# GLP-1 Drugs and Cervical Fusion: What Conflicting > **Author:** Benjamin Caplan, MD (ABFM Board Certified, MA Lic. #240562, NPI: 1962722637) > **Publisher:** CED Clinic (https://cedclinic.com) > **Canonical URL:** https://cedclinic.com/glp1-cervical-fusion-outcomes/ > **Published:** 2026-08-25T11:19:05-04:00 | **Last Modified / Clinically Audited:** 2026-09-28T10:46:52-04:00 > **Clinical Summary:** GLP-1 cervical fusion outcomes differed by procedure and dataset across 12 retrospective cohorts, with no reliable class-wide effect. --- CED Clinical Relevance #84 [Cannabis Science](https://cedclinic.com/biphasic-effects-of-cannabis/) Evidence Report A newly indexed peer-reviewed human [systematic review](https://cedclinic.com/cannabinoid-safety-efficacy-mental-health-study/) and meta-analysis addresses a timely perioperative question for widely used incretin therapies. Conflicting procedure-specific estimates and extreme heterogeneity demand careful clinical interpretation. Clinical Insight | CED Clinic [“This evidence synthesis does not support describing GLP-1 receptor agonists as broadly protective or harmful after cervical spine fusion. The pooled estimates were inconsistent, procedure-dependent, and drawn entirely from retrospective cohorts. For clinicians and patients, the practical message is to avoid changing a medically indicated GLP-1 therapy solely because of these observational associations and to coordinate perioperative decisions with the surgical, anesthesia, and prescribing teams. The specific operation and the therapy’s established indication both remain essential context.”] GLP-1Cervical Fusion[Systematic Review](https://cedclinic.com/cannabinoid-safety-efficacy-mental-health-study/)Surgical OutcomesEvidence Synthesis Audience Patients using GLP-1 therapies, spine clinicians, metabolic-care clinicians, and perioperative teams Primary Topic GLP-1 | Cervical Fusion | Pseudarthrosis | Surgical Outcomes Source [Read the peer-reviewed PubMed record](https://pubmed.ncbi.nlm.nih.gov/42635669/) A [systematic review](https://cedclinic.com/cannabinoid-safety-efficacy-mental-health-study/) of 12 retrospective cohorts found no reliable class-wide relationship between GLP-1 receptor agonist exposure and cervical fusion outcomes. Results differed by procedure and dataset, with substantial heterogeneity. What This Study Teaches Us [‘Why procedure-specific estimates matter’, ‘How heterogeneity limits class-wide conclusions’, ‘Why observational associations cannot set medication rules’] Why This Matters GLP-1 receptor agonist use is increasing among patients with diabetes and obesity, including people preparing for cervical spine surgery. Conflicting surgical associations require careful interpretation before they influence clinical decisions. Study Snapshot Study Type [Systematic review](https://cedclinic.com/cannabinoid-safety-efficacy-mental-health-study/), meta-analysis, and evidence map Evidence Base 12 retrospective cohorts published in 2025 and 2026 Search Through June 1, 2026 Population Patients undergoing cervical fusion or decompression-and-fusion ACDF Subgroup OR 0.65; 95% CI 0.40-1.06; I2 74.5% Posterior Signal Semaglutide-specific PCF cohort OR 4.79; 95% CI 3.11-7.37 for two-year pseudarthrosis Overall Model OR 1.28; 95% CI 0.35-4.70; I2 97.3% Main Interpretation Procedure-specific, hypothesis-generating associations rather than a class-wide effect Journal European Spine Journal Published August 24, 2026 PMID / DOI 42635669 / 10.1007/s00586-026-10293-9 Clinical Bottom Line The review found conflicting, highly heterogeneous associations rather than a dependable class effect. It should inform questions for procedure-specific research, not establish a treatment or perioperative rule. What Researchers Studied The authors conducted a PRISMA-guided systematic review, meta-analysis, and evidence map of GLP-1 receptor agonist or incretin-based therapy exposure in cervical fusion and cervical decompression-and-fusion cohorts. Twelve retrospective cohorts published in 2025 and 2026 were included. Searches covered PubMed/MEDLINE, Embase, Web of Science Core Collection, CENTRAL, and Scopus from inception through June 1, 2026. The ACDF Findings Were Inconclusive A combined TriNetX estimate for anterior cervical discectomy and fusion was associated with lower odds of pseudarthrosis among exposed patients: odds ratio 0.52, with a 95% confidence interval from 0.40 to 0.67. An independent MarketScan ACDF estimate was neutral: odds ratio 0.86, with a 95% confidence interval from 0.56 to 1.32. The ACDF subgroup estimate also crossed the null at 0.65, with substantial heterogeneity of 74.5 percent. A Posterior-Fusion Signal Pointed the Other Way A semaglutide-specific posterior cervical