Stroke Risk Following Nonarteritic Anterior Ischemic Optic Neuropathy.

Importance: The association between nonarteritic anterior ischemic optic neuropathy (NAION) and an increased risk of stroke has been a subject of debate. However, multinational studies on this topic are scarce. Objective: To evaluate the short-term and long-term stroke risk after NAION compared with a matched control group. Design, Setting, and Participants: This global, retrospective, population-based cohort study used aggregated electronic health records from January 1, 2004, through March 19, 2024, sourced from the Global Collaborative Network of TriNetX, which includes data from over 152 million patients across 17 countries. Patients in the study were followed up for a maximum duration of 10 years. Patients with NAION and age-related cataract were included in the analysis. Those with stroke before the diagnosis of NAION and age-related cataract were excluded. Propensity score matching was applied to balance age, sex, race, ethnicity, comorbidities, and medication use. Exposure: International Statistical Classification of Diseases and Related Health Problems, Tenth Revision (ICD-10) diagnosis code for NAION or age-related cataract. Main Outcomes and Measures: The primary outcome was the relative risk (RR) of stroke (ICD-10 code I60-63) in the NAION cohort vs the matched controls. Multivariable logistic regression analyses were applied to identify potential clinical factors associated with stroke within the NAION cohort. Results: A total of 89 811 patients were identified in both the NAION (mean [SD] age, 57.2 [18.5] years; 38 678 men [43.1%]) and control (mean [SD] age, 57.0 [17.9] years; 40 014 men [44.6%]) cohorts after matching. The NAION cohort demonstrated a significantly higher all-stroke risk at all time points: 1 month (RR, 5.04; 95% CI, 4.41-5.78), 3 months (RR, 3.79; 95% CI, 3.40-4.21), 1 year (RR, 2.50; 95% CI, 2.32-2.70), 5 years (RR, 1.54; 95% CI, 1.45-1.63), and 10 years (RR, 1.33; 95% CI, 1.23-1.43). Sensitivity analysis in patients without comorbidities similarly revealed a significantly increased all-stroke risk across all intervals: 1 month (RR, 7.55; 95% CI, 4.74-12.03), 3 months (RR, 6.70; 95% CI, 4.48-10.04), 1 year (RR, 3.96; 95% CI, 2.94-5.34), 5 years (RR, 2.85; 95% CI, 2.18-3.72), and 10 years (RR, 1.68; 95% CI, 1.25-2.26). Among all the clinical factors of interest, only hypertension was consistently associated with all subtypes of stroke following NAION. Conclusions and Relevance: This cohort study of patients with NAION found a significantly elevated risk of stroke compared with matched controls, independently of comorbidities. These findings underscore the importance of regular stroke workups following the onset of NAION.