Among neurologic problems, stroke is one of the most serious and remains a leading cause of disability. Although transient ischemic attack (TIA) is recognized as a warning event, the risk of stroke after TIA has not been clearly defined. Studies with five-year follow-up have concluded that the cumulative risk of a stroke after TIA was about 22.5 percent depending on age, presence of diabetes, and other risk factors. Estimates of the annual risk of vascular ischemic events range from 4 to 11 percent depending on the population studied and outcomes measured. van Wijk and colleagues studied 2,473 Dutch patients with TIA admitted to a hospital between 1986 and 1989 to assess long-term prognosis and clarify risk factors for death or vascular events following TIA.
The authors analyzed data from a study that randomized patients to receive 30 mg or 283 mg of aspirin following TIA symptoms lasting less than 24 hours, or after minor strokes that did not affect daily activities (Rankin scale of 3 or less). Patients with clotting disorders or cardiac sources of emboli were excluded from the study. The diagnosis was confirmed in all patients by detailed neurologic examination, laboratory investigations, and computed tomography of the brain. Patients were reassessed by a neurologist every four months. Data were collected through December 2003 from neurologists, general practitioners, individual patients, family members, and others to ascertain the long-term health status of the patients. The primary outcome measures were the first incidences of total mortality, vascular mortality, nonfatal stroke, and myocardial infarction.
The average age of the participants was 65 years at the time of the TIA or minor stroke and the mean follow-up was 10 years. During the observation period, 1,489 patients (60 percent) died. The leading cause was vascular death (1,076 patients or 72 percent). The cumulative risk of death was 3.4 percent at one year, 19.4 percent at five years, and 42.7 percent at 10 years. The 10-year risk of death was higher in patients presenting with minor stroke (46.6 percent) than those presenting with TIA (34.1 percent). The strongest factors associated with death were age greater than 65 years, diabetes, history of claudication or of surgery for peripheral vascular disease, and Q or T wave changes on electrocardiography.
At least one vascular event was documented in 1,336 patients during follow-up. The cumulative risk of a first vascular event was 6.8 percent at one year, 24.4 percent at five years, and 44.1 percent at 10 years. The overall 10-year risk of vascular events in patients presenting with minor stroke was 47.8 percent, compared with 35.8 percent for patients who presented with TIA. The risk factors identified were identical to those for mortality.
The authors conclude that within 10 years of TIA and minor stroke, about 60 percent of patients die, and 54 percent experience at least one new vascular event. The risk for mortality rises gradually throughout the follow-up period, but the risk of a new vascular event peaks soon after presentation, declines over the first three years, then rises steadily. They urge greater efforts to prevent vascular disease in patients presenting with TIA or minor stroke.