Predictive ability of functional tests for postural instability and gait difficulty in Parkinson's disease

The objective of this study is to identify clinical determinants for postural instability and gait difficulty in persons with Parkinson's disease (PD). Ninety-one persons (68 males; 74.7%) with PD were studied. Their mean age was 68.73 +/- 8.74 years. The average time since diagnosis was 7.69 +/- 5.23 years. The average Hoehn and Yahr stage was 2.43 +/- 0.44. Age, gender, disease duration, disease severity and motor impairment were recorded. Participants were asked to perform timed clinical mobility tests that included a 5-step test, turns, forward walk, backward walk, and a sideways walk. The mobility tests were investigated for their contribution to predict the postural instability and gait difficulty (PIGD) score (falling, freezing, walking, gait and postural stability) of the Unified Parkinson Disease Rating Scale (UPDRS). PIGD score was significantly correlated with age, disease duration, Hoehn and Yahr score, comorbidity, UPDRS motor score, gait speed of forward, backward and sideways walks, and time to turn. PIGD score was marginally significantly correlated with timed 5-step test. After controlling for age, disease duration, disease severity, comorbidity, and motor impairment, sideway gait speed (beta = - 0.335; p = 0.024), timed 5-step test (beta = - 0.397; p = 0.003) and time to turn (beta = 0.289; p = 0.028) significantly predicted postural instability and gait difficulty. Walking sideways, 5-step test, and turning are significant predictors of PIGD score. These simple mobility tests can be quickly applied in clinical practice to determine postural instability and gait problems in persons with PD.