Minimal clinically important difference of Liverpool Elbow Score in elbow arthroplasty.

BACKGROUND

The minimal clinically important difference (MCID) that allows the interpretation of small but meaningful changes after intervention has not been reported for the Liverpool Elbow Score (LES). This study aimed to determine the MCID for the LES in patients undergoing total elbow replacement.

METHODS

This observational study is based on preoperative and 1-year postoperative clinical outcome of total elbow replacement (Discovery Elbow System) in 71 patients using the LES. A 4-point Likert-like transition scale was used to evaluate patient satisfaction after total elbow replacement. A combination of distribution-based methods (standard deviation [SD] of change in the LES, standard error of mean, smallest detectable change [SDC]) and anchor-based methods (receiver operating curve, difference of mean of change in LES) was used to determine range of MCID values.

RESULTS

The mean change in the LES value was 2.4 (SD, 2.1). The estimated SDC value with upper limit of 90% confidence interval was 1.5. The mean change in LES of "satisfied" and "somewhat satisfied" patient groups was 2.4 (SD, 2.1) and 1.1 (SD, 1.4), respectively, and the difference between both means (MCID based on difference of mean in 2 subgroups) was 1.3. According to receiver operating curve analysis, the value of MCID was 1.6.

CONCLUSION

The MCID value for the LES was estimated to range between 0.7 and 1.8. The estimated SDC value was 1.5. We propose that the "true" MCID value of the LES would be between 1.6 and 1.8 to ensure that the value is higher than the measurement error of the LES.