Content validation of the Kamath and Stothard questionnaire for carpal tunnel syndrome diagnosis: a cognitive interviewing study.

The content validity of the current iteration of the KSQ was not established. The problematic questions identified in the study have been reported to have low specificity and negative predictive values in a previous quantitative study. The content validity issues identified may explain the poor performance. Recommendations were made to modify the wording of the KSQ and the potential addition of three new questions. Future studies should determine whether the modified questionnaire can provide better diagnostic accuracy and psychometric properties. The results of this study may assist in ruling in or out CTS diagnosis to a wide variety of target audience, such as hand specialists, physical and occupational therapists, as well as family doctors.