Generalizability of Eccentric Exercise for Patients with Subacromial Pain Syndrome to Real-world Clinical Practice: A Propensity Score-based Analysis

OBJECTIVES: Subacromial pain syndrome is a common problem in primary care. Although several randomized controlled trials have shown that eccentric exercise is effective in patients with subacromial pain syndrome, its generalizability to real-world clinical practice is unknown. This study aimed to investigate, using propensity score analysis, the generalizability of eccentric exercise for patients with subacromial pain syndrome to real-world daily clinical practice. METHODS: In this study, 78 patients underwent eccentric exercise in addition to traditional exercise, and 77 patients underwent only traditional exercise for 4 weeks. Outcomes measured using a visual analog scale (VAS) and American Shoulder and Elbow Surgeons Society Standardized Shoulder Assessment Form (ASES) scores were assessed at baseline and at 4 weeks. RESULTS: In the propensity score-matched analysis, 65 patients in each group were successfully matched (130 of 155 patients, 84% overall). After 4 weeks of exercise, pain intensity was lower in the eccentric exercise group than in the traditional exercise group (VAS −14.5, 95% CI −21.2 to −7.9, P<0.001). No significant difference in the improvement in function was found between the two groups (ASES 4.1, 95% CI −2.0 to 10.2, P=0.18). CONCLUSIONS: Eccentric and traditional exercise in combination could reduce pain in patients with subacromial pain syndrome to a greater extent than traditional exercise alone. These findings have clinical relevance to primary care practitioners who provide conservative treatment for patients with subacromial pain syndrome.