Women Report Better Outcomes After Surgery for Degenerative Lumbar Spondylolisthesis

• Updated on: 2018-03-17
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Women were significantly more likely than men to be satisfied with outcomes at 1 year following surgery for degenerative lumbar spondylolisthesis, according to a retrospective analysis of a prospective multicenter study published in the January issue of Neurosurgical Focus. “Though women fared better, both men and women report good outcomes following spondylolisthesis surgery,” lead author Andrew K. Chan, MD, told SpineUniverse. “Therefore, surgery should still be a viable option to all well-selected patients—woman or man—who have failed conservative management strategies,” said Dr. Chan, who is Resident Physician in the Department of Neurological Surgery at the University of California, San Francisco.

“Most of the previous literature investigating the impact of gender on spinal surgical outcomes show either inferior or equivocal patient reported outcomes for women,” Dr. Chan explained. “In fact, several studies following patients after lumbar spine surgery, female gender was associated with dissatisfaction following surgery. The concern is that such data may be interpreted by multiple stakeholders—surgeons and patients—in a manner, which discourages spinal surgery for women.”

“Therefore, it is important to highlight the contrary finding contained within our manuscript,” Dr. Chan emphasized. “That is, for some subsets of the spinal surgical population (specifically, patients with grade 1 degenerative lumbar spondylolisthesis), being a woman is associated with better outcomes.”

Prospective, Multicenter Study The researchers analyzed data from 477 patients who underwent surgery for grade 1 degenerative lumbar spondylolisthesis in the period from July 2014 through December 2015. Patient satisfaction was assessed using the North American Spine Society (NASS) Satisfaction Questionnaire 12 months post-operatively, which scores answers from 1 (most satisfied; surgery met my expectations) to 4 (least satisfied; I am the same as or worse than before surgery).

A majority of patients were most satisfied with outcomes (53.5%) and 5.5% were least satisfied. The least satisfied patients were more likely to have coronary artery disease (CAD; 26.9% vs 12.2%, P=0.04) and a higher body mass index (32.9±6.5 vs 30.0±6.0 kg/m, P=0.02). In addition, most satisfied patients had significantly lower Numeric Rating Scale back and leg pain and Oswestry Disability Index scores and a greater EuroQol health survey score at 3 and 12 months post-operatively (P<0.001 for all comparisons).

Only female sex was associated with the most satisfaction in multivariate analysis (OR 2.9, P=0.02).

Why Are Women More Likely to Be Satisfied With Surgery Outcomes? There are many possible reasons for greater satisfaction with spondylolisthesis surgery found among women in this study, Dr. Chan said. For example, the association may be related to differences in the etiology of spondylolisthesis as this study focuses specifically on patients with degenerative grade 1 lumbar spondylolisthesis, while many of the prior investigations on gender and spinal outcomes focused on other diseases (eg, lumbar degenerative disc disease) or were comprised of heterogeneous groups of diseases.

“Though the data is robust to a certain extent given several factors (ie, large size, prospectively collected), it still remains a retrospective analysis and thus is limited in its ability to discern causality,” Dr. Chan said.

Obesity and Coronary Artery Disease May Affect Patient Outcomes “Though obesity and CAD were not ultimately significantly predictive factors in the multivariate model, these [diseases] are generally markers of poorer health and comorbidity so patients may be advised to lose weight or optimize cardiac comorbidities before this elective surgery,” Dr. Chan said. “Further prospective registry studies, however, should clarify the short- and long-term impact of these comorbidities.”

“Additionally, patients with obesity and CAD may still have excellent outcomes following surgery for spondylolisthesis, so these factors should not necessarily preclude patients from surgery,” Dr. Chan noted.

Research on Longer-Term Outcomes Is Needed “While, one year outcomes are important and can help to set patient expectations following surgery, longer-term outcomes are needed to establish if the results are durable,” Dr. Chan said. “It will be important to follow the patients longitudinally so as to see whether these gender-based differences remain the further out patients progress from surgery.”

Commenting on the study, Clinton J. Devin, MD, expressed concern that there were not enough patients in the two cohorts to perform a statistically sound multivariate analysis given that the number of patients in general needs to be 15 per variable tested as a rough estimate.

Dr. Chan replied to this comment by stating, “The literature regarding the minimum number of events required per variable in linear regression analysis has been debated for quite some time and there is a vast literature on the topic. Unfortunately, there is still no resolution, with some authors suggesting as few as two events per variable necessary in multivariable/multiple linear regression models to guarantee unbiased estimation of coefficients and adjusted R2 values.”

Other Factors Linked to Satisfaction in Lumbar Spine Surgery “We looked at this same topic in all elective lumbar spine patients and found that higher disability at 12 months the biggest predictor of having dissatisfaction at 12 months,” said Dr. Devin, who is Associate Professor of Neurological Surgery and of Orthopaedic Surgery and Rehabilitation at Vanderbilt University Medical Center in Nashville, TN. “We also looked at this topic in all spine elective spine surgery and found that inability to achieve a clinically meaningful improvement in disability and NRS pain scores, Medicaid/uninsured payer status, and higher baseline back pain/neck pain and disability scores were independent factors of dissatisfaction.”

“Defining quality in spine care is an important effort and requires a combination of measurements, including validated patient reported outcomes, safety of care provided, and satisfaction with care,” Dr. Devin continued. “Satisfaction is dependent on expectations. Predictive analytics are allowing us to provide patients with a better understanding of where they may end up one year after surgery.”

“Furthermore, it allows interventions on those characteristics that are modifiable, such as psychiatric distress, smoking, opioid use, diabetes among others,” Dr. Devin told SpineUniverse. “Even though patients with significant disability may have dramatic improvements after surgery, they may not be satisfied if their expectation is that they will be normal following surgery.”

“Satisfaction is something society can get their hands around and will always be an important outcome; therefore, future work should focus on merging predictive analytics with categories of outcomes a patient can understand,” Dr. Devlin concluded. “Being able for a patient to tell the physician that they would like to get back to dancing and the physician being able to state the percent likelihood of accomplishing that goal is the holy grail.”

Dr. Devlin disclosed that he is a consultant and has obtained from research support Stryker Spine and Medtronic TLIF design team and has performed expert witness work.