OA09 Progression of foot involvement in individuals at risk of rheumatoid arthritis: findings from a UK cohort study

Foot involvement is prevalent and disabling in rheumatoid arthritis (RA); foot symptoms persist even when clinical remission is achieved. Targeted therapies for local inflammation and mechanically-based impairments (foot orthoses) have been shown to reduce foot symptoms in early disease. A preclinical phase of RA, during which anti-CCP positive at-risk (CCP+ at-risk) individuals develop autoantibodies and/or symptoms before progressing to clinical arthritis, is well established. This study aimed to describe foot involvement (patient-reported painful and tender joints, clinician-reported tender and swollen joints, ultrasound imaging features) in individuals at risk of RA and at the point of RA development.

CCP+ at-risk individuals with musculoskeletal symptoms without synovitis were recruited to the Leeds CCP cohort (2008-2022). In individuals who developed RA (n = 170, 120 [70.6%] women, mean age [SD] 53.4 [13.5] years), foot-related (ankle, metatarsophalangeal [MTP] joints) patient-reported and clinician-reported outcomes, and ultrasound abnormalities (bone erosions, power Doppler, greyscale), at baseline and at the point of RA development, were described.

Foot-related symptom progression at the point of RA development is presented in Table 1. Between 25.8% (n = 24/93) and 31.2% (n = 29/93) participants had worsening patient-reported pain and/or tenderness at the point of RA development, compared to baseline. Between 12.4% (n = 19/153) and 20.9% (n = 32/153) participants had new/worsening clinician-reported swelling and/or tenderness in the ankle or MTP joints. New/worsening erosive disease was most prevalent in the 5^th MTP joint (17.2%, n = 16/93), followed by the 1^st MTP joint (5.4%, n = 5/93). New/worsening power Doppler scores in the MTP joints occurred in 6.5% (n = 6/93) to 11.8% (n = 11/93) participants, and new/worsening greyscale scores were common in all foot sites assessed (32.4% [n = 22/68] to 55.4% [n = 51/92] participants).

Patient-reported and clinician-reported foot involvement is more common at the point of RA diagnosis than at baseline, consistent with power Doppler and greyscale measures. Erosive damage occurs in the foot prior to RA diagnosis. In line with established RA, bony erosions are most common in the 5^th MTP joint during the preclinical phase of RA. These findings indicate the importance of asking about and examining the feet in individuals at risk of RA, with early input from specialist foot services recommended.

L.S. Chapman: None. L. Duquenne: None. L. Garcia-Montoya: None. J.L. Nam: None. M. Wilson: None. E.M.A. Hensor: None. P. Emery: Consultancies; Lilly, Galapagos. Honoraria; Novartis, Lilly, Abbvie, Gilead, Galapagos. Grants/research support; Lilly, Samsung. Other; Participation on advisory boards for Lilly, Astra Zeneca, BMS. K.S. Mankia: Consultancies; Abbvie, UCB, Galapagos, Lilly, Serac Healthcare, Zura Bio, Deepcure. Grants/research support; Gilead, Eli Lilly, Serac Healthcare, Astra Zeneca, Deepcure. H.J. Siddle: Honoraria; Janssen.