Parkinson's disease (PD) is the second most common neuro-degenerative disease in the United States (US) after Alzheimer's disease (Tanner & Goldman, 1992). For PD patients who suffer from the long-term complications of medication management (i.e., levodopa), and experience decline in function, deep brain stimulation (DBS) is accepted as a surgical alternative to symptom management (Volkman, 2004, Weaver et al. 2009; Follett et al. 2010). Stimulation of the subthalamic nucleus (STN) or the internal globus pallidum (GPi) have been shown to be efficacious in relieving motor fluctuations and dyskinesias associated with PD (Volkman, 2004, Follett et al. 2010). However, the choice of surgical site may impact other outcomes including costs of care and health-related quality of life. Evidence from previous small uncontrolled studies has found that STN DBS usually results in a substantial decrease in PD medications compared with GPi DBS (Volkman, 2004; Weaver, et al., 2005). Because PD medication costs are approximately $4,500 per patient annually before DBS (Tomaszewski & Holloway, 2001), reduction in medication could result in substantial cost savings from STN over GPi DBS. Moreover, because GPi DBS involves stimulation of a larger area of the brain than STN DBS, GPi DBS may require greater stimulation energy resulting in more frequent replacement of the battery, at a cost of $18,000 (2007 dollars; Medtronic Neurological). However, there have been reports of more adverse events including mood and behavior changes requiring hospitalization and medications following STN than GPi DBS (Vitek, 2002). While previous smaller studies have identified potential differences in cost and quality of life outcomes between the surgical sites, these differences have not been confirmed in a large multi-site randomized controlled trial. The proposed study addressed this gap and provided information about the costs and consequences resulting from the choice of surgical site for DBS.
The goal of this study was to examine the costs and effectiveness of best medical therapy vs. deep brain stimulation (Phase 1) and for STN vs. GPi DBS (Phase II) by capitalizing on the multi-site VA Cooperative Studies Program (CSP) randomized trial of surgery for persons with PD (CSP 468; Weaver et al. 2009; 2012; Follett et al. 2010). The proposed study took advantage of the data from the CSP 468 study to examine health care costs, quality of life and cost-effectiveness up to 3 years post surgery for veterans and non-veterans who receive DBS.
Our primary aims were:
1. To estimate the total and disease-specific costs of Parkinson's disease-related care for patients following STN vs. GPi DBS up to 3 years post surgery;
2. To determine effectiveness between patients receiving STN vs. GPi DBS up to 3 years following surgery; and
3.To estimate the cost-effectiveness of STN vs. GPi DBS up to 3 years following surgery.
Our secondary aims included:
1. To compare the costs of care for patients receiving best medical therapy (BMT) to those who underwent DBS at 6 months;
2. To compare the effectiveness of best medical therapy to DBS at 6 months; and
3. To examine costs and effectiveness by age (<70 and 70+ years) and disease stage.
This was a secondary data analysis study to determine cost-effectiveness. We supplemented data from the VA cooperative studies (#468) with utilization and cost data extracted from VA administrative files for Veterans. We also requested Medicare and Medicaid claims data for our entire cohort. Utilization data were merged with patient study data including demographics, intervention data and quality of well-being to create an analysis file.
Results are provided for the Veteran cohort; analyses are ongoing for the non-Veteran patients. Participants included 77 Veterans who received BMT and 70 Veterans who underwent DBS in Phase I. They had a mean age of 62 years, 97% were male and 99% white. Excluding the DBS procedure, DBS patients utilized more outpatient visits (13.7 v. 8.4; p=0.0025), less 30-day PD medication prescriptions (13.8 v. 16.9; p<0.34) and more patients received DME (61% v. 25%; p<0.0001) than the BMT group over 6 months. While levodopa equivalents were higher for BMT than DBS (1,398 v.1, 101; p=0.005); PD medication costs did not differ by BMT v. DBS ($1589 v. $1750; p=0.55).
In Phase II, 85 patients received GPi and 76 received STN DBS. Their average age was 61 years old and 99% were white. There was no difference in initial costs for DBS procedure for GPi v. STN ($54,554 v. $50,752; p=0.15). Although the cost of the initial DBS procedure did not differ by target, total costs over 3 years (excluding travel and caregiver costs) was significantly higher for GPi than STN patients ($140,401 v. $117,892; p=0.041). The greater costs for GPi were due to greater costs of PD follow-up procedures ($18,470 v. $8,797; p=0.012) and medication costs ($7320 v. $5091; p=0.006).
The $22,509 greater costs for the GPi group is likely due to in large part to a larger number of reoperations for explanation and/or replacement of some component(s) of the DBS device for GPi than STN patients. At three years of follow-up, quality-adjusted life years (QALYs) were similar GPi and STN patients (1.153 v. 1.093 QALYs; p=0.38).
Health care utilization and costs were very similar by group over three years following DBS. The battery life is shorter for the GPi patients, on average, due to the higher frequency required. Thus, battery replacement is likely to occur sooner in GPi patients. Medication costs also were lower for the STN patients, but accounted for a 5% of total costs.
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