Reliability and Validity of The Finnish Version of The Boston Carpal Tunnel Questionnaire among Surgically Treated Carpal Tunnel Syndrome Patients

Background and Aims: The Boston Carpal Tunnel Questionnaire is the most commonly used outcome measure in the assessment of carpal tunnel syndrome. The purpose of this study was to translate the original Boston Carpal Tunnel Questionnaire into Finnish and validate its psychometric properties. Materials and Methods: We translated and culturally adapted the Boston Carpal Tunnel Questionnaire into Finnish. Subsequently, 193 patients completed the Finnish version of the Boston Carpal Tunnel Questionnaire, 6-Item CTS Symptoms Scale, and EuroQol 5 Dimensions 12 months after carpal tunnel release. The Boston Carpal Tunnel Questionnaire was re-administered after a 2-week interval. We calculated construct validity, internal consistency, test-retest reliability, and coefficient of repeatability. We also examined floor and ceiling effects. Results: The cross-cultural adaptation required only minor modifications to the questions. Both subscales of the Boston Carpal Tunnel Questionnaire (Symptom Severity Scale and Functional Status Scale) correlated significantly with the CTS-6 and EuroQol 5 Dimensions, indicating good construct validity. The Cronbach's alpha was 0.93 for both the Symptom Severity Scale and Functional Status Scale, indicating high internal consistency. Test-retest reliability was excellent, with an intraclass correlation coefficient greater than 0.8 for both scales. The coefficient of repeatability was 0.80 for the Symptom Severity Scale and 0.68 for the Functional Status Scale. We observed a floor effect in the Functional Status Scale in 28% of participants. Conclusion: Our study shows that the present Finnish version of the Boston Carpal Tunnel Questionnaire is reliable and valid for the evaluation of symptom severity and functional status among surgically treated carpal tunnel syndrome patients. However, owing to the floor effect, the Functional Status Score may have limited ability to detect differences in patients with good post-operative outcomes.