A PROSPECTIVE REEVALUATION OF TRANSIENT ISCHEMIC ATTACKS AS A RISK FACTOR FOR DEATH AND FATAL OR NONFATAL CARDIOVASCULAR EVENTS

Background and Purpose Transient ischemic attack (TIA) is generally considered a risk factor for death and cardiovascular events. This assumption is based on comparisons of the survival of the TIA population with that of the general population. Such comparisons may provide biased estimates of the risk associated with TIA because the general population is usually more healthy than TIA patients. Methods Using a prospective case-control study design, we report the comparison of a TIA population (n=280) and a control group (n=399) with a comparable cardiovascular risk factor burden. Proportional hazards analysis was used to compare survival time and time to fatal or nonfatal stroke and/or myocardial infarction for the two study groups. Comparisons were made without adjustment for risk factors and after adjustment for age, race, sex, and major cardiovascular risk factors. Results Before adjustment for age-race-sex or risk factors, TIA proved to be a risk factor for early mortality, stroke, and myocardial infarction (P<.05). Adjustment for age-race-sex disparities between the case and control groups explained much of the differences in mortality, as the hazard ratio was reduced from 2.2 to 1.4. However, adjustment for age-race-sex or age-race-sex and risk factors did not markedly reduce the role of TIA as a risk factor for stroke or myocardial infarction. Conclusions Although TIA proved to be a risk factor for stroke or myocardial infarction, it apparently plays a smaller role in the risk of death.