Stroke risk high after transient ischaemic attack

Patients with transient ischaemic attack (TIA) or minor stroke are at increased risk of subsequent stroke, according to systematic review and meta-analysis.

Researchers searched multiple online databases for prospective or retrospective cohort studies in which stroke risk during a minimum follow-up of 1 year in patients with TIA or minor stroke was assessed. The primary outcome was any stroke. Potential sources of variability in stroke rates among studies were investigated by looking at study-level characteristics.

A total of 38 studies involving 171,068 patients (median age 69 years, 57 percent male) were included in the meta-analysis. Pooled data showed that the rate of stroke after TIA was 5.94 events per 100 person-years (95 percent confidence interval [CI], 5.18–6.76; 38 studies; I2=97 percent) in the first year, 1.80 events per 100 person-years (95 percent CI, 1.58–2.04; 25 studies; I2=90 percent) annually in the second through fifth year, and 1.72 events per 100 person-years (95 percent CI, 1.31–2.18; 12 studies; I2=84 percent) annually in the sixth through 10th year.

The cumulative incidence of stroke was 12.5 percent (95 percent CI, 11.0–14.1) at 5 years and 19.8 percent (95 percent CI, 16.7–23.1) at 10 years. Notably, stroke rates were higher in studies conducted in North America (rate ratio [RR], 1.43, 95 percent CI, 1.36–1.50) and Asia (RR, 1.62, 95 percent CI, 1.52–1.73) compared with those conducted in Europe. Higher rates were also observed in cohorts recruited in or after 2007 (RR, 1.42, 95 percent CI, 1.23–1.64) as well as in studies that used active vs passive outcome ascertainment methods (RR, 1.11, 95 percent CI, 1.07–1.17).

Conversely, stroke rates were lower in studies focusing solely on patients with TIA (RR, 0.68, 95 percent CI, 0.65–0.71) or first-ever index events (RR, 0.45, 95 percent CI, 0.42–0.49) relative to studies with an unselected patient population.

The findings point to a need to improve long-term stroke prevention measures in this patient group.