Methodological Factors in Determining Risk of Dementia After Transient Ischemic Attack and Stroke

Background and Purpose—Cognitive outcomes in cohorts and trials are often based only on face-to-face clinic assessment. However, cognitive impairment is strongly associated with increased morbidity and mortality, leading to substantial loss to clinic follow-up. In the absence of previous population-based data, we determined the effect of such attrition on measured risk of dementia after transient ischemic attack and stroke. Methods—Patients with transient ischemic attack or stroke prospectively recruited (2002–2007) into the Oxford Vascular (OXVASC) study had baseline clinical/cognitive assessment and follow-up to 2014. Dementia was diagnosed through face-to-face clinic interview, supplemented by home visits and telephone assessment in patients unable to attend clinic and by hand-searching of primary care records in uncontactable patients. Results—Of 1236 patients (mean age/SD, 75.2/12.1 years; 582 men), 527 (43%) died by 5-year follow-up. Follow-up assessment rates (study clinic, home visit, or telephone...