Myths and facts about the EARLYSTIM study

Abstract

DBS of the STN improves quality of life (QoL) and motor function not only in advanced Parkinson's disease (PD), but also in PD with early motor complications, as shown in the recent EARLYSTIM study. In spite of the evidence in favor of STN-DBS, the findings of the EARLYSTIM study have recently been controversially debated. Here, we argue that a placebo or lessebo effect is unlikely to have relevantly contributed to the favorable outcome of STN-DBS in the EARLYSTIM study. The method of quantification of the placebo effect of DBS in a previous publication reveals flaws leading to implausible results, and therefore the placebo effect of DBS remains currently elusive, especially because blinding of PD patients with STN-DBS as a crucial preassumption for assessing a placebo effect is practically impossible. Moreover, we claim that the extent of such a placebo effect is most likely very small. Specific challenges of STN-DBS at an earlier stage of PD and inclusion criteria are the risk of inclusion of patients who later evolve to atypical parkinsonism, the risk of a floor effect for the benefit from DBS, the need for experienced multidisciplinary care including prevention of suicidal behavior, and the need for highly qualified long-term follow-up. The EARLYSTIM study has shown that STN-DBS may be proposed earlier on in the course of PD, as soon as motor complications start to cause relevant disability despite proper medical management. This can lead to a gain of several years of improved QoL.

Keywords: EARLYSTIM study; Parkinson's disease; deep brain stimulation; placebo effect; subthalamic nucleus.