Is there a threshold of preoperative function that predicts failure to achieve clinically significant outcomes after total and reverse shoulder arthroplasty?

Abstract

BackgroundThe purpose of this study was to determine if there is a threshold of preoperative function that is predictive of postoperative outcomes and the likelihood of achieving clinically significant outcomes following shoulder arthroplasty (SA). MethodsWe retrospectively identified patients who underwent a primary SA at our institution. Patients with preoperative and postoperative American Shoulder and Elbow Surgeons scores (ASES) were included in our analysis. A receiver operating characteristic (ROC) analysis was utilized to reach a preoperative ASES threshold correlated with achievement of the following clinically significant outcomes: minimal clinically important difference (MCID), substantial clinical benefit (SCB), and patient acceptable symptom state. This analysis was performed for our entire SA cohort and subanalyzed for total shoulder arthroplasty (TSA) and reverse shoulder arthroplasty (RSA). Fischer exact tests were used to analyze categorical data while continuous data were analyzed using t-tests. For the ROC, area under the curve (AUC) was calculated, along with bootstrap 95% confidence intervals and P values, with <0.05 as significant. ResultsA total of 516 patients were included (164 TSA and 352 RSA). ROC analysis yielded a preoperative ASES above 54 as predictive of failure to achieve MCID for all SAs (AUC, 0.77; P < .001), above 49 for TSA (AUC 0.74, P < .001), and above 56 for RSA (AUC 0.79, P < .001). Patients with preoperative ASES scores above 54 were significantly less likely to achieve MCID (odds ratio 5.1, P < .001) and SCB (odds ratio 7.2, P < .001); however, they had higher postoperative ASES scores (84 vs. 78, P < .001). A preoperative ASES score of 73 corresponded to a 50% chance of achieving MCID. ROC analysis also yielded a preoperative ASES score above 51 as predictive of failure to achieve SCB for all SA, TSA, and RSA (AUC: 0.79, 0.78, and 0.80, respectively, all P < .001). A preop ASES score of 52 corresponded to a 50% chance of achieving SCB. ConclusionPreoperative ASES scores above 49-56 are predictive of failure to achieve MCID and SCB following TSA and RSA. Although patients above these preoperative thresholds achieve higher absolute ASES scores at the final follow-up, they experienced less relative improvement from baseline. This will help surgeons counsel individual patients about appropriate expectations after arthroplasty.