THE IMPACT OF OBESITY IN COMPLEX SPINAL RECONSTRUCTION

By Patrick A. Sugrue, MD, Advocate Health Care

OBESITY IS PREVALENT IN THE US

The rate of obesity in the United States has steadily increased over the last few decades to the point where more than one third of adults in America are considered obese.1, 2 We define obesity using a measurement called body mass index (BMI), which takes into account one’s height and weight. The National Institute of Health defines “obese” as a BMI =30 kg/m2 and “morbidly obese” as a BMI =40 kg/m2. While the rate of obesity has increased, so has the prevalence of patients with adult spinal deformity, including approximately 5 million Americans disabled with a spine disorder.1, 3, 4 Associated with the increase in spine-related morbidity, we have seen an increase in the number of spinal surgeries being performed each year with an increase of 62.3% from 2004-20015.1, 5, 6

RISKS OF COMPLEX SPINE SURGERY

The impact that adult spinal deformity has on one’s life is significant and can lead to a significant decline in overall quality of life.7 Surgical intervention for adult deformity has been shown to improve overall quality of life quite significantly. However, there are some very significant challenges that accompany any spine surgery, especially procedures designed to treat adult spinal deformity with long construct fusion and complex reconstruction. The reported complication rates for surgery involving complex reconstruction can be as high as 95%.8 When we counsel patients prior to undergoing such an operation we often say “it’s not if but when a complication will occur”. Despite that, success rates for patients undergoing complex reconstruction for adult deformity are typically quite good when compared to nonoperative treatment.9

When planning for surgery and counseling a patient and their family, we try to focus on the risks versus benefits of such an operation. The risks of surgery can occur during the operation or postoperatively and encompass medical, surgical/technical, and social factors that accompany a complex operation and the challenging recovery that follows. We all want to reduce risk and maximize benefit and thus we try to modify or optimize all of the risk factors that go into the planned operation. Nonmodifiable risk factors include things like age and magnitude of deformity. However, one modifiable risk factor that can have a significant impact on outcome is obesity.

OBESITY IS A MODIFIABLE RISK FACTOR

Obesity as a risk factor has been studied across multiple surgical disciplines and has been shown to increase complication rates. Specifically in adult spinal deformity surgery, obesity (BMI =30 kg/m2) has been shown to be an independent predictor of increased risk for major complications and wound infections, as well as blood loss and longer operative times.8,10 Not surprisingly, along with the increased complication rate comes a higher cost of care and higher cost per quality-adjusted life years. Reports have also shown an increased rate of revision surgery over the long term in obese patients compared to the nonobese.11, 12

Despite the negative association with obesity, both obese and nonobese patients experience a significant increase in overall quality of life when comparing pre-operative to post­operative patient reported quality of life outcome measures.8, 10, 11 However, obese patients experienced less overall magnitude of improvement and a lower rate of improvement over time.8

With that in mind, prior to surgery we want to optimize a patient as best as possible. When discussing these issues with patients prior to surgery I typically use the following analogy. If you plan to run a marathon, you don’t just get out of bed one day and show up at the starting line. You train for it. Spine surgery, specifically complex reconstruction, is like running a marathon and is a massive stress to one’s body. Thus, you want to train and prepare your mind and body for the marathon.

PREHAB

Reducing obesity is one way to significantly improve your likelihood of achieving a good sustainable outcome. We call this process “prehab.” Patients also benefit greatly from improved nutrition and exercise. We will often have our nutritionists work with the patients to optimize their nutritional status and create a balanced diet. Likewise, we encourage regular physical activity and aerobic exercise to prepare for the stress of an operation. For patients who cannot tolerate much activity due to their obesity and/or spine-related disability, we encourage aquatic therapy, which can take some stress off the spine by being in the water but allows the patient to increase their heart rate and gain the benefits of the aerobic exercise.

RISK-BENEFIT EQUATION

In conclusion, obesity plays a major role in the risk versus benefit equation that must be weighed prior to undergoing any operation, particularly a complex reconstruction. Fortunately, obese patients can gain similar benefits to nonobese patients, but their operative and post-operative course may be more difficult because of the obesity. Therefore, we want to optimize these modifiable risk factors as much as possible prior to surgery to increase the likelihood of achieving the desired outcome.

REFERENCES

  1. Elsamadicy, A.A., et al., Reduced Impact of Obesity on Short-Term Surgical Outcomes, Patient-Reported Pain Scores, and 30-Day Readmission Rates After Complex Spinal Fusion (>/=7 Levels) for Adult Deformity Correction. World Neurosurg, 2019. 127: p. e108-e113.
  2. Hales, C.M., et al., Trends in Obesity and Severe Obesity Prevalence in US Youth and Adults by Sex and Age, 2007-2008 to 2015-2016. JAMA, 2018. 319(16): p. 1723-1725.
  3. Cowan, J.A., Jr., et al., Changes in the utilization of spinal fusion in the United States. Neurosurgery, 2006. 59(1): p. 15-20; discussion 15-20.
  4. Di Capua, J., et al., Diabetes Mellitus as a Risk Factor for Acute Postoperative Complications Following Elective Adult Spinal Deformity Surgery. Global Spine J, 2018. 8(6): p. 615-621.
  5. Martin, B.I., et al., Trends in Lumbar Fusion Procedure Rates and Associated Hospital Costs for Degenerative Spinal Diseases in the United States, 2004 to 2015. Spine (Phila Pa 1976), 2019. 44(5): p. 369-376.
  6. Rajaee, S.S., L.E. Kanim, and H.W. Bae, National trends in revision spinal fusion in the USA: patient characteristics and complications. Bone Joint J, 2014. 96-B(6): p. 807-16.
  7. Bess, S., et al., The Health Impact of Symptomatic Adult Spinal Deformity: Comparison of Deformity Types to United States Population Norms and Chronic Diseases. Spine (Phila Pa 1976), 2016. 41(3): p. 224-33.
  8. Soroceanu, A., et al., Impact of obesity on complications, infection, and patient-reported outcomes in adult spinal deformity surgery. J Neurosurg Spine, 2015. 23(5): p. 656-664.
  9. Smith, J.S., et al., Outcomes of Operative and Nonoperative Treatment for Adult Spinal Deformity: A Prospective, Multicenter, Propensity-Matched Cohort Assessment With Minimum 2-Year Follow-up. Neurosurgery, 2016. 78(6): p. 851-61.
  10. Goyal, A., et al., Impact of obesity on outcomes following lumbar spine surgery: A systematic review and meta-analysis. Clin Neurol Neurosurg, 2019. 177: p. 27-36.
  11. Brown, A.E., et al., Obesity negatively affects cost efficiency and outcomes following adult spinal deformity surgery. Spine J, 2020. 20(4): p. 512­518.
  12. Rihn, J.A., et al., Does obesity affect outcomes of treatment for lumbar stenosis and degenerative spondylolisthesis? Analysis of the Spine Patient Outcomes Research Trial (SPORT). Spine (Phila Pa 1976), 2012. 37(23): p. 1933-46.