Postural instability in idiopathic Parkinson's disease: discriminating fallers from nonfallers based on standardized clinical measures.

Background: Parkinson's disease (PD) predisposes one to falls, which in turn may lead to serious injury and decreased quality of life. Therefore, it is critical to accurately identify those at risk of falling so that preventive measures may be properly applied.

Methods: Forty-nine participants (25 retrospectively identified fallers and 24 nonfallers) with a diagnosis of idiopathic PD were included in this study. Each was assessed using three categories of measurement tools: PD-specific scales (modified Hoehn and Yahr [HY] and Unified Parkinson's Disease Rating Scale [UPDRS]), balance-specific scales (Berg Balance Scale [BBS], Sensory Organization Test [SOT], and Activities-Specific Balance Confidence Scale [ABC]), and functional gait scales (Self-Selected Gait Velocity [SSGV], Dynamic Gait Index [DGI]), and a standardized obstacle course.

Results: Using discriminant function analysis, the BBS, HY, and UPDRS-Activities of Daily Living subscale (UPDRS-ADL) were found to be the best discriminators of faller or nonfaller group membership. Receiver operating characteristic (ROC) curves were employed to suggest cutoff scores and to determine overall predictability. The area under the ROC curves, and the corresponding cutoff scores were as follows for the highest three clinical tests: UPDRS-ADL (0.888/12.5), UPDRS-Overall (0.879/36.5), and the BBS (0.851/43.5). The odds ratios for the UPDRS-ADL, UPDRS-Overall, and the BBS were 32.8, 26.7, and 48.9, respectively. Using positive likelihood ratios and a pretest probability of 51.0%, the changes in posttest probability were UPDRS-ADL (85.9%), UPDRS-Overall (89.9%), and BBS (94.4%).

Conclusion: Results from this study suggest that the UPDRS-ADL, UPDRS-Overall, and the BBS are the best clinical tests for discriminating falls in persons with PD.