Health-related quality of life in Parkinson's: impact of 'off' time and stated treatment preferences.

Abstract

Long-term levodopa therapy and related fluctuating plasma concentrations are associated with between-dose periods of 'off time' resulting in substantial variation in symptoms and functioning throughout the day in people with Parkinson's (PwP). PwP across UK, France, Spain and Italy completed an online survey to explore: the impact of 'off time' on (1) health-related quality of life (HRQL) and (2) on functioning and ability to undertake usual activities; (3) the value of 'off time' relative to other factors associated with Parkinson's through a stated preference discrete choice experiment (SPDCE). In total, 305 PwP completed the online survey. Overall mean HRQL (utility) score was significantly lower for 'off time' (0.37) than for 'on time' (0.60). All attributes within the SPDCE were significant predictors of treatment choice, although increased duration of 'on time' (per hour per day: odds ratio (OR)=1.40) and predictability of 'off time' to within 30min (OR=1.42) were valued most highly. 'On time' and predictability of 'off time' are highly valued by PwP. Due to substantial diurnal variation of Parkinson's symptoms, standard patient-reported outcome (PRO) assessments may not adequately capture the impact of 'off time' on HRQL and participation in daily activities.