The Reliability, Validity, and Responsiveness of the Timed 360° Turn Test in Patients With Parkinson's Disease

Turning ability is assessed by using the timed 360° turn test. In the timed 360° turn test, a piece of colored tape is placed on the floor to mark the starting position. Each subject was required to stand with arms by his/her side and feet comfortably apart and pointing to the tape. Timing was started from the word "go" and stopped when subject's shoulders were facing forward again. The time taken to complete the turn was recorded (in seconds) by a stopwatch.

Functional balance is assessed by using the Berg Balance Scale. During the test, participants are asked to perform 14 tasks frequently used in daily life activities. Each item is scored between 0 (unable to perform the task) and 4 (task is performed independently) according to the ability of the person while performing the task. The highest possible score is 56 points. A higher score indicates better balance.

Trunk performance is assessed by using the trunk impairment scale. The Trunk Impairment Scale consists of three subscales: static sitting balance, dynamic sitting balance and co-ordination. A higher score indicating a better performance.

The Functional Reach Test assesses balance by measuring the limits while the patient reaches forwards as far as possible, having the arms in 90° flexion and without lifting the heels off the floor.

The Four Square Step Test measures dynamic balance and clinically assesses the person's ability to step over objects forward, sideways, and backward. A square was formed by 4 canes resting flat on the floor. The participants were instructed to try and complete the sequence as fast as possible without touching the canes with both feet, making contact with the floor in each square.

Functional mobility is assessed by using the timed up and go test. The timed up and go test measures the time that a patient needs to stand up from a chair, walk a 3-m distance, come back and sit back on the chair.

Disease stage is assessed by the Hoehn and Yahr Scale. The Hoehn and Yahr scale is a commonly used diagnostic tool for quantifying the progression of Parkinson's Disease symptoms. Stages range from 0 (no signs of disease) to 5 (requiring a wheelchair, or bedridden unless assisted).

The Unified Parkinson's Disease Rating Scale is increasingly used as a gold standard reference scale and includes four components (Part I, Mentation, Behavior and Mood; Part II, Activities of Daily Living; Part III, Motor;Part IV, Complications). A lower score indicates lower disease severity.