Impact of advancing age on post-operative complications of deep brain stimulation surgery for essential tremor

Essential tremor (ET) was the original indication for deep brain stimulation (DBS), with USA Food and Drug Administration approval since 1997. Despite the efficacy of DBS, it is associated with surgical complications that cause sub-optimal clinical outcomes. Given that ET is a progressive disease with increase in symptom severity with increasing age, this study evaluated the impact of increasing age on short-term complications following DBS surgery for ET. The Thomson-Reuters MarketScan database was utilized (New York, NY, USA). Patients selected were over age 18 and underwent DBS for ET between the years 2000 and 2009. Multivariable logistic regression analysis was used to calculate complication odds ratios (OR) for a 5 year increase in age, after controlling for other covariates. Six hundred sixty-one patients were included in the analysis. The mean (standard deviation) age was 61.9 (14.3) years, with 17% of individuals aged ⩾75 years. Overall 56.9% of patients were male, and 44.6% had a Charlson Comorbidity Score of ⩾1. Additionally, 7.1% of patients experienced at least one complication within 90 days, including wound infections (3.0%), pneumonia (2.4%), hemorrhage or hematoma (1.5%), or pulmonary embolism (0.6%). Increasing age was not significantly associated with the overall 90 day complication rates (OR 0.89; 95% confidence interval [CI] 0.77-1.02; p=0.102). The risk of the two most common procedure-related complications, hemorrhage and infection, did not significantly increase with age (hemorrhage: OR 1.02; 95%CI 0.77-1.37; p=0.873; and infection: OR 0.88; 95%CI 0.72-1.07; p=0.203). Our findings suggest that age should not be a primary exclusion factor for determining candidacy for DBS and also suggest a possible expansion of the traditional therapeutic window since post-operative complications remained relatively stable.