Predicting outcomes across treatment settings in patients with shoulder pain referred to physiotherapy: a secondary analysis of two comparable prospective cohort studies.

Objective: Previous studies have examined factors that may contribute to predicting outcomes for patients with shoulder pain. However, there is still a lack of consensus on which factors predict the results and whether there are differences based on the treatment setting. Thus, this study aimed to analyse and compare how baseline variables are associated with future outcomes in patients with shoulder pain in primary and secondary care settings. Methods: This study conducted a secondary analysis of two observational prospective cohort studies involving patients with shoulder pain in primary care (n=150) and secondary care (n=183). Multiple regression analyses were employed, with one interaction term at a time, to examine potential differences in association with baseline characteristics and future outcomes between the two settings. Results: Changes in pain and function were statistically significant at 6 months for patients in primary care and secondary care. However, associations for most baseline variables and outcomes did not differ significantly across these two treatment settings. The only statistically significant interactions observed were for the associations between baseline level of pain, function and fear avoidance beliefs and change in pain scores at 6 months, with lower change scores observed among patients in the secondary care. Conclusion: This study revealed that the association with outcomes did not differ across settings for most baseline characteristics. These findings suggest that it could be feasible to generalise the prognostic value of most baseline variables for patients with shoulder, irrespective of the treatment setting.