Tosteson et al1,2 used data from a concurrent prospective cohort study, comparing spinal surgical procedures with nonoperative treatment in 2 patient groups, stenosis with or without degenerative spondylolisthesis. The other 2 studies completed retrospective reviews of cohort data.3,4 Burnett et al3 compared laminectomy procedures with nonoperative treatment in patients with stenosis and spondylolisthesis. Udeh et al4 compared laminectomy procedures with nonoperative treatment, in the form of epidural spinal injections, in patients with stenosis without spondylolisthesis.
All studies reported that surgical procedures had a greater cost (in US dollars) than nonoperative care; Table 3.1–4 This was based on an insurer/payer perspective in 2 studies3,4 and a societal perspective in the Spine Patient outcomes Research Trial.1,2 Three studies used a 2-year time horizon for their analysis and Tosteson et al1,2 updated their report in 2011 with a 4-year time horizon.3,4 Udeh et al4 reported surgical costs as $5883 greater than nonoperative costs. However, they did not report the individual costs and attained values through the 2013 Medicare payer perspective.3 Tosteson et al1,2 reported that the average surgical cost in patients without spondylolisthesis was $12,703 (2-yr time horizon) and $13,147 (4-yr time horizon) more than nonoperative care (defined as usual care, including but not limited to injection use and medication/narcotics). The treatment of stenosis with a spondylolisthesis was 2 times greater at $26,035 (2-yr time horizon) and $22,127 (4-yr time horizon) due to the inclusion of more arthrodesis procedures. Burnett et al3 reported laminectomy costs to be $5895 greater than that of conservative management.
In patients with spondylolisthesis, during a 2-year time horizon, Burnett et al3 and Tosteson et al1 noted that surgical treatment had gains over nonoperative treatment with QALY improvements of 0.0991 and 0.22 respectively. Tosteson et al2 report a QALY gain of 0.34 for the surgical treatment group during a 4-year time horizon. Regarding patients without spondylolisthesis, Tosteson et al1 reported a QALY gain of 0.17 (2-yr time horizon) and 0.22 (4-yr time horizon) from surgical treatments. Udeh et al4 noted gains in both the operative (QALY, 0.11) as well as nonoperative (QALY, 0.19) with nonoperative care dominating. Tosteson et al1 calculated an incremental cost-effectiveness ratio (ICER) at the 2-year time point of $77,600 for stenosis without spondylolisthesis and $115,600 for operative treatment of stenosis with degenerative spondylolisthesis. At the 4-year time horizon, an ICER of $59,400 for stenosis without spondylolisthesis and $64,300 for operative treatment of stenosis with degenerative spondylolisthesis was reported.2 Udeh et al4 reported that laminectomy alone cost more than nonoperative care and was less effective, thus nonoperative care dominated. Burnett et al3 calculated an ICER of $59,487 for stenosis with spondylolisthesis.
Key Question 2
Comparison of Spinal Decompression With and Without Fusion
A total of 3 cost-utility studies were retained, appraised, abstracted, and summarized for key question 2 (Table 2). The study by Tosteson et al1, as noted in the earlier text, used data from a prospective cohort study, comparing decompression with and without fusion in 2 patient populations, degenerative patients with spondylolisthesis with and without stenosis. Kim et al5 used data from a retrospective cohort study, comparing decompression alone with decompression with instrumented fusion, in patients diagnosed with degenerative lumbar spondylolisthesis. Kuntz et al6 completed a retrospective review of cohort data to compare laminectomy alone with laminectomy with noninstrumented fusion in patients with degenerative spondylolisthesis.
