Fusion risk score: evaluating baseline risk in thoracic and lumbar fusion surgery

Retrospective cohort study.

The fusion risk score (FRS) is introduced to assess baseline risk of spine fusion surgery preoperatively. An objective method of stratifying risk allows the surgeon to control risk through tailoring intervention and explain differences in complication profile in high-complexity practice.

Research has identified an elevated risk of serious complications in performing spine fusion surgery in the elderly, yet the rate of such surgery continues to increase. A range of comorbidities and the surgical factors are demonstrated predictors of perioperative risk.

Retrospective review was made of 364 consecutive fusion surgical procedures in patients older than 65 years in an 18-month period. Logistic regression analysis was performed to identify factors predictive for the occurrence of perioperative events. The predictive variables were incorporated in a weighted fashion into the FRS scaled from 1 to 20. Patient demographics and comorbidities were incorporated into the FRS patient score (maximum 10) and surgical approach, levels, and osteotomies into the FRS procedure score (maximum 10).

Multivariate analysis demonstrated chronic kidney disease (odds ratio [OR] = 5.3, 95% confidence interval [CI]: 1.5-18.6, P = 0.008), chronic obstructive pulmonary disease (OR = 5.3, 95% CI: 2.0-14.2, P < 0.001), ischemic heart disease (OR = 4.1, 95% CI: 2.0-8.4, P < 0.001), an open anterior approach (OR = 3.6, 95% CI: 1.4-9.3, P = 0.010), diabetes (OR = 3.0, 95% CI: 1.4-6.4, P = 0.004), previous spinal surgery at the same site (OR = 2.6, 95% CI: 1.3-4.9, P = 0.005), age (OR = 1.07, 95% CI: 1.01-1.13, P = 0.019), and the number of motion segments fused (P = 0.049) to be predictive of perioperative events. When applied, the FRS was highly predictive of perioperative events, intensive care unit admission, operative time, blood loss, and length of stay (all P < 0.0001). A score over threshold 9 carries a greater than 50% risk of perioperative events.

The FRS predicts the risk of complications after spine fusion surgery on the basis of patient and surgery characteristics. It also predicts the risk of intensive care unit admission and correlates with operative time, blood loss, and postoperative length of stay. By balancing the FRS procedure score to the individual FRS patient score, the surgeon can quantify and control perioperative risk.