The Achilles tendon Total Rupture Score (ATRS): development and validation

Abstract

Background: There is a need for a patient-relevant instrument to evaluate outcome after treatment in patients with a total Achilles tendon rupture.

Purpose: To develop and validate a new patient-reported instrument for measuring outcome after treatment for total Achilles tendon rupture.

Study design: Cohort study (diagnosis); Level of evidence, 1.

Methods: Development of this instrument consisted of item generation and test construction, item reduction, validation, evaluation of structure and internal consistency, test-retest, and test for responsiveness. The final version, the Achilles tendon Total Rupture Score (ATRS), was tested for validity, structure, and internal consistency (Cronbach's alpha) on 82 patients and 52 healthy persons. A correlation analysis was performed of the ATRS with the 2 validated foot/ankle/Achilles tendon scores, the Foot and Ankle Outcome Score (FAOS) and the Swedish version of the Victorian Institute of Sports Assessment-Achilles questionnaire (VISA-A-S). Structure was evaluated with factor analysis. Test-retest reliability was evaluated on 43 patients. The ATRS responsiveness was tested on 43 patients by calculating the effect size.

Results: The total score for the patients ranged from 17 to 100 with a mean (median) of 77 (85) and a standard deviation (interquartile range) of 21.4 (23). A significantly (P < .0001) higher total score was found for the healthy subjects, ranging from 94 to 100 with a mean (median) of 99.8 (100) and a standard deviation (interquartile range) of 1.1 (0). The ATRS correlated significantly (P < .01) with all subscales of the FAOS (r = 0.60-0.84) and the VISA-A-S (r = 0.78). The factor analysis gave 1 factor of importance. The internal consistency was 0.96 as measured with Cronbach's alpha. The test-retest produced an intraclass correlation coefficient of 0.98. The tests for responsiveness showed an effect size between 0.87 and 2.21.

Conclusion: The ATRS is a patient-reported instrument with high reliability, validity, and sensitivity for measuring outcome after treatment in patients with a total Achilles tendon rupture.

Clinical relevance: The ATRS is a self-administered instrument with high clinical utility, and we suggest the score for measuring the outcome, related to symptoms and physical activity, after treatment in patients with a total Achilles tendon rupture.