Reliability and Validity of Hand Function Tests in Carpal Tunnel Syndrome

Carpal tunnel syndrome is a condition that causes numbness, tingling, and weakness in the hand due to pressure on the median nerve in the wrist. This condition often negatively affects a person's hand functions and ability to perform daily activities. While various tests are used in clinics to measure hand function, dexterity, and fine motor skills, there is still a lack of clear consensus in the literature regarding the specific reliability and validity of these particular tests for this patient population. Consequently, it remains uncertain which of these tests are truly accurate, consistent, and most appropriate for routine clinical use in carpal tunnel syndrome. Therefore, it is crucial to scientifically evaluate these tests to fill this gap in the literature. The purpose of this study is to investigate reliability and construct validity of the Jebsen-Taylor Hand Function Test (JTHFT), the Minnesota Dexterity Test (MDT), and the Nine-Hole Peg Test (NHPG) in patients with carpal tunnel syndrome (CTS). To achieve these objectives, a rigorous methodological protocol will be implemented (COSMIN criteria). Test-retest reliability will be evaluated by repeating the assessments within a 7-to-14-day interval. To control for potential learning, fatigue, and adaptation effects, the order of all performance tests will be strictly randomized using a permutation approach during both the initial (baseline) and the second (retest) evaluation sessions. Additionally, measurement error will be calculated using Standard Error of Measurement and Minimal Detectable Change to determine the true clinical precision of these tools. For construct validity, a specific testing sequence and strict randomization strategy will be utilized to minimize response bias. Participants will complete all patient-reported outcome questionnaires prior to undergoing any physical testing. This ensures that a patient's subjective evaluation of their daily life activities is not influenced by their immediate performance or perceived success on the physical tests. Following the questionnaires, hand strength measurements and dexterity performance tests will be administered. The sequence of these physical tests will be fully randomized both among different test modalities and within their internal subtests for each participant. Construct validity will be evaluated through predefined hypothesis testing based on COSMIN guidelines. Convergent validity will be confirmed if a moderate correlation (r≥0.40 or r≤-0.40) is observed between the dexterity tests and structurally related parameters. Divergent validity will be confirmed by a weak correlation (r≥-0.39 and r≤0.39) with structurally unrelated or distinct clinical parameters. Construct validity of the assessments will be considered satisfactory if at least 75% of these predefined hypotheses are confirmed by the statistical analysis.