Purpose: Carpal tunnel syndrome (CTS) is one of the most common hand problems and a major cause of work disability. The purpose of this study was to use confirmatory factor analysis (CFA) to assess the factor structure of the Boston Carpal Tunnel Questionnaire (BCTQ) in patients with CTS.
Methods: One hundred and twenty-three patients with CTS were recruited from two hospitals. Each patient completed the functional status scale and the symptom severity scale of the BCTQ. CFA was used to assess the model fit between the data and pre-established theoretical measurement models.
Results: CFA showed that all three-factor models were better than the original two-factor model. Among the three-factor models, the simplified model, with 11 items assessing daytime pain, nocturnal numbness/tingling, and hand function was the best, for the model fit the data better than did the other models. Specifically, the Comparative Indices were larger than 0.95 (Tucker-Lewis Index and Comparative Fit Index values), and the Absolute Fit Indices and information-theoretic measures were the smallest. Moreover, all factor loadings were significant and high in magnitude (ranging from 0.66 to 0.99), the composite reliabilities exceeded 0.60 (ranging from 0.78 to 0.94), and the average variance extracted exceeded 0.50 (ranging from 0.61 to 0.89).
Conclusion: The simplified model showed the highest reliability and validity, and the factor structure was the simplest/clearest one. The simplified model is recommended for clinical use due to its convenience and precision for assessing the problems of patients with CTS.
Keywords: Carpal tunnel syndrome; Confirmatory factor analysis; Construct validation; Model selection; Reliability.