Sight Unseen: Glucagon-Like Peptide-1 (GLP-1) Agonism Therapy and Nonarteritic Anterior Ischemic Optic Neuropathy.
This retrospective cohort study used the TriNetX Global Collaborative Network to investigate whether GLP-1 receptor agonist (GLP-1 RA) therapy is associated with an increased risk of nonarteritic anterior ischemic optic neuropathy (NAION) in adults with type 2 diabetes mellitus (T2DM). Researchers divided patients into two groups: those with T2DM receiving GLP-1 RA treatment and those with T2DM not receiving GLP-1 RAs. After one-to-one propensity-score matching on 20 covariates, each cohort contained 388,333 patients. Over a five-year follow-up period, the GLP-1 RA-treated cohort showed a statistically significant higher risk of NAION (risk ratio 1.339, 95% CI 1.137–1.577; risk difference 0.022%; p = 0.005). An E-value sensitivity analysis suggested the association was moderately robust to unmeasured confounding. The authors caution that the absolute risk difference is small and that GLP-1 RAs carry well-established cardiovascular and metabolic benefits. Key limitations include the retrospective, observational design using de-identified administrative data, potential residual confounding, and an inability to confirm causality. The authors call for prospective studies to clarify the mechanism and refine clinical guidelines.
Why this grade: Although the sample size is very large and propensity-score matching was used, the retrospective observational design with administrative claims data limits causal inference and is susceptible to residual confounding.
Introduction Nonarteritic anterior ischemic optic neuropathy (NAION) is one of the most common causes of blindness among adults. Numerous risk factors have been noted (such as systemic diseases and medications); however, the underlying pathophysiology has yet to be elucidated. In recent years, however, glucagon-like peptide-1 (GLP-1) receptor agonists have emerged as a cause of NAION, albeit evidence is mixed. As a result, the primary objective of this study is to further analyze the risk of NAION over a five-year period in type 2 diabetes mellitus patients treated with GLP-1 receptor agonists. Methods We utilized TriNetX Global Collaborative Network to perform a retrospective cohort analysis, using de-identified patient data. Patients were divided into two cohorts (cohort A: type 2 diabetes mellitus with GLP-1 treatment; cohort B: type 2 diabetes mellitus without exposure to GLP-1). One-to-one propensity-score matching was employed for n = 20 covariates. We employed a measure of association, calculating risk difference, risk ratio, and 95% confidence interval. Furthermore, those with the outcome of interest (NAION) prior to the index event were excluded from analysis. Results After propensity-score matching, we arrived at n = 388,333 per cohort (n = 776,666 total). Over a five-year period, cohort A demonstrated a statistically significant increased risk of NAION (risk difference 0.022%, 95% CI 0.01%-0.034%; risk ratio 1.339, 95% CI 1.137-1.577, p = 0.005). Additionally, E-value sensitivity analysis confirmed a moderately robust association. Conclusion Whilst of statistical significance, the implicated clinical significance is less concrete, due to a well-established strong benefit-to-risk ratio with the therapeutic class. The exact mechanism of NAION in relation to GLP-1 therapy remains unknown. Further prospective studies are required to evaluate such findings and adjust existing guidelines as appropriate.
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