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00007632-201303150-0000400007632_2013_38_471_carreon_effectiveness_6miscellaneous< 87_0_7_4 >Spine© 2013 Lippincott Williams & Wilkins, Inc.Volume 38(6)15 March 2013p 471–475Cost-Effectiveness of Single-Level Anterior Cervical Discectomy and Fusion Five Years After Surgery[Cervical Spine]Carreon, Leah Y. MD, MSc*; Anderson, Paul A. MD†; Traynelis, Vincent C. MD‡; Mummaneni, Praveen V. MD§; Glassman, Steven D. MD**Department of Orthopaedic Surgery, Norton Leatherman Spine Center, Louisville, KY†Department of Orthopedic Surgery, University of Wisconsin School of Medicine and Public Health, Madison, WI‡Department of Neurosurgery, Rush University Medical Center, Chicago, IL; and§Department of Neurological Surgery, University of California, San Francisco, CA.Address correspondence and reprint requests to Leah Y. Carreon, MD, MSc, Norton Leatherman Spine Center, 210 East Gray Street, Ste 900, Louisville, KY 40202; E-mail: leah.carreon@nortonhealthcare.orgAcknowledgment date: June 13, 2012. First revision date: July 31, 2012. Acceptance date: September 5, 2012.The device(s)/drug(s) is/are FDA-approved or approved by corresponding national agency for this indication.No funds were received in support of this work.Relevant financial activities outside the submitted work: consultancy, travel accommodations/meeting expenses, royalties, stock options, patents, payment for development of educational presentations.AbstractStudy Design. Longitudinal cohort.Objective. The purpose of this study is to determine the cost per quality-adjusted life year (cost/QALY) gained for single-level instrumented anterior cervical discectomy and fusion (ACDF) over 5 years.Summary of Background Data. Economic value is an increasingly important component of health care policy decision making.Methods. Control patients who had undergone ACDF with complete 5-year follow-up data who were part of the Investigational Device Exemption trials for cervical disc arthroplasty were identified. Direct costs for each intervention reported as part of the trial were determined using the 2012 Medicare Fee schedule. Health utility was determined using the Short Form-6D, calculated by transformation from the Short Form-36.Results. There were 352 patients (182 women, 170 men), mean age was 44.6 years (22–73 yr). Cost per patient for the index ACDF was $15,714. Over 5 years, 41 repeat ACDFs, 15 posterior fusions, 6 foraminotomies, 2 implant removals, 2 hematoma evacuations, and 1 esophageal fistula repair were performed. Mean QALY gained in each year of follow-up was 0.16, 0.18, 0.17, 0.18, and 0.18 for a cumulative 0.88 QALY gain over 5 years. The resultant cost/QALY gain at 1 year was $104,831; $53,074 at year 2; $37,717 at year 3; $28,383 at year 4; and $23,460 at year 5. In this cohort, 11 nerve releases and 26 rotator cuff repairs were done within 5 years after the index ACDF. Subanalysis to include upper extremity procedures was performed. The cost/QALY gained at 1 year including upper extremity procedures was $106,256; $54,622 at year 2; $38,836 at year 3; $29,454 at year 4; and $24,479 at year 5.Conclusion. Increasing health care costs call for demonstration of cost-effectiveness in order to justify payment for interventions, including ACDFs. This study indicates that at 5-year follow-up, single-level instrumented ACDF is both effective and durable resulting in a favorable cost/QALY gained as compared to other widely accepted health care interventions.Anterior cervical discectomy and fusion (ACDF) is a commonly performed procedure to treat cervical radiculopathy or myelopathy with a rate of 35.8 per 100,000 Medicare beneficiaries in 2005.1 The original technique described by Cloward,2 and Smith and Robinson3 has been modified by the use of allograft4,5 or cages6 instead of iliac crest autograft for interbody grafting and the addition of spanning plates7,8 to allow early mobilization and eliminate the need for bracing.9Despite being a commonly performed procedure, there are very few studies evaluating the cost-effectiveness of single-level ACDF10–12; and most surgeons remain unfamiliar with the standard evaluation tools