Clinimetric analysis of the numeric pain rating scale, patient-rated tennis elbow evaluation, and tennis elbow function scale in patients with lateral elbow tendinopathy.

Background: Currently, there is conflicting clinimetric data on the patient-rated tennis elbow evaluation (PRTEE) and a paucity of evidence regarding the reliability, validity, and responsiveness of the numeric pain rating scale (NPRS), and tennis elbow function scale (TEFS) in patients with lateral elbow tendinopathy.

Objective: Perform a comprehensive clinimetric analysis of the NPRS, PRTEE, and TEFS in a sample of patients (n = 143) with lateral elbow tendinopathy.

Methods: Establish the reliability, construct validity, responsiveness, meaningful clinically important difference (MCID), and minimal detectable change (MDC₉₀) values for the NPRS, PRTEE, and TEFS at the 3-month follow-up.

Results: The NPRS [intraclass correlation coefficient (ICC_2,1): 0.54, 95% confidence interval (CI): 0.17-0.78], PRTEE (ICC_2,1: 0.62, 95% CI: 0.21-0.86), and the TEFS (ICC_2,1: 0.71, 95% CI: 0.14-0.90) exhibited moderate reliability. All three outcomes exhibited excellent responsiveness [NPRS: area under the curve (AUC): 0.94, 95% CI: 0.89-0.98]; PRTEE: (AUC: 0.96, 95% CI 0.93-0.99); TEFS: (AUC: 0.95, 95% CI: 0.91-0.98). The MCID and MDC₉₀ were 2.3 and 1.4 for the NPRS, 14.8 and 9.7 for the PRTEE, and 7.5 and 5.7 for the TEFS, respectively. All three patients reported outcome measures also demonstrated strong construct validity (Pearson's r from 0.71 to 0.83, p < .001).

Conclusion: The NPRS, PRTEE, and TEFS are clinimetrically sound patient reported outcome measures for patients with lateral elbow tendinopathy at a 3-month follow-up.

Registration at clinicaltrials.gov: NCT03167710.