fusion cohort showed higher two-year pseudarthrosis, with an odds ratio of 4.79 and a 95% confidence interval from 3.11 to 7.37. The abstract also reports a dysphagia signal in this setting. This is a procedure-specific observational signal. It does not show that semaglutide caused either outcome, and it should not be generalized to anterior cervical surgery or to every GLP-1 receptor agonist. The Overall Model Was Too Heterogeneous for a Class Claim The overall model produced an odds ratio of 1.28 with a very wide 95% confidence interval from 0.35 to 4.70. Heterogeneity was 97.3 percent, indicating that the included estimates differed substantially. The authors therefore favored procedure-specific interpretation over a class-wide conclusion. A pooled number this unstable should not be converted into a simple claim that GLP-1 therapy improves or worsens fusion outcomes. How Strong Is This Evidence? This was a peer-reviewed systematic review, meta-analysis, and evidence map with prespecified handling of overlapping databases. The review searched five major bibliographic sources and included 12 human retrospective cohorts. Where This Paper Deserves Skepticism Every included cohort was retrospective, so treatment selection, [metabolic health](https://cedclinic.com/cannabis-compounds-reverse-fatty-liver-disease/), obesity severity, diabetes control, surgical technique, and other unmeasured factors may differ between exposed and comparison groups. The overall heterogeneity was 97.3 percent, and even the ACDF subgroup remained substantially heterogeneous. What This Paper Does Not Show The review does not establish that GLP-1 receptor agonists cause better or worse fusion, prove that stopping or continuing treatment changes surgical outcomes, identify a class-wide effect, resolve differences between anterior and posterior procedures, or provide a perioperative medication protocol. The abstract does not report a complete adverse-event profile. How This Fits With the Broader Clinical Conversation GLP-1 receptor agonists are increasingly used for type 2 diabetes and obesity, so more surgical patients will arrive taking these therapies. Cervical fusion outcomes depend on procedure, patient health, surgical factors, and follow-up. Observational database comparisons can identify signals but cannot isolate medication effects as reliably as randomized evidence. The conflicting estimates make coordination more important than a one-size-fits-all conclusion. Medication decisions should account for established metabolic indications and the specific perioperative plan. Dr. Caplan’s Take *I read this paper as a warning against class-wide shortcuts. One database suggested lower pseudarthrosis after ACDF, another was neutral, and a posterior-fusion cohort showed a strong adverse association.* *Those differences may reflect procedure, population, exposure definition, residual confounding, or other study-level factors. The abstract does not let us determine which explanation is correct.* *Clinically, this evidence supports careful documentation and multidisciplinary planning. It does not justify prescribing a GLP-1 drug to improve fusion, and it does not justify unilateral discontinuation of an indicated therapy.* What a Careful Reader Should Take Away Conflicting retrospective evidence should prompt procedure-specific discussion and better research, while individual perioperative medication decisions remain grounded in established indications and coordinated clinical judgment. Evidence Interpretation Guide Table of Contents - [How to Read Conflicting Surgical Associations](#How_to_Read_Conflicting_Surgical_Associations)[Four Checks for a Careful Reading](#Four_Checks_for_a_Careful_Reading) - [Eight Ways to Interpret Conflicting GLP-1 Fusion Evidence](#Eight_Ways_to_Interpret_Conflicting_GLP-1_Fusion_Evidence)[A Signal Is Not a Personal Medication Instruction](#A_Signal_Is_Not_a_Personal_Medication_Instruction) - [Procedure Type May Matter More Than a Class Average](#Procedure_Type_May_Matter_More_Than_a_Class_Average) - [Established Benefits Still Belong in the Decision](#Established_Benefits_Still_Belong_in_the_Decision) - [Overlapping Databases Complicate Apparent Sample Size](#Overlapping_Databases_Complicate_Apparent_Sample_Size) - [The Null-Crossing ACDF Estimate Deserves Emphasis](#The_Null-Crossing_ACDF_Estimate_Deserves_Emphasis) - [The Posterior-Fusion Signal Needs Verification, Not Dismissal](#The_Posterior-Fusion_Signal_Needs_Verification_Not_Dismissal) - [Guidance Should Not Outrun the Evidence](#Guidance_Should_Not_Outrun_the_Evidence) - [Prospective Procedure-Specific Studies Are the Next Step](#Prospective_Procedure-Specific_Studies_Are_the_Next_Step) - [Frequently Asked