Predictors of road crossing safety in pedestrians with Parkinson's disease.

Road-crossing safety is an important issue in an aging society. Information regarding the risk of crossing the street to pedestrians with Parkinson's disease (PD) is limited. To assess the risk and predictors of unsafe crossing behaviors in patients with PD, we compared 31 pedestrians with mild-to-moderate PD to 50 age/gender/education-matched controls using a battery of cognitive, visual, and motor tests. With a simulated simple street-crossing situation, we determined the remaining time and safety margin for each participant in different traffic situations, including variable motor vehicle speed, time gap, and time of the day. Odds ratios (ORs) were estimated by logistic regression models. We found that pedestrians with PD were more vulnerable to traffic accidents than controls (OR 1.61 [1.28-2.02], P=0.01). The risk of crossing road correlated in a dose-dependent manner with the severity of PD, based on both Hoehn and Yahr (H&Y) stages and unified Parkinson's disease rating scale (UPDRS) motor scores (OR 1.13 for each increasing point of UPDSR, P<0.01). Among PD patients, scores of clock drawing test (OR 0.8 [0.74-0.88], P<0.01) and visual form discrimination (OR 1.14 [1.07-1.22], P<0.01) predicted worsening of safety errors, rather than executive function. Environmental factors, such as fast approaching motor vehicle speed (OR 4.50 [2.92-6.95], P<0.01), short time gap (OR 45.98 [27.04-78.18], P<0.01), and time of day (OR 4.45 [3.11-6.36], P<0.01) also affected road-crossing safety. Future large sample studies are needed to confirm our findings. Training programs or portable stimulator devices that compensate for the visual-spatial disabilities of PD patients are required to improve road safety for PD patients.