The Increasing Morbidity of Elective Spinal Stenosis Surgery: Title and subTitle BreakIs It Necessary?

Surgical treatment of older patients with severe and protracted symptoms from neurogenic claudication or radicular pain syndromes can provide rapid improvement. The most common clinical presentation, spinal stenosis with primary radicular pain, can be effectively treated with lumbar decompression alone. The use of the operative microscope, minimal dissection, and rapid postoperative mobilization, as developed over the last 20 years, has decreased surgical morbidity. Large observational and controlled studies have shown that most patients with spinal stenosis can realize large and durable gains in pain relief and functional improvement with this procedure, despite multilevel vertebral involvement, advanced age, and common comorbid medical conditions.^{1 - 3}

A minority of patients with symptomatic spinal stenosis have a combination of spinal deformity, such as degenerative spondylolisthesis or scoliosis, which complicate the spinal stenosis pathology. Decompressive surgery alone in these instances (removing the bone, ligament, and facet joint materiel compressing the spinal root) may destabilize the spine and result in progressive deformity. Spinal fusion, for cases in which only 1 or 2 levels of instability are present appears to be a worthwhile addition to the decompression procedure in some patients. Results with simple fusion techniques often appear to give highly reliable and durable results.⁴ However, the available evidence suggests little or no advantage in routinely applying more complex fusion techniques such as instrumentation, bone graft augmentations, or combined anterior and posterior approaches.⁵

A still smaller proportion of patients with spinal stenosis may have a more global degenerative collapse of the lumbar spine with pronounced instability. Multiple vertebral levels may be scoliotic, rotated, or displaced out of alignment. Among these patients, the spine is commonly unbalanced and tilted forward, lumbar lordosis is lost, and the neurological symptoms are complicated by severe positional back pain. Nonsurgical care is minimally effective and patients usually have chronic pain, functional disability, and poor quality of life.⁶ However, for many years the high risk of serious or catastrophic complications (50%-60%)^{7 - 8} in treating this group of patients made both surgeons and patients reluctant to proceed in these circumstances. Deformity correction with older instrumentation was difficult and unreliable. Poor bone quality and metabolic disease made achieving a long fusion unlikely due to high rates of pseudarthrosis, instrumentation failure, and recurrent deformity.

During the last 10 years, a combination of innovations has made certain technical aspects of complex adult deformity surgery more feasible. Instrumentation is less likely to break or pull out of bone, vertebral augmentation with bone cement or the pharmacological treatment of metabolic disease has improved bony fixation, fusion technology including structural and biological bone graft augmentation has decreased the risk of pseudarthrosis.^{7 - 8} Despite these improvements, the complex reconstruction of spinal deformity in older patients remains a difficult and dangerous enterprise. Complication rates have declined but remain concerning (30%-40%)^{7 - 9} and the reoperation rates, in a population for whom there is a high risk of both medical and anesthetic complications with additional surgery, remains at 10% to 20% in the most optimistic reports.⁹ Moreover, despite these major interventions, this approach is still not effective in 30% to 40% of patients.⁷

In this issue of JAMA, Deyo and colleagues¹⁰ report that the rate of spinal stenosis surgery in the Medicare population has remained more or less stable, but the rate of complex surgery for this disease has increased from negligible levels in 2002 to nearly 15% of all spinal stenosis surgeries in 2007. These more complex surgeries are also reported to be independently associated with increased perioperative mortality, major complications, rehospitalization, and cost.

The findings do not provide explanations for the increase in complex surgery that has occurred during the past 6 years. Ideally, because the complex surgical techniques are used to treat complex deformities, the data should show that patients undergoing these procedures usually have these complex deformities. The diagnoses reported, however, do not support this “ideal” explanation; 50% of these new complex fusion operations were performed in patients with spinal stenosis alone and no deformity. Spinal stenosis with scoliosis by coding, accounted for only 6% of the complex fusions performed.

As in most studies using administrative databases, there are questions about data quality and completeness, such as how well the presence of instability and deformity are coded in the hospital records. Although this may have been a serious limitation in the past, reimbursement practices and quality surveillance widely in place during the time frame of this study create tangible incentives to code accurately and comprehensively serious comorbid conditions.

More likely the data are generally accurate. Newer and more complex technologies are being used for patients with little specific indication for the approaches and for whom there is good evidence that simpler methods are highly effective. These findings corroborate a recent study by Cahill et al¹¹ that reported similar findings regarding the use of recombinant human bone morphogenetic proteins (rh-BMP) in spinal surgery. Although rh-BMP was developed as a supplement for complex and extensive spinal fusion, the authors found that this expensive and occasionally hazardous technology was used for 40% of all lumbar fusions, and 85% of use was in simple 1- or 2-level fusions.¹¹ Most of this use is currently considered off label, suggesting that vigorous promotion of this approach by industry-supported surgeons and publications may have been a factor in the increased use of rh-BMP.¹²

The proliferation of risky and expensive practice beyond reasonable supporting evidence is commonly mentioned as a fundamental failing of medical practice in the United States.¹³ Although it is unclear why this phenomenon occurs in many areas, conflicting economic incentives are clearly at work in spinal surgery. Just as simpler interventions in other clinical fields usually have no sponsor beyond the conscientious and compassionate clinician, simple decompression operations rarely have well-funded advertising campaigns or well-orchestrated promotions at professional meetings.

The fact that lumbar decompression is well studied and highly effective in spinal stenosis does not mean that it is well-compensated. In the Medicare population studied by Deyo et al,¹⁰ surgeon reimbursement for a simple decompression for spinal stenosis is approximately US $600 to $800, whereas the reimbursement for a complex fusion may be 10-fold greater.¹⁴ Paradoxically, a thorough decompression procedure that does not destabilize the spine is in many respects a more technically demanding operation than the decompression that will be followed by an instrumented fusion. Similarly, a posterior fusion requires more meticulous attention to arthrodesis technique than a combined anterior and posterior fusion with instrumentation and biologic fusion augmentation. In some respects, it may be easier and safer for a surgeon to perform the larger operation.

Furthermore, in common spinal decompression, there is little or no profit to be made from the use of an implant, device, or spinal biologics agent. For instance, the charges for implants alone in a complex fusion procedure may exceed $50 000.^{10 - 11 ,15} These devices are aggressively marketed, so much so that their promotion may sometimes cross the line of professional conflict of interest among profession leaders and institutions. In traditional Medicare, there seems to be little concern by the surgeon that the economic burden of a larger procedure will be borne by the patient, and patients often may not be concerned about these Medicare-covered in-hospital expenses. However, the study by Deyo et al¹⁰ demonstrates a definite human cost to this practice in terms of a clear increased risk of surgical mortality, major complications, and prolonged morbidity associated with these more complex approaches. As the report by Deyo et al suggests, there is no evidence that these factors have been adequately considered.

In 2007, the final year of data reported in the study by Deyo et al, Consumer Reports¹⁶ rated spinal surgery as number 1 on its list of overused tests and treatments. This was a harsh rebuke given the benefit associated with many common spinal surgeries. However, the findings from the study by Deyo et al should not only remind patients, surgeons, and payors that the efficacy of basic spinal techniques must be assessed carefully against the plethora of unproven but financially attractive alternatives, but also should serve as an important reminder that as currently configured, financial incentives and market forces do not favor this careful assessment before technologies are widely adopted. When applied broadly across medical care in the United States, the result is a formidable economic and social problem.