that drive economic health care policy. The current measure for comparing the value of competing health care interventions is the cost per quality-adjusted life year (cost/QALY) gained.13,14 Generally, interventions with a cost/QALY gained between $50,000 and $100,000, or less, are considered cost-effective.15,16 Interventions with a cost/QALY gained less than the country's per capita gross domestic product is also considered cost-effective.17Aside from the cost of the intervention, cost/QALY gained is also reflective of the durability of the intervention. If a treatment intervention generates lasting clinical benefit, there is continued incremental QALY gain during subsequent years. Surgical procedures have a high initial cost; and to be cost-effective must have lasting benefit and low additional costs. The purpose of this study is to determine the cost/QALY gained for single-level instrumented ACDF over 5 years.MATERIALS AND METHODSAfter receiving Institutional Review Board approval, raw data from subjects who were enrolled in the control arm as part of the Food and Drug Administration (FDA) Investigational Device Exemption (IDE) trial for the BRYAN (Medtronic, Memphis, TN) and PRESTIGE (Medtronic, Memphis, TN) were made available. Subjects with 5-year follow-up data were identified. All patients had a single-level ACDF using allograft with an ATLANTIS plate (Medtronic, Memphis, TN). Data on clinical outcomes were collected prior to surgery, 6 weeks, 3 months, 6 months, 1 year, and annually thereafter.To determine QALYs, the Short Form-6D (SF-6D), a utility index derived from the Short Form-36 version 1 (SF-36v1), using the method developed by Brazier et al, 18 was used. The SF-6D is composed of 6 multilevel dimensions of health constructed from a sample of 11 items selected from the SF-36. A selection of 249 states defined by the SF-6D have been valued by a representative sample of the UK general population (n = 611) using the standard gamble. Regression models were estimated to predict single index scores for all health states defined by the SF-6D. The resultant algorithm can be used to convert SF-36 data at the individual level to a preference-based index.For patients in which the SF-6D value could not be determined due to incomplete responses to the SF-36, the SF-6D was calculated from the transformation of the Neck Disability Index.19 For patients with no SF-6D or NDI values at certain time points, their SF-6D was imputed on the basis of the previous available and next available time points.Patients who were lost to follow-up, withdrew from the trial, or did not have 5-year follow-up data to compute the SF-6D were excluded from the data analysis. Data on deceased patients were included in all analyses, with no gain in utility in the years after death.All adverse events and in-patient health care events during 5 years were identified and scored as per Anderson.20 Direct costs for the index instrumented ACDF and each intervention within the 5 years follow-up were determined using the 2012 Medicare National Average Payment.21 Health care visits or adverse events not reported as part of the FDA IDE were not included in the analysis. A subanalysis to include indirect costs due to work productivity lost during 5 years was also done. The cost per days off work was obtained using National Average Wage Index for 2010, the most recent year for which data are available.22 All analyses were performed using IBM SPSS Statistics v20 (IBM Corporation, Somers, NY). All analyses and interpretation of the results were done by the authors independent of Medtronic.RESULTSOf the 486 subjects enrolled in both studies, 5-year data on 352 (72%) subjects were available for analysis. There were no differences in baseline demographics or clinical outcome scores at any time point before 5 years between those who were available for follow-up and those who were not. Of the 352 patients (182 women, 170 men) the mean age was 44.6 years (22–73 yr) and 96 (27%) were smokers. The mean clinical outcome scores at each evaluation time point are summarized in Table 1. There was a statistically significant improvement in all measures at all time-points compared