Corticosteroid injection for shoulder pain: single-blind randomized pilot trial in primary care

BACKGROUND Shoulder pain is a very common presentation in primary care. Evidence of benefit for subacromial corticosteroid injection is inconclusive and confined largely to studies with short follow-up. We plan a large, definitive, primary-care-based trial to determine efficacy and safety in patients with rotator cuff tendinopathy, and conducted a pilot trial to explore feasibility. METHODS Six general practitioners (GPs) from Oxfordshire, UK underwent update training in assessing painful shoulders and injecting the subacromial space. Each then recruited patients aged 35 to 74 years from primary care complaining of shoulder pain lasting no more than 6 months. Eligible participants were randomized to receive either methylprednisolone acetate 40 mg with lidocaine 1% (total volume 1 ml), or lidocaine 1% alone (total volume 1 ml), injected into the subacromial space. The participants were blinded to treatment allocation. Feasibility outcomes were rates of recruitment, withdrawal, adherence to the protocol, completeness of follow-up, and success of patient masking. Clinical outcomes were the Oxford Shoulder Score (OSS) at baseline and at 4 and 12 weeks, and responses to three satisfaction questions at 2, 4 and 12 weeks. Outcome data were collected by postal questionnaires. RESULTS A total of 40 participants were randomized (80% of the target 50 participants) over 26 weeks giving an overall recruitment rate of 1.5 participants per week. Rates of follow-up were maintained to a high level for the full 12 weeks. Four participants requested a 'rescue' corticosteroid injection but no patients withdrew. The trial GPs gave high scores for their confidence that the patient had remained blinded to treatment allocation during the procedure. The OSS at 4 and 12 weeks and the responses to the satisfaction questions are reported. CONCLUSIONS It is feasible to recruit participants with shoulder pain in the primary care setting for a blinded, randomized trial of corticosteroid injection. Online randomization of participants from the practice is also feasible, and postal questionnaires provide an effective means of gathering outcome data in this area of study. The lessons learned from this pilot will usefully inform the design of a large, definitive efficacy trial in primary care. TRIAL REGISTRATION Current Clinical Trials ISRCTN82357435.