A Review of Spinal Cord Stimulation Cost Studies

First SCS Cost Study Compared Pre/PostSCS Healthcare Use

In an abstract presented at the American Pain Society meeting in October 1990 and printed the following March, Cicala and Wright compared preSCS and postSCS (with percutaneous electrodes) costs in 10 patients. SCS “significantly” reduced healthcare expenditures by reducing the need for pain medication, physical therapy, and emergency room and physician office visits ( ).

Outpatient Percutaneous Electrodes Versus Inpatient Paddles

The second cost publication, also an abstract, estimated the cost of using percutaneous electrodes with an outpatient screening trial versus laminotomy (paddle) electrodes with an inpatient trial ( ). For trials not complicated by infection, the percutaneous electrode cost approximately $1600 less than the laminectomy electrode. Infection was more likely with a laminectomy electrode and increased the cost savings of the percutaneous electrode to approximately $9000.

Inpatient SCS Cost

In one of four studies that query a United States database, present information from 1004 hospitals in 37 states on 57,486 inpatient SCS procedures from 1993 to 2006. During this period the average length of stay decreased from 4.0 days to 2.1 days, and average per-patient cost increased from $15,342 to approximately $58,088. By 2006 the total annual cost was approximately $215 million (35% Medicare and 41% private insurance), even as the number of procedures decreased from 4424 to 3749.

Impact of the Treatment Continuum on PostSCS Healthcare Costs

In their review of SCS treatment among 424 patients during a 23-year period to identify factors that predict success, Kumar and Wilson found that the longer the interval between the onset of pain and SCS, the lower the success rate. In Lad et al. queried reimbursement claims reported in the United States database mentioned above for April 2008 through March 2013 to investigate the impact of time from diagnosis to SCS implant on first-year postoperative consumption of healthcare resources. Among 7527 patients, 762 survived the exclusion criteria. For every year beyond the mean 1.35 between diagnosis and implantation, patients were more likely to be in the high medical costs group during their first postimplant year because of more opioid use, office visits, and hospitalizations. These findings indicate that delayed SCS treatment subjects patients to additional morbidity before and after SCS implantation. The therapeutic benefit and cost effectiveness of SCS will thus likely be greater in patients where the therapy is delivered at an optimal time.

Technological Improvements and Cost of SCS

In Khalessi et al. conducted a sensitivity analysis of results from a randomized comparison of two methods of parameter adjustment in patients with implanted pulse generators who served as their own controls. In that study ( ), compared with clinician manual adjustment, a computerized patient interactive system resulted in more settings tested in a given time, significantly greater pain/paresthesia overlap, increased battery life, and an estimated $303,756 reduction in lifetime per-patient cost. Neither the time of usage per day, inflation, the discount rate, nor years of use reduced the cost savings produced by the increase in battery life from computerized adjustment.

Modeling Cost Impact of Rechargeable Batteries

The first published paper to estimate the lifetime cost of a nonrechargeable versus a rechargeable SCS system in a typical failed back surgery syndrome (FBSS) patient ( ) provided another model of how SCS treatment “flows.” Although the model as illustrated failed to include a repeat SCS procedure (reimplantation) should a complication require system removal, the tabulated calculation of total costs included replacement costs. The authors posited that approximately 80% of patients undergoing a screening trial receive an implanted system. Yields as high as this have been reported in some clinical trials with selected patients, but the figure likely is smaller in clinical practice, in which the trial might be offered more liberally and evaluated more critically ( ). The age of the base-case patient was set at 46 years, derived from a patient population with mixed indications for SCS and peripheral nerve stimulation ( ), and assumed nonrechargeable battery life at 49 months and life expectancy at 80.2 years. The model, however, limited the total number of SCS implantations to six (initial plus five replacements), which would not cover the life expectancy of the base-case patient.

The authors calculated that the base-case patient would need 5.9 “replacement procedures,” but an 80.2-year life expectancy minus 46 years at first implantation equals 34.2 years of remaining life, which is approximately 408 months to be divided by the 49-month nonrechargeable battery life, which equals 8.3 batteries and 7.3 replacements. The investigators also concluded that the base-case patient would need 2.2 replacements for a rechargeable system, given its assumed life of 17.5 years (range 10–25), but the original implantation would serve the 46-year-old patient until age 63.5, and one replacement would bring this patient’s age to 81 (exceeding life expectancy). Taking into account these discrepancies, the cost-effectiveness of the rechargeable system would have been more robust than the analysis suggests.

Modeling High-Frequency SCS Costs in Patients With FBSS

assessed high-frequency (10 kHz) SCS using a rechargeable generator versus conventional medical management (CMM), reoperation, and “traditional” SCS using either nonrechargeable (assumed to last 4 years) or rechargeable (assumed to last 10 years) pulse generators. The investigators used a decision tree and Markov model ¹

1 In probability theory, a Markov model is a stochastic model used to model randomly changing systems where it is assumed that future states depend only on the current state not on the events that occurred before it (that is, it assumes the Markov property). Taken from the internet: https://www.google.com.au/?gfe_rd=cr&ei=AELfWImiEYHp8wfa47HIBg#q=what+is+a+markov+model&∗ .

to project costs and quality-adjusted life years (QALYs) ²

2 The quality-adjusted life year or quality-adjusted life-year ( QALY ) is a generic measure of disease burden, including both the quality and the quantity of life lived. It is used in economic evaluation to assess the value for money of medical interventions. One QALY equates to 1 year in perfect health. Taken from the internet: https://www.google.com.au/?gfe_rd=cr&ei=ZzrfWPb2JpDp8wfP4aHoCg#q=qalys&∗ .

