M05.59 ICD-10-CM Code: Rheumatoid polyneuropathy with rheumatoid arthritis of multiple sites
HCC Buddy Code Card
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FY 2026 Apr update / Diseases of the musculoskeletal system and connective tissue (M00-M99) / Inflammatory polyarthropathies (M05-M14)
M05.59
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceRheumatoid polyneuropathy with rheumatoid arthritis of multiple sites
Rheumatoid arthritis with nerve damage affecting multiple joints throughout the body.
Buddy Insight
Represents rheumatoid arthritis with polyneuropathy affecting multiple sites, indicating severe systemic inflammatory disease with widespread joint and neurological involvement.
CMS-HCC V28
MappedHCC 93
RAF 0.617
CMS-HCC V24
MappedHCC 40
RAF 0.421
+ HCC 75
ACA/HHS
MappedHCC 56, 115
Varies by metal level
ESRD/PACE
MappedHCC 40
RAF 0.058
+ HCC 75
RXHCC
MappedHCC 83
RAF 0.222
+ HCC 158
Code Book Path
Inclusion Terms
OfficialICD-10-CM does not list inclusion terms for M05.59 in this effective period.
Excludes 2
OfficialICD-10-CM does not list Excludes 2 notes for M05.59 in this effective period.
Related Child Codes
Includes
OfficialICD-10-CM does not list Includes notes for M05.59 in this effective period.
Excludes 1
OfficialICD-10-CM does not list Excludes 1 notes for M05.59 in this effective period.
Code First
OfficialICD-10-CM does not list Code First sequencing instructions for M05.59 in this effective period.
Use Additional
OfficialICD-10-CM does not list Use Additional Code instructions for M05.59 in this effective period.
Code Also
OfficialICD-10-CM does not list Code Also instructions for M05.59 in this effective period.
Buddy Documentation Tip
MEAT Support
Audit Caution
Common Mistakes
Current with CMS: FY2026 ICD-10-CM Apr 1 update (effective Apr 1 – Sep 30, 2026) · CMS-HCC V28, 100% phased in for payment year 2026. FY2027 code set already staged for October 1, 2026. How HCC Buddy stays current →
Is M05.59 an HCC code?
Yes. M05.59 (Rheumatoid polyneuropathy with rheumatoid arthritis of multiple sites) maps to Rheumatoid Arthritis and Other Specified Inflammatory Rheumatic Disorders under the CMS-HCC V28 risk adjustment model (and Rheumatoid Arthritis and Inflammatory Connective Tissue Disease under V24), with a community non-dual aged RAF of 0.617. It is billable for payment year 2026.
Coder answer: M05.59 is billable and maps to V28 HCC 93, Rheumatoid Arthritis and Other Specified Inflammatory Rheumatic Disorders. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.
- Code
- M05.59
- Description
- Rheumatoid polyneuropathy with rheumatoid arthritis of multiple sites
- HCC (V28)
- HCC 93 — Rheumatoid Arthritis and Other Specified Inflammatory Rheumatic Disorders
- RAF
- 0.617
- Billable
- Yes
- Payment year
- 2026
HCC Category Mapping
Each model's RAF is its CMS base weight for that model's standard population, so weights are not directly comparable across models: CMS-HCC V28 and V24 use Community, Non-Dual, Aged; ESRD uses the dialysis continuing-enrollee model; RxHCC is the Part D continuing-enrollee, non-low-income, aged weight (a larger scale than CMS-HCC). ACA/HHS has no single weight — it varies by metal level. 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.
Work M05.59 in the Code Book — tabular path, V28 RAF, and MEAT checklist →
MEAT Criteria for M05.59
For M05.59 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 M05.59 during that encounter, not just copy-forwarded from a problem list.
Coder workflow notes
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What This Code Means
M05.59 is the ICD-10-CM diagnosis code for rheumatoid polyneuropathy with rheumatoid arthritis of multiple sites. Rheumatoid arthritis with nerve damage affecting multiple joints throughout the body. M05.59 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, M05.59 maps to Rheumatoid Arthritis and Other Specified Inflammatory Rheumatic Disorders (HCC 93) with a community, non-dual, aged base RAF weight of 0.617. Under the older CMS-HCC V24 model, M05.59 maps to Rheumatoid Arthritis and Inflammatory Connective Tissue Disease (HCC 40) with a community, non-dual, aged base RAF weight of 0.421. 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.
This code indicates involvement of three or more joint sites. Because M05.59 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 M05.59 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •This code indicates involvement of three or more joint sites
- •Document should clearly show polyneuropathy and rheumatoid arthritis affecting multiple anatomical locations
Clinical Significance
Represents rheumatoid arthritis with polyneuropathy affecting multiple sites, indicating severe systemic inflammatory disease with widespread joint and neurological involvement. This diagnosis reflects the most complex form of RA with extensive organ system involvement requiring intensive medical management.
Documentation Requirements
- ✓Confirmed rheumatoid arthritis diagnosis with established criteria
- ✓Documentation of polyneuropathy through clinical or diagnostic evidence
- ✓Multiple joint sites involvement clearly documented
- ✓Evidence of systemic inflammation and high disease activity
- ✓Comprehensive neurological assessment confirming polyneuropathy
- ✓Functional assessment showing multi-system impairment
- ✓Documentation of aggressive treatment regimen including biologics
- ✓Physician documentation of RA-polyneuropathy causal relationship
Commonly Confused Codes
- •M05.60: RA with organ involvement but without multiple site specification
- •M06.89: Other specified rheumatoid arthritis without polyneuropathy
- •G62.9: Polyneuropathy without rheumatoid arthritis connection
- •M79.3: Panniculitis without confirmed RA diagnosis
- •M35.9: Connective tissue disorder without specific RA diagnosis