Quality of life predicts outcome of deep brain stimulation in early Parkinson disease

Abstract

Objective: To investigate predictors for improvement of disease-specific quality of life (QOL) after deep brain stimulation (DBS) of the subthalamic nucleus (STN) for Parkinson disease (PD) with early motor complications.

Methods: We performed a secondary analysis of data from the previously published EARLYSTIM study, a prospective randomized trial comparing STN-DBS (n = 124) to best medical treatment (n = 127) after 2 years follow-up with disease-specific QOL (39-item Parkinson's Disease Questionnaire summary index [PDQ-39-SI]) as the primary endpoint. Linear regression analyses of the baseline characteristics age, disease duration, duration of motor complications, and disease severity measured at baseline with the Unified Parkinson's Disease Rating Scale (UPDRS) (UPDRS-III "off" and "on" medications, UPDRS-IV) were conducted to determine predictors of change in PDQ-39-SI.

Results: PDQ-39-SI at baseline was correlated to the change in PDQ-39-SI after 24 months in both treatment groups (p < 0.05). The higher the baseline score (worse QOL) the larger the improvement in QOL after 24 months. No correlation was found for any of the other baseline characteristics analyzed in either treatment group.

Conclusion: Impaired QOL as subjectively evaluated by the patient is the most important predictor of benefit in patients with PD and early motor complications, fulfilling objective gold standard inclusion criteria for STN-DBS. Our results prompt systematically including evaluation of disease-specific QOL when selecting patients with PD for STN-DBS.

Clinicaltrialsgov identifier: NCT00354133.

Copyright © 2019 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the American Academy of Neurology.

Figures

Figure 1. Correlation between 39-item Parkinson's Disease Questionnaire summary index (PDQ-39-SI) at baseline and change to 24 months

The relation between PDQ-39-SI at baseline and the improvement PDQ-39-SI between baseline and 24 months is shown. The correlation is more pronounced for the deep brain stimulation (DBS) group than for the best medical treatment (BMT) group.

Figure 2. 39-Item Parkinson's Disease Questionnaire summary index (PDQ-39-SI) by baseline category

Four categories of PDQ-39-SI baseline values were formed: 0–15, 15–30, 30–45, and >45 points. Higher values on the PDQ-39 scale mean worse quality of life. The ordinate indicates the change of PDQ-39-SI over the 2 years of the EARLYSTIM study period; negative values mean worsening of quality of life, positive values mean improvement. BMT = best medical treatment (i.e., control group); DBS = deep brain stimulation of the subthalamic nucleus plus best medical treatment; n = number of patients in each group. *DBS vs BMT statistically significant (adjusted model-based p values <0.05).

Figure 3. Individual 39-item Parkinson's Disease Questionnaire summary index (PDQ-39-SI) change

Change of quality of life (PDQ-39) depending on the baseline PDQ-39 (B). All data at the 3 visits (5, 12, and 24 months) of all patients are shown depending on the baseline value of the PDQ-39 (left column). The response is highlighted by colors (green, better; red, no change). Patients with higher PDQ-39 values at baseline show a better improvement.