to baseline. These improvements were maintained throughout the follow-up period of 5 years. The mean health utility value gained each year postoperatively was 0.16, 0.18, 0.17, 0.18, and 0.18 for a cumulative 0.88 QALY gain over the 5-year interval.TABLE 1. Summary of Health-Related Quality-of-Life MeasuresCost per patient for the index ACDF was $15,714. During 5 years, 41 revision ACDFs, 15 posterior fusions, 6 foraminotomies, 2 implant removals, 2 hematoma evacuations, and 1 esophageal fistula repair were performed (Table 2). The resultant cost/QALY gained at 1 year was $104,831; $53,074 at year 2, $37,717 at year 3; $28,383 at year 4; and $23,460 at year 5. In this cohort, 10 carpal tunnel releases, 1 cubital tunnel release, and 26 rotator cuff repairs were done within 5 years after the index ACDF. Subanalysis to include upper extremity procedures was performed. The cost/QALY gained at 1 year including upper extremity procedures was $106,256; $54,622 at year 2; $38,836 at year 3; $29,454 at year 4; and $24,479 at year 5. Other adverse events reported included 29 patients with dysphonia or dysphagia, only one of whom was referred to an otolaryngologist. One subject had deltoid weakness that resolved on follow-up.TABLE 2. Additional SurgeriesOnly 226 (64%) patients were working prior to the surgery, with 205 returning to work within the 5-year follow-up period (Table 3). The majority of patients had returned to work within 2 months after surgery. Of the 24 patients on leave of absence (paid or unpaid), 11 returned to work within 2 months after surgery and an additional 8 returned to work within the first year. Thirty-seven of the 81 patients who were unemployed prior to surgery were working within 3 years after surgery. Using the National Average Wage Index for 2010 (the most recent year available) to determine lost wages,22 the cost/QALY gained including indirect costs at 1 year was $104,905; $53,111 at year 2; $37,743 at year 3; $28,403 at year 4; and $23,478 at year 5. The cost/QALY gained at 1 year including indirect costs and upper extremity procedures was $106,330; $54,660 at year 2; $38,863 at year 3; $29,474 at year 4; and $24,496 at year 5 (Table 4).TABLE 3. Number of Patients Returning to Work at Each Time IntervalTABLE 4. Summary of Cost Per QALY GainedDISCUSSIONThe quality of evidence supporting the efficacy and cost-effectiveness of lumbar fusion for certain lumbar degenerative disorders has increased in the past few years.23–26 There is, however, limited cost-effectiveness data for instrumented ACDF. This is despite the fact that the number of Medicare beneficiaries undergoing an ACDF has increased from 12.6 to 35.8 per 100,000 or 184% from 1992 to 2005.1 Increasing health care costs call for demonstration of cost-effectiveness of health care interventions, even those that have been the standard of care for decades, such as ACDF. A few studies have looked at costs of the index surgery11,12 or cost and utility data within a year of surgery.27 However, especially with surgical interventions, determination of cost-effectiveness requires not only an evaluation of the initial cost versus clinical benefit, but also a measure of durability. That is, interventions in which clinical improvement or gains in health state values are sustained over time, without additional cost, become increasingly cost-effective.In the current study, the resultant cost/QALY gained at 5 years was $23,460. This is similar to the value of $32,560 reported by Angevine10 who used a decision analytic model of ACDF with allograft and plating during a 5-year period using costs, probabilities for complications and revisions, and health state utility values from the literature. This is smaller than the traditional $50,000 cost/QALY value threshold16 and also smaller than the US per capita gross domestic product of $47,000.28 Even when indirect costs due to lost wages are included in the analysis, the resultant cost/QALY gained at 5 years is still below this threshold at $23,477. As the indirect cost calculations were based on the national average wage index, these costs may be affected by the individual's age and profession. In addition, the cost