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Scott L. Parker, David N. Shau, Stephen K. Mendenhall and Matthew J. McGirt

Object

Revision lumbar fusion procedures are technically challenging and can be associated with tremendous health care resource utilization and cost. There is a paucity of data regarding specific factors that significantly contribute to increased cost of care. In light of this, the authors set out to identify independent risk factors predictive of increasing 2-year direct health care costs after revision lumbar fusion.

Methods

One hundred fifty patients undergoing revision instrument-assisted fusion for adjacent-segment disease (50 cases), pseudarthrosis (47 cases), or same-level stenosis (53 cases) were included in this study. Patient demographics, comorbidities, preoperative health states as assessed by patient-reported outcome questionnaires and perioperative complications were collected and analyzed. Two-year back-related medical resource utilization and direct health care costs were assessed. The independent association of all variables to increasing cost was assessed using multivariate linear regression analysis.

Results

There was a wide range ($24,935–$63,769) in overall 2-year direct costs for patients undergoing revision lumbar fusion (mean $32,915 ± $8344 [± SD]). Preoperative variables independently associated with 2-year direct health care costs included diagnosis of congestive heart failure, more severe leg pain (visual analog scale), greater back-related disability (Oswestry Disability Index), and worse mental health (12-Item Short Form Health Survey Mental Component Summary score). There was a 1.1- to 1.2-fold increase in cost for patients in the greatest quartiles compared with those in the lowest quartiles for these variables. Surgical site infection, return to the operating room, and spine-related hospital readmission during the 90-day global health period were postoperative variables independently associated with 2-year cost. Patients in the greatest versus lowest quartiles had a 1.7- to 1.9-fold increase in cost for these variables.

Conclusions

Revision lumbar fusion can be associated with considerable 2-year health care costs. These costs can also vary widely among patients, as evidenced by the 2.6-fold overall cost range in this series. Although comorbidities and preoperative severity of disease states contribute to cost of care, the primary drivers of increased cost include perioperative complications such as surgical site infection, return to the operating room, and readmission during the global health period. Measures focused on health service improvement will be most successful in reducing the cost of care for patients undergoing revision lumbar fusion.

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Scott L. Parker, Saniya S. Godil, David N. Shau, Stephen K. Mendenhall and Matthew J. McGirt

Object

Treatment effectiveness following spine surgery is usually gauged with the help of patient-reported outcome (PRO) questionnaires. Although these questionnaires assess pain, disability, and general health state, their numerical scores lack direct, clinically significant meaning. Thus, the concept of minimum clinically important difference (MCID) has been introduced, which indicates the smallest change in an outcome measure that reflects clinically meaningful improvement to patients. The authors set out to determine anterior cervical discectomy and fusion (ACDF)–specific MCID values for the visual analog scale (VAS), Neck Disability Index (NDI), 12-Item Short-Form Health Survey (SF-12), and EQ-5D (the EuroQol health survey) in patients undergoing ACDF for cervical radiculopathy.

Methods

Data on 69 patients who underwent ACDF for cervical radiculopathy were collected in the authors' web-based, prospective registry during the study enrollment period. Patient-reported outcome questionnaires (VAS–neck pain [NP]), VAS–arm pain [AP], NDI, SF-12, and EQ-5D) were administered preoperatively and 3 months postoperatively, allowing 3-month change scores to be calculated. Four established calculation methods were used to calculate anchor-based MCID values using the North American Spine Society (NASS) patient satisfaction scale as the anchor: 1) average change, 2) minimum detectable change (MDC), 3) change difference, and 4) receiver operating characteristic (ROC) curve analysis.