Tosteson et al1 reported that decompression and fusion costs were $20,967 greater than decompression alone for patients with spondylolisthesis and $17,545 for the population without spondylolisthesis. There was no significant difference in QALYs gained, and an ICER was not calculated (Table 3). Kim et al5 in a study based on a single-provider perspective during a 10-year time horizon, found that decompression and fusion was $14,283 more expensive than decompression alone. In addition, Kuntz et al6 analyzed from a societal perspective, also during a 10-year time horizon, and reported that laminectomy with noninstrumented fusion cost $5940 more than laminectomy alone. In all the lumbar spondylolisthesis studies, the addition of arthrodesis provided a greater gain in QALYs than decompression alone (mean difference: 0.02–0.115).1,5,6
The study by Kim et al5 had a cost-utility ICER of $185,878 for instrumented arthrodesis compared with decompression alone. It is noted that in that study there was a significantly lower proportion of females in the decompression group that might have affected the results. The series by Kuntz et al6 calculated ICER to be $56,500. Tosteson et al1 did not calculate an ICER because there was no difference in QALY gained between treatments.
Key Question 3
Comparison of Spinal Fusion, With and Without Instrumentation
A total of 2 cost-utility studies were retained, appraised, and summarized for key question 3 (Table 2). Tosteson et al1, again, used data from a concurrent prospective cohort study, comparing decompression without instrumented fusion with decompression with instrumented fusion in patients with degenerative spondylolisthesis. Kuntz et al6 completed a retrospective review of cohort data to compare laminectomy with and without instrumented fusion with degenerative lumbar stenosis and spondylolisthesis.
Kuntz et al6 used a 10-year time horizon and analyzed costs from a hospital accounting system. Tosteson et al1 analyzed only a 2-year time horizon with costs from the Medicare allowable amounts and patient health care diaries, as well as indirect costs, sourced from the standard human capital approach. Fusion with instrumentation was more costly than that without instrumentation in both studies (mean difference: $87046 and $22581) with no difference in QALY gained.
Attempts to quantify the value of surgery for spine care has significant societal implications especially because degenerative disorders of the lumbar spine have become increasingly recognized in societies with aging populations. Two conditions, lumbar stenosis, and spondylolisthesis, have become increasingly prevalent as they often present fairly typically with clinical symptoms of pain with standing and ambulation. There are estimates that these 2 conditions affect greater than 20% of adults older than 65 years.7 In addition to nonoperative strategies, surgical decompression and arthrodesis are 2 accepted treatment options for these conditions.
Operative Versus Nonoperative Therapy
The first question proposed (surgical vs. nonsurgical treatment) attempts to assess the cost-effectiveness of operative versus nonoperative treatment for lumbar spine disease in the presence or absence of a spondylolisthesis. It is expected that surgical therapies would have a higher upfront cost due to their invasive nature with the need for hospitalization, operative time, and anesthesia support. Surgery removes the degenerative overgrowth that has led to neural impingement and in cases of instability, instrumentation may be added to stabilize the surgically decompressed and unstable motion segment. The removal of the neural element compression should provide a prolonged relief of symptoms and return the patient to contribute to society in a meaningful fashion thereby dissipating (or “amortizing”) the upfront costs over time.
All 3 studies selected analyzing operative versus nonoperative treatment costs reported that the surgical procedures' upfront financial cost (in US dollars) were greater than nonoperative care.1,3,4 Burnett et al3 reported that laminectomy alone costs $5895 more than nonoperative care. As expected, the addition of arthrodesis (fusion) further increased surgical costs and instrumentation arthrodesis had the greatest upfront financial cost. Tosteson et al1,2 reported that the average surgical cost of lumbar stenosis without a spondylolisthesis was $12,703 more than nonoperative care at a 2-year time horizon, and slightly less during 4 years. The cost of treatment in similar population with the presence of a spondylolisthesis was 2 times greater at $26,035 at a 2-year time horizon most likely due to the inclusion of arthrodesis procedures, in approximately 90% of those patients ($22,127 during 4 yr).
Overall, there was a significant variability of costs assigned to procedures in these articles. One would expect costs to be somewhat consistent due to expected similar treatment algorithms. This was not the case and there was a 400% difference in the individual costs for surgical treatment, in the range from $9349 to $53,222. However, this significant variability was also noted in the nonoperative therapies (range from $3454 to $31,095). These wide discrepancies in cost are related in the different methodologies used to construct cost estimates. An example is the use of direct hospital charges billed to the patient versus standardized reimbursement from a government payer such as Medicare (Unites States). The surgical procedures and nonoperative treatments also varied dramatically across the studies. These differences illustrate the difficulty with comparing treatment options due to heterogeneity in the definitions of costs of surgical and nonoperative care and making generalizing statements.