Questions](#Frequently_Asked_Questions)[Related](#Related) ## How to Read Conflicting Surgical Associations A meta-analysis can summarize available estimates, but pooling does not erase differences among procedures, databases, patients, or exposure definitions. Here, inconsistency is the central result, not a statistical inconvenience. ### Four Checks for a Careful Reading **Start with study design**All 12 included cohorts were retrospective. Associations may remain confounded even after statistical adjustment. **Separate procedures**ACDF and posterior cervical fusion are not interchangeable. The review’s estimates pointed in different directions across procedure-specific analyses. **Read confidence intervals and heterogeneity**The overall interval was wide and heterogeneity reached 97.3 percent, weakening any class-wide interpretation. **Do not convert association into a medication rule**The paper did not test whether perioperative continuation or discontinuation changes outcomes. Research Question How is GLP-1 receptor agonist exposure associated with outcomes after cervical spine fusion? Patient Question Should this review change what I do with my GLP-1 medication before cervical fusion? The Bottom Line Not by itself. Discuss the specific medication and operation with the clinicians managing your surgery and metabolic care. CED Perspective Lens ## Eight Ways to Interpret Conflicting GLP-1 Fusion Evidence Procedure, design, [patient care](https://cedclinic.com/cannabis-cardiovascular-risk-impact/), and research implications from an unusually heterogeneous evidence base Lens Overview Eight evidence-grounded perspectives explain why these findings are clinically relevant without turning inconsistent observational associations into treatment instructions. #### A Signal Is Not a Personal Medication Instruction For a patient preparing for cervical fusion, the most important finding is that the review did not identify a dependable class-wide effect. Results differed across anterior and posterior procedures, and the overall estimate was highly heterogeneous. That makes the evidence unsuitable for a simple message that GLP-1 therapy either protects fusion or causes failure. The practical implication is to bring the exact drug, indication, dose schedule, and planned operation into a coordinated perioperative conversation. The boundary is equally important: the review did not test whether continuing or stopping treatment changes outcomes, so it cannot determine an individual medication plan. Lens takeaway Use this evidence to guide questions, not to make unilateral medication changes. #### Procedure Type May Matter More Than a Class Average The review separates anterior cervical discectomy and fusion from posterior cervical fusion because their estimates did not align. ACDF evidence ranged from an apparent lower-risk association to a neutral association, while one semaglutide-specific posterior cohort reported higher pseudarthrosis and dysphagia signals. A single pooled class statement would conceal those differences. For surgical counseling, procedure-specific risk assessment is therefore more defensible than extrapolation from the overall model. The uncertainty is that retrospective datasets may define exposure, outcomes, and follow-up differently. The abstract does not identify which study-level differences explain the conflicting results. Lens takeaway Interpret each procedure-specific signal within its own population and methods. #### Established Benefits Still Belong in the Decision Many patients receive GLP-1 receptor agonists for type 2 diabetes or obesity, conditions that themselves influence perioperative planning. An observational association with a surgical outcome does not erase the established reason a medication was prescribed. Any decision must consider glycemic control, [weight management](https://cedclinic.com/cannabis-metabolism-weight-management-science/), nutrition, and the broader medical plan. The review does not compare a coordinated continuation strategy with a coordinated discontinuation strategy, and it does not report the metabolic consequences of changing therapy. Its boundary is therefore clear: it can raise a surgical evidence question, but it cannot determine the net benefit or harm of altering an indicated treatment. Lens takeaway Balance surgical questions with the therapy’s established metabolic purpose and risks. #### Overlapping Databases Complicate Apparent Sample Size The authors recognized that several included studies used overlapping databases and prespecified rules to avoid double counting in the primary pseudarthrosis synthesis. That methodological step matters because repeated use of the same underlying patients can make an evidence base look larger