quality of life predicts outcome of deep brain stimulation in early parkinson disease objective to investigate predictors for improvement of diseasespecific quality of life qol after deep brain stimulation dbs of the subthalamic nucleus stn for parkinson disease pd with early motor complicationsmethods we performed a secondary analysis of data from the previously published earlystim study a prospective randomized trial comparing stndbs n 124 to best medical treatment n 127 after 2 years followup with diseasespecific qol 39item parkinsons disease questionnaire summary index pdq39si 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 parkinsons disease rating scale updrs updrsiii off and on medications updrsiv were conducted to determine predictors of change in pdq39siresults pdq39si at baseline was correlated to the change in pdq39si after 24 months in both treatment groups p 005 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 groupconclusion 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 stndbs our results prompt systematically including evaluation of diseasespecific qol when selecting patients with pd for stndbsclinicaltrialsgov identifier nct00354133