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The Spine Blog

Friday, October 6, 2017

Predictors of poor outcomes following PLIF

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 for effectiveness.5 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

 

REFERENCES

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) 2009;34:2351-60.

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.