for a cohort of 1000 patients over a period of 15 years. The resulting incremental cost-effectiveness ratio (ICER) ³

3 The incremental cost-effectiveness ratio ( ICER ) is a statistic used in cost-effectiveness analysis to summarise the cost-effectiveness of a health care intervention. It is defined by the difference in cost between two possible interventions, divided by the difference in their effect. Taken from the internet: https://www.google.com.au/?gfe_rd=cr&ei=RjvfWKjDBI_p8weo7KnACg#q=icer+definition&∗ .

for high-frequency SCS was £3153 per QALY versus CMM and £2666 versus reoperation. Compared with CMM and reoperation, all three SCS treatments were cost effective. High-frequency SCS was dominant (providing more QALYs at less cost) over both nonrechargeable and rechargeable traditional SCS, but equipment longevity and cost were the “driving parameters in the model.” This becomes clinically important if for some reason SCS implants are unable to deliver traditional as well as 10 kHz waveforms with the same generator.

Complications and Costs of Percutaneous Versus Paddle Electrodes

In another United States database analysis, used propensity scoring to match 4536 patients who received SCS with percutaneous versus paddle electrodes from 2000 to 2009. Significantly more paddle than percutaneous patients had a complication at 90 days, but significantly more percutaneous patients had reoperations by 2-year and ≥5-year follow-up. Paddles led to significantly lower costs at 1 and 2 years, but long-term costs were similar between the groups.

Retrospective Analysis of the Cost of Complications

detailed the incidence and cost of complications in 160 patients treated during a 10-year period. Of 51 adverse events in 42 patients, 39 were hardware related (not including premature battery failure) and 12 were biological. The mean per-patient costs were (in Canadian dollars) $7092 for treating complications, $23,205 for implantation, and $3609 for annual maintenance.

First Full Report on Cost of SCS

tracked healthcare costs in 14 FBSS patients during the 2-year period following implantation and found that SCS reduced healthcare costs and the level of disability—advantages that more than offset the cost of the equipment.

Health Technology Assessment From WHO

In 1993 the World Health Organization’s Health Technology Assessment Information Service ( ) calculated the cost effectiveness of SCS for FBSS at various levels of efficacy and concluded that “SCS appears to be cost-effective versus alternative therapies costing $20,000 per year or more, with 78% or less efficacy.”

SCS Versus “Chronic Maintenance”

A few years later, modeled the annual cost in FBSS patients of SCS with an externally powered radiofrequency generator or a primary cell generator, each versus “chronic maintenance” (a mix of surgical and nonsurgical interventions). They modeled a 17% probability of failing the screening trial and reverting immediately to chronic maintenance, a 46% probability of enjoying long-term clinical efficacy with SCS, and a 15% probability of requesting system removal for failure before entering chronic maintenance. Patients who did not request removal of a failed system were presumed to incur healthcare costs equal to nonsurgical chronic maintenance. The model predicted that “cost neutrality” would occur in 4.3–5.0 years for battery systems (with a 4-year lifespan) and 3.2–3.7 years for radiofrequency-coupled devices. Sensitivity analyses revealed that clinically efficacious SCS would pay for itself within 2.1 years.

Snapshot of Cost and Effectiveness of SCS for FBSS in One Practice

queried 69 FBSS patients treated over a period of 13 years to determine outcomes and cost. Of these, 27 received a system powered by external radiofrequency (RF) and 42 an implanted battery; 43 (15 RF and 28 battery) used SCS for an average of 4.9 years. The $3660 average annual SCS cost (implantation, screening trials, electrode revisions, and battery replacements, but not pain medication) dropped to $3400 for those who benefitted from the therapy. Recalculation as if all procedures took place on an outpatient basis reduced these figures to $3030 for the entire cohort and $2730 for those who achieved success.

Patients Serving as Their Own Controls Reveal SCS Payback Date

collected preimplantation and postimplantation cost data on 20 patients for the year before and 5 years after SCS implantation to evaluate social benefits, employment, pain, QOL, mobility, sleep, and analgesic use associated with SCS versus CMM.

Despite the increase in costs caused by premature battery depletion in 25% of patients (prompting a switch to externally powered generators during the study) and by other surgical adjustments to the equipment in 20%, the investigators concluded that SCS became cost neutral after 5 years.

Long-Term Costs in FBSS Patients Who Passed Versus Those Who Failed an SCS Screening Trial

Also in , Kumar et al. published results in 60 consecutive FBSS patients who received SCS systems and 44 who failed SCS screening and received CMM. Over a 5-year period the investigators calculated all costs associated with diagnosis and treatment, and collected QOL data. The cost of SCS treatment exceeded that of CMM only for the first 2.5 years. Generator replacement brought the SCS cost for the fourth year close to (but still under) that of CMM. Extrapolation over a 10-year period “magnified” SCS cost savings. SCS also improved the QOL in 27% of patients versus 12% with CMM, and 15% of the SCS patients (versus none of the CMM patients) returned to work.

Long-Term Prospective Multisite Cost-Effectiveness Analysis

reported a multisite study (nine hospitals) that collected cost and pain data from 43 FBSS patients before SCS treatment and at 24 months follow-up. Success occurred in 70% with sciatica and 29% with low back pain, and QOL improved in 39%. SCS reduced the cost of pain treatment by a mean 64% per patient per year. This does not include the cost of screening.