Rates of spine surgery in the elderly have increased dramatically over the past decade, with the most dramatic increase noted for lumbar fusion. In 2003, Medicare spent over one billion dollars on spine surgery. In 1992, lumbar fusion accounted for only 14% of spending, by 2003, fusion accounted for almost half of total spending on spine surgery. At the same time, rates of lumbar spine fusion varied dramatically across U.S. regions and were substantially more variable than rates of lumbar decompression.
The strengths and limitations of administrative databases for evaluating practice patterns must be kept in mind. We can determine with good precision the rates of different surgeries and procedures across different regions. However, patient characteristics are limited to basic demographic information. Thus, all the rates presented are appropriately adjusted for age, race and gender; however, the clinical indications and proportion of patients operated on for particular pathological conditions is not easily obtainable. Thus we cannot evaluate the appropriateness or inappropriateness of any given procedure. However, we can infer that the rates of fusion cannot all be optimal given the very large variation in rates across regions with demographically similar populations.
Patient preferences are unlikely to explain the dramatic differences in rates observed across U.S. regions. Four sources of evidence support this conclusion. Prior studies have failed to detect systematic differences in patient preferences as the cause of variations in surgical rates.11,12
Striking differences in rates between neighboring geographic regions would appear to be inconsistent with this explanation. Also, an increasing body of experimental research reveals that formal decision aids lead patients to make different decisions than when left to receive routine advice from their clinicians. Finally, the strong correlation of local surgical rates over time – both for lumbar fusion and for lumbar discectomy/laminectomy, is consistent with a model of decision-making in which local physician opinion is an important determinant of local practice.
The evidence base guiding the use of the most variable orthopedic procedure, lumbar back surgery with fusion, is, with few exceptions (e.g., lumbar spondylolisthesis of various etiologies), particularly weak, even though it is the procedure enjoying the most rapid increase in use over the past 10 years. During this period, there has been growing interest in expanding the indications for surgical intervention along with a proliferation of new technologies to address the many causes of low back symptoms. Many have involved fusion additives in the form of devices and more recently biologics, e.g., bone morphogenic proteins. Most all have been brought to market in the absence of randomized trials to test their efficacy and effectiveness. Most have been brought forth based on FDA criteria for safety. Nearly all have demonstrated improved rates of fusion by various methods–clearly an intended outcome–but the effect on patient-based outcomes such as functional health status or quality of life remain uncertain. The real question remains, “Who are the most appropriate candidates for fusion?” How do we make the diagnosis and can we agree?
The scientific evaluation of outcomes for spine surgery has not kept up with the changes in operative techniques.14
Recent reviews of the quality of clinical evidence of surgical treatment of these conditions undertaken by the Cochrane collaboration illustrate the serious weaknesses in the clinical science.15–17
Given the paucity of clinical trials, it is not possible, with few exceptions, to draw conclusions concerning the role of instrumented fusion for a given spinal condition, much less to evaluate the relative efficacy or effectiveness of any particular device on patient outcomes.
Scientific uncertainty contributes to variability in clinical decision-making. Major surgery is often conducted without an adequate scientific basis for making a reasonably accurate estimate of the likely outcomes. This is clearly the case for some degenerative conditions of the back. Left alone, practice variations will not go away. Expansion of the research agenda will require not only the early evaluation of new technologies and new theories about the use of current technologies, but also the ongoing evaluation of existing practices.
Effective technology assessment will therefore require the mobilization of both academic medical centers and physicians in community practice, and will require support from funding and regulatory agencies such as, in the US, the NIH, the FDA and the Centers for Medicare and Medicaid Services (CMS). One of these initiatives is the reengineering of the clinical research enterprise, which, we believe, is inevitably about patient preferences and practice variation. But for such research to be successful there must be broad acceptance by the clinician community and by patients of the need for all patients and physicians to participate in the ongoing evaluation of new and existing technologies. The reengineering required for evaluation research must therefore move beyond the confines of the laboratory or even the wards of single institutions to involve the patients in everyday practice.4
Patients who suffer with lower spine disorders are numerous and unlikely to disappear. The ability to do randomized trials is not the question; the question is, given the necessary resources why aren’t we doing more?
- Lumbar surgery rates, especially those for fusion, have increased markedly in the decade between 1992 and 2003.
- Rates of spine surgery are among the most variable of all surgeries.
- The underlying causes of the international and regional variations found in rates of spine surgery include lack of scientific evidence, financial incentives and disincentives to surgical intervention, and differences in clinical training and professional opinion.
- The mobilization of talent and focus of interest required to meet the larger task of improving the scientific basis of everyday practice will require the active participation of the funding agencies and academic medical centers.