Introduction
A Substantial Clinical Benefit (SCB) value is the amount of change in a patient reported outcome measure required for a patient to feel they significantly improved from an intervention. Previously published SCB values are often cited by researchers when publishing outcomes data. Where these SCB values are set can have a large impact on the conclusions drawn from a study citing them. As such, the goal of this study was to determine the generalizability of SCB values for a procedure when stratified by time and geographic region.
Methods
A nationwide outcomes database was utilized to obtain preoperative, one-year, and two-year postoperative outcome measurements for patients who underwent anatomic (aTSA) or reverse total shoulder arthroplasty (rTSA). The data was divided into three geographic regions: South, Midwest, and West. SCB values were calculated for four outcomes measures: Single Assessment Numeric Evaluation score, American Shoulder Elbow Society score, Visual Analogue Scale, and Western Ontario Osteoarthritis of the Shoulder score. SCB values were calculated for each region, for each procedure, and at both one and two years postoperatively. Simulated datasets were then created for each region to determine a distribution of possible calculated SCBs.
Results
380 aTSA patients and 543 rTSA patients were included for analysis. There was a high degree of variability of SCB values when stratified by procedure, time, and region. While some simulated datasets did produce homogenous SCB distributions amongst regions, some outcome measures demonstrated a large heterogeneity in distribution amongst regions, with concomitant large distributions of values within individual regions.
Conclusions
There is notable heterogeneity of SCB values when stratified by region or time. The current method of citing previously published SCB values for determining the efficacy of an intervention may be inappropriate.