Results

Sixty-one patients (88%) were available at follow-up. At 3 months postoperatively, statistically significant improvement (p < 0.001) was observed for the following PROs assessed: VAS-NP (2.7 ± 3.3), VAS-AP (3.7 ± 3.6), NDI (23.2% ± 19.7%), SF-12 physical component score (PCS; 10.7 ± 9.7), and EQ-5D (0.20 ± 0.23 QALY). Improvement on the SF-12 mental component score (MCS) trended toward significance (3.4 ± 11.4, p = 0.07). The 4 MCID calculation methods generated a range of MCID values for each of the PROs: VAS-NP 2.6–4.0, VAS-AP 2.4–4.2, NDI 16.0%–27.6%, SF-12 PCS 7.0–12.2, SF-12 MCS 0.0–7.2, and EQ-5D 0.05–0.24 QALY. The maximum area under the curve (AUC) was observed for NDI (0.80), and the minimum AUC was observed for SF-12 MCS (0.66) and EQ-5D (0.67). Based on the MDC approach, the MCID threshold was 2.6 points for VAS-NP, 4.1 points for VAS-AP, 17.3% for NDI, 8.1 points for SF-12 PCS, 4.7 points for SF-12 MCS, and 0.24 QALY for EQ-5D. The mean improvement in patient scores at 3 months surpassed the MCID threshold for VAS-NP, NDI, and SF-12 PCS but not for VAS-AP, SF-12 MCS, and EQ-5D.

Conclusions

The ACDF-specific MCID is highly variable depending on the calculation technique used. The MDC approach seems to be most appropriate for MCID calculations in the ACDF population, as it provided a threshold value above the 95% confidence interval of nonresponders (greater than the measurement error) and was closest to the average change of most PROs reported by responders. When the MDC method was applied with the NASS patient satisfaction scale as the anchor, the MCID thresholds were 2.6 points for VAS-NP, 4.1 points for VAS-AP, 17.3% for NDI, 8.1 points for SF-12 PCS, 4.7 points for SF-12 MCS, and 0.24 QALY for EQ-5D.

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Scott L. Parker, Saniya S. Godil, Stephen K. Mendenhall, Scott L. Zuckerman, David N. Shau and Matthew J. McGirt

Object

Current health care reform calls for a reduction of procedures and treatments that are less effective, more costly, and of little value (high cost/low quality). The authors assessed the 2-year cost and effectiveness of comprehensive medical management for lumbar spondylolisthesis, stenosis, and herniation by utilizing a prospective single-center multidisciplinary spine center registry in a real-world practice setting.

Methods

Analysis was performed on a prospective longitudinal quality of life spine registry. Patients with lumbar spondylolisthesis (n = 50), stenosis (n = 50), and disc herniation (n = 50) who had symptoms persisting after 6 weeks of medical management and who were eligible for surgical treatment were entered into a prospective registry after deciding on nonsurgical treatment. In all cases, comprehensive medical management included spinal steroid injections, physical therapy, muscle relaxants, antiinflammatory medication, and narcotic oral agents. Two-year patient-reported outcomes, back-related medical resource utilization, and occupational work-day losses were prospectively collected and used to calculate Medicare fee–based direct and indirect costs from the payer and societal perspectives. The maximum health gain associated with medical management was defined as the improvement in pain, disability, and quality of life experienced after 2 years of medical treatment or at the time a patient decided to cross over to surgery.

Results

The maximum health gain in back pain, leg pain, disability, quality of life, depression, and general health state did not achieve statistical significance by 2 years of medical management, except for pain and disability in patients with disc herniation and back pain in patients with lumbar stenosis. Eighteen patients (36%) with spondylolisthesis, 11 (22%) with stenosis, and 17 (34%) with disc herniation eventually required surgical management due to lack of improvement. The 2-year improvement did not achieve a minimum clinically important difference in any outcome measure. The mean 2-year total cost (direct plus indirect) of medical management was $6606 for spondylolisthesis, $7747 for stenosis, and $7097 for herniation.

Conclusions

In an institution-wide, prospective, longitudinal quality of life registry that measures cost and effectiveness of all spine care provided, comprehensive medical management did not result in sustained improvement in pain, disability, or quality of life for patients with surgically eligible degenerative lumbar spondylolisthesis, stenosis, or disc herniation. From both the societal and payer perspective, continued medical management of patients with these lumbar pathologies in whom 6 weeks of conservative therapy failed was of minimal value given its lack of health utility and effectiveness and its health care costs. The findings from this real-world practice setting may more accurately reflect the true value and effectiveness of nonoperative care in surgically eligible patient populations.

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Owoicho Adogwa, Scott L. Parker, David Shau, Stephen K. Mendelhall, Joseph Cheng, Oran Aaronson, Clinton J. Devin and Matthew J. McGirt

Object

The number of low-back fusion procedures for the treatment of spine disorders has increased steadily over the past 10 years. Lumbar pseudarthrosis is a potential complication of lumbar arthrodesis and can be associated with significant pain and disability. The aim of this study was to assess, using validated patient-reported outcomes measures, the long-term effectiveness of revision arthrodesis in the treatment of symptomatic pseudarthrosis.

Methods

This is a retrospective study of 47 patients who underwent revision lumbar arthrodesis for pseudarthrosis-associated back pain. Baseline 2-year outcomes were assessed using the following: visual analog scale (VAS) for back pain, Oswestry Disability Index (ODI), Zung Self-Rating Depression Scale, time to narcotic independence, time to return to work, EuroQol health-state utility, and physical and mental quality of life (Short Form [SF]–12 Physical and Mental Component Summary scores).

Results

The mean duration of time between prior fusion and development of symptomatic pseudarthrosis was 2.69 years. Bone morphogenetic protein was used in 4 cases (8.5%) of revision arthrodesis. A significant improvement in VAS back pain (7.31 ± 0.81 vs 5.06 ± 2.64, p = 0.001), ODI (29.74 ± 5.35 vs 25.42 ± 6.0, p = 0.001), and physical health SF-12 (23.83 ± 6.89 vs 27.85 ± 8.90, p = 0.001) scores was observed when comparing baseline and 2-year post–revision arthrodesis scores, respectively, with a mean cumulative 2-year gain of 0.35 quality-adjusted life years. The median time to narcotics independence was 12.16 (interquartile range 1.5–24.0) months and the median time to return to work was 4 months (interquartile range 3–5 months). By 2 years after revision surgery, no patients had experienced pseudarthrosis. The SF-12 Mental Component Summary (44.72 ± 7.90 vs 43.46 ± 7.51, p = 0.43) and Zung Self-Rating Depression Scale scores (39.36 ± 7.48 vs 41.39 ± 10.72, p = 0.37) were not significantly improved by 2 years.

Conclusions

The authors' study suggests that revision lumbar arthrodesis for symptomatic pseudarthrosis provides improvement in low-back pain, disability, and quality of life. Revision lumbar arthrodesis should be considered a viable treatment option for patients with pseudarthrosis-related back pain. Mental health symptoms from pseudarthrosis-associated back pain may be more refractory to revision surgery.

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Owoicho Adogwa, Scott L. Parker, David N. Shau, Stephen K. Mendenhall, Clinton J. Devin, Joseph S. Cheng and Matthew J. McGirt

Object

Over the past decade, there has been a dramatic increase in the number of spinal fusions performed in the US and a corresponding increase in the incidence of adjacent-segment disease (ASD). Surgical management of symptomatic ASD consists of decompression of neural elements and extension of fusion. It has been shown to have favorable long-term outcomes, but the cost-effectiveness remains unclear. In this study, the authors set out to assess the cost-effectiveness of revision surgery in the treatment of ASD over a 2-year period.

Methods

Fifty patients undergoing neural decompression and extension of fusion construct for ASD-associated back and leg pain were included in the study. Two-year total back-related medical resource utilization, missed work, and health state values (quality-adjusted life years [QALYs], calculated from the EQ-5D with US valuation) were assessed. Two-year resource use was multiplied by unit costs based on Medicare national allowable payment amounts (direct cost), and patient and caregiver workday losses were multiplied by the self-reported gross-of-tax wage rate (indirect cost). Mean total 2-year cost per QALY gained after revision surgery was assessed.

Results

The mean (± SD) interval between prior fusion and revision surgery for ASD was 3.07 ± 2.02 years. A mean cumulative 2-year gain of 0.76 QALYs was observed after revision surgery. The mean total 2-year cost of extension of fusion constructs was $47,846 ± $32,712 (surgery cost: $24,063 ± $300; outpatient resource utilization cost: $4175 ± $3368; indirect cost: $19,607 ± $32,187). Revision decompression and extension of fusion was associated with a mean 2-year cost per QALY gained of $62,955.

Conclusions

In the authors' practice, revision decompression and extension of fusion provided a significant gain in health state utility for patients with symptomatic ASD, with a 2-year cost per QALY gained of $62,995. When indicated, revision surgery for ASD is a valuable treatment option for patients experiencing back and leg pain secondary to ASD. The findings provide a value measure of surgery that can be compared with future cost-per-QALY-gained studies of medical management or alternative surgical approaches.

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Scott L. Parker, Stephen K. Mendenhall, David N. Shau, Owoicho Adogwa, William N. Anderson, Clinton J. Devin and Matthew J. McGirt

Object

Spine surgery outcome studies rely on patient-reported outcome (PRO) measurements to assess treatment effect, but the extent of improvement in the numerical scores of these questionnaires lacks a direct clinical meaning. Because of this, the concept of a minimum clinically important difference (MCID) has been used to measure the critical threshold needed to achieve clinically relevant treatment effectiveness. As utilization of spinal fusion has increased over the past decade, so has the incidence of same-level recurrent stenosis following index lumbar fusion, which commonly requires revision decompression and fusion. The MCID remains uninvestigated for any PROs in the setting of revision lumbar surgery for this pathology.

Methods

In 53 consecutive patients undergoing revision surgery for same-level recurrent lumbar stenosis–associated back and leg pain, PRO measures of back and leg pain were assessed preoperatively and 2 years postoperatively, using the visual analog scale for back pain (VAS-BP) and leg pain (VAS-LP), Oswestry Disability Index (ODI), Physical and Mental Component Summary categories of the 12-Item Short Form Health Survey (SF-12 PCS and MCS) for quality of life, Zung Depression Scale (ZDS), and EuroQol-5D health survey (EQ-5D). Four established anchor-based MCID calculation methods were used to calculate MCID (average change; minimum detectable change; change difference; and receiver operating characteristic curve analysis) for 2 separate anchors (health transition index of the SF-36 and the satisfaction index).

Results

All patients were available for 2-year PRO assessment. Two years after surgery, a significant improvement was observed for all PROs assessed. The 4 MCID calculation methods generated a range of MCID values for each of the PROs (VAS-BP 2.2–6.0, VAS-LP 3.9–7.5, ODI 8.2–19.9, SF-12 PCS 2.5–12.1, SF-12 MCS 7.0–15.9, ZDS 3.0–18.6, and EQ-5D 0.29–0.52). Each patient answered synchronously for the 2 anchors, suggesting both of these anchors are equally appropriate and valid for this patient population.

Conclusions

The same-level recurrent stenosis surgery-specific MCID is highly variable based on calculation technique. The “minimum detectable change” approach is the most appropriate method for calculation of MCIDs in this population because it was the only method to reliably provide a threshold above the 95% confidence interval of the unimproved cohort (greater than the measurement error). Based on this method, the MCID thresholds following neural decompression and fusion for symptomatic same-level recurrent stenosis are 2.2 points for VAS-BP, 5.0 points for VAS-LP, 8.2 points for ODI, 2.5 points for SF-12 PCS, 10.1 points for SF-12 MCS, 4.9 points for ZDS, and 0.39 QALYs for EQ-5D.

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Scott L. Parker, Stephen K. Mendenhall, David Shau, Owoicho Adogwa, Joseph S. Cheng, William N. Anderson, Clinton J. Devin and Matthew J. McGirt

Object

Spinal surgical outcome studies rely on patient-reported outcome (PRO) measurements to assess treatment effect. A shortcoming of these questionnaires is that the extent of improvement in their numerical scores lack a direct clinical meaning. As a result, the concept of minimum clinical important difference (MCID) has been used to measure the critical threshold needed to achieve clinically relevant treatment effectiveness. As utilization of spinal fusion has increased over the past decade, so has the incidence of adjacent-segment degeneration following index lumbar fusion, which commonly requires revision laminectomy and extension of fusion. The MCID remains uninvestigated for any PROs in the setting of revision lumbar surgery for adjacent-segment disease (ASD).

Methods

In 50 consecutive patients undergoing revision surgery for ASD-associated back and leg pain, PRO measures of back and leg pain on a visual analog scale (BP-VAS and LP-VAS, respectively), Oswestry Disability Index (ODI), 12-Item Short Form Health Survey Physical and Mental Component Summaries (SF-12 PCS and MCS, respectively), and EuroQol-5D health survey (EQ-5D) were assessed preoperatively and 2 years postoperatively. The following 4 well-established anchor-based MCID calculation methods were used to calculate MCID: average change; minimum detectable change (MDC); change difference; and receiver operating characteristic curve (ROC) analysis for the following 2 separate anchors: health transition item (HTI) of the SF-36 and satisfaction index.

Results

All patients were available for 2-year PRO assessment. Two years after surgery, a statistically significant improvement was observed for all PROs (mean changes: BP-VAS score [4.80 ± 3.25], LP-VAS score [3.28 ± 3.25], ODI [10.24 ± 13.49], SF-12 PCS [8.69 ± 12.55] and MCS [8.49 ± 11.45] scores, and EQ-5D [0.38 ± 0.45]; all p < 0.001). The 4 MCID calculation methods generated a range of MCID values for each of the PROs (BP-VAS score, 2.3–6.5; LP-VAS score, 1.7–4.3; ODI, 6.8–16.9; SF-12 PCS, 6.1–12.6; SF-12 MCS, 2.4–10.8; and EQ-5D, 0.27–0.54). The area under the ROC curve was consistently greater for the HTI anchor than the satisfaction anchor, suggesting this as a more accurate anchor for MCID.

Conclusions

Adjacent-segment disease revision surgery–specific MCID is highly variable based on calculation technique. The MDC approach with HTI anchor appears to be most appropriate for calculation of MCID after revision lumbar fusion for ASD because it provided a threshold above the 95% CI of the unimproved cohort (greater than the measurement error), was closest to the mean change score reported by improved and satisfied patients, and was not significantly affected by choice of anchor. Based on this method, MCID following ASD revision lumbar surgery is 3.8 points for BP-VAS score, 2.4 points for LP-VAS score, 6.8 points for ODI, 8.8 points for SF-12 PCS, 9.3 points for SF-12 MCS, and 0.35 quality-adjusted life-years for EQ-5D.

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Owoicho Adogwa, Scott L. Parker, David N. Shau, Stephen K. Mendenhall, Oran Aaronson, Joseph S. Cheng, Clinton J. Devin and Matthew J. McGirt

Object

Despite advances in technology and understanding in spinal physiology, reoperation for symptomatic same-level recurrent stenosis continues to occur. Although revision lumbar surgery is effective, attention has turned to the question of the utility and value of revision decompression and fusion procedures. To date, an analysis of cost and heath state gain associated with revision lumbar surgery for recurrent same-level lumbar stenosis has yet to be described. The authors set out to assess the 2-year comprehensive cost of revision surgery and determine its value in the treatment of same-level recurrent stenosis.

Methods

Forty-two patients undergoing revision decompression and instrumented fusion for same-level recurrent stenosis–associated leg and back pain were included in this study. Two-year total back-related medical resource utilization, missed work, and health state values (quality-adjusted life years [QALYs], calculated from the EQ-5D with US valuation) were assessed. Two-year resource use was multiplied by unit costs based on Medicare national allowable payment amounts (direct cost), and patient and caregiver workday losses were multiplied by the self-reported gross-of-tax wage rate (indirect cost). Mean total 2-year cost per QALY gained after revision surgery was assessed.

Results

The mean (± SD) interval between prior and revision surgery was 4.16 ± 4.64 years. Bone morphogenetic protein was used in 7 cases of revision arthrodesis (16.7%). A mean cumulative 2-year gain of 0.84 QALY was observed after revision surgery. The mean total 2-year cost of revision fusion was $49,431 ± $7583 (surgery cost $21,060 ± $4459; outpatient resource utilization cost $9748 ± $5292; indirect cost $18,623 ± $9098). Revision decompression and extension of fusion was associated with a mean 2-year cost per QALY gained of $58,846.

Conclusions

In the authors' practice, revision decompression and fusion provided a significant gain in health state utility for patients with symptomatic same-level recurrent stenosis, with a 2-year cost per QALY gained of $58,846. When indicated, revision surgery for same-level recurrent stenosis is a valuable treatment option for patients experiencing back and leg pain secondary to this disease. The authors' findings provide a value measure of surgery that can be compared with the results of future cost-per-QALY-gained studies of medical management or alternative surgical approaches.