Preoperative HbA1c and Postoperative Outcomes in Spine Surgery

Study Design. Systematic review and meta-analysis. Objective. To perform a systematic review and meta-analysis of previous studies on HbA1c in preoperative risk stratification in patients undergoing spinal procedures and provide an overview of the consensus recommendations. Summary of Background Data. Diabetes mellitus (DM) and hyperglycemia have been shown to be independent risk factors for increased surgical complications. Glycated Hemoglobin A1C (HbA1c), a surrogate for long term glycemic control, is an important preoperative parameter that may be optimized to reduce surgical complications and improve patient-reported outcomes. However, comprehensive systematic reviews on preoperative HbA1c and postoperative outcomes in spine surgery have been limited. Methods. We systematically searched PubMed, EMBASE, Scopus, and Web-of-Science for English-language studies from inception through April 5 th , 2022, including references of eligible articles. The search was conducted according to PRISMA guidelines. Only studies in patients undergoing spine surgery with preoperative HbA1c values and postoperative outcomes available were included. Results. A total of 22 articles (18 retrospective cohort studies, 4 prospective observational studies) were identified with level of evidence III or greater. The majority of studies (n=17) found that elevated preoperative HbA1c was associated with inferior outcomes or increased risk of complications. Random-effect meta-analysis demonstrated that patients with preoperative HbA1c >8.0% had increased risk(s) of postoperative complications (RR: 1.85, 95% CI: [1.48, 2.31], P <0.01) and that patients with surgical site infection (SSI) had higher preoperative HbA1c (Mean Difference: 1.49%, 95% CI: [0.11, 2.88], P =0.03). Conclusion. The findings of this study suggest that HbA1c >8.0% is associated with an increased risk of complications. HbA1c was higher by 1.49% on average among patients with SSI when compared to patients who did not experience SSI. These results suggest that elevated HbA1c is associated with less favorable outcomes following spine surgery. Level of Evidence. IV