Ultrasound-detected synovitis of the forefoot in patients with early rheumatoid arthritis, unlike that of the hand, does not correlate positively with 28-joint disease activity scores.

Abstract

Objective : This study aimed to clarify the relationship between the ultrasound (US)-detected forefoot synovitis and systemic disease activity and functional disability in patients with early rheumatoid arthritis (ERA). Methods : Thirty-eight ERA patients (6 men, 32 women) prior to initiation of tight-control treatment were included. Semiquantitative US assessment for bilateral finger, wrist, and forefoot joints was conducted using gray-scale (GS) and power Doppler (PD), and each summation was defined as hand, foot, and total scores. The accuracy of US based on the physical examination for the metatarsophalangeal (MTP) joints was determined. The relationshio between each US score and composite measures using 28-joint counts, serum biomarkers, and patient-reported functional impairment scores was analyzed. Results : Based on MTP joint swelling and tenderness, for GS and PD scores ≥ 1, the positive predictive value was low (GS: 16.0%, 12.5%; PD: 38.5%, 17.5%). Hand US scores, especially in hand PD scores, showed a significant moderate positive correlation with disease activity scores and biomarkers; however, foot US scores showed no positive correlation with any factor. The results were robust in multivariate analyses that incorporated each score and were adjusted for age. Conclusions : US-detected forefoot synovitis may not be reflected in the composite disease activity scores not including direct forefoot assessment in ERA patients.