M05.49Rheumatoid myopathy with rheumatoid arthritis of multiple sites

M05.49 is the ICD-10-CM diagnosis code for rheumatoid myopathy with rheumatoid arthritis of multiple sites. It belongs to category M05 (rheumatoid arthritis with rheumatoid factor), block M05-M14 (inflammatory polyarthropathies) and chapter 13 (diseases of the musculoskeletal system and connective tissue). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.

Within M05.4 (rheumatoid myopathy with rheumatoid arthritis), M05.49 is specifically for rheumatoid myopathy with rheumatoid arthritis of multiple sites. Related codes cover of unspecified site (M05.40), of shoulder (M05.41), of elbow (M05.42), of wrist (M05.43), of hand (M05.44), of hip (M05.45), of knee (M05.46) and of ankle and foot (M05.47).

As a secondary diagnosis it is a CC (complication or comorbidity), which can move an inpatient stay into the "with CC" MS-DRG of its family, unless the principal diagnosis excludes it.

In MS-DRG v44.0, it is part of the grouping logic for DRG 545 (Connective Tissue Disorders with MCC, relative weight 2.3892), DRG 546 (Connective Tissue Disorders with CC, relative weight 1.1745) and DRG 547 (Connective Tissue Disorders without CC/MCC, relative weight 0.7526), in MDC 08 (Diseases and Disorders of the Musculoskeletal System and Connective Tissue), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.

Before ICD-10, this condition was coded in ICD-9-CM as 359.6 (symptomatic inflammatory myopathy in diseases classified elsewhere) and 714.0 (rheumatoid arthritis).