of the surgery may be offset by the production gains to society because 37 of 81 patients who were unemployed prior to surgery were working within 3 years after surgery. Also, 205 of the 226 (91%) patients who were working prior to surgery were back at work at 5 years. This is important for spinal conditions where functional improvement is the major goal including, most importantly, return to work. Thus instrumented ACDF is cost-effective because of sustained gains in QALY over 5 years and relatively quick return to work.Within the 5-year follow-up period around 18% of the patients required cervical revision surgery including repeat ACDFs for nonunions or adjacent segment degeneration, posterior spinal fusion or foraminotomies. This translated to a mean additional cost of around $20,000 per patient per year. However, this additional cost is offset because of the relatively large sustained gains in utility during the 5-year follow-up period. Interestingly there were 37 upper extremity procedures done within 5 years after the index ACDF giving a prevalence of 10%. A sensitivity analysis was done to include these surgeries as it was difficult to discern whether these were performed as part of treating the patient's continuing symptoms or if these were a totally separate pathology. When costs for upper extremity surgeries such as rotator cuff repairs and carpal tunnel release were included, the cost/QALY increased only by a little more than $1000.Limitations of this study include the use of an FDA IDE trial sample that is an idealized cohort with strict inclusion and exclusion criteria. Costs associated with health care interventions not reported as adverse events or revisions were not included. Another important limitation is the lack of a comparison intervention and thus incremental cost-effectiveness ratios are not reported. While ideally incremental cost-effectiveness ratios should be presented, few surgical studies have been or will be able follow nonoperative patients with adequate detail to report costs during a 5-year treatment interval. Keeping this in mind, the simpler cost/QALY based on direct medical costs seems a more plausible economic measure for routine use. A proportion of patients were lost to follow-up as these studies were initially designed with 2-year follow-up period. At the request of the FDA, the follow-up period was increased; which required re-review by the local IRBs and re-consenting subjects. Several sites and some patients did not participate in the expanded study accounting for the patients lost to follow-up. There were no statistically significant differences in demographics, patient reported outcomes in each follow-up period, and adverse event rates between patients who were included in the analysis and those lost to follow-up.Despite these limitations, this study is one of the few that reports on cost-effectiveness for single-level instrumented ACDF at 5 years after surgery. The findings are consistent with a previously published decision analytic model of ACDF10 which showed that cost/QALY for instrumented single-level ACDF falls within an acceptable range for cost-effectiveness. The data at 5-year follow-up suggests that reasonable durability exists and therefore there was potential for further improvement in cost-effectiveness in the future.Increasing health care costs call for demonstration of cost-effectiveness as well as clinical efficacy to justify payment for medical and surgical interventions, including single-level instrumented ACDF. This study indicates that at 5-year follow-up, single-level instrumented ACDF is both effective and durable resulting in a favorable cost/QALY gain as compared with other widely accepted health care interventions.13–16Key Points * Although ACDF is commonly performed to treat cervical radiculopathy or myelopathy, there are few studies evaluating the cost-effectiveness of single-level ACDF. * Raw data from subjects in the control arm of the FDA IDE trial for BRYAN and PRESTIGE who had a single-level ACDF using allograft with an Atlantis plate with 5-year follow-up data were identified. * The cost/QALY gained at 1 year was $104,831, $53,074 at year 2, $37,717 