Background and purpose: One of the primary reasons for measuring outcomes during rehabilitation is to determine the effect of physiotherapy. Repeated measurement situations are susceptible to several sources of error, including inconsistencies caused by the subject, the procedure, the instrument and the examiner. Therefore, the reliability of the measures needs to be examined.
Method: The present study used a repeated-measures design. Two studies were undertaken to examine the test-retest and inter-rater reliability for physical functioning measures. The interval between the measurements was one week. The sample consisted of 19 ambulatory subjects with multiple sclerosis (MS) in the test-retest and nine subjects in the inter-rater reliability study. The measures were selected to assess different domains of the World Health Organization International Classification of Functioning, Disability and Health (WHO, 2001). Several parameters of the Box and Block Test (BBT), the Berg Balance Scale (BBS), the Kela Coordination test, the postural stability test, the timed 10-metre gait test, the six-minute walk test, the shoulder tug test, grip strength, maximal isometric force of the knee extensors, muscle endurance tests, the modified Ashworth Scale and passive straight leg raise test were examined in terms of reliability.
Results: The intra-class coefficient (ICC) values for test-retest reliability were >0.80 in 17 of 23 parameters, and correspondingly so in 20 out of 26 parameters for inter-rater reliability. Poor reliability (defined as ICC < or = 0. 60) was obtained only for the patient classification index (PCI) of the six-minute walk test in the test-retest reliability study. In general, the coefficient of variation was good. A moderate amount of variability was discovered for the Kela Coordination test, and for postural stability and muscle endurance tests. The data obtained from the modified Ashworth Scale and the shoulder tug test were highly skewed and the percentage of agreement ranged between 63.9% and 93.4%.
Conclusions: The study revealed acceptable test-retest and inter-rater reliability of these measures in ambulatory subjects with MS, with the exception of the Modified Ashworth Scale and the shoulder tug test.