[en] Objective Toinvestigatepredictorsforimprovementofdisease-speciﬁcqualityoflife(QOL)afterdeepbrainstimulation (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 randomizedtrialcomparingSTN-DBS(n= 124)tobestmedicaltreatment(n= 127)after2yearsfollow-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)wereconductedtodeterminepredictors of change in PDQ-39-SI. Results PDQ-39-SIatbaselinewascorrelatedtothechangeinPDQ-39-SIafter24monthsinbothtreatmentgroups (p<0.05).Thehigherthebaselinescore(worseQOL)thelargertheimprovementinQOLafter24months. 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.