Abstract WP181: Incidence of Transient Ischemic Attack in Auckland, New Zealand, in 2011-2012

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Introduction: There have been few recent population studies reporting the burden of TIA. We aimed to determine the incidence (first ever in a lifetime) of TIA in an ethnically diverse population. Hypothesis: The incidence of TIA may vary by different ethnic group. Methods: The fourth Auckland Regional Community Stroke study (ARCOS IV) used multiple overlapping ascertainment methods to identify all hospitalized and non-hospitalized cases of definite TIA in people ≥16 years of age usually resident in Auckland (population ≥16 years was 1.12 million), over 12 months from March 2011. TIA was defined as an acute loss of focal cerebral or ocular function with symptoms lasting <24 hours, of presumed vascular cause. Patients with isolated vertigo, diplopia and non-focal symptoms were excluded. Results: There were 785 people with TIA [402 (51.2%) women, mean (SD) age 71.5 (13.8) years]. Of these, 614 (78%) were European, 32 (4.1%) Maori (indigenous people of New Zealand), 62 (8%) Pasifika (originating from the Pacific Islands) and 75 (10%) Asian/Others. Most (82%) TIA patients were seen in a hospital setting (emergency room, outpatient clinic or admitted). The annual age-standardized incidence of TIA was 40 (95% CI 36-43) per 100,000 people. The annual age-standardized incidence per 100,000 people of TIA was less in Maori (27; 95% CI 8-40) and Asian/Others (21; 95% CI 16-27) than in Europeans (45; 95% CI 41-50). Vascular risk factor profiles and treatment at presentation varied between the different ethnic groups. For example, non-Europeans were more likely to be diabetic (p<0.01), and Maori and Pasifika were less likely to be taking lipid-lowering therapy (p<0.01), than other groups. Conclusions: This study has demonstrated ethnic differences in the burden of TIA in an era of aggressive primary and secondary vascular risk factor management. We speculate that that the lower incidence of TIA seen in ethnic minorities may reflect a failure to seek medical attention as opposed to a true difference in incidence. If confirmed, programs targeting different ethnic groups, particularly those of lower socioeconomic status, and aimed at improving health literacy around vascular disease and reducing barriers to accessing health care, will be required.