Subjectively determined impaired quality of life (QoL), as assessed by the 39-item Parkinson Disease Questionnaire summary index (PDQ-39-SI), may be effective for predicting QoL improvements in patients with Parkinson disease (PD) and early motor complications, according to a study published in Neurology.

Investigators from the study performed a secondary analysis of the EARLYSTIM study, which compared subthalamic nucleus deep brain stimulation (STN-DBS; n=124) with best medical treatment (n=127) at 2-year follow-up.

The primary endpoint of the study included disease-specific QOL, as determined by the PDQ-39-SI.

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Predictors of change in the PDQ-39-SI were evaluated in analyses adjusted for age, disease duration, duration of motor complications, and disease severity with the Unified Parkinson’s Disease Rating Scale (UPDRS; UPDRS-III, “off” and “on” medications; UPDRS-IV) at baseline.

In a regression model for each treatment, a correlation was found between the baseline PDQ-39-SI value and the change in QoL during the 2-year period (P <.001 for both). A stronger correlation was found in patients in the STN-DBS group vs patients in the medical control group (P =.0262).

According to the UPDRS-III, the change in QoL during follow-up was independent of the severity of parkinsonian motor signs in the condition “off” and “on” medications. In addition, the change in QoL was independent of the severity of levodopa-induced complications and the “off” time.

A limitation of the study includes its highly selected patient population, which may reduce the generalizability of the findings.

“The subjective individual suffering as measured with the PDQ-39-SI should be taken into account as a predictive factor for outcome when selecting patients with early motor complications for STN-DBS,” the researchers concluded.


Schuepbach WMM, Tonder L, Schnitzler A, et al; for the EARLYSTIM study group. Quality of life predicts outcome of deep brain stimulation in early Parkinson disease. Neurology. 2019;92(10):e1109-e1120.