Preoperative HbA1c and Postoperative Outcomes in Spine Surgery

Abstract

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 5th, 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

Letter to the Editor Regarding “Preoperative HbA1c and Postoperative Outcomes in Spine Surgery

“…A recent study 1 revealed an association between higher preoperative HbA1c levels and an increased incidence of postoperative adverse events. Nevertheless, several concerns deserve further clarification.…”

“…First, as described in Table 1, 1 it is evident that some included studies consisted of both diabetic and nondiabetic patients. Obviously, diabetic patients often exhibit substantially different HbA1c levels compared with nondiabetic individuals.…”

RE: Preoperative HbA1c and Postoperative Outcomes in Spine Surgery

“…First, we agree that the distinction between diabetic and nondiabetic patients is critical. The two studies included in the meta-analysis compared mean difference in hemoglobin A1C (HbA1c) level between Surgical Site Infection and non-Surgical Site Infection group included both diabetic and nondiabetic populations 1 . One study was excluded from the meta-analysis because it included diabetic patients only as this would have been incongruent with the other two studied and had a higher average HbA1c which potentially could have confounded the meta-analysis.…”

A commentary on ‘The impact of diabetes on postoperative outcomes following spine surgery: a meta-analysis of 40 cohort studies with 2.9 million participants’

“…Preoperative glycemic control, as reflected by HbA1c levels, is a critical factor in reducing the risk of postoperative complications, including infections. Studies have shown that achieving target HbA1c levels before surgery can significantly improve outcomes 10 . Therefore, it is essential to discuss and include analyses related to the optimal level of HbA1c that should be controlled before spine surgery.…”