Modifiable pre-operative physiological predictors of length of stay following shoulder arthroplasty: a systematic review

Shoulder arthroplasty volumes have increased markedly, intensifying pressure on hospital resources. Prolonged hospital length of stay (LOS) elevates costs, complications, and societal burden. Identifying modifiable pre-operative predictors of LOS may enable targeted optimization to improve outcomes and efficiency. A systematic search of PubMed, Embase, Medline, Scopus, and Web of Science was conducted through July 20, 2025, following Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 and Synthesis Without Meta-analysis guidelines. Studies including adults undergoing shoulder arthroplasty, reporting patient- or procedure-related factors associated with LOS, were included. Due to heterogeneity, qualitative synthesis was performed. Sixty-four studies (n = 2,435,166) were included. Prolonged LOS was consistently associated with anemia (7 studies, 1.8-5.0 days depending on severity), malnutrition or nutritional risk (2 studies, 2.2-3.7 days), hypoalbuminemia (3 studies, 2.3-3.5 days), insulin-dependent or complicated diabetes (9 studies, 0.5-0.7-day increase), higher American Society of Anesthesiologists grade (7 studies, 2.6-4.3 days), frailty or functional indices (3 studies, graded increases), cumulative comorbidity burden (≥10 studies), and pre-operative opioid use (7 studies, 1.4-2.3 days). Dehydration (2 studies), electrolyte disturbances (3 studies), and mental health disorders particularly depression (7 studies, 2.0-3.0 days) were also associated with longer LOS. Morbid obesity (body mass index ≥40 kg/m2) modestly increased LOS (mean difference 0.3-0.4 days), whereas general obesity (body mass index 30-40) showed inconsistent associations across 13 studies. Global physiological measures (American Society of Anesthesiologists grade, frailty, comorbidity burden) outperformed individual comorbidities in predicting LOS. Physiological reserve, metabolic factors, and mental health are key modifiable determinants of LOS after shoulder arthroplasty. Pre-operative optimization targeting anemia, nutrition, glycemic control, and mental health may reduce hospital LOS and facilitate short-stay or same-day pathways. These findings provide an evidence-based framework for perioperative planning to improve patient outcomes and resource utilization.