Reviews/P2Y12 Antiplatelets/Prasugrel major bleeding vs clopidogrel
Pras · P2Y12-PRAS-02 · v1
One large, directly relevant trial randomised patients with acute coronary syndromes who were scheduled for a stent procedure to prasugrel or clopidogrel, and found more serious bleeding on prasugrel (2.4% versus 1.8%) [2]. The same trial's analysis in patients without diabetes showed the same direction [17]. Every other study in this corpus that looked at the two drugs found no clear bleeding difference, but each of those used a reduced prasugrel dose, steered the stronger drug toward lower-risk patients, counted only stomach bleeds, or lumped prasugrel together with a different drug [18][16][9][15]. The panel judged that the bleeding increase is real and points in a consistent direction, but that the only statistically clear signal comes from a single trial programme. That is why it was placed below the top tier rather than treated as settled.
The pivotal randomised trial [2] reports major bleeding in 2.4% of prasugrel patients versus 1.8% of clopidogrel patients (hazard ratio 1.32; 95% CI 1.03 to 1.68; P=0.03), with life-threatening bleeding also higher (1.4% vs 0.9%; P=0.01) and fatal bleeding higher (0.4% vs 0.1%; P=0.002). Its diabetes-stratified analysis [17] reproduces the increase in the non-diabetic stratum (TIMI major 1.6% vs 2.4%; HR 1.43; P=0.02) while finding no excess in diabetic patients (2.6% vs 2.5%; HR 1.06; P=0.81). The independent studies are null: adjusted-dose prasugrel in Japanese patients showed non-CABG major bleeding of 1.9% vs 2.2% [18], a guideline-channelled Swiss cohort showed BARC 3-5 bleeding of 3.8% vs 5.5% [16], a GI-bleeding cohort gave HR 0.996 (95% CI 0.497 to 1.996) in a small prasugrel subgroup [9], and a chronic-coronary-syndrome cohort pooling prasugrel with ticagrelor gave bleeding adjHR 0.75 (95% CI 0.46 to 1.21) [15]. The contested point: The division is whether the bleeding excess is independently established or rests on a single source. The one statistically significant prasugrel-versus-clopidogrel signal comes entirely from the TRITON programme ([2] and its subgroup [17]), while every independent study in the corpus is null; the panel reads those nulls as explainable by dose reduction, channelling, or scope rather than as refutation.
All 18 papers behind this claim with their DOIs and what each does to it, the panel’s arbitration, the evidence gap map and the open research questions. Free, and sent to your inbox.
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One reviewer's only job is to attack the finding. The challenges below were weighed before the grade was set.
The only statistically significant prasugrel-vs-clopidogrel major-bleeding excess comes from a single trial programme ([2] and its subgroup [17]); every independent study in the corpus is null, so evidential independence for the positive signal is weak.
Null replications are explained but not corroborative: [18] used a halved maintenance dose, [16] documents label-driven channelling of prasugrel to lower-risk patients, [9] measures only GI bleeding in ~104 prasugrel patients with a CI spanning 0.5-2.0, and [15] pools prasugrel with ticagrelor in chronic coronary syndromes.
Where it remains uncertain. Every independent study is null, but each used a reduced dose [18], channelled prasugrel to lower-risk patients [16], counted only GI bleeds in a tiny subgroup [9], or pooled prasugrel with ticagrelor in chronic coronary syndromes [15].
Aleatory
The excess in [2] is 0.6 percentage points (2.4% vs 1.8%), small enough that sampling variation leaves meaningful uncertainty around the effect.
Epistemic
The only significant excess comes from one trial programme ([2] and its subgroup [17]); no independent study reproduces a significant increase.
The load-bearing papers from a corpus of 18, each classified by what it does to the claim. Every DOI is taken from the corpus the claim was graded on.
Primary direct evidence: significant increase in major bleeding with standard-dose prasugrel vs clopidogrel in ACS-PCI patients.
“prasugrel therapy was associated with significantly reduced rates of ischemic events, including stent thrombosis, but with an increased risk of major bleeding, including fatal bleeding.”
Panel auditInternal validity: high · scope of inference: Moderate-to-high-risk ACS patients undergoing scheduled PCI on standard-dose prasugrel vs clopidogrel.Key limitations: standard 10 mg maintenance dose only
No GI major-bleeding difference, but wide CI and tiny prasugrel subgroup make it uninformative.
“Adjusted hazard ratios (HRs) showed no between-group differences in the risk for major (clopidogrel vs. new antiplatelets: HR 0.996; 95% confidence interval 0.497-1.996)”
