An example: patients with chronic pain due to shoulder impingement who participated in the Can Shoulder Arthroscopy Work? trial

Shoulder pain is a common condition in the general population, with prevalence in the UK of about 14%. It is associated with high socioeconomic burden because it limits patients' ability to work and to perform everyday tasks. Standard therapy is arthroscopic subacromial decompression, though there is little evidence to support its effectiveness. In light of this, the Can Shoulder Arthroscopy Work? (CSAW) trial was devised. CSAW is a three-group parallel design RCT assessing the clinical and cost-effectiveness of arthroscopic subacromial decompression for shoulder pain. This trial was initiated because, although subacromial decompression is frequently performed, the evidence of effectiveness of this procedure is limited and there is an equipoise whether removal of a bony spur on the acromion of the scapula relieves shoulder pain. In this trial, patients were randomised either to arthroscopic surgery with spur removal (active arm), diagnostic arthroscopy only (placebo arm) or active monitoring with specialist reassessment (control arm). The patients were told that arthroscopy only did not include the critical element of the standard procedure. The risks associated with both these procedures were fully explained. Importantly, the placebo intervention (arthroscopy only) in this trial had direct clinical benefits as patients with alternative diagnosis were removed from the trial and received appropriate treatment. The study is described in more detail in the protocol.14 The trial is still ongoing, and first results will be available at the end of 2016.