Research

Original Investigation

Effect of Advancing Age on Outcomes of Deep Brain Stimulation for Parkinson Disease Michael R. DeLong, BA; Kevin T. Huang, AB; John Gallis, ScM; Yuliya Lokhnygina, PhD; Beth Parente, PA; Patrick Hickey, DO; Dennis A. Turner, MD; Shivanand P. Lad, MD, PhD

IMPORTANCE Deep brain stimulation (DBS) is a well-established modality for the treatment of

Author Audio Interview at jamaneurology.com

advanced Parkinson disease (PD). Recent studies have found DBS plus best medical therapy to be superior to best medical therapy alone for patients with PD and early motor complications. Although no specific age cutoff has been defined, most clinical studies have excluded patients older than 75 years of age. We hypothesize that increasing age would be associated with an increased number of postoperative complications. OBJECTIVE To evaluate the stepwise effect of increasing age (in 5-year epochs) on short-term complications following DBS surgery. DESIGN, SETTING, AND PARTICIPANTS A large, retrospective cohort study was performed using the Thomson Reuters MarketScan national database that examined 1757 patients who underwent DBS for PD during the period from 2000 to 2009. MAIN OUTCOMES AND MEASURES Primary measures examined included hospital length of stay and aggregate and individual complications within 90 days following surgery. Multivariate logistic regression analysis was used to calculate complication-related odds ratios (ORs) for each 5-year age epoch after controlling for covariates. RESULTS Overall, 132 of 1757 patients (7.5%) experienced at least 1 complication within 90 days, including wound infections (3.6%), pneumonia (2.3%), hemorrhage or hematoma (1.4%), or pulmonary embolism (0.6%). After adjusting for covariates, we found that increasing age (ranging from 75 years) who were selected to undergo DBS surgery showed a similar 90-day complication risk (including postoperative hemorrhage or infection) compared with younger counterparts. Our findings suggest that age alone should not be a primary exclusion factor for determining candidacy for DBS. Instead, a clear focus on patients with medication-refractory and difficult to control on-off fluctuations with preserved cognition, regardless of age, may allow for an expansion of the traditional therapeutic window.

JAMA Neurol. 2014;71(10):1290-1295. doi:10.1001/jamaneurol.2014.1272 Published online August 25, 2014. 1290

Author Affiliations: Division of Neurosurgery, Department of Surgery, Duke University Medical Center, Durham, North Carolina (DeLong, Huang, Parente, Turner, Lad); Department of Biostatistics and Bioinformatics, Duke University, Durham, North Carolina (Gallis, Lokhnygina); Department of Neurology, Duke University Medical Center, Durham, North Carolina (Hickey). Corresponding Author: Shivanand P. Lad, MD, PhD, Division of Neurosurgery, Department of Surgery, Duke University Medical Center, PO Box 3807, Durham, NC 27710 ([email protected]). jamaneurology.com

Copyright 2014 American Medical Association. All rights reserved.

Downloaded From: http://archneur.jamanetwork.com/ by a University of St. Andrews Library User on 05/31/2015

Effect of Advancing Age on Outcomes of DBS for PD

P

arkinson disease (PD) affects an estimated 1 million patients in the United States and is a cause of significant disability for those affected.1 For patients with advanced PD who have severe levodopa-induced motor fluctuations and dyskinesia, deep brain stimulation (DBS) has been found to be an effective treatment in reducing motor disability and improving quality of life.2 As with any surgical procedure, DBS has inherent risks and has been associated with postoperative complications, including hemorrhage, wound infection, and pneumonia.3 Recent results from the Controlled Trial of Deep Brain Stimulation in Early Patients with Parkinson’s Disease4 (mean age, 52 years) demonstrated that DBS plus best medical therapy was superior to best medical therapy alone for patients with PD and early motor complications, potentially expanding the therapeutic window to treat patients earlier in the disease process. However, PD remains a chronic progressive disease of elderly populations, with a mean age at diagnosis of approximately 60 years and a disease duration of 14 years before DBS is performed.5,6 The effect of increasing age on DBS candidacy and surgical complications is of increasing importance because the number of individuals with PD is expected to double by 2030.7 The purpose of our study was to describe the population-level risk of adverse outcomes among older patients undergoing DBS for PD and to assess the effect of advancing chronologic age on postoperative complications. We hypothesize that increasing age would result in a higher number of postoperative complications, including risk of hemorrhage, wound infection, pneumonia, and pulmonary embolism in older patients with PD. Critical analyses are needed to provide much needed clinical evidence, influence future treatment strategies, and guide future health care policy.