A patient's greatest concern is the degree of improvements of function and reduction of pain as a result of an intervention while minimizing risk and need for repeat procedures for the same condition. All 3 of the studies comparing operative versus nonoperative care detected an improvement in patient's QALYs of surgical over nonoperative care (Table 3). In 3 of the 4 studies, at up to 4-year follow-up, there was a greater degree of improvement in QALY for surgical treatment than nonoperative treatment. This was presumed because of the removal of the pathological condition and amelioration of symptoms. However, Udeh et al4 reported that decompression alone resulted in a loss in QALY, compared with nonoperative care (mean difference: −0.08) (Table 3).
The calculated ICER of surgical versus nonoperative management in the article by Burnett et al3 was $59,487 (Table 3). This suggests a significant cost/benefit of surgical treatment compared with nonoperative therapy. The degenerative spondylolisthesis treatment was more expensive due to treatment with arthrodesis and instrumentation. The other studies noted that surgical treatment was more expensive per QALY or nonoperative care dominated.
It is important to realize that these cost-effectiveness measurements were determined only at 2 years postoperatively in 3 of the 4 studies. One would suspect that with increased time the overall cost of surgery treatment would decrease, particularly compared with continued cost of nonoperative management. This was confirmed in an analysis on the costs of treatment for lumbar disc herniations, where cost per QALY decreased from $77,600 at 2 years to $59,400 at 4 years for spinal stenosis the decreased went from $115,600 at 2 years to $64,300 at 4 years.2 At 2-year follow-up, surgical procedures were not found to be highly cost-effective, however surgery seems to be more cost-effective at more than 4-year follow-up.2
When comparing interventions, an analysis of the most similar populations is beneficial. Unfortunately, there were several areas of inconsistency and variability in these studies. Burnett et al3 did not report demographic information in their model-based retrospective literature review. Tosteson et al1 reported significantly healthier patients in the nonoperative care population (based on Short Form-36, Oswestry Disability Index, and EuroQol-5D preoperative scores), with the nonoperative population being significantly older. In addition, Burnett et al3 and Udeh et al4 used a mathematical modeling program for their studies with numerous implicit assumptions. These assumptions are subject to some biases, as expressed in the study by Burnett et al3 by the authors by stating that, “we have made assumptions that were neutral or that favored ... nonoperative treatment over laminectomy.”3 This makes drawing definitive conclusions of cost-effectiveness difficult.
Decompression With and Without Arthrodesis
The previous section reviews the literature comparing surgical and nonsurgical treatment of lumbar spine disease. As mentioned in the earlier text, the data are sparse and very heterogeneous. Further, only the article by Tosteson et al1 is based on actual patient data, whereas the others are determined by mathematical modeling algorithms. Despite these limitations, the ICER calculations illustrate that there is a cost-benefit from surgical treatment of lumbar stenosis with spondylolisthesis.3 Additional analysis was performed to examine if there was a further cost-benefit for treating lumbar stenosis (with or without spondylolisthesis) with or without arthrodesis. This is an important consideration because the addition of a fusion to a lumbar decompression significantly increases hospital costs by 50% and an instrumented arthrodesis increases these costs by more than 100%.8 Invariably, the addition of arthrodesis adds to the morbidity of a procedure and in a Medicare population may increase the rate of revision surgery.9–11
Unfortunately, there are a significant number of revision procedures after decompression-alone surgical procedures for lumbar stenosis and spondylolisthesis. These revision rates have been reported to affect between 8% and 11% of patients who underwent decompression at follow-up of 2 to 4 years after surgery.9,12 Thus, lumbar fusion procedures have been advocated to stabilize a more aggressive decompression as well as prevent revision surgical procedures due to spondylolisthesis progression and recurrent stenosis. However, the arthrodesis procedures require more extensive surgical resources due to a greater dissection, potential need to harvest bone graft, longer surgical time, and greater blood loss, and potentially instrumentation, increasing the financial costs. This was confirmed in the analysis where all arthrodesis procedures cost more than decompression alone, in the range from $5940 to $20,967.1,5,6
These added financial costs of an arthrodesis procedure did correlate with improved patient outcomes, where all the fusion studies noted gains in quality of life, in the range from 1.53 to 8.05 QALY.1,5,6 However, compared with nonoperative management, the analysis by Tosteson et al1 on lumbar stenosis without spondylolisthesis noted that the patients who underwent decompression alone had slightly better quality improvement than patients who underwent fusion (QALY 0.01). This suggests that there was no a significant cost/benefit of adding a fusion procedure in the presence of stenosis alone.
