Long-Term Risk of Stroke After Transient Ischemic Attack or Minor Stroke

Importance After a transient ischemic attack (TIA) or minor stroke, the long-term risk of stroke is not well-known. Objective To determine the annual incidence rates and cumulative incidences of stroke up to 10 years after TIA or minor stroke. Data Sources MEDLINE, Embase, and Web of Science were searched from inception through June 26, 2024. Study Selection Prospective or retrospective cohort studies reporting stroke risk during a minimum follow-up of 1 year in patients with TIA or minor stroke. Data Extraction and Synthesis Two reviewers independently performed data extraction and assessed study quality. Unpublished aggregate-level data on number of events and person-years during discrete follow-up intervals were obtained directly from the authors of the included studies to calculate incidence rates in individual studies. Data across studies were pooled using random-effects meta-analysis. Main Outcomes and Measures The primary outcome was any stroke. Study-level characteristics were investigated as potential sources of variability in stroke rates across studies. Results The analysis involved 171 068 patients (median age, 69 years [IQR, 65-71]; median proportion of male patients, 57% [IQR, 52%-60%]) from 38 included studies. The pooled rate of stroke per 100 person-years was 5.94 events (95% CI, 5.18-6.76; 38 studies; I 2 = 97%) in the first year, 1.80 events (95% CI, 1.58-2.04; 25 studies; I 2 = 90%) annually in the second through fifth years, and 1.72 events (95% CI, 1.31-2.18; 12 studies; I 2 = 84%) annually in the sixth through tenth years. The 5- and 10-year cumulative incidence of stroke was 12.5% (95% CI, 11.0%-14.1%) and 19.8% (95% CI, 16.7%-23.1%), respectively. Stroke rates were higher in studies conducted in North America (rate ratio [RR], 1.43 [95% CI, 1.36-1.50]) and Asia (RR, 1.62 [95% CI, 1.52-1.73]), compared with Europe, in cohorts recruited in or after 2007 (RR, 1.42 [95% CI, 1.23-1.64]), and in studies that used active vs passive outcome ascertainment methods (RR, 1.11 [95% CI, 1.07-1.17]). Studies focusing solely on patients with TIA (RR, 0.68 [95% CI, 0.65-0.71) or first-ever index events (RR, 0.45 [95% CI, 0.42-0.49]) had lower stroke rates than studies with an unselected patient population. Conclusions and Relevance Patients who have had a TIA or minor stroke are at a persistently high risk of subsequent stroke. Findings from this study underscore the need for improving long-term stroke prevention measures in this patient group.