Rheumatoid Arthritis ICD-10-CM codes

Rheumatoid arthritis is split by rheumatoid factor status. M05 is RA with rheumatoid factor (seropositive) and M06 is other RA, which includes seronegative disease in M06.0-. M06.9 (rheumatoid arthritis, unspecified) is the default when serology is not documented and is the most frequently reported code. M05.A, added in FY2024, is RA with both abnormal rheumatoid factor and anti-CCP antibody. Adult-onset Still disease is M06.1 and inflammatory polyarthropathy without a firm RA diagnosis is M06.4.

The site-specific subcategories use a 5th character for the joint (1 shoulder, 2 elbow, 3 wrist, 4 hand, 5 hip, 6 knee, 7 ankle and foot, 8 vertebrae, 9 multiple sites, 0 unspecified) and a 6th character for laterality. Seropositive RA without organ involvement affecting multiple joints is M05.79; the seronegative equivalent is M06.09. The M05.1- through M05.6- subcategories are combination codes for RA with lung, vascular, cardiac, muscle or nerve involvement and take the place of a separate organ code. Juvenile RA is category M08 and is not reported with M05 or M06.

Add the long-term drug codes that reflect current therapy: Z79.52 for systemic steroids, Z79.631 for methotrexate as an antimetabolite, Z79.620 for a biologic such as a TNF inhibitor, and Z79.622 for a JAK inhibitor. Osteoarthritis and RA in the same patient are coded separately; do not report RA codes for an unspecified inflammatory arthritis that the provider has not called rheumatoid.