Translation and Validation of the Bulgarian Version of the Boston Carpal Tunnel Questionnaire

Background and Objective: Carpal tunnel syndrome (CTS) is the most common mononeuropathy in humans. Despite the continuous improvement of diagnostic and treatment methods, difficulties remain in the evaluation and quantification of such symptoms as pain, paresthesias, hypesthesia, and hyperesthesia. Numerous tests and questionnaires have been developed for patients with upper limb disease, but the most specific for CTS and the most commonly used is the Boston Carpal Tunnel Questionnaire (BCTQ). BCTQ has been translated and validated for use in many languages, but there is no valid version in Bulgarian yet. The purpose of this work is to create and validate a Bulgarian version of BCTQ, with a recommendation for its use in Bulgarian patients.

The process was divided into two parts. The first part included a translation and a cultural-linguistic adaptation of the Bulgarian version of BCTQ. In the second part, verification of the psychometric properties of the Bulgarian BCTQ, we investigated the reliability, validity and responsiveness of the Bulgarian version of BCTQ. We evaluated BCTQ's construct validity by comparing its results with the score of the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire. The study was performed on a group of 64 patients with a confirmed diagnosis of CTS. All patients were evaluated using the BCTQ and DASH questionnaires. A subgroup of 26 patients underwent open surgical decompression of the carpal canal using a mini-incision technique. The subgroup was evaluated through BCTQ and DASH questionnaires preoperatively and through BCTQ postoperatively at the third month after the intervention.

In the first part of the study, the final version of the questionnaire was presented. Cronbach's alpha coefficient was 0.88 for the Symptom Severity Scale (SSS) and 0.87 for the Functional Status Scale (FSS). The reproducibility of scores showed an extremely high degree of correlation between the two consecutive BCTQ scores at one-week interval (SSS r=0.99, p<0.0001; FSS r=1, p<0.0001). The criterion validity of the Bulgarian version of BCTQ revealed a strong correlation between the results of the BCTQ and the DASH questionnaires. (SSS r(62)=0.569, p<0.00001; FSS r(62)=0.605, p<0.00001). There was a statistically significant decrease in BCTQ results after surgery for both the SSS (t=-9.43, p<0.00001) and the FSS (t=-9.82, p<0.00001).

Our study created a translated and culturally adapted version of BCTQ. The Bulgarian version of BCTQ is reliable, valid, and responsive for measuring symptoms and functional deficits in patients with CTS.