Reliability and validity of the timed 360° turn test in people with multiple sclerosis.

: To investigate (1) the intrarater, interrater, and test-retest reliability of the timed 360° turn test in people with Multiple Sclerosis (MS); (2) the minimum detectable change in the timed 360° turn test times; (3) the concurrent and discriminant validity of the timed 360° turn test times; and (4) the cut-off times that best discriminate people with MS from healthy people and fallers from non-fallers with MS.: Sixty-one people with MS (Expanded Disability Status Scale, EDSS, 0-6.5) and 34 healthy people were recruited in this cross-sectional study. The timed 360° turn test was administered along with the Timed Up and Go Test, Berg Balance Scale, Four Square Step Test, and EDSS by two independent raters.: The timed 360° turn test showed good intrarater, interrater, and test-retest reliability. Minimal detectable changes were 1.49 s and 1.53 s for the dominant and non-dominant sides, respectively. The timed 360° turn test was strongly correlated with other outcome measures. Significant differences in 360° turn times were found between people with MS and healthy people and between fallers and non-fallers with MS ( < .001 and < .001, respectively). The cut-off times of 2.65 s on the dominant side and 2.42 s on the non-dominant best discriminated people with MS from healthy people, while 3.65 s on the dominant side and 3.75 s on the non-dominant best discriminated fallers from non-fallers with MS.: The timed 360° turn test is a simple and reliable tool for assessing turning ability in MS.