Introduction: In 2008, nearly 500,000 spine surgeries were performed in the U.S. Spinal fusions are the most expensive hospital-based procedure nationally, incurring more than $12 billion in annual hospital costs alone. Accordingly, identifying risk factors for reoperation may prevent unnecessary surgical intervention in a growing population of patients with comorbid disease. We hypothesized that serum glycated hemoglobin is a surrogate biomarker for the risk of reoperation.
Methods: All patients undergoing decompression, fusion, instrumentation, or augmentation of the spine from 2001-2015 at a single tertiary care institution were eligible for inclusion. The primary outcome was the cumulative incidence of reoperation at the index surgical site. Multivariate proportional hazards regression was used to adjust for confounding demographic, comorbid, and operative covariates.
Results: 13,244 patients underwent surgery during the study period. The majority of interventions were conducted in the lumbosacral spine (82%). Preoperatively, the median HbA1c was 6.0%, with 39% of patients meeting the criterion for pre-diabetes and 31% of patients meeting the criterion for diabetes.
At a median of 1 month following index intervention, 2,684 patients (20%) underwent reoperation. Reoperation was more common among patients with diabetes (23%) than pre-diabetes (19%) or normal glucose tolerance (21%) (p=0.02). Similarly, the 12-month cumulative incidence of reoperation was greater among patients with diabetes (18%) than patients with pre-diabetes (15%) or normal glucose tolerance (16%) (p=0.03). 30- and 90-day emergency room visits and readmissions were not significantly different among cohorts.
After multivariate analysis, HbA1c > 6.4% was identified as an independent risk factor for reoperation (HR 1.13, 95% CI 1.02 – 1.29, p=0.04).
Conclusions: In the present investigation, the hazard rate of reoperation was modestly increased among patients meeting the criterion for diabetes. Patients with pre-diabetes were not at elevated risk compared to those with normal glucose tolerance. Preoperative medical management may mitigate the increased cost and morbidity of reoperation.
Patient Care: If glucose intolerance is a risk factor for reoperation following spine surgery, HbA1c may represent a useful biomarker for risk stratification at the time of index surgery. Aggressive medical management preoperatively may reduce the future risk of reoperation, which represents a burden upon patient quality of life and healthcare expenditures.
Learning Objectives: By the conclusion of this session, participants should be able to:
1) Describe the clinical benefit, morbidity, and cost of reoperation following spine surgery.
2) Discuss, in small groups, efforts to mitigate the risk of reoperation at the time of index surgery.
3) Identify an effective preoperative care path to optimize diabetic status in an effort to prevent reapportion.