EVALUATION OF THE FACTORS PREDICTING THE OUTCOME OF SURGERY
IN THE TREATMENT OF LUMBAR SPINAL STENOSIS
Title.
Systematic review of the prognostic factors
of the outcome of surgery for spinal stenosis.
Background.
Surgery is usually recommended for patients
with spinal stenosis in whom conservative treatment has failed.
However, those patients tend to be of an advanced age and
many suffer other ailments, so the surgery's success rate
in these cases is variable. International scientific literature
suggests that it is situated between 60 and 70%.
According to some studies and to clinical perception, it
was suspected that certain factors had an influence in the
surgery's prognosis in those cases and that these factors
could be determined before the operation. Some of the factors
depended on the patient's general state, and others on specific
aspects of the disorder. Bearing in mind that the surgery
is relatively aggressive and that the patients tend to present
a delicate state of health, it was thought to be very useful
to define those factors to determine in each specific case
whether the hoped for improvement from surgery compensated
the inherent risk of the operation itself.
Most of the studies made on the subject had been carried
out with relatively small and not always well-defined samples.
Additionally, they centered on different potential prognostic
factors and sometimes gave contradictory results, perhaps
because their scientific quality was very uneven. For that
reason, it was useful to perform a systematic review that
summarized all the available scientific evidence on this subject
and would weigh the conclusions of each study according to
the reliability the research method used provided.
Objective.
To find and analyze the existing scientific
literature on prognostic factors of the outcome of surgery
in the cases of symptomatic lumbar spinal stenosis and summarize
it in a solid recommendation.
Methodology.
It was a systematic review of scientific
literature. All the studies on surgery for symptomatic lumbar
spinal stenosis in which the effect of potential prognostic
factors was appraised were identified.
To find those studies, an electronic search strategy based
on that developed by the Cochrane Collaboration was used and
applied to the databases: PubMed/Medline, Cochrane Library,
Medic, Índice Médico Español (Spanish
Medical Index), Lilacs and those of the NHS Centre for Reviews
and Dissemination (DARE, NHSEED and HTA).
All meta-analyses, controlled clinical trials (randomized
or not), and prospective cohort studies that centered on patients
operated on for spinal stenosis and studied the influence
of possible prognostic factors were included. Retrospective
studies were rejected. Also, the bibliographic references
of each one of the identified studies that met the criteria
for inclusion were reviewed to identify other possible studies.
Once a study was included, its scientific quality was evaluated
according to a list of 13 methodological criteria relating
to the study's population, the size of the sample, the follow-up,
the variables evaluated and the statistical analysis of the
results. The studies that met 7 or more of these criteria
were considered high quality and the rest low quality. The
methodological quality of each study was evaluated independently
by two experts. In the cases in which the evaluations did
not agree, these were discussed jointly and when necessary
the study was evaluated by a third expert who acted as arbiter
of the discussion until reaching an agreement by consensus.
A specific sheet of data extraction was designed to record
all the data identifying the study, its design and results.
Two reviewers received separately the data of each study.
All of the studies identified were described structurally
in detail and the effect of each studied factor on the outcome
was determined, as well as its magnitude and meaning.
Participants, along with the Foundation's
Science Department.
Department of Rehabilitation and Physical
Medicine of the Kuopio University Hospital (Finland).
The study was co-funded by EVO (University Hospital of Kuopio)
and the Kovacs Foundation.
Status.
The study has been completed and its results
are being analyzed and published.
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