Background/Purpose: A one-year methotrexate treatment in CSA has been shown to induce sustained reduction in subclinical inflammation during 2-years follow-up. We aim to study if treatment response, defined at the level of subclinical joint inflammation, is present in all CSA-patients and if not, what characterizes the subgroup of patients who do respond.

Methods: Within the randomized, placebo-controlled TREAT EARLIER trial 236 CSA-patients with subclinical inflammation were randomized to receive a singular intramuscular glucocorticoid injection and a one-year course of oral Methotrexate (n=119), followed by one-year observational follow-up. MRI scans were repeated after 4, 12 and 24 months, and at development of clinical arthritis. Treatment response was defined as a reduction of either synovitis, tenosynovitis or osteitis beyond the smallest detectable difference (SDC) at 12 months. Patients with treatment response were compared to patients without treatment response on their baseline clinical, serological and imaging characteristics. Predictive values of these baseline characteristics for treatment response were calculated. Longitudinal differences in patient-reported outcomes and HAQ-DI were compared between patients with and without treatment response.

Results: 38% of the patients treated showed a treatment response. These patients also improved on morning stiffness duration (-42 min), VAS pain (-22 mm) and physical functioning (HAQ-DI -0.29). In univariate analyses of baseline clinical and serological characteristics, morning stiffness >60 minutes and total HAQ-DI score were associated with treatment response and among the imaging characteristics, synovitis, tenosynovitis and osteitis. Only tenosynovitis and osteitis were associated with treatment response in multivariable analysis. The AUC was 0.84. Having > 2 locations of tenosynovitis or having > 1 location of tenosynovitis with > 2 locations of osteitis predicted treatment response well in this population (PPV 77%, 83%).

Conclusion: A subgroup of CSA patients responded best to methotrexate; these patients can be recognized with imaging and by having ≥2 tendon sheaths with tenosynovitis or ≥ 1 site of tenosynovitis with ≥ 2 bones with osteitis. These data may contribute to personalized medicine for individuals with arthralgia who are at risk for RA.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/which-arthralgia-patients-at-risk-for-ra-benefited-from-treatment-with-methotrexate-results-from-the-treat-earlier-trial/