Unilateral versus bilateral ultrasound of the hands in patients with clinically suspect arthralgia: what is the difference? A longitudinal study

Objective In clinically suspect arthralgia(CSA) ultrasound(US) can be used to detect subclinical joint-inflammation, which is a known predictor for progression to clinically apparent inflammatory arthritis(IA). Most US-protocols include both hands, while a more efficient, unilateral US approach is also sufficient, has never been investigated. Therefore, we described US-findings for one and both hands in CSA-patients and investigated if a US-protocol that includes one hand is as predictive as a protocol with two hands. Methods CSA-patients of two cohorts underwent bilateral US. Subclinical synovitis and tenosynovitis (Gray Scale ≥2 and/or Power Doppler ≥1) in one and both hands were described per hand and joint. Additionally, we analyzed the association between inflammatory arthritis (IA)-development and US-positivity. Results In total, 320 patients were studied. In cohort 1, 23% patients had bilateral US-detected subclinical (teno)synovitis, 20% only in the dominant hand and 10% only in non-dominant hand. In cohort 2, 10% had bilateral involvement, 12% in the dominant hand only and 8% in the nondominant hand only. US of the dominant hand predicted IA-development almost equal compared to US of both hands, with hazard ratios of 2.8(95%CI 1.3-6.0) for both hands and 2.6(95%CI 1.3-5.3) for the dominant hand in cohort 1. In cohort 2, HRs were comparable. Conclusion US-detected subclinical (teno)synovitis in CSA-patients is partly bilateral and partly unilateral. Predictive values for IA-development are comparable. To reduce scanning time in clinical practice one could consider scanning the one hand instead of both hands in patients with CSA.