Association of frailty indices with post-operative outcomes in shoulder surgery: a systematic review.

Hypothesis and/or Background: Frailty is a multidimensional state of diminished physiologic reserve that increases vulnerability to surgical stress and adverse post-operative outcomes. Although frailty indices have been associated with adverse outcomes across a variety of medical and surgical specialties, their role in shoulder surgery remains unclear. Methods: This systematic review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 guidelines. PubMed, Embase, Scopus, Web of Science, and the Cochrane Library were searched for studies evaluating frailty in patients undergoing shoulder surgery. Eligible studies included those that applied any frailty index and reported post-operative outcomes. Study quality was assessed using the Quality in Prognosis Studies tool. Results: Nineteen retrospective cohort studies were included. The surgical procedures evaluated were total shoulder arthroplasty, reverse shoulder arthroplasty, arthroscopic rotator cuff repair, and surgical management of proximal humerus fractures. The modified 5-item Frailty Index was the most frequently used frailty measure, followed by the Hospital Frailty Risk Score. Studies were categorized into four groups according to their original data source because several studies used overlapping databases. Frailty was consistently associated with increased post-operative complications, readmission, length of stay, non-home discharge, reoperation, and mortality. Limited evidence was available regarding the association between frailty and long-term functional outcomes. Overall, most studies were judged to have low to moderate risk of bias, although reliance on administrative databases and short-term outcomes was common. Discussion and/or Conclusion: Frailty indices are associated with an increased risk of complications, greater health-care utilization, and mortality following shoulder surgery. However, current evidence suggests that their ability to predict shoulder-specific complications, patient-reported outcomes, and long-term functional recovery remains limited. Frailty assessment may assist peri-operative risk stratification and patient counseling, although prospective studies using standardized, multidimensional frailty measures are needed to better define its prognostic value.