The impact of freezing of gait on functional dependency in Parkinson's disease with regard to motor phenotype.

BACKGROUND AND OBJECTIVE: Freezing of gait (FOG) is a disabling symptom more frequent in Parkinson's disease (PD) patients with postural instability gait difficulty (PIGD) phenotype. The aim of this study was to determine the prevalence of self-reported FOG in a large group of PD patients as well as assess its relationship with functional dependency with regard to motor phenotype. METHODS: The data correspond to the baseline evaluation of the COPPADIS-2015 study. Patients with FOG were identified as those with a score of 1 or greater on item-3 of the freezing of gait questionnaire (FOG-Q). Functional dependency was defined as a Schwab and England (S&E) ADL scale score less than 80%. PIGD and non-PIGD (tremor dominant + indeterminate) groups were considered regarding to motor phenotype. RESULTS: Among the 689 PD patients (62.6 ± 8.9 years old, 59.8% males), 240 reported FOG (34.8%), whereas 63 presented functional dependency (9.1%). A total of 22.1% of patients with FOG presented functional dependency vs. only 2.2% of those without FOG (p < 0.0001). FOG was related to functional dependency (OR = 3.470; 95%CI 1.411-8.530; p = 0.007) after adjustment to age, gender, disease duration, daily equivalent levodopa dose, comorbidity (number of non-antiparkinsonian drugs/day), motor status (UPDRS-III), PIGD phenotype, motor complications (UPDRS-IV), NMS burden (NMSS total score), cognition (PD-CRS), and mood (BDI-II). However, according to motor phenotype, FOG was related to functional dependency only in PIGD patients (OR = 7.163; 95%CI 1.206-42.564; p = 0.030). CONCLUSIONS: Self-reported FOG is associated with functional dependency in PIGD but not in non-PIGD motor phenotype patients.