ICD-10 M05.40
Billable / Specific CCRheumatoid myopathy with rheumatoid arthritis of unspecified site
About ICD-10-CM M05.40
ICD-10-CM code M05.40 represents Rheumatoid myopathy with rheumatoid arthritis of unspecified site. This is a billable/specific code in the Musculoskeletal and Connective Tissue chapter (block M05). The 2026 edition of ICD-10-CM M05.40 became effective on October 1, 2025.
Coding Tips for M05.40
Specialist guidance from the PayerReady Medical Coding Team. Specificity warnings, HCC capture rules, sequencing notes.
M05.40 is designated CC for MS-DRG grouping. On inpatient claims, this code can shift the DRG to the with-CC variant when documented as a present-on-admission secondary diagnosis. Hospital CDI programs flag CC opportunities during chart review. Failure to capture this code may leave 30 to 80 percent of the inpatient stay revenue unrealized.
Medicare Advantage HCC Impact
Capture this diagnosis annually for accurate risk adjustment. Missed HCC captures are the #1 revenue leak in Medicare Advantage risk programs.
Inpatient DRG Impact, CC
codes Rheumatoid myopathy with rheumatoid arthritis of unspecified site. As a Complication/Comorbidity (CC), this contributes to DRG severity adjustment when documented alongside the principal diagnosis.
Medicare LCD Coverage for M05.40
Local Coverage Determinations (LCDs) from CMS MACs that list M05.40 as a covered diagnosis.
Showing top 10 of 85 total . Click a CPT for full coverage scope.
Commercial Payer Coverage
Coverage policies from major commercial payers referencing M05.40.
1 Cigna
5 Medicare
1 Aetna
CPT Codes Commonly Billed with M05.40
Procedures frequently paired with this diagnosis based on PayerReady's Dx↔Px linkage data.
- 81599 CMS LCD: Billing and Coding: MolDX: Molecular Biomarker Testing to Guide Targeted Therapy Selection in Rheumatoid Arthritis CMS LCD
Convert M05.40 to ICD-9-CM
Per CMS General Equivalence Mappings (GEMs), useful for legacy data review and historical claim analysis.
| ICD-10 | ICD-9 | Mapping Flags |
|---|---|---|
| M05.40 | 3596 | 10112 |
| M05.40 | 7140 | 10111 |
Flags format (5 digits): Approximate · No Map · Combination · Scenario · Choice List. Source: CMS 2017 GEMs (final version).
Codes Adjacent To M05.40
Other codes in section M05-M14 (Inflammatory polyarthropathies).
ICD-10 M05.40, Billing FAQ
Is ICD-10 code M05.40 billable? +
Yes, M05.40 is a billable ICD-10-CM code that can appear as a primary or secondary diagnosis on claims.
Is M05.40 a CC or MCC for inpatient DRG? +
Yes, this code is designated as CC. Documenting as a secondary diagnosis on inpatient claims can shift the DRG to a higher-weighted category.
What CPT codes are commonly billed with M05.40? +
Procedures frequently paired with M05.40 include: 81599.
What ICD-9 codes does M05.40 map to? +
Per CMS GEMs, M05.40 maps to ICD-9 codes: 3596, 7140. Useful for legacy data review and historical claim analysis.
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Reviewed by the PayerReady Medical Coding Team
Verified against the CMS 2026 code set on May 31, 2026.
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