Spinal stenosis is the most common reason for lumbar surgery in patients over age 65, and a
substantial proportion of stenosis patients present with concomitant lumbar degenerative
spondylolisthesis (LDS). This condition is characterized by the anterior translation of a
vertebra due to degenerative changes in the facet joints and disk, most commonly at L4-L5,
and is most prevalent in women over age 50. The translation commonly results in spinal
stenosis, and patients tend to present with various combinations of low back pain,
radiculopathy, and neurogenic claudication. The Spine Patient Outcomes Research Trial (SPORT)
demonstrated better outcomes for patients treated with surgery compared to non-operative
treatment. However, all patients met strict inclusion criteria including the presence of
radicular pain or neurogenic claudication, cross-sectional imaging demonstrating spinal
stenosis consistent with their symptoms, and duration of symptoms for over three months.
Additionally, specific patient and disease characteristics were shown to significantly affect
surgical and non-operative outcomes. While the literature makes it clear that surgery results
in better outcomes than non-operative treatment for the "average" LDS patient, surgeons have
to help make treatment decisions for patients with a diverse array of characteristics that
can have positive and negative effects on surgical outcomes. Additionally, many LDS patients
do not meet the inclusion criteria of SPORT, and extrapolating the results to these patients
is inappropriate. The currently available evidence provides surgeons with some general
principles to help guide decision-making but does not inform decision-making at the
individual patient level.
Many studies have evaluated the effect of specific patient and disease characteristics on
surgical outcomes for spinal stenosis. These have generally shown worse surgical outcomes for
patients with medical and psychological comorbidities, lower socioeconomic status and
educational attainment, smokers, those with predominant back pain, those receiving workers'
compensation, and patients involved in litigation. However, subgroup analysis of the SPORT
degenerative spondylolisthesis cohort, the first study that evaluated predictors of both
surgical and non-operative LDS outcomes, demonstrated that these factors tended to predict
both worse surgical and non-operative outcomes. As a result, most of these subgroups tended
to have a similar treatment effect of surgery (i.e. relative advantage of surgical compared
to non-operative outcomes) even if their absolute degree of improvement with surgery was
less. While these data suggest that most LDS patients meeting the SPORT inclusion criteria
will improve more with surgery than with non-operative treatment, many LDS patients do not
meet the SPORT inclusion criteria, and evidence is needed to provide treatment guidelines for
these patients.
In an ideal world, randomized-controlled trials (RCT) would be performed for multiple
subgroups in order to compare outcomes among all available treatment options. The SPORT LDS
RCT demonstrated the difficulty in performing a seemingly straightforward RCT comparing
surgery to non-operative treatment, with only 64% of patients assigned to surgery having
undergone an operation within 2 years, and 49% of patients randomized to non-operative
treatment having undergone surgery by 2 years. Given that it is not possible to perform
sufficiently powered RCTs to compare surgical and non-operative outcomes for multiple LDS
subgroups, other methods must be considered to generate guidelines to help surgeons and LDS
patients select the most appropriate treatment based on their individual characteristics. One
such alternative is the RAND appropriateness method (RAM), which combines a detailed review
of the literature with a modified Delphi panel approach to create appropriateness criteria
based on collective expert opinion. A major strength of the RAM is that is involves a high
level of clinical detail, allowing for treatment recommendations to be made based on a number
of relevant patient and disease characteristics that can be applied to individual patients.
The RAM has been widely used and studied by several groups in various countries in relation
to different spinal problems. The RAM is considered most useful for procedures that are used
frequently, associated with a substantial amount of morbidity and/or mortality, consume
significant resources, have wide variation among geographic areas in rates of use, and whose
use is controversial. All these criteria apply to the procedures commonly used in the
surgical treatment of LDS. Depending on the definition of success, success rates at 1 year
after surgery range from 50% to 94%. The rate of lumbar fusion in the United States Medicare
population has been shown to vary nearly 20-fold across hospital referral regions. In the
SPORT LDS cohort, significant differences were found across different study centers in
patients' baseline neurological deficit, stenosis location and severity, and number of
stenotic levels as well as in their functional outcome out to 4 years after surgery. High
levels of geographic variation are frequently attributed to uncertainty about the most
appropriate treatment for a given condition, usually reflecting a lack of strong evidence.
Given the lack of treatment recommendations that can be applied at the individual LDS patient
level, an international group of experts were convened to use the RAM to create
appropriateness criteria for surgery for LDS.3
The RAM process included 14 experts from the USA, UK, Belgium, Sweden, Norway, Spain,
Switzerland, and Hungary with backgrounds in orthopaedic surgery, neurosurgery, rheumatology,
and physical medicine. The experts considered the appropriateness of decompression alone,
uninstrumented fusion with or without decompression, and instrumented fusion with or without
decompression for 744 patient scenarios. The variables defining the scenarios included
symptomatology (back pain, radicular pain, and/or neurogenic claudication), severity of
neurological deficit, presence of significant foraminal and/or central stenosis, level of
disability, presence of significant medical comorbidities, clinically relevant "instability",
and the presence of significant psychosocial "yellow flags". The appropriateness of each type
of surgery was rated on a 1-9 scale (1-3 inappropriate, 4-6 uncertain, and 7-9 appropriate)
in two separate rounds by the expert panel. Surgery of one type or another was considered
appropriate in 27% of scenarios, uncertain in 41%, and inappropriate in 31%. In general,
scenarios in which symptoms were limited to back pain in the absence of instability were
considered inappropriate for surgery, whereas the presence of radiculopathy or claudication,
neurologic deficit, and instability increased the likelihood of a scenario being considered
appropriate for surgery. The presence of medical comorbidities and "yellow flags" decreased
the likelihood of a scenario being considered appropriate for surgery. There was widespread
disagreement about the appropriate use of instrumentation, but, in general, fusion of some
variety was more likely to be considered appropriate in the presence of back pain or
instability.
The RAM was successfully employed to develop appropriateness criteria for LDS surgery. Prior
to widespread clinical implementation, the results need to be validated in the LDS
population. If validated successfully, a computer-based algorithm could be developed to help
surgeons and patients select treatment using the appropriateness criteria. This would
represent a significant advancement in shared decision making for LDS, effectively moving
from population-based recommendations to those that can be applied at the individual patient
level.
