Long-term Cost Utility of Spinal Cord Stimulation in Patients with Failed Back Surgery Syndrome.

BACKGROUND Failed back surgery syndrome (FBSS) is a cause of significant morbidity for up to 40% of patients following spine surgery, and is estimated to cost almost $20 billion. Treatment options for these patients currently include conventional medical management (CMM), repeat operation, or spinal cord stimulation (SCS). Much of the published data regarding cost effectiveness of SCS comprise smaller scale randomized controlled trials (RCTs) rather than large databases capturing practices throughout the US. SCS has been shown to have superior outcomes to CMM or repeat spinal operation in several landmark studies, yet there are few large studies examining its long-term economic impact. OBJECTIVES This study compares health care utilization for SCS compared to other management in patients with FBSS. STUDY DESIGN Retrospective. SETTING Inpatient and outpatient sample. METHODS Patients with a history of FBSS from 2000 to 2012 were selected. We compared those who received SCS to those who underwent conventional management. A longitudinal analysis was used to model the value of log(cost) in each one year interval using a generalized estimating equations (GEE) model to account for the correlation of the same patient's cost in multiple years. Similarly, a Poisson GEE model with the log link was applied to correlated count outcomes. RESULTS We identified 122,827 FBSS patients. Of these, 5,328 underwent SCS implantation (4.34%) and 117,499 underwent conventional management. Total annual costs decreased over time following implantation of the SCS system, with follow-up analysis at 1, 3, 6, and 9 years. The longitudinal GEE model demonstrated that placement of an SCS system was associated with an initial increase in total costs at the time of implantation (cost ratio [CR]: 1.74; 95% confidence interval [CI]: 1.41, 2.15, P < 0.001), however there was a significant and sustained 68% decrease in cost in the year following SCS placement (CR: 0.32; 95% CI: 0.24, 0.42, P < 0.001) compared to CMM. There was also an aggregate time trend that for each additional year after SCS, cost decreased on average 40% percent annually (CR: 0.60; 95% CI: 0.55, 0.65, P < 0.001), with follow-up up to 1, 3, 6, and 9 years post-procedure. LIMITATIONS Costs are not correlated with patient outcomes, patients are not stratified in terms of complexity of prior back surgery, as well as inherent limitations of a retrospective analysis. CONCLUSIONS We found that from 2000 to 2012, only 4.3% of patients across the United States with FBSS were treated with SCS. Long-term total annual costs for these patients were significantly reduced compared to patients with conventional management. Although implantation of an SCS system results in a short-term increase in costs at one year, the subsequent annual cumulative costs were significantly decreased long-term in the following 9 years after implantation. This study combines the largest group of FBSS patients studied to date along with the longest follow-up interval ever analyzed. Since SCS has repeatedly been shown to have superior efficacy to CMM in randomized clinical trials, the current study demonstrating improved long-term health economics at 1, 3, 6, and 9 years supports the long-term cost utility of SCS in the treatment of FBSS patients. Key words: Failed back surgery syndrome, spinal cord stimulation, back pain, leg pain, neuromodulation, FBSS, SCS.