Longitudinal Reliability Validated for OMERACT Thumb Base Osteoarthritis MRI Scoring System

Study data published in The Journal of Rheumatology confirm the longitudinal reliability of the Outcome Measures in Rheumatology thumb base osteoarthritis (OA) magnetic resonance imaging (MRI) scoring system (TOMS).

Paired MRI data of 25 patients from the Hand Osteoarthritis in Secondary Care cohort study were scored in known time-order by 3 independent readers. All participants had a clinical diagnosis of hand OA, and each underwent an MRI at baseline and at 2 years’ follow-up.

Additional data were abstracted from paired MRI data of 24 patients with hand OA from a double-blind trial comparing lutikizumab with placebo. For this subcohort, MRI data were available at baseline and at 6 months follow-up. MRI scans were assessed for synovitis, subchondral bone defects, osteophytes, cartilage assessment, bone marrow lesions, and subluxation.

On average, minimal change was observed in TOMS scores between those assessed at 6 months and those assessed at 2 years. However, within-patient differences were observed over time.

Average-measure intraclass correlation coefficients were typically within the “good” to “excellent” range (≥0.71), with the exception of synovitis (0.55-0.83) and carpometacarpal-1 osteophytes (0.47) and cartilage assessment (0.39).

Percentage exact and close agreement values for all joint features ranged from 52% to 92%, and from 68% to 100%, respectively, except for bone marrow lesions at 2 years. For each feature, the smallest detectable change was calculated and was below the scoring increment for all metrics except in subchondral bone defects and bone marrow lesions.

These data support the longitudinal reliability of the TOMS as a metric of OA. Limited change in patient condition over time may have limited assessment, however. Further research with patients in varying disease stages may further elucidate the effectiveness of TOMS.

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Reference

Kroon FPB, van Beest S, Gandjbakhch F, et al. Longitudinal reliability of the OMERACT thumb base osteoarthritis magnetic resonance imaging scoring system (TOMS) [published online December 15, 2018]. J Rheumatol. doi: 10.3899/jrheum.180949