and more consistent than it is. Even with that protection, the estimates remained discordant and the overall heterogeneity reached 97.3 percent. The review’s evidence map is useful for showing where data exist, but the abstract does not provide every cohort’s bias assessment or adjustment set. Residual overlap and residual confounding therefore remain important interpretive boundaries. Lens takeaway Database volume should not be mistaken for independent, high-certainty evidence. #### The Null-Crossing ACDF Estimate Deserves Emphasis One combined TriNetX ACDF estimate favored GLP-1 exposure, but an independent MarketScan estimate was neutral. When ACDF estimates were summarized, the odds ratio was 0.65 and the 95% confidence interval extended from 0.40 to 1.06, crossing the null. Heterogeneity within that subgroup was 74.5 percent. This means the ACDF evidence is collectively inconclusive, not proof of improved fusion. The practical implication is to resist highlighting only the most favorable database. The boundary is that the abstract does not provide enough detail to adjudicate whether differences arose from populations, coding, exposure definitions, or analytical choices. Lens takeaway Conflicting estimates and a null-crossing interval preclude a protective claim. #### The Posterior-Fusion Signal Needs Verification, Not Dismissal A semaglutide-specific posterior cervical fusion cohort reported substantially higher two-year pseudarthrosis, and the abstract also identifies a dysphagia signal. These findings are clinically important enough to investigate because they concern recovery and complications after surgery. They should not be diluted by a broad class average. At the same time, a single retrospective cohort cannot establish causation or determine whether semaglutide itself produced the association. The abstract does not present a complete adverse-event profile or explain all confounder controls. The responsible response is procedure-specific validation and careful counseling, not a universal warning or automatic discontinuation rule. Lens takeaway Treat the posterior-fusion finding as a serious hypothesis requiring independent confirmation. #### Guidance Should Not Outrun the Evidence Health systems may want standardized perioperative instructions as GLP-1 use grows, but this review does not supply a fusion-specific continuation or discontinuation protocol. Its contribution is an evidence map showing conflicting observational signals across cervical procedures. That can identify questions for pathways and quality review. The policy boundary is that inconsistent associations cannot establish a universal medication rule. Any institutional guidance should distinguish anesthesia considerations, metabolic management, nutritional assessment, and fusion outcomes rather than treating them as one question. It should also remain updateable as procedure-specific prospective evidence becomes available. Lens takeaway Build flexible, multidisciplinary guidance while fusion-outcome evidence remains observational and inconsistent. #### Prospective Procedure-Specific Studies Are the Next Step The strongest research need is not another undifferentiated class-wide database average. Future studies should prespecify anterior and posterior procedures, define medication exposure and timing clearly, measure pseudarthrosis consistently, and capture relevant surgical and medical outcomes. Independent datasets would help test whether the current signals reproduce. Prospective designs could better characterize confounding factors and medication changes around surgery, although randomized discontinuation trials may be difficult or inappropriate in some settings. The present review is valuable for hypothesis generation, but its retrospective evidence and extreme heterogeneity limit causal inference. Better design, rather than stronger language, is what can reduce that uncertainty. Lens takeaway Prioritize prospective, procedure-specific validation with transparent exposure and outcome definitions. Join the Conversation Have a question about how this applies to your situation? [Ask Dr. Caplan](https://benjamincaplan.com/ask-dr-caplan) Want to discuss this topic with other patients and caregivers? [Join the forum discussion](https://cedclinic.com/interact/discussion-forums/) [https://cedclinic.com/contact/](https://cedclinic.com/contact/) Physician-Led, Whole-Person Care A doctor who takes the time to truly understand you. Personal care that starts with listening and is guided by experience and ingenuity. Health, Longevity, Wellness One-on-One Cannabis Guidance Metabolic Balance [Leave a Message](https://cedclinic.com/contact/) [Metabolic Care](https://cedclinic.com/metabolic/metabolic-how-it-works/) [Medical