Migraine May Represent an Independent Risk Factor for Retinal Stroke: A Population-Based Cohort Study

Migraine is an established risk factor for cerebral ischemic stroke, with an especially robust association in patients with migraine with aura. However, it is not known if migraine is a risk factor for retinal stroke (central or branch retinal artery occlusion; CRAO or BRAO).

We performed a retrospective, observational, cohort study using population-based data from the State Inpatient Databases and State Emergency Department Databases from New York (2006-2015), California (2003-2011), and Florida (2006-2015) to determine the association between hospital-documented migraine and retinal stroke. The primary exposure was hospital-documented migraine (ascertained from admission or emergency department diagnosis codes). The primary endpoint was time to hospital-documented CRAO (ICD-9-CM code 362.31 in the primary diagnosis position) and secondary endpoints included time to BRAO and any retinal artery occlusion (RAO). Cause-specific hazard models were used to model the association between migraine and subsequent CRAO.

Of 39,835,024 patients included in the study, 1109,140 had migraine documented during our two year ascertainment window. Patients with migraine were younger (40.2±15.2 vs. 46.9±19.8, standardized difference (SD) 0.38), more likely to be female (81.4 % vs. 54.7 %, SD 0.6), and had a lower burden of atrial fibrillation (4.5 % vs. 6.9 %, SD 0.1), chronic kidney disease (1.9 % vs. 3.6 %, SD 0.2), and congestive cardiac failure (2.7 % vs. 5.1 %, SD 0.12). Migraine was not associated with CRAO in the primary diagnostic position (adjusted hazard rate (aHR) 1.15 (95 % CI: 0.79-1.67). However, it was associated with CRAO in any diagnostic position (aHR 1.39 (95 % CI: 1.08-1.78). As positive controls, we replicated previously established associations of migraine with cerebral ischemic stroke (aHR 1.35 (95 % CI: 1.32-1.38) and embolic ischemic stroke (aHR 1.15 (95 % CI: 1.08-1.22).

In a large, nationally-representative, claims-based study of patients from 3 regions in the United States (US), we did not find an adjusted association between migraine and a primary discharge diagnosis of CRAO. Our hypothesis-generating finding that migraine was associated with CRAO when using a broader definition sets the stage for future work leveraging both outpatient and pharmacy based claims to further explore this finding.