Test-retest intra-rater reliability of grip force in patients with stroke.

OBJECTIVE Coefficients of repeatability and reproducibility can be guides in differentiating between real changes and measurement error. The aim was to evaluate test-retest intra-rater reliability of a clinical procedure measuring grip force with Grippit in stroke patients, to assess relationship between grip force of the hands and between sustained and peak grip force. PATIENTS AND METHODS Eighteen patients were tested using the Grippit at two occasions one hour apart. Each occasion comprised three consecutive trials per hand. RESULTS The paretic hand needs to score a 50 N change within and between occasions to exceed the measurement error in 95% of the observations, irrespective of calculation method. Expressed by CV(within) the measurement error was 10%. There was no learning or fatigue effect during measuring. There was a wide variation between subjects but the mean ratio between sides was 0.66. The mean ratio between sustained and peak grip force was 0.80-0.84. CONCLUSION The measurement errors were acceptable and the instrument can be recommended for the use in stroke patients at a department of rehabilitation medicine.