The Proximal Humerus Outcome Score at One Year (POSY) Predicts Which Patients Have Poor Functional Outcomes Following Operative Fixation of Proximal Humerus Fractures

Background: The ability to predict long-term outcomes following surgical fixation of proximal humerus fractures would help identify patients at risk of poor functional outcomes. The purpose of this study was to develop a simple score based on preoperative data that can accurately predict functional outcomes for patients following operative management of proximal humerus fractures. Methods: Over a 12-year period, all proximal humerus fractures surgically treated with a locked proximal humerus plate at a single institution were enrolled in a prospective database. Inclusion criteria in this analysis were any patient with a minimum of a one-year functional outcome score. Patients were assigned to the poor outcome cohort if their Disabilities of the Arm, Shoulder, and Hand (DASH) score at that time point was greater than 10 points above the mean DASH score. Logistic regression was used to build a predictive formula for cohort membership using p < 0.15 and an area under the receiver operator characteristic curve (AUROC) value was calculated to define the overall predictive capacity. Results: A total of 165 patients with an average age of 60.91±13.5 years met the inclusion criteria, with 47 (28.5%) patients assigned to the poor outcome group and 118 (71.5%) patients assigned to the good outcome group. Older age (p = 0.088), BMI (p = 0.019), age-adjusted CCI (p = 0.001), non-Caucasian race (p = 0.017), no college degree (p < 0.0005), unemployed (p < 0.0005), and worker’s compensation case (p = 0.002) were found to be significant predictors of poorer outcome and were used to create a final formula through logistic regression which predicted the probability of a poor outcome (Nagelkerke R Square = 0.403; Hosmer and Lemeshow = 0.902; AUROC = 0.839 [CI: 0.762-0.917]). Once each patient was assigned a score, cutoff values were defined that divided the cohort into three groups. High-risk patients had a score above 50%, and 19 (73.1%) of these patients had a poor outcome. Conclusions: The POSY score is a tool that can predict the functional outcome at one year or greater following surgical intervention for a proximal humerus fracture. Patients who score above 50% are considered at high risk for a poor functional outcome. In the era of value-based care, the POSY score may be used to direct resource utilization while improving outcomes.