Predictive Models in Risk Stratification Approach to Spinal Surgical Management

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

This article is a continuation of Risk Stratification Approach to Spinal Surgical Management, and features predictive models and conclusion made by the presenter, Sigurd H. Berven, MD.

Predictive Models

Tools for risk stratification used in predictive modeling include personal experience, peer review/case conferences, expert opinion (such as Delphi panels), and modeling based on identification of predictor variables.

Predictors of complications used in predictive modeling are patient and surgical factors.

Patient factors are age, comorbidities, preoperative health status, and prior surgery. Surgical factors are combined anterior and posterior approaches, staged surgeries, osteotomies, and large correction of sagittal plane deformity.
The words "Predictive Analytics" and releated words.Predictors of complications used in predictive modeling are patient and surgical factors. Photo

The Spine Patient Outcomes Research Trial (SPORT) Spine Treatment Calculator

This online calculator, directed to patients, yields possible results for physical activity, pain, and overall health after surgical and nonsurgical treatment for low back-related pain. Patients select one diagnosis: sciatica/ruptured disc (herniated disc), pinched nerve (spinal stenosis), or slipped vertebra (degenerative spondylolisthesis).


A predictive modeling tool based on data from the Spine End Results Registry of 1476 patients. The Spine End Results Registry is a prospectively collected data registry of all patients undergoing spine surgery at Harborview Medical Center and the University of Washington Medical Center from 2003 through 2004.

Several multivariate log-binomial analyses were performed to identify and quantify risk factors for complications after spine surgery. Extensive comorbidity and demographic data were defined a priority and collected prospectively for each surgical patient. Complications were defined a priority and prospectively recorded for at least 2 years following surgery.

2014 Predictive Model for Medical Complications After Spine Surgery

Clinicians input the following variables:

  • Age, gender, smoking status, alcohol use, diabetes, body mass index, insurance stats, surgical approach, revision surgery, surgery region, diagnosis, surgical invasiveness
  • Hypertension, congestive heart failure, chronic obstructive pulmonary disease
  • Rheumatoid arthritis, renal disease, liver disease, cancer, anemia, bleeding disorder

Percent chances of major complications, all complications, infection, and dural tear are rendered.

2016 Risk Calculator of Surgical Outcomes Beyond Perioperative Mortality Rate

The calculator is the Commission on Global Surgery’s recommendation on improving quality in surgery by reporting observed to expected outcome rates. The risk calculator was built using data collected from 2.7 million operations from 586 hospitals that participated in the American College of Surgeons National Surgical Quality Improvement Program from 2010-2014. The clinician inputs a procedure name or CPT code, as well as the presence or absence of approximately 20 health-related patient risk factors.

Percent risk outcomes are generated for the selected procedure, along with the patient’s specific risk, the average risk, and whether the chance of the outcome is below or above average. Risk of serious complications, any complication, pneumonia, cardiac complication, surgical site infection, urinary tract infection, venous thromboembolism, renal failure, readmission, return to the operating theater, death, and discharge to a nursing or rehabilitation facility are tabulated.

The American College of Surgeons National Surgical Quality Improvement Program Surgical Risk Calculator is similar to the 2016 Risk Calculator of Surgical Outcomes Beyond Perioperative Mortality Rate (above).

Limiting Perioperative Risk

Preoperative, intraoperative, and postoperative, as well as discharge considerations, are the following:

Preoperative considerations

  • Risk assessment: assess risk/benefit; assess appropriateness of surgery; align expectations, and provide shared decision-making.
  • Medical optimization: smoking, nutrition, obesity, diabetes, cardiopulmonary, bone health, and narcotics.
  • Surgical planning: multidisciplinary planning, preoperative planning conference, manage adjacent levels, osteoporosis, and guidance system.
  • Physical optimization: general physical conditioning, body mass index, physical therapy, independence, and home support.

Intraoperative factors

  • Blood conservation/fluid management: Amicar/TXA, Cellsaver, transfusion protocol, and colloid to crystalloid ratio.
  • Neuromonitoring: protocols, algorithm for positive change
  • Surgical technique: two attendings, protocol for staging, equipment, radiography, and achieve intra- and postoperative surgical goals.
  • Reduce complications: pain management, antibiotic prophylaxis, blood sugar control, and normothermia.

Postoperative considerations

  • Pain management: standardized protocol, chronic pain considerations
  • Mobilization: early mobilization, postoperative chairs, physical therapy protocols
  • Nutrition: early enteric feeding, 2400 kcal daily
  • Medical complications: deep vein thrombosis prophylaxis, delirium prevention, Foley catheters

Discharge considerations

  • Home: preoperative preparation, home health services, physical and/or occupational therapy
  • Rehabilitation: mobilization protocols, communication of care plan, precautions
  • Skilled nursing facility: mobilization, physical therapy protocols
  • Communication pathways: health loop, nurse navigator, clinic visits preferable to emergency department visits


Risk stratification is key to empowering informed choice regarding surgery, and to determining the in appropriateness of surgical management for spinal deformity. Risk assessment is based on variables that are difficult to measure, including patient- and surgery-based factors. It is crucial to establish reasonable and accurate standards for complications using risk stratification as we move toward an era of accountability for care.

Quality measures, including complication rates may not reflect the patient’s healthcare experience adequately. Value measures encompassing risk/cost and benefit are more useful than quality measures in assessing the overall impact of care.

Updated on: 05/27/19
Continue Reading
Surgical Approach Is a Risk Factor for Infection in Spinal Surgery

Get new patient cases delivered to your inbox

Sign up for our healthcare professional eNewsletter, SpineMonitor.
Sign Up!