Weaver FM, et al. - The clinicians performed this work to compare survival rates for Parkinson's disease (PD) patients who underwent deep brain stimulation (DBS) with those who were medically managed. When compared with a matched group of patients who did not undergo DBS, DBS was associated with a modest survival advantage. Whether the survival advantage reflected a moderating influence of DBS on PD or on comorbidities that could shorten life or whether differences could be a result of unmeasured differences between groups was not known.