Correlation between Quality of Life and severity of Parkinson's Disease by assessing an optimal cut-off point on the Parkinson's Disease questionnaire (PDQ-39) as related to the Hoehn & Yahr (H&Y) scale.

Strong evidence shows that symptoms in individuals with Parkinson's Disease (PD) restrict both their independence and social participation, leading to a low Quality of Life (QoL). Conversely, a reduced QoL has a negative impact on symptoms. The aim is to evaluate the correlation between QoL and severity of PD by assessing the presence of an optimal cut-off point on the Parkinson's disease questionnaire (PDQ-39) as related to the Hoehn &Yahr (H&Y) scale in a cohort of Italian adults with PD. A multicenter, cross-sectional study was performed. This study was conducted on a cohort of consecutive individuals. All participants were evaluated with the PDQ-39, and the severity of PD was recorded according to the H&Y scale by a neurologist. Receiver op-erating characteristic (ROC) curves and coordinates, visually inspected, were used to find cut-off points with optimal sensitivity and specificity. These were in turn used to determine the optimal PDQ-39 cut-off score for identifying disease severity according to H&Y stages. 513 individuals were included in the study. The ROC curve analysis showed that QoL worsened with an increase in disease severity and age. Moreover, QoL was worse in females. The results of this study allowed for the correlation of QoL and disease severity in a cohort of individuals with PD. With this cut-off point, it is now possible to make a determination of QoL of an individual with PD at a certain stage of the disease, in a specific age range, and of a particular gender.