Methods Data Set Data for the study were obtained using the Thomson Reuters MarketScan national database, which contains information from Commercial Claims and Encounters, the Medicare Supplemental and Coordination of Benefits, and the Medicaid databases. Within this database, a cross section of inpatient admissions, inpatient services, outpatient services, outpatient pharmaceuticals, and enrollment tables in the United States between 2000 and 2009 were examined. This database subset was compared with the total number of new DBS implants performed in the United States, as recorded by the manufacturer (Medtronic), and represents approximately 7% of all new DBS implant cases in the same time period. The Duke University institutional review board reviewed and approved this study. Data were obtained from a third-party, de-identified database. This was a large, retrospective study without direct patient contact, required consent, or financial compensation.

Study Sample Diagnosis (International Classification of Diseases, Ninth Revision, Clinical Modification [ICD-9-CM]) and procedure (Current Procedural Terminology [CPT]) codes were used to identify patients with paralysis agitans (ICD-9-CM code 332.0) who have underjamaneurology.com

Original Investigation Research

gone an implant of intracranial neurostimulation leads (ICD-9CM code 02.93 and CPT-4 code 61683 or 61687) for inclusion in our study. Using these criteria, we identified a total of 1757 patients as the study population, including 590 with unilateral implants, 551 with bilateral implants, 122 with staged implants, and the remainder with indeterminate implants.

Methods of Data Abstraction For purposes of describing the population, patients (at the time of the DBS procedure) were divided into 5-year epochs (ranging from 1 day) was analyzed using logistic regression. Age was analyzed as a continuous variable, with odds ratio (OR) results given for a 5-year linear increase in age. Multivariate models were adjusted for Charlson Comorbidity Index (dichotomized as 0 or >0), insurance type (Medicare, Medicaid, or commercial), and sex. Insurance status was included in the multivariate model to ensure that age was the variable being assessed, and its removal did not substantially change the results. Several knot points were examined to include a spline term for age in the model, in order to capture a possible nonlinear effect of increasing age, but these spline terms did not significantly change the model. Statistical significance was defined by P < .05. All analyses were conducted using SAS version 9.3 (SAS Institute Inc).

Results Patient Cohort A total of 1757 patients met the inclusion criteria, having undergone DBS for PD between 2000 and 2009, and were included in the analysis. Demographic characteristics of the cohort are listed in Table 1. The mean (SD) patient age was 61.2 (10.1) years, with 582 (33.1%) individuals 65 years of age or older and 123 (7.0%) individuals 75 years of age or older. Of the total study population, 1198 (68.2%) were men, and 642 (36.5%) had a Charlson Comorbidity Index of 1 or greater. The majority of patients had either commercial (940 patients [53.5%]) or Medicare (746 patients [42.5%]) insurance. In total, 132 patients (7.5%) had at least 1 postoperative complication within 90 days of surgery, as defined by the limited subset of ICD-9-CM codes that were analyzed. The most common complication observed within 90 days was wound infection (64 patients [3.6%]), followed by pneumonia (41 patients [2.3%]), hemorrhage or hematoma (25 patients [1.4%]), and pulmonary embolism (10 patients [0.6%]). Within 90 days, lead replacement or revision was performed for JAMA Neurology October 2014 Volume 71, Number 10

Copyright 2014 American Medical Association. All rights reserved.

Downloaded From: http://archneur.jamanetwork.com/ by a University of St. Andrews Library User on 05/31/2015

1291

Research Original Investigation

Effect of Advancing Age on Outcomes of DBS for PD

Table 2. Multivariate Logistic Regression Resultsa

Table 1. Patient Demographics and Univariate Results Variable Total

Model Adjusted OR (95% CI) P Value Effect of 5-y Increase in Age on Postoperative Complications Within 90 d

Patients, No. (%) 1757 (100.0)

Age, y

Complications

Mean (SD)

61.2 (10.1)

All

1.10 (0.96-1.25)

.17

Median (Q1-Q3)

61.0 (55.0-68.0)

Hemorrhagic

0.82 (0.63-1.07)

.14

Infectious

1.04 (0.87-1.24)

.69

Pulmonary

1.53 (0.92-2.54)

.10

Pneumonia

1.28 (0.99-1.64)

.06

Age category, y

Effect of advancing age on outcomes of deep brain stimulation for Parkinson disease.

Deep brain stimulation (DBS) is a well-established modality for the treatment of advanced Parkinson disease (PD). Recent studies have found DBS plus b...
211KB Sizes 0 Downloads 8 Views