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

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.