The noninstrumented fusions did provide greater clinical benefit to patients with lumbar spondylolisthesis procedures over decompression procedures alone based on the increased QALY measurements. This finding is consistent with several prospective studies in the spine literature.13–15 Herkowitz and Kurz13 reported on 50 patients with degenerative spondylolisthesis whose spines were decompressed with and without a noninstrumented fusion. Patients were followed up for a mean of 3 years (range, 2–4 yr) and the patient who developed arthrodesis had significantly better results with respect to relief of pain in the back and lower limbs.13
There was variable cost-effectiveness of decompression and noninstrumented arthrodesis compared with decompression alone when ICERs were calculated. Kuntz et al6 and Kim et al5 demonstrated a cost-benefit per QALY of $56,500 to $185,878 for arthrodesis at 10 years. However, Tosteson et al1 found that spondylolisthesis treated with noninstrumented fusion costs were $20,967 more than decompression alone and there was only a minimal improvement in QALY (0.02). Thus, ICERs were not calculated because there was no significant difference in QALYs between the 2 treatment groups, which favored the less-expensive treatment. Table 3 provides details on the economic findings of these studies.
Arthrodesis With Instrumentation
The earlier text discussed the utilization of arthrodesis in the setting of a spondylolisthesis and noted greater improvement in QALY than with decompression alone. However, not all patients with noninstrumented arthrodesis proceed to developing a solid fusion. Several studies have shown that patients with lumbar spine problems with pseudarthrosis have poorer clinical results than patients with solid fusions.1,16–21 In one prospective analysis of lumbar arthrodesis for patients with spondylolisthesis, there was excellent-to-good outcome in 86% of patients with solid arthrodesis and only 56% of patients with pseudarthrosis (P = 0.01).1
Pedicle screw spinal instrumentation has been used to provide instantaneous stability to the involved spinal segments and enhance fusion rates.22,23 Glaser et al24 reported that 242 of 244 patients with pedicle screw lumbar fusions had solid radiographical fusions at 10 years. Fischgrund et al14 reported only a 45% fusion rate in the absence of instrumentation. However, there is a significant increase in the cost of the procedure due to the added time to place instrumentation, and the associated price of the implants.
In this analysis, the addition of the instrumentation did not lead to significant increase in quality of life, as measured by QALY. Kuntz et al6 reported only a minimal gain of 0.003 QALYs and similarly Tosteson et al1 noted only a 0.02 gain in QALYs. Kuntz et al6 further calculated ICER between noninstrumented and instrumented fusion for lumbar spondylolisthesis as $3,112,800 and based on the 1-day gain in QALY with instrumentation.6 This high ICER cost is because of the limited improvement in QALY (1 d) with additional increased expense of the instrumentation. The analysis made by Tosteson et al1 did not calculate an ICER because they reported no significant difference in QALYs. Table 3 provides details on the economic findings of these studies.
These studies suggest that there is very high cost/benefit in the placement of instrumentation for lumbar spondylolisthesis. Christensen et al25 performed a 5-year prospective randomized study on instrumented fusion compared with noninstrumented fusion in grade I and II lumbar spondylolisthesis. These authors noted no significant difference with regard to functional outcome as measured by both the Dallas Pain Questionnaire and low back pain rating scale and this was maintained greater than 10 years.25,26 These studies call into question the cost-effectiveness of instrumentation in the treatment of lumbar spondylolisthesis. However, these findings contrast with those of other clinical series that suggest that instrumentation does provide a beneficial effect.14,27 Interestingly, Christensen et al25 did note that some subsets of patients with lumbar spondylolisthesis, primary degenerative instability, did have a significant improvement with instrumentation (P < 0.02). Therefore, suggesting that less heterogeneous and focal subgroup analysis may be beneficial.
