Neither Proven Better: Choosing a Long-Term Antiplatelet When the Head-to-Head Trial Fell Short
The trial built to compare two long-term antiplatelet regimens head to head failed to establish either as noninferior to the other — so the real decision, months out from the stroke that put this patient here, comes down to bleeding, tolerability, and which regimen she will actually keep taking.
B.F., a 58-year-old woman who manages scheduling and billing for a busy dental practice, had a moderate ischemic stroke four months ago — left MCA territory, noncardioembolic, attributed to non-stenotic atherosclerotic disease of the extracranial carotid artery without a flow-limiting lesion severe enough to warrant intervention. She has recovered well, with only mild residual word-finding difficulty under fatigue, and is now several months out, stable, and being seen for long-term secondary-prevention planning rather than acute management. She has hypertension and type 2 diabetes, both managed with a regimen she describes candidly as "a lot of pills already, and I forget one about as often as I remember it."
She has been on clopidogrel monotherapy since discharge, started as a reasonable default at the time, and today's visit is about whether that remains the right long-term choice or whether a different regimen might serve her better. CAPRIE, an early large trial comparing clopidogrel against aspirin alone across a mixed vascular population, found a modest but real relative benefit for clopidogrel, though the effect size in the stroke-specific subgroup was smaller than in the overall trial population. ESPS-2 separately established that aspirin combined with extended-release dipyridamole outperformed aspirin alone. PRoFESS, the largest head-to-head trial actually comparing clopidogrel against aspirin-ER-dipyridamole directly in secondary stroke prevention, found recurrent stroke rates that landed almost on top of each other, 9.0% against 8.8% — but it is worth being exact about what that did and didn't establish. The trial did not meet its own prespecified noninferiority margin, so the formal conclusion was that neither regimen could be declared superior or noninferior to the other, not that equivalence was demonstrated. Nor was safety a wash: major hemorrhagic events were more frequent on aspirin-dipyridamole, 4.1% against 3.6%, with intracranial hemorrhage running about 40% higher on that arm. The one clear difference PRoFESS did find was tolerability: the twice-daily aspirin-dipyridamole regimen carried a materially higher rate of headache-related discontinuation than once-daily clopidogrel. She already juggles metformin, glipizide, lisinopril, and atorvastatin on a schedule she admits she doesn't always follow precisely, a detail that turns out to matter more to today's decision than the trial-level efficacy numbers alone.
At follow-up, four months out, planning the long-term regimen
I'd keep her on clopidogrel 75mg once daily. PRoFESS, the largest head-to-head trial actually comparing it against aspirin-ER-dipyridamole for secondary stroke prevention, found near-identical recurrent stroke rates, and once-daily dosing is simpler to maintain long-term than the twice-daily alternative.
Worth being precise about the fuller picture behind that recommendation, though — clopidogrel's own original evidence, from CAPRIE, showed only a modest benefit over aspirin alone, and the stroke-specific subgroup effect was smaller than the trial's overall result. That doesn't argue for switching her off clopidogrel — and I'd add that PRoFESS never actually called them equivalent. It missed its noninferiority margin, which is a statement about what the trial couldn't establish, not a finding that the two are interchangeable. The one thing it did show cleanly on safety ran in clopidogrel's favor: more major hemorrhage, and more intracranial hemorrhage specifically, on the dipyridamole arm.
I don't think the efficacy comparison is actually what should decide this for her specifically. She's already told us directly that she doesn't reliably keep up with the medications she's on now, and PRoFESS itself found a materially higher headache-driven discontinuation rate with the twice-daily aspirin-dipyridamole regimen — real patients stopping a real medication because it gave them headaches often enough to quit.
A trial-level equivalence doesn't help her if she stops taking the harder-to-tolerate option in six months. Once-daily clopidogrel, which she's already on and tolerating without complaint, is the pragmatic choice given her own stated life circumstances, not just the trial numbers on their own.
Agreed: continue clopidogrel 75mg daily rather than switching to aspirin-extended-release dipyridamole, given her own adherence history and PRoFESS's tolerability data. A pill organizer and simplified once-daily dosing schedule for her other medications, where feasible, was discussed as a separate adherence-support measure.
Not agreed: whether cilostazol, which carries real supporting secondary-prevention data from trials conducted predominantly in East Asian populations, deserves more routine consideration as a nonstandard option in specific circumstances — raised by the pharmacologist as a genuinely separate open question, not resolved for her or generally in this visit.