Risk Stratification Approach to Spinal Surgical Management

Meeting highlight from the American Association of Orthopaedic Surgeons 2017 Annual Meeting

Sigurd H. Berven, MD presented Building a Data Driven Approach to Patient Selection: What Is the Current Status of Risk Stratification? at the American Association of Orthopaedic Surgeons 2017 Annual Meeting held in San Diego, CA. Dr. Berven is Professor in Residence of the Center for Outcomes Research at the University of California, San Francisco.

Risk Stratification Empowers Choice

Dr. Berven asserted that risk stratification is important in empowering informed choice regarding surgery, and in determining the appropriateness of surgical management in spinal deformity. As we move toward an era of accountability of care, it is crucial to establish reasonable and accurate standards for complications using risk stratification.

  • Risk is the basis of informed choice and appropriate care, and empowers informed choice in the management of spine deformity.
  • Calculating risk provides valid information on natural history, as well as on outcomes of operative and non-operative options.
  • Risk calculation also quantifies the risks and expected benefits of management choices.

Man standing on a road, looking out at many other roads.Risk is the basis of informed choice and appropriate care, and empowers informed choice in the management of spine deformity. Photo Source: 123RF.com.


The approaches to spinal deformity vary regionally. Surgical signature, patient values and preferences, and the recognition of factors that predict outcome and risk vary regionally from 1.30 to 4.48, and in some regions, from 0.21 to <0.75. These factors vary globally as well.

Variability is a proxy for care, and reducing variability is related to improved quality of care. To reduce variability, we rely on clinical practice guidelines to establish appropriate use criteria. We look at areas of consensus, discordance, and those needing further study.

The Rand/UCLA Area Under the Curve Methodology

This methodology, derived by Fitch et al in 2001, guides informed choices under conditions of uncertainty, from most inappropriate to most appropriate, on a scale from one to nine.

1 – 3: An inappropriate procedure or management strategy is defined as one in which the value (benefit per unit cost) is low, that is, the expected negative consequences exceed the expected health benefit such that the procedure should not be performed.

4 – 6: A reasonable procedure or management strategy is one in which the balance of risk and benefit is not known, but a reasonable chance of positive net benefit, with limited risk, is established.

7 – 9: An appropriate procedure or management strategy is defined as one in which the value (benefit per unit cost) is high. The expected health benefit exceeds expected negative consequences by a sufficiently wide margin that the procedure is worth undertaking.

Appropriate use criteria indicate reasonable care based on available evidence combined with a rigorous, transparent recommendation process and well-defined scenarios. Appropriate use criteria specify when it is appropriate to perform a medical procedure or service. An appropriate procedure is one for which the expected health benefits exceed the expected health risks by a wide margin.          

Four drivers of appropriateness of surgery for degenerative lumbar scoliosis were developed by the Lumbar Scoliosis Appropriateness Group and published in Spine in 2016. The four drivers:

  1. Reoperative symptoms
  2. Progression of deformity
  3. Sagittal alignment
  4. Comorbidities

What Is an Acceptable Level of Risk?

Defining risk requires accurate risk stratification and global standardization / benchmarking. Defining risk of a surgical procedure involves calculating the observed rate of complications, expected rate of complications, and observed/expected ratio provides a meaningful metric of quality of care.

Detecting Perioperative Complications

Reported rates of perioperative complications vary widely across the world and are gathered in databases. Institutional, voluntary society and insurance databases carry limitations. They record the need to return to the operating theater for resolution and perioperative vs late complications.

Morbidity and Mortality of Adult Scoliosis Surgery

In a 2011 issue of Spine (36[9]:E593-597), the Scoliosis Research Society published a review of 4980 cases performed from 2004-2007. A total of 521 patients experienced complications (10.5%), and 669 complications (13.4%) were recorded. Predictors of complications were osteotomies, revision surgery, and combined anterior/posterior approaches. Age and type of scoliosis were not predictive of complications.

The most common complication was dural tear, which occurred in 2.9% (n=142) of patients. The second most common complication was deep (1.5%, n=73) and superficial (0.9%, n=46) wound complications.

The 2016 Scoli-RISK-1 Study

This prospective, multicenter study assessed neurologic outcomes at discharge and after 6 weeks and 6 months. At discharge, 59 of 266 patients (23%) experienced a decline in neurological outcomes. At 6 weeks postoperatively, 48 of 268 patients (18%) had experienced a decline in neurological outcomes. At 6 months postoperatively, 30 of 268 patients (11%) had experienced a decline in neurological outcomes.

Complications Associated with Adult Spinal Deformity Surgery 

In the February 26, 2016 issue of J Neurosurg Spine, the International Spine Study Group published a prospective multicenter assessment of perioperative and ≥2-year postoperative complication rates associated with adult spinal deformity surgery.

A total of 291 patients with 2 years of follow-up, mean age 56.2 years, were studied. Overall, 203/291 patients (69.8%) suffered at least one complication:

  • 52.2% of patients experienced a perioperative complication
  • 42.6% of patients experienced a delayed complication
  • 28.2% required at least one revision

A total of 469 (n=207 minor, n=262 major) complications occurred (mean 171 [0.71 minor, 0.90 major]) in 203 (69.8%) of patients. The most common complication categories were implant (14/67, 27.8%); radiographic (29/52, 27.8%); neurological (37/44, 27.8%); and operative (41/33, 25.4%).

Morbidity and Mortality of Fusions

In 2011, the morbidity and mortality of fusions from the thoracic spine to the pelvis in adults was detailed in Spine (36(17):1397-1401). A total of 103 cases were reviewed. Return to the operating theater and medical complications were quantified. Forty-three patients (35%) returned to the operation theater. The most common reasons for reoperation were: infection in 17% (n=18) and adjacent segment disease in 12% (n=12). Twenty-three patients (12%) experienced a major complication, the most common of which were myocardial infarction, pulmonary embolism, adult respiratory distress syndrome, and pneumonia.

Updated on: 05/04/19
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