In participants in the Framingham Heart Study from 1948 to 2017, a transient ischemic attack (TIA) was associated with a significantly increased risk of subsequent stroke, according to study results published in JAMA.
Determining the relationship between TIA and subsequent stroke can improve stroke exposure and stroke prevention in the general population. The study researchers attempted to assess population-based TIA incidence, as well as long-term and short-term stroke risk after TIA. To do this, they performed a retrospective analysis of prospectively collected data from the long-term Framingham heart study. They included 14,059 participants from the study without a TIA or a stroke at baseline who were followed from 1948 to 2017. Participants with a TIA with a first incident were assigned to a sample of participants without a TIA based on age and gender.
The primary results included TIA incidence, the proportion of post-TIA stroke in the short (7, 30, and 90 days) versus long-term follow-up (> 1-10 years). In addition, the study researchers examined the incidence of stroke after TIA compared to stroke in matched TIA-free controls, as well as the time trends of strokes 90 days after TIA between 1948 and 1985, 1986 and 1999, and 2000 and 2017.
A total of 435 participants in the sample developed a TIA over 66 years of follow-up. These patients were matched to 2175 control subjects without a TIA. The study researchers estimated the crude TIA incidence rate to be 1.19 / 1000 person-years. About 29.8% (n = 130) of the participants suffered a stroke over a mean follow-up period of 8.86 years. A total of 28 (21.5%) strokes occurred over a 7-day period, while 40 (30.8%) occurred over a 30-day period, 51 (39.2%) over a 90-day period, and 63 ( 48.5%). occurred more than 1 year after the index TIA.
The median time to stroke from the TIA index was 1.64 (interquartile range, 0.07-6.6) years. The age- and gender-adjusted 10-year cumulative risk of stroke in patients with TIA was 0.46 (95% CI, 0.39-0.55) versus 0.09 (95% CI, 0.08-0.111 ) with matching control persons without TIA (fully adjusted) hazard rate [HR]4.37; 95% CI, 3.31-5.78; P <0.001).
The 90-day stroke risk rate after TIA between 1986 and 1999 compared to the risk rate between 1948 and 1985 was 11.1% and 16.7%, respectively. Between 2000 and 2017, the 90-day TIA stroke risk was 5.9%. Compared to the HR for the 90-day stroke risk in the first epoch (HR, 1 [reference]) the HR in the second epoch was 0.60 (95% CI, 0.33-1.12) and in the third epoch 0.32 (95% CI, 0.14-0.75) (P = 0.005 for Trend).
Limitations of this study were the inclusion of participants of predominantly white European descent, the possible misclassification of TIA in the dataset, and incomplete data on medical and surgical treatments after TIA.
Based on these results, the study’s researchers concluded, “It is likely that the estimate from this study is a fairly accurate representation of the current TIA incidence in the general population.” “The risk of stroke, they added,” was after TIA significantly higher than in control persons without TIA, and the risk of stroke after TIA was significantly lower in the last epoch from 2000 to 2017 compared to an earlier period from 1948-1985. ”
Lioutas VA, Ivan CS, Himali JJ et al. Incidence of transient ischemic attack and association with long-term risk of stroke. JAMA. 2021; 325 (4): 373- 381. doi: 10.1001 / jama.2020.25071