TIA in the Swedish Stroke Register (Riksstroke). Aspects on diagnostic validation, risk factors, investigations, and therapies

Sammanfattning: Background: Transient ischemic attacks (TIA) indicate an increased risk of stroke, one of the leading causes of death and disability worldwide. In order to prevent stroke, our knowledge of diagnosis, demographics, risk factors, investigations, and treatment of patients with TIA needs to be improved.Aims: The aims of this thesis were to validate data and diagnoses in the Riksstroke TIA module (Riksstroke-TIA), to clarify the role of atrial fibrillation (AF) in TIA and the extent of oral anticoagulant (OAC) treatment in patients with AF, to assess characteristics, risk factors, and secondary preventive treatment in TIA patients with a history of stroke in comparison to those without, and evaluate the degree of carotid imaging and determinants for its non-use in patients with TIA.Methods: Paper I was based on a study sample of 180 patients from 6 different hospitals, extracted from the cohort of patients registered in Riksstroke-TIA between 1/7/2011 to 30/6/2012 (n=7825). Medical files were retrieved from each hospital. Paper II – IV were based on data from patients registered in Riksstroke-TIA between 1/7/2011 to 30/6/2013 (n=15064). For comparison, data on patients with ischemic stroke (IS) registered in Riksstroke during the corresponding period of time were included in paper II – IV (n=44416).ResultsPaper I: Two independent assessors agreed on a likely or possible diagnosis of TIA in 77% (137/180), in 3% (5/180) on a diagnosis of IS, and in 2% (3/180) that a diagnosis of TIA was unlikely. The quality of documentation was fair.Paper II: AF was present in 19% (2779/14980) of patients with TIA compared to 30% (13258/44173) in those with IS. Proportions of AF increased markedly with age. At discharge, 64% (1778/2771) of patients with TIA and AF and 50% (5502/10899) of patients with IS and AF were treated with OACs.Paper III: Patients with TIA and a history of stroke were older, more likely to be male, and they had higher proportions of AF, hypertension, and diabetes mellitus than those without a history of stroke. In TIA patients with prior stroke aged ≥85 years, AF was present in 41% (300/724) compared to 30% (604/2028) in those without prior stroke. At discharge, levels of OAC treatment in TIA patients with AF and prior stroke were lower than in those without prior stroke.Paper IV: Carotid imaging was performed in 70% (10545/15023) of patients with TIA. Determinants for its non-use were age ≥85 years, age 74-84 years, female sex, AF, a history of stroke, and care at a non-university hospital. There were substantial regional variations regarding proportions of carotid imaging, especially in the very elderly.Conclusions: There was interobserver agreement on TIA diagnoses in a majority of cases. More systematic documentation aided by a guide or checklist might improve diagnostic certainty. Data registered in Riksstroke-TIA was valid and suited for scientific evaluation. AF was a common but insufficiently treated risk factor in TIA. Certain patient groups appeared neglected with regard to carotid imaging and secondary preventive treatment, namely the very elderly, women, those with AF, and a history of stroke. Opportunities of secondary prevention were likely missed in a substantial number of patients.