Background/Purpose:

Despite extensive involvement of the feet in early RA, few studies report clinical and imaging changes in the feet over time. In this observational study, we aimed to 1) characterize 1-year changes in the feet using US, physical exam, and patient-reported outcomes; and 2) determine the associations between 1-year changes in these assessments.

Methods:

Patients with early RA (ACR criteria, DMARD naïve) were examined at baseline, 6 weeks, 3 months, 6 months, and 1 year. At each time point, the 2^nd -5^th MTP joints were examined by a rheumatologist [swollen joint count (SJC), tender joint count (TJC)], and imaged using US. Synovial thickening (ST) and power Doppler (PD) on US were graded semiquantitatively (0-3, max. score=24/patient for each). Patients also completed the Leeds Foot Impact Scale (LFIS) and Health Assessment Questionnaire (HAQ) at each visit.

Results:

Forty patients were enrolled [mean (SD) age=52.1(10.4) years, n=32 female]. Paired t-tests revealed significant 1-year improvements in inflammation on US (ST and PD), SJC and TJC, and patient-reported outcomes (Table 1). Over 1-year, ST scores improved in 30 patients and worsened in 7; PD scores improved in 16 patients and worsened in 5. Total ST and PD scores significantly correlated with each other at baseline (r=0.53, p<0.05) and 1-year (r=0.37, p<0.05); 1-year change scores were also correlated (r=0.42, p<0.05). Changes in PD scores, but not ST scores, significantly correlated with changes in LFIS and HAQ (Table 2). US findings did not significantly correlate with clinical exam at any time point or over 1-year. Associations between changes in SJC and TJC and patient reported outcomes are shown in Table 2.

Table 1: Mean scores of US, joint counts, and patient-report questionnaires at baseline and 1-year, and their respective paired t-test results.

* p<0.05, ** p<0.01, *** p<0.001

Table 2: Correlations between 1 year change in US findings, joint counts, and patient-reported questionnaires, accounting for their respective baseline values as covariates.

* p<0.05, ** p<0.01

Conclusion: Although all indicators of disease activity showed significant improvements after 1-year, only change in PD and change in SJC significantly correlated with change in patient-reported outcomes. Changes in ST may take longer to develop than 1-year, which may account for its insignificance. The lack of association between US and joint counts suggests that swelling and tenderness in the feet may be influenced by factors other than inflammation.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/one-year-changes-in-ultrasound-findings-in-the-feet-are-associated-with-patient-reported-outcomes-but-not-clinical-examination-a-prospective-observational-study-of-patients-with-early-rheumatoi/