Hand function in Charcot Marie Tooth: test retest reliability of some measurements

Objective: To evaluate the reliability of some measurements of hand function in people with Charcot Marie Tooth disease. Design: Test retest study. Setting: University, hospitals/clinics in northern Sweden. Subjects: Twenty people with Charcot Marie Tooth disease. Main outcome measures: Measures of (1) dexterity; Box and Block Test and Nine-Hole Peg Test, (2) strength; Grippit instrument (grip and pinch), (3) tactile sensation; Shape Texture Identification Test. Statistics used: intraclass correlation (ICC 2.1), limits of agreement, coefficient of repeatability, coefficient of variation, and linear weighted kappa. Results: The ICC for the Box and Block Test was very high (0.95). The limits of agreement, coefficient of repeatability (CR) (11.5 blocks/min) and coefficient of variation (CV) (8.4%) were acceptable. There was bias towards a better result on the second occasion. For the Nine-Hole Peg Test, the reliability was good if performance was within 2 min (ICC =0.99, CR = 4.3 s, CV = 3.9%). Grip strength proved to be reliable (ICC = 0.99, CR = 26.7 N, CV = 6.6%), while pinch strength was less reliable. The kappa value of the Shape Texture Identification Test was 0.87, which was considered very good although the test has limitations in terms of how well it can describe patients either performing very well or very poorly. Conclusions: The tested instruments can all be used to evaluate hand function in people with Charcot Marie Tooth. Certain factors, however, like limited time aspects for the Nine-Hole Peg Test and the number of trials used, should be taken into consideration. Pinch strength evaluation should be interpreted with caution.