Study of DAPT after TIA or minor stroke finds high-risk subgroup benefits more, has higher bleeding rates

An analysis of patients with transient ischemic attack (TIA) or minor ischemic stroke found a subgroup that gained greater absolute benefit from treatment with dual antiplatelet therapy (DAPT), a study found.

Researchers assessed how baseline stroke risk modified the efficacy of the DAPT regimen of clopidogrel-aspirin by conducting an unplanned secondary analysis of the POINT (Platelet-Oriented Inhibition in New Transient Ischemic Attack and Minor Ischemic Stroke) trial. There were 4,841 trial participants randomized to short-term DAPT (2,400) or aspirin and placebo (2,430). The researchers evaluated the associations of the CHA₂DS₂-VASc and stroke prognosis instrument II (SPI-II) scores with the risk of incident ischemic stroke and major hemorrhage (intracranial hemorrhage or major systemic hemorrhage). Results were published Jan. 4 by Stroke.

The SPI-II score, but not the CHA₂DS₂-VASc score, was associated with the risk of incident ischemic stroke, with a high-risk SPI-II score (>3) associated with greater risk of incident ischemic stroke (hazard ratio [HR] 1.84 [95% CI, 1.44 to 2.35] relative to low-risk SPI-II score; P<0.001). These patients had a numerically greater risk of major hemorrhage, but it did not meet statistical significance (HR, 1.80 [95% CI, 0.90 to 3.57]; P=0.10).

The relative risk reduction with DAPT was similar across SPI-II strata, but the absolute risk reduction for ischemic stroke with DAPT compared with aspirin was nearly fourfold higher (2.80% vs. 0.76%; number needed to treat, 31 vs. 131) in the high-risk SPI-II stratum relative to the low-risk stratum. However, the absolute risk increase for major hemorrhage was threefold higher with DAPT compared with aspirin (0.84% vs. 0.30%; number needed to harm, 119 vs. 331) in the high-risk SPI-II stratum relative to the low-risk stratum.

The researchers concluded that:

• The modified SPI-II score was associated with 21- and 90-day stroke risks within the clinical trial setting and, thus, is a valid tool to use in future analyses;
• Stratification by baseline stroke risk found populations that derive greater absolute benefit from DAPT over aspirin;
• There was a threefold increase in major hemorrhage risk across stroke-risk groups, supporting the notion that ischemic stroke risk factors tend to also be risk factors for major bleeding and intracranial hemorrhage; and
• Baseline stroke risk did not modify the relative benefit of treatment with DAPT after TIA or minor stroke.

“These descriptive statistics may be considered a resource for clinicians interested in more accurately conveying and weighing the benefits and risks of treatment with DAPT after high-risk TIA or minor ischemic stroke,” the researchers wrote.