PAIN-RELIEF ALTERNATIVE FOR SHOULDER SURGERY (PASS TRIAL): The Novel Anterior Suprascapular Nerve Block vs. Conventional Interscalene Brachial Plexus Block for Pain-Relief Following Arthroscopic Shoulder Surgery: A Multi-centre Randomized, Patient and Assessor Blinded, Non-inferiority Trial

Introduction Interscalene nerve block (ISB) is the pain relief standard for shoulder surgery. But ISB is invasive and associated with complications. Suprascapular nerve block (SSNB) may be an alternative; but evidence of comparative efficacy is sparse. We examine whether SSNB is non-inferior to ISB for pain after shoulder surgery. Methods 140 shoulder surgery patients were enrolled into this multi-centre non-inferiority trial. Patients were randomized to ISB or SSNB. Pain at 6 hours (Numerical Rating Scale, NRS) was designated as primary outcome. A difference of -1.3 units was set as non-inferiority margin. Results The mean difference (90% confidence interval) in pain for the (ISB-SSNB) comparison was -0.40 (-1.10, 0.30), less than the non-inferiority margin (P=0.016), suggesting non-inferiority of SSNB for pain at six hours. Conclusion SSNB is an effective alternative to ISB for pain after shoulder surgery. SSNB can be considered for patients at high risk for complications with ISB.M.Sc