Patients and spine surgeons have long sought out tools to
predict outcomes following surgery in order to make more informed treatment
decisions. In general, patient characteristics such as medical comorbidities,
psychosocial problems, and being involved in worker’s compensation claims or
litigation have been stronger predictors of outcomes than surgical factors such
as fusion technique.1-4
In order to assess risk factors for poor outcomes following PLIF for
degenerative spondylolisthesis and/or foraminal stenosis requiring complete
facetectomy, Dr. Makino and colleagues from Japan evaluated 2 year outcomes for
100 consecutive patients undergoing one or two level PLIF. Their main outcome
measure was effectiveness on the Japan Orthopaedic Association Back Pain
Evaluation Questionnaire (JOABPEQ), defined as an improvement of over 20 points
or final score of over 90. This questionnaire evaluates five different domains
(pain-related disorders, lumbar spine dysfunction, gait disturbance, social
life dysfunction, and psychological disorders), with each domain scored 0-100, with
100 being the best possible score. Two-year effectiveness of surgery ranged
from 31% on psychological disorders to 78% for gait dysfunction. In their
multivariate analysis, the strongest predictor of ineffectiveness across most domains
was increasing age. A post-operative decrease in lumbar lordosis predicted poor
outcomes on pain-related disorders, social life dysfunction, and psychological
disorders. Surgical factors such as increased number of fused levels,
pseudarthrosis, and radiographic adjacent segment degeneration (ASD) predicted
worse outcomes on lumbar spine dysfunction and gait disturbance.
The authors have done a nice analysis of risk factors for
poor outcomes on the relatively new JOABPEQ, which has not been used in this
type of study in the past. Most prior studies of risk factors for poor outcomes
have used legacy instruments such as the SF-36, Oswestry Disability Index, and
Roland Morris Disability Questionnaire. The major limitation of this study is
that the authors only included age, sex, and body mass index as patient-related
variables in their model. Characteristics such as medical comorbidities,
psychosocial factors such as depression, educational attainment, and
socioeconomic status, and work-related factors such as disability or litigation
were not included. Given that these factors have been the strongest predictors
of outcomes in prior studies, it is hard to interpret the results of this
study. Age seems to be a predictor of surgical ineffectiveness, but that might
be a function of the definition of effectiveness which includes patients who
obtain a score of over 90. A prior study has shown that JOABPEQ scores decrease
with age, so older patients likely had to improve more to reach this threshold
Finally, the number of patients in the subgroups analyzed likely became very
small (i.e. there were only 22 patients in the non-effective group for
pain-related disorders, and only 5 among them with a pseudarthrosis), making it
underpowered to detect the effects of many variables. Despite the limitations
of this paper, it does suggest that certain surgical factors such as multilevel
fusion, post-operative loss of lumbar lordosis, pseudarthrosis, and
radiographic ASD are associated with worse outcomes. However, it remains likely
that the strongest drivers of outcomes are patient-related factors.
Please read Dr. Makino’s article in the October 1 issue.
Does this change how you think about risk factors for failure following lumbar
fusion? Let us know by leaving a comment on The Spine Blog.
Adam Pearson, MD, MS
Associate Web Editor
1. Abdu WA, Lurie JD, Spratt KF, et al.
Degenerative spondylolisthesis: does fusion method influence outcome? Four-year
results of the spine patient outcomes research trial. Spine (Phila Pa 1976)
2. Ekman P, Moller H, Tullberg T, Neumann P, Hedlund R.
Posterior lumbar interbody fusion versus posterolateral fusion in adult isthmic
spondylolisthesis. Spine (Phila Pa 1976) 2007;32:2178-83.
3. Pearson AM, Lurie JD, Tosteson TD, Zhao W, Abdu WA,
Weinstein JN. Who should undergo surgery for degenerative spondylolisthesis?
Treatment effect predictors in SPORT. Spine (Phila Pa 1976) 2013;38:1799-811.
4. Slover J, Abdu WA, Hanscom B, Weinstein JN. The impact of
comorbidities on the change in short-form 36 and oswestry scores following
lumbar spine surgery. Spine (Phila Pa 1976) 2006;31:1974-80.
5. Hashizume H, Konno S,
Takeshita K, et al. Japanese orthopaedic association back pain evaluation
questionnaire (JOABPEQ) as an outcome measure for patients with low back pain:
reference values in healthy volunteers. J Orthop Sci 2015;20:264-80.