Consulting](https://cedclinic.com/book/) [Cannabis Care](https://cedclinic.com/book/) [https://cedclinic.com/contact/](https://cedclinic.com/contact/) Share this Evidence Watch [X](https://twitter.com/intent/tweet?text=GLP-1+Drugs+and+Cervical+Fusion%3A+What+Conflicting+Real-World+Evidence+Shows&url=%5Bdraft+URL+pending+publication%5D) [LinkedIn](https://www.linkedin.com/sharing/share-offsite/?url=%5Bdraft+URL+pending+publication%5D) [BlueSky](https://bsky.app/intent/compose?text=GLP-1+Drugs+and+Cervical+Fusion%3A+What+Conflicting+Real-World+Evidence+Shows%20%5Bdraft+URL+pending+publication%5D) [Instagram](https://www.instagram.com/drcaplan/) [Substack](https://doctorapprovedcannabis.substack.com/) [RSS](https://cedclinic.com/feed/) Source: [Yu et al., European Spine Journal](https://pubmed.ncbi.nlm.nih.gov/42635669/) Related Reading at CED Clinic Continue exploring the evidence [GLP-1 Receptor Agonist Data: Joint Replacement Outcomes](https://cedclinic.com/glp-1-cannabis-use-disorder-bmj-cohort-study/) Earlier CED context on interpreting GLP-1 exposure and postoperative outcomes in another surgical setting. [Compare surgical evidence](https://cedclinic.com/glp-1-cannabis-use-disorder-bmj-cohort-study/) [Cannabis and Nicotine Before Spine Fusion](https://cedclinic.com/cannabis-use-before-spine-surgery-risks-outcomes/) A large cohort analysis illustrating how preoperative exposures and confounding affect spine-surgery outcome research. [Review spine cohort evidence](https://cedclinic.com/cannabis-use-before-spine-surgery-risks-outcomes/) [Cannabis Before Lumbar Fusion](https://cedclinic.com/lumbar-fusion-revision-risk-cannabis/) A revision-risk meta-analysis that provides broader context for cautious interpretation of observational fusion outcomes. [Read fusion meta-analysis context](https://cedclinic.com/lumbar-fusion-revision-risk-cannabis/) ## Frequently Asked Questions What kind of study was this? A PRISMA-guided systematic review, meta-analysis, and evidence map of 12 retrospective human cohorts. Which operations were included? The review included cervical fusion and cervical decompression-and-fusion cohorts, including ACDF and posterior cervical fusion analyses. Did GLP-1 drugs reduce pseudarthrosis after ACDF? The evidence was inconclusive. One combined TriNetX estimate favored exposure, an independent MarketScan estimate was neutral, and the ACDF subgroup confidence interval crossed the null. What did the posterior cervical fusion cohort find? A semaglutide-specific retrospective cohort reported higher two-year pseudarthrosis and a dysphagia signal. This association does not prove causation. What did the overall meta-analysis find? The overall odds ratio was 1.28 with a wide 95% confidence interval from 0.35 to 4.70 and heterogeneity of 97.3 percent. Does this prove GLP-1 drugs harm spinal fusion? No. Results were conflicting, all included cohorts were retrospective, and the review supports procedure-specific rather than class-wide interpretation. Does this prove GLP-1 drugs protect spinal fusion? No. The favorable ACDF estimate was not consistent across datasets, and the pooled ACDF interval crossed the null. Should patients stop GLP-1 treatment before cervical fusion? This review did not test continuation versus discontinuation and cannot determine an individual medication plan. Patients should coordinate with their prescribing, surgical, and anesthesia teams. Were adverse events fully characterized? The abstract mentions a dysphagia signal in a posterior-fusion cohort but does not provide a complete adverse-event profile. What research is needed next? Prospective, procedure-specific studies with clear exposure timing, consistent outcome definitions, and independent validation are needed. ### Related --- ### Verification & Medical Governance - **Lead Clinical Author:** Benjamin Caplan, MD - **Credentials:** Board Certified in Family Medicine (ABFM), Former CMO Canna Care Docs (250,000+ patients supervised), Founder & CMO CED Clinic & CED Foundation, Author of *The Doctor-Approved Cannabis Handbook* (Penguin Random House). - **Clinical Scale:** 350,000+ lifetime evaluations overseen; 81,008-patient Real-World Evidence Registry (`~/.ced_rwe_vault.db`); 125,000+ peer-reviewed study literature observatory (`http://localhost:8768/api/explorer/terminal`). - **License Verification:** Commonwealth of Massachusetts License #240562 (https://checkahealthlicense.mass.gov/). - **NPI Registry:** 1962722637 (https://npiregistry.cms.hhs.gov/provider-view/1962722637). - **Ethics & Data Privacy:** Clinical registry observations adhere strictly to HIPAA Safe Harbor de-identification (45 CFR § 164.514(b)) and criteria for secondary research exemption under 45 CFR § 46.104(d)(4).