Measuring clinically important change with the Patient-rated Tennis Elbow Evaluation

Introduction. The Patient-rated Tennis Elbow Evaluation (PRTEE) enables quantitative rating by the patient of pain and functional impairment associated with tennis elbow or lateral elbow tendinopathy. When used as an outcome measure in trials of therapies, a minimum clinically important difference (MCID) value is required to interpret trial outcomes. This study aimed to calculate the MCID for a sample of patients diagnosed with lateral elbow tendinopathy (LET). Methods. The PRTEE was used as an outcome measure with participants in a trial of a novel therapy for LET. It was administered at baseline and after treatment, three weeks later. Score changes were compared with patient-rated global change scores using receiver operating curve analysis. MCID values were calculated for two different criteria of clinically important difference and the effects of baseline symptom severity on the MCID were investigated. Results. Data were available from 57 participants, with PRTEE scores in the range 13-81/100. For clinical significance defined as 'a little better' the MCID for the total PRTEE score was 7/100 or 22% of baseline score. For clinical significance defined as 'much better' or 'completely recovered', the MCID was 11/100 or 37% of baseline score. The MCID value was higher for a subgroup with greater baseline severity. Conclusions. Substantial changes in the PRTEE scores are required before they can be considered clinically significant. Clinically significant change varies according to the baseline score. The instrument may be less sensitive to change when used by people who are symptomatic in their non-dominant arm.