Risk factors for freezing of gait in Parkinson's disease.

Freezing of gait is an episodic gait disorder that may occur in patients with Parkinson's disease. The risk factors for this disorder are poorly understood. To determine the relevant risk factors for this condition, we screened 160 consecutive patients with Parkinson's disease for freezing of gait and assessed 36 potentially related variables. Freezers and non-freezers were compared using statistical univariate analysis, followed by bivariate and multivariate logistic regression, receiver operating characteristics curves and Kaplan-Meier estimates. Seventy-one patients (44.4%) reported freezing of gait. At onset, the mean disease duration was 8.1±6.3years. Freezers experienced falls more frequently than non-freezers (57.7% vs 23.6%, p<0.001). Disease duration was the independent variable most associated with freezing of gait (OR=1.10, 95% CI=1.01-1.19, p=0.020). Its specificity was 77%, but its sensitivity was low, and Hoehn and Yahr staging and the UPDRS (part III) score showed similar accuracy to that of disease duration in predicting freezers. Previous antiparkinsonian treatments and predominant motor signs (tremor/akinesia-rigidity subtypes) at the onset of Parkinson's disease were not related to freezing of gait. Patients who developed Parkinson's disease before the age of 60years experienced freezing of gait earlier than older patients (log-rank, p<0.005). Freezing of gait is a common and disabling motor complication of Parkinson's disease that is related to the progression of the disease. It is not primarily associated with dopamine replacement therapy and may occur early in young patients.