at year 3, $28,383 at year 4, and $23,460 at year 5. * Two hundred five of 226 patients working prior to surgery and 56 of 105 patients not working prior to surgery returned to work within the 5-year period. The cost/QALY gained including indirect costs at 1 year was $104,905, $53,111 at year 2, $37,743 at year 3, $28,403 at year 4, and $23,478 at year 5. * At 5-year follow-up, single-level instrumented ACDF is both effective and durable resulting in a favorable cost/QALY gain as compared with other widely accepted health care interventions.References1. Wang MC, Kreuter W, Wolfla CE, et al. Trends and variations in cervical spine surgery in the United States: medicare beneficiaries, 1992 to 2005. Spine (Phila Pa 1976) 2009;34:955–61. [Context Link]2. Cloward RB. The anterior approach for removal of ruptured cervical disks. J Neurosurg 1958;15:602–1 [CrossRef] [Medline Link] [Context Link]3. Smith GW, Robinson RA. The treatment of certain cervical-spine disorders by anterior removal of the intervertebral disc and interbody fusion. J Bone Joint Surg Am 1958;40-A:607–24. [Medline Link] [Context Link]4. An HS, Simpson JM, Glover JM, et al. 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Text]00007632-200805200-00005ovid.com:/bib/ovftdb/00007632-201303150-0000400007632_2008_33_1305_anderson_arthrodesis_|00007632-201303150-00004#xpointer(id(R20-4))|11065405||ovftdb|00007632-200805200-00005SL00007632200833130511065405P72[Medline Link]18496341ovid.com:/bib/ovftdb/00007632-201303150-0000400000605_2008_149_845_tosteson_spondylolisthesis_|00007632-201303150-00004#xpointer(id(R25-4))|11065213||ovftdb|00000605-200812160-00003SL00000605200814984511065213P77[CrossRef]10.7326%2F0003-4819-149-12-200812160-00003ovid.com:/bib/ovftdb/00007632-201303150-0000400000605_2008_149_845_tosteson_spondylolisthesis_|00007632-201303150-00004#xpointer(id(R25-4))|11065404||ovftdb|00000605-200812160-00003SL00000605200814984511065404P77[Full Text]00000605-200812160-00003ovid.com:/bib/ovftdb/00007632-201303150-0000400000605_2008_149_845_tosteson_spondylolisthesis_|00007632-201303150-00004#xpointer(id(R25-4))|11065405||ovftdb|00000605-200812160-00003SL00000605200814984511065405P77[Medline Link]19075203ovid.com:/bib/ovftdb/00007632-201303150-0000400007632_2008_33_2789_weinstein_nonoperative_|00007632-201303150-00004#xpointer(id(R26-4))|11065213||ovftdb|00007632-200812010-00015SL00007632200833278911065213P78[CrossRef]10.1097%2FBRS.0b013e31818ed8f4ovid.com:/bib/ovftdb/00007632-201303150-0000400007632_2008_33_2789_weinstein_nonoperative_|00007632-201303150-00004#xpointer(id(R26-4))|11065404||ovftdb|00007632-200812010-00015SL00007632200833278911065404P78[Full Text]00007632-200812010-00015ovid.com:/bib/ovftdb/00007632-201303150-0000400007632_2008_33_2789_weinstein_nonoperative_|00007632-201303150-00004#xpointer(id(R26-4))|11065405||ovftdb|00007632-200812010-00015SL00007632200833278911065405P78[Medline Link]19018250ovid.com:/bib/ovftdb/00007632-201303150-0000400006123_2011_68_622_ghogawala_effectiveness_|00007632-201303150-00004#xpointer(id(R27-4))|11065213||ovftdb|00006123-201103000-00006SL0000612320116862211065213P79[CrossRef]10.1227%2FNEU.0b013e31820777cfovid.com:/bib/ovftdb/00007632-201303150-0000400006123_2011_68_622_ghogawala_effectiveness_|00007632-201303150-00004#xpointer(id(R27-4))|11065404||ovftdb|00006123-201103000-00006SL0000612320116862211065404P79[Full Text]00006123-201103000-00006ovid.com:/bib/ovftdb/00007632-201303150-0000400006123_2011_68_622_ghogawala_effectiveness_|00007632-201303150-00004#xpointer(id(R27-4))|11065405||ovftdb|00006123-201103000-00006SL0000612320116862211065405P79[Medline Link]21164373In this study, the 5-year cumulative cost and Short Form-6D were determined in 352 patients who underwent single-level anterior cervical discectomy and fusion (ACDF). Single-level instrumented ACDF is both effective and durable, with a $23,460-cost per quality-adjusted life year gained at 5 years after surgery.Cost-Effectiveness of Single-Level Anterior Cervical Discectomy and Fusion Five Years After SurgeryCarreon, Leah Y. MD, MSc; Anderson, Paul A. MD; Traynelis, Vincent C. MD; Mummaneni, Praveen V. MD; Glassman, Steven D. MDCervical Spine638