Real-world assessment of the impact of "OFF" episodes on health-related quality of life among patients with Parkinson's disease in the United States.

Background: Many patients with Parkinson's disease (PD) who receive carbidopa/levodopa experience symptom reemergence or worsening, or "OFF" episodes. This study assessed the association of "OFF" episodes with health-related quality of life (HRQoL).

Methods: US-specific data from the 2017 and 2019 Adelphi Real World Disease Specific Programme for PD, a real-world cross-sectional survey, were used. Neurologists provided data for 10-12 consecutive patients with PD who completed the 39-item Parkinson's Disease Questionnaire (PDQ-39) and the EuroQol 5-Dimension (EQ-5D). Data were grouped by patients who experienced "OFF" episodes versus those who did not and by average hours of daily "OFF" time. Differences between patient groups were assessed for demographics and clinical characteristics; regression analyses were used to model the relationship between HRQoL and "OFF" episodes with age, sex, body mass index, current PD stage on the Hoehn and Yahr scale, and number of concomitant conditions related and unrelated to mobility as covariates.

Results: Data from 722 patients were analyzed. Overall, 321 patients (44%) had "OFF" episodes (mean of 2.9 h of daily "OFF" time). Patients who experienced "OFF" episodes were less likely to work full-time and more likely to live with family members other than their spouse/partner or reside in a long-term care facility than those without "OFF" episodes. The presence of "OFF" episodes, regardless of the average hours of daily "OFF" time, was significantly associated with high scores (reflecting poor HRQoL) on most PDQ-39 dimensions and the summary index and low scores (reflecting poor health status) on the EQ-5D health utility index, visual analog scale (VAS), and all dimensions. Furthermore, increased average hours of daily "OFF" time was significantly correlated with higher scores for all PDQ-39 dimensions and the summary index, as well as with the EQ-5D health utility index and VAS scores. Patients with "OFF" episodes experienced reduced HRQoL even after correcting for potentially confounding variables.

Conclusions: This study demonstrated that the occurrence of "OFF" episodes in patients with PD is associated with reduced HRQoL and that the impact on HRQoL increased incrementally with increasing average hours of daily "OFF" time.