Five factors may predict the long-term risk for another stroke in people who have experienced a transient ischemic attack (TIA) or minor stroke, according to a new study.

The systematic review and meta-analyses examined 28 observational cohort studies, totaling 86,810 patients with a history of TIA or minor stroke, to identify which risk factors affected prognosis for secondary stroke events at 1 year or longer.

Hypertension, smoking, and three subtypes of ischemic stroke — cardioembolism, large artery atherosclerosis, and small vessel disease — were the main factors contributing to long-term secondary stroke risk. Minor stroke accounted for a larger proportion of later strokes than TIA.

“Even though these are known factors for stroke risk, there were some contradictory findings in the literature. We wanted to clarify the associations that had mixed interpretations,” lead author Faizan Khan, PhD, Canadian Institutes of Health Research (CIHR) Banting Postdoctoral Fellow at the University of Calgary in Calgary, Alberta, Canada, told Medscape Medical News.

The study also estimated each risk factor’s population attributable fraction, which quantifies the strength of its association with long-term stroke risk and its prevalence, allowing clinicians to see “which factors are more important and should be prioritized,” Khan said.

Stroke Risk Beyond 90 Days

The findings build on the earlier PERSIST study, which examined secondary stroke risk in patients with TIA or minor stroke beyond the typical 90-day monitoring window.

“We didn’t have a good understanding of the risk of secondary stroke past 90 days. The PERSIST study found the risk was significant and continued to rise,” Khan said. The results showed about 20% of patients with TIA or minor stroke were likely to have another stroke within 10 years, and more than half of all later strokes occurred a year or more after the initial event.

“The new paper tried to identify, in a systematic way, which factors impact the long-term risk of secondary stroke,” he said.

Modifiable Factors and More

For this study, TIAs were events in which stroke symptoms lasted 24 hours or less or showed no obstructions in imaging, while minor strokes were events with National Institutes of Health Stroke Scale scores of up to 5 and visible obstructions.

Starting with a pool of 14,732 relevant citations from the MEDLINE, Embase, and Web of Science databases, researchers selected studies that examined prognostic factors for later strokes after at least 1 year in patients with TIA or minor stroke. Most had been conducted in Europe, were based on prospectively enrolled cohorts, and had a maximum follow-up of at least 5 years. Twelve studies focused on TIA or minor stroke (19,893 patients), 14 considered only TIA (66,197 patients), and two evaluated only minor stroke (720 patients).

The cohorts were mostly men (median, 57%; interquartile range [IQR], 52-60) with a median age of 69 years (IQR, 65-71). A high percentage (median, 94%; IQR, 86-99) received antithrombotic medications after their hospital discharge.

Older age (adjusted hazard ratio [aHR], 1.04 per year increase; 95% CI, 1.02-1.05) and male sex (aHR, 1.25; 95% CI, 1.15-1.36) were the top non-modifiable risk factors associated with later strokes. Hypertension (aHR, 1.60; 95% CI, 1.31-1.94), smoking (aHR, 1.29; 95% CI, 1.05-1.60), and etiologic stroke subtypes, including cardioembolism (aHR, 2.16; 95% CI, 1.53-3.05), large artery atherosclerosis (aHR, 2.19; 95% CI, 1.68-2.86), and small vessel disease (aHR, 1.69; 95% CI, 1.14-2.49), were the leading modifiable factors. 

High blood pressure and tobacco use had population attributable fractions (PAFs) of 19.3% and 11.2%, respectively, suggesting “hypertension and smoking are worthwhile to focus on when it comes to long-term secondary stroke prevention,” Khan said. “PAF can help tailor strategies…to those patients who can be helped the most.”

The study was presented at the American Heart Association’s EPI Lifestyle Scientific Sessions (AHA-EPI) 2026 on March 18 and simultaneously published in Circulation.

Need for Secondary Prevention Efforts

The authors showed stroke risk was elevated long after the traditional 90 days of follow-up, and that finding runs counter to the current practice, said Clemens Schirmer, MD, PhD, director of the comprehensive stroke centers at Geisinger in Danville, Pennsylvania. Schirmer was not involved in the study.

“I think that’s important because it underlines that secondary prevention…is an ongoing imperative and it should be done even years later because your risk doesn’t just revert back to baseline after 30 or 90 days,” he told Medscape Medical News.

Schirmer noted that the authors’ distinctions between TIA and minor stroke, while theoretically clear in a textbook, may not be so in practice. For example, he said, TIA may be understood as an event with symptoms that go away in 24 hours, but most doctors will treat it as a stroke without waiting 24 hours to see if symptoms disappear. Definitions of TIA and minor stroke have also evolved over time, and it was unclear if the analyzed papers distinguished between the two variables in a uniform way, Schirmer said.

However, whether a patient has a TIA or a minor stroke, he said clinicians should treat it as a serious wake-up call to figure out the cause of the event and engage in long-term secondary prevention.

“That effort should not be a punctuated, focal effort around the time of the event’s happening, but in the sense that those modifiable risk factors — and the main one here is hypertension — need to be addressed in the long run,” he said.

The study was supported by the Banting Postdoctoral Fellowship from the CIHR awarded to Khan. Khan declared employment with Bristol Myers Squibb that commenced after completion of the study. Schirmer reported having no disclosures.

Kat Long is a science journalist in the Washington, DC area.