In terms of quality analysis, this study has several limitations. The primary limitation was the paucity of literature on the cost-effective treatment of lumbar spinal disorders. There is also a limited amount of comparative evidence that evaluates and synthesizes the costs and consequences of surgical and nonoperative treatments for patients with lumbar degenerative diseases. Many of the studies that met the inclusion criteria of this systematic review were conducted by similar author parties and/or their institutions, leading to a very limited selection of authors and opening the possibility for inadvertent author bias.
Despite these limitations, the ultimate question when analyzing cost-effectiveness is “how much is society willing or can afford to pay for each QALY by an intervention?” Historically the figure $50,000 per QALY was used as a threshold for intervention.28–30 However, this figure was determined on the basis of costs of dialysis in patients with end-stage renal disease and seems to be an arbitrary figure and not relevant to many individuals or disease states.28
Typically with surgical procedures there is a significant financial cost and when analyzing cost-effectiveness there is no standard time for which cost-effectiveness is measured. This concept of delayed gratification is particularly important to consider when analyzing a procedure that will have a prolonged course of action such as spine procedures. Should analyses be made at 2 years, 10 years, or even at a further time point? Several of the studies used only a 2-year time window, which may not be a long enough period to see an effect. The Spine Patient outcomes Research Trial cost-effectiveness analysis did demonstrate a reduction in the cost per QALY for all surgical procedures.2 Suggesting a longer time interval (>4 yr) may be required to measure cost-effectiveness of spine surgical treatments and should be used in future studies.
In 2005, Brauer et al31 reviewed the orthopedic literature to determine the quality and quantity of cost-utility articles. These authors noted a paucity of data and concluded, “the current body of literature on orthopedic cost-utility analyses has a limited ability to guide policy.” There has been an increase in the evaluation of spinal procedures during the last decade, particularly in North America, as seen in this analysis. Recently, Rampersaud et al32 evaluated cost (Canadian dollars) per QALY gained in 3 common orthopedic procedures total knee arthroplasty, total hip arthroplasty, and focal lumbar spinal stenosis. ICER calculations using the median 5-year follow-up data were $5682/QALY for total hip arthroplasty, $6489/QALY for total knee arthroplasty, $2994/QALY for spinal decompression, and $10,806/QALY for spinal decompression with fusion.32 This suggests, as the authors concluded, that surgical treatment of “lumbar stenosis with and without spondylolisthesis is associated with a comparable and durable cost-utility to that of primary total hip arthroplasty and total knee arthroplasty for osteoarthritis at a median of 5 years after surgery.”32 This statement was supported by Laupacis et al33 who concluded in their analysis that surgical management of primary osteoarthritis of the spine, hip, and knee results in durable cost-utility ratios that are well below accepted thresholds for cost-effectiveness.
A systematic review of the literature was performed to assess the relevant literature on cost-effective treatments of lumbar degenerative conditions. This review noted a limited but increasing number and improving amount data, of not high quality from selected centers using heterogeneous populations. Surgical and nonoperative treatments improved patient's quality of life with variable costs depending on the analysis model. Despite more recent interest related to this topic, no definitive conclusions on cost-effectiveness of lumbar treatments can be made. It is important that future research efforts focus on constructing higher quality trials with consistent predetermined cost values and longer term follow-up in this area to help determine the most optimal cost-effective care.
- Limited available data on the cost-effectiveness of treatments for lumbar degenerative disease.
- Surgical and non-operative treatment improved patients QALY.
- Among patients undergoing surgical treatment, inclusion of arthrodesis and instrumentation significantly increased surgical costs.
- Further research is required in this field to define the most cost-effective treatment strategies.
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lumbar spine; cost; quality; stenosis; fusion; spondylolisthesis; ICER; QALY; instrumented fusion; arthrodesis
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