Does pre-operative metabolic and nutritional assessment have greater association with perioperative complications than frailty following surgical intervention for proximal humerus fractures?

Background Proximal humerus fractures (PHF) often occur in an elderly population at-risk for complications following surgery. However, it is unknown whether acute preoperative metabolic and nutritional (M+N) variables versus more chronic frailty evaluation is better linked to these poor outcomes. The purpose of this study is to compare the associations of the M+N index versus frailty with the outcomes of surgical intervention for PHFs. Methods A patient-deidentified, national database was queried from 2015-2020 for patients undergoing surgical management of PHFs. Tiered frailty scores were calculated as defined by the revised Risk Analysis Index (RAI). M+N index was derived using backstep stepwise logistic regression modeling to identify preoperative nutritional and metabolic lab values associated with development of any complication following surgery. Outcomes included 30-day mortality, readmission, length of stay, and complications. ANOVA and binary logistic regression were used to assess associations with odds ratio (OR) and 95% confidence interval (CI). Discriminatory accuracy was quantified by Receiver Operating Characteristic curve analysis and C-statistics. Results A total of 6,020 patients with PHFs underwent surgical intervention (67% ORIF, 33% rTSA). The generated M+N index was composed of the following variables significantly associated with complications: creatinine, albumin, hematocrit, INR, and sodium. The M+N index had superior predictability to RAI for any complication (AUC: 0.749 vs. 0.674), postoperative blood transfusion (AUC: 0.812 vs. 0.704), length of stay greater than 3 days (0.901 vs. 0.679) and reoperation (AUC: 0.656 vs. 0.542), with each significant association also seen in a frail-only cohort. In a mixed effects model, M+N index factors and RAI generated independent significant effects (both p<.001). Discussion While frailty assessment may play a role in evaluating preoperative risk and informing optimization strategies, preoperative metabolic and nutritional status has greater association with perioperative complications and disposition following surgery for proximal humerus fractures. These values may also be more readily optimized in the inpatient setting and, therefore, future studies should focus on the effects of implementing management strategies to alter metabolic and nutritional status prior to surgical intervention and potentially mitigate perioperative risk.