Weight Loss Meds and Repeat Spinal Surgery

CHICAGO – Semaglutide, a drug used for diabetes and weight loss, has been linked to a significantly higher risk of repeat operations in diabetes patients undergoing lumbar surgery, according to a new study.

The risk for additional surgeries increases with prolonged use of the popular weight loss and diabetes medication.

Investigators say this study is the first to provide evidence on the impact of semaglutide on spine surgery outcomes.

“We expected better postoperative outcomes, including fewer wound complications, but instead, we found increased odds of needing additional surgeries in our diabetic patients,” said Dr. Syed I. Khalid, a neurosurgery resident at the University of Illinois Chicago, in an interview with Medscape Medical News.

The findings were presented on May 3 at the American Association of Neurological Surgeons (AANS) 2024 Annual Meeting.

Additional Surgery at Year 1

The study utilized the all-payer Mariner database to identify patients aged 18-74 with type 2 diabetes who underwent elective one- to three-level transforaminal lumbar interbody fusions (TLIFs) between January 2018 and October 2022. Patients were matched 3:1 for age, sex, hypertension, obesity, smoking history, chronic kidney disease, osteoporosis, insulin use, and spinal fusion level, resulting in 447 patients using semaglutide and 1334 not using it. Over half (56%) were female, 62% used insulin, and 81% underwent single-level TLIF.

Total medical complications were higher in the semaglutide group at 13.4% compared to 7.7% in the non-semaglutide group (odds ratio [OR], 1.85). This increase was due to higher rates of urinary tract infections (6.7% vs. 2.5%) and acute kidney injuries (6.3% vs. 3.9%), complications previously observed with semaglutide, Khalid said. However, total surgical complications were lower in the semaglutide group at 3.8% versus 5.2% in the non-semaglutide group (OR, 0.73).

Patients on semaglutide experienced fewer wound healing complications (5 vs. 31), hematomas (1 vs. 9), surgical-site infections (12 vs. 44), and cerebrospinal fluid leaks (2 vs. 3).

Nonetheless, semaglutide users were nearly 12 times more likely to require an additional lumbar surgery within a year compared to non-users (27.3% vs. 3.1%; OR, 11.79; 95% CI, 8.17-17.33).

Kaplan-Meier plots showed a significant divergence in outcomes based on semaglutide exposure of more than or less than nine months (log-rank P < .0001).

Currently under review for publication, this study provides the first evidence on semaglutide’s impact on spine surgery, Khalid said. A follow-up study, also under review, examines morbidly obese patients without diabetes who took semaglutide for weight loss and showed a similar trend.

Sarcopenia the Cause?

The additional surgeries were primarily extensions of constructs, with more levels requiring fusion, Khalid noted.

“One hypothesis is that muscle loss, or sarcopenia, in conjunction with fat loss might be causing these issues,” Khalid explained.

The mechanism remains speculative, but other studies have shown that patients with frailty, weaker bones, and sarcopenia have worse outcomes with spine surgery.

The researchers plan to use artificial intelligence to evaluate changes in body composition after semaglutide use in patients who underwent imaging prior to spine surgery or even before back pain occurred. Since these medications are uptitrated over time, follow-up studies will investigate whether these changes occur at specific doses, Khalid added.

Based on this analysis of generic semaglutide, it is not yet clear whether other glucagon-like peptide 1 (GLP-1) receptor agonists will yield similar findings, but “the odds of a class effect are high,” Khalid said.

Commenting on the findings, Dr. Walavan Sivakumar, director of neurosurgery at Pacific Neuroscience Institute, noted that recent guidance from the American Society of Anesthesiologists recommends stopping GLP-1 receptor agonists before elective surgery to reduce anesthesia-related complications.

“It’s an incredibly topical point and appears to be a daily concern for clinicians in neurosurgery,” Sivakumar said. “This study is thought-provoking and a great first step.”

Sivakumar also observed that frailty is a critical issue in neurosurgery. “It significantly impacts all surgical outcomes and is currently a major focus of study in neurosurgical research.”