The usefulness of ultrasound in predicting outcomes in patients with shoulder pain: a prospective observational study.

Abstract

Shoulder pain is common but current clinical classification has limited utility. We aimed to determine whether groups of ultrasound-based shoulder pathologies exist and to evaluate outcomes according to identified groups and individual pathologies. Prospective study of a community-based cohort with shoulder pain referred for their first ultrasound scan at a single radiology unit, with subsequent routine clinical care. Patient-reported outcomes were collected at baseline, 2 weeks and 6 months; standardised ultrasound reporting was employed. Latent class analysis (LCA) identified ultrasound pathology-based groups. Multiple linear regression analysis explored associations between baseline pathologies, subsequent treatment and shoulder pain and disability index (SPADI). Short-term response to corticosteroid injections was investigated. Of 500 participants (mean age 53.6; 52% female), 330 completed follow-up. LCA identified 4 groups: bursitis with (33%) or without (27%) acromioclavicular joint degeneration, rotator cuff tear (21%), no bursitis/tear (19%). Total SPADI was higher at baseline for cuff tears (mean 55.1 vs 49.7-51.3; overall p= 0.005), but accounting for this, groups did not differ at 6 months (43.5 vs 38.5-40.5; p= 0.379). Baseline SPADI was the only predictor of 6-month SPADI retained by penalised modelling; neither LCA-derived US groups nor individual pathologies were selected. Response to baseline injection at week 2 did not differ between groups (mean SPADI 40.1-43.8; p= 0.423). Ultrasound-based classification (groups or individual pathologies) of shoulder pain did not predict medium-term outcomes using current treatments. The role of routine diagnostic ultrasound for shoulder pain needs consideration; it may be useful if evidence-based therapies for specific pathologies are established.