Background/Purpose: A phase of arthralgia precedes the emergence of rheumatoid arthritis (RA). It is unknown if patients have functional limitations in this phase. We assessed functional disability in patients with Clinically Suspect Arthralgia, its association with MRI-detected subclinical inflammation and with progression to clinical arthritis.

Methods: From April 2012 to April 2015, 255 CSA-patients had arthralgia for <1 year and were, based on clinical presentation, considered at risk for RA by their rheumatologists. At baseline, functional disability was assessed using HAQ-scores. Subclinical inflammation was assessed using unilateral 1.5Tesla MRI of MCP, wrist and MTP-joints. Synovitis, tenosynovitis and bone marrow edema scores were summed in the total MRI-inflammation score. Patients were followed on arthritis development.

Results: Median HAQ-score at presentation was 0.50. Higher total MRI-inflammation scores were associated with higher HAQ-scores (β=0.017, 95%CI=0.004-0.030). During median 61 weeks follow-up, 41 patients progressed to clinical arthritis. HAQ-scores ≥1.0 were associated with arthritis development (HR=4.60, 95%CI=1.54-13.75). Within converters, median HAQ-scores did not increase from presentation with Clinically Suspect Arthralgia to arthritis development (0.88 and 0.75, p-value=0.59).

Conclusion: Functional limitations already exist during the symptomatic pre-arthritis phase, with a similar severity as in the early clinical arthritis-phase. HAQ-scores ≥1.0 were associated with progression to clinical arthritis. Figure 1. Kaplan-Meier One Minus Survival plot showing cumulative progression to clinical arthritis for CSA-patients divided in four groups based on their baseline HAQ-score. Glossary: Patients were appointed into quartiles according to their total HAQ-score to create four subgroups with equal numbers, see supplementary file 2. Each line represents one HAQ-score quartile and cumulative progression to clinical arthritis. The lowest quartile contains patients with HAQ-scores <0.25 with N=49. The second quartile contains HAQ-scores 0.25–0.50 (N=67), with a HR for progression to clinical arthritis of 1.2 (95%CI=0.37–4.3). Patients in the third quartile had HAQ-scores 0.63–0.88 (N=53) with a HR for progression to clinical arthritis of 2.4 (95%CI 0.77–7.8). Finally, the quartile with the highest HAQ-scores contains HAQ-scores ≥ 1.0. (N=49).The hazard ratio for this quartile (HR=4.60, 95%CI=1.54–13.75) was significantly elevated, compared to the lowest quartile.