Strokes after TIAs have declined over time, shows JAMA study

Among 14,059 Framingham participants, 435 had a TIA. Researchers compared the TIA-positive group against a second group of 2,175 participants who did not have a TIA.

People who experienced a TIA had a 4.5- to five-fold higher risk of having a stroke, Dr. Lioutas said. This was the estimate even after taking in to account that patients with TIAs have higher rates of vascular risk factors such as high blood pressure, high cholesterol or diabetes, he said.

The study analyzed three epochs of time, 1948 to 1985, 1986 to 1999, and 2000 to 2017.

"We examined 66 years of follow-up from Framingham participants, which allowed us to study trends over time," Dr. Seshadri said. "We can see that starting in the very early years of the Framingham study, the 1950s, moving on to the most recent times, the risk of subsequent stroke went down a lot."

In the most recent epoch of 2000 to 2017, that risk was significantly lower than in the earlier period from 1948 to 1985. One- and five-year risks of post-TIA stroke in the 2000-2017 epoch were 7.6% and 16.1%, compared to 23.9% and 35.5% during the 1948 to 1985 epoch.

The study didn't set out to show the reason for the improvement, Dr. Seshadri said, but one likely explanation "is that we have gotten better at preventing strokes, we are more aware of the importance of TIAs, and we are doing a better job than in earlier years about stroke prevention."

Dr. Lioutas said it is important for patients who have a TIA to get the same medical workup that stroke patients receive, so that the causes of the TIA can be identified and treated.