Reliability of outcome measures in individuals with Parkinson's disease

The purpose of this study was to conduct a preliminary evaluation of the test-retest reliability of timed functional tests, the Physical Performance Test, and the Physical Activity Rating scale in individuals in Stage 2 or 3 of Parkinson's disease (PD). Eleven patients were recruited. Participants performed five functional timed tests including bed mobility, chair transfers, five chair stands, gait velocity and 360 degree turns. Participants also completed the Physical Performance Test (PPT) and were interviewed using the Physical Activity Rating Scale. The same procedures were retested the next day. Test-retest reliability was established with intraclass correlation coefficients (ICCs) and ranged from a low of .50 (for bed mobility) to a high of .99 (for gait velocity). Two of the timed measures (gait velocity and 360 degree turn) had excellent reliability and two had good reliability (chair transfers and chair stands). Bed mobility had low reliability in this patient population. The Physical Performance Test (PPT) and Physical Activity Rating scale were reliable with Spearman correlation coefficients of .92 and .75, respectively. Timed functional tests and a self-assessed rating scale were reliable when applied to individuals with PD. These measures will enable the clinician to use appropriate tools to evaluate patients with PD.