Early development of the standing-start 180° turn test

Objectives: To design and validate a new video-based tool for quantifying turning during gait in people with Parkinson's Disease. Dysfunctional turning is common in Parkinson's Disease but most existing measurement tools are inadequate for this group, lack validity and are laboratory-based.Design: Descriptors of turning were identified and the new tool, the Standing-start 180° Turn Test (SS-180), was derived from a short-list. Criterion validity was tested using Cartesian Optoelectronic Dynamic Anthropometry (CODA) as the criterion measure, and intra-rater and inter-rater reliability were tested.Participants: Thirty-two healthy adults (aged 21–83 years) and eight people with Parkinson's Disease (aged 69–85 years).Results: Seventy descriptors were identified and 20 were short-listed and combined to form four items: Turning Steps, Turn Time, Turn Type and Turn Quality. Time measurements from video and CODA agreed within 0.5 s on 95% of occasions in healthy adults and within 20% of each other in people with Parkinson's Disease; there was 92% agreement on Turning Steps and 84% agreement on Turn Type. Intra-rater reliability was 100% for Turning Steps, Turn Type and Turn Quality; mean Turn Time difference 0.1 s (95% limits of agreement ?0.3 to 0.1 s). Inter-rater reliability was 80% for Turning Steps, 100% for Turn Type and 90% for Turn Quality; mean Turn Time difference 0.0 s (95% limits of agreement ?0.4 to 0.5 s).Conclusions: The video-based SS -180 was developed for measurement in Parkinson's Disease. Preliminary studies suggest that the simple turn test compares well with a laboratory-based criterion measure, and that reliability exceeds similar existing observational analysis tool