GLP-1 Drugs and Lumbar Fusion Surgery

A systematic review and meta-analysis published September 17, 2026 in the International Journal of Spine Surgery pooled seven retrospective cohorts and 28,525 patients undergoing lumbar fusion surgery^[1] to test something anesthesiologists have worried about since 2023: whether taking a GLP-1 receptor agonist, a drug class that includes semaglutide and tirzepatide and works by mimicking a gut hormone that slows digestion and curbs appetite, before spine surgery changes how patients do afterward. The short answer from this dataset: no significant difference turned up on any of the outcomes the authors tracked.

What the meta-analysis found

Across the pooled cohorts, preoperative GLP-1 receptor agonist exposure was not associated with a statistically significant change in reoperation or revision surgery, using an odds ratio, a measure of how much more or less likely an outcome is in one group compared with another, where 1.0 means no difference at all: odds ratio 0.74, 95 percent confidence interval 0.44 to 1.24^[1]. The same held for postoperative infection (odds ratio 0.83, 95 percent CI 0.68 to 1.00), wound complications (odds ratio 0.86, 95 percent CI 0.65 to 1.12), and postoperative respiratory complications (odds ratio 1.08, 95 percent CI 0.63 to 1.84)^[1]. Deep vein thrombosis, pulmonary embolism, and unplanned emergency department visits also showed no significant differences between patients who were and were not on a GLP-1 receptor agonist before surgery^[1].

The infection result sits right at the edge of statistical significance, at P = 0.05. The authors flagged that number instead of smoothing over it. It is the kind of result that could shift either way with a slightly different patient mix, not a finding that closes the question.

Why anesthesiologists have been cautious anyway

The caution predates this meta-analysis by three years. In June 2023, the American Society of Anesthesiologists issued consensus-based guidance recommending that patients consider holding daily-dosed GLP-1 receptor agonists on the day of a procedure, and weekly-dosed versions a week beforehand^[4]. The rationale was mechanistic, not a reaction to reported cases: these drugs slow gastric emptying, meaning the stomach takes longer to move its contents into the small intestine, and a stomach that has not fully emptied raises the risk of regurgitation and pulmonary aspiration (stomach contents entering the lungs) once a patient is under general anesthesia^[4].

That original guidance applied regardless of dose, indication, or procedure type, and it told anesthesiologists to treat unresolved gastrointestinal symptoms, nausea, vomiting, bloating, as a possible reason to delay elective surgery^[4]. It was a reasonable, precautionary read of the pharmacology at a time when almost no perioperative outcome data existed for this drug class.

What the aspiration-specific evidence actually shows

A separate 2025 analysis in the Journal of the Endocrine Society looked directly at aspiration events instead of the broader complication list, across three surgical studies covering 386,973 patients. The combined risk ratio was 1.00, 95 percent CI 0.76 to 1.30, meaning no measurable increase in aspiration among patients on a GLP-1 receptor agonist compared with those who were not^[3]. A parallel review of four endoscopy studies covering 154,435 patients found a similar picture: a risk ratio of 1.10, 95 percent CI 0.95 to 1.27, which is not statistically significant^[3].

Put together, the lumbar fusion data and the aspiration-specific data are telling a consistent story. The theoretical mechanism, delayed gastric emptying, is real and well documented. What large retrospective datasets have not found, so far, is that mechanism reliably translating into more aspiration events, infections, or reoperations once patients are actually in an operating room.

What this does not show

None of this is settled science. Every study in the lumbar fusion meta-analysis was observational, drawn mostly from large administrative databases rather than randomized trials, and the authors explicitly called for prospective research with standardized definitions of GLP-1 receptor agonist exposure and perioperative management^[1]. A 2024 multi-society guidance document, jointly issued by the American Gastroenterological Association, the American Society for Metabolic and Bariatric Surgery, the American Society of Anesthesiologists, and two other surgical and endoscopy societies, still recommends the original hold schedule for patients judged to be at elevated risk of delayed gastric emptying, while allowing lower-risk patients to continue the medication through surgery^[2]. The authors of that document were candid that what they produced is guidance rather than an evidence-based guideline, because so little systematic data existed at the time they wrote it^[2].

The lumbar fusion meta-analysis also cannot speak to same-day aspiration events during anesthesia induction specifically. It tracked postoperative respiratory complications, wound problems, infection, and reoperation, not what happens in the first hour on the operating table. That is a narrower and different question from the one the aspiration-specific analysis above addressed directly.

What this means

For a reader considering spine surgery while taking semaglutide or tirzepatide, the practical takeaway is that the newest and largest dataset on fusion-specific outcomes did not find a safety signal, and the largest available aspiration-specific analysis did not either. Neither finding overrides the perioperative guidance a surgical team is already working from, and neither should be read as a reason to change a medication schedule without talking to the prescribing clinician and the anesthesia team first. Guidance on holding or continuing these drugs before surgery is still evolving as more outcome data accumulates, and it is the surgical team, not a published meta-analysis, that makes the call for an individual patient.