 M05.70 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Use this code when the specific joint location is not documented; request clarification on affected site for more specific coding
- •The absence of organ involvement distinguishes this from more severe systemic forms of rheumatoid arthritis
Clinical Significance
This code represents rheumatoid arthritis with positive rheumatoid factor at an unspecified location without systemic involvement, indicating localized inflammatory arthritis. While less severe than systemic forms, it still represents chronic inflammatory disease requiring ongoing management and monitoring.
Documentation Requirements
- ✓Confirmation of rheumatoid arthritis diagnosis
- ✓Positive rheumatoid factor laboratory result
- ✓Documentation that joint location is unspecified or unknown
- ✓Confirmation that no organ or system involvement is present
- ✓Clinical evidence of inflammatory arthritis
- ✓Exclusion of extra-articular manifestations
- ✓Disease activity assessment documentation
Commonly Confused Codes
- •M0570 vs M05.9: M05.9 is unspecified seropositive RA which may include systemic forms
- •M0570 vs M06.9: M06.9 is unspecified RA (may be seronegative)
- •M0570 vs M79.3: M79.3 is panniculitis, not rheumatoid arthritis
- •M0570 vs specific site codes: Use specific anatomic codes when location is documented
- •M0570 vs M05.40: M05.40 is rheumatoid myopathy with organ involvement