The Maastricht Ultrasound Shoulder pain trial (MUST): Ultrasound imaging as a diagnostic triage tool to improve management of patients with non-chronic shoulder pain in primary care

This randomised controlled trial (RCT) will involve 226 adult patients with suspected subacromial disorders recruited by general practitioners. During a Qualification period of two weeks, patients receive care as usual as advised by the Dutch College of General Practitioners, and patients are referred for US. Patients with insufficient improvement qualify for the RCT. These patients are then randomly assigned to the intervention or the control group. The therapies used in both groups are the same (corticosteroid injections, referral to a physiotherapist or orthopedic surgeon) except that therapies used in the intervention group will be tailored based on the US results. Ultrasound diagnosed disorders include tendinopathy, calcific tendinitis, partial and full thickness tears, and subacromial bursitis. The primary outcome is patient-perceived recovery at 52 weeks, using the Global Perceived Effect questionnaire. Secondary outcomes are disease specific and generic quality of life, cost-effectiveness, and the adherence to the initial applied treatment. Outcome measures will be assessed at baseline, 13, 26, 39 and 52 weeks after inclusion. An economic evaluation will be performed from both a health care and societal perspective with a time horizon of 52 weeks.The results of this trial will give unique evidence regarding the cost-effectiveness of US as a diagnostic triage tool in the management of SP in primary care.With up to 100 new patient encounters per general practitioner (GP) per year, and a prevalence of 17-20% in the general population, shoulder pain (SP) is a common and sizable problem in primary care [1-4]. About 70% of the patients with a new episode of SP show incomplete recovery within six weeks, 50% report persistent complaints after six months, and 40% are not recovered after one year [4]. Troublesome pain is the most prominent symptom in adult patients with SP until the age of 65 years [5]. Prolonged and recurrent pain episodes result in frequent consulta