Outcomes of basilar artery occlusion in patients aged 75 years or older in the Basilar Artery International Cooperation Study Mervyn D. I. VergouwenAnnette CompterDavid TanneStefan T. Engelter • Heinrich AudebertVincent ThijsGabriel de FreitasAle Algra • L. Jaap KappelleWouter J. Schonewille

Patients with an acute basilar artery occlusion (BAO) have a high risk of long-lasting disability and death. Only limited data are available on functional outcome in elderly patients with BAO. Using data from the Basilar Artery International Cooperation Study, we aimed to determine outcomes in patients C75 years. Primary out- come measure was poor functional outcome (modified Rankin scale score 4-6). Secondary outcomes were death, insufficient vessel recanalization (defined as thrombolysis in myocardial infarction score 0-1) and symptomatic intracranial hemorrhage (SICH). Patients were divided into four age-groups, based on quartiles: 18-54, 55-64, 65-74, and C75 years. Outcomes were compared between patients C75 years and patients aged 18-54 years. Risk ratios with corresponding 95 % confidence intervals (CI) were calcu- lated and Poisson regression analyses were performed to calculate adjusted risk ratios (aRR). We included 619 patients (18-54 years n = 153 (25 %), 55-64 years n = 133 (21 %), 65-74 years n = 171 (28 %), and C75 years n = 162 (26 %)). Compared with patients aged 18-54 years, patients C75 years were at increased risk of poor functional outcome (aRR 1.33 (1.14-1.55)) and death (aRR 2.47 (1.75-3.51)). Nevertheless, 35/162 (22 %, 95 % CI 15-28 %) of patients C75 years had good functional outcome. No significant differences between age groups were observed for recanalization rate and incidence of SICH. Although patients C75 years with BAO have an increased risk of poor outcome compared with younger patients, a substantial group of patients C75 years survives with a good functional outcome. On behalf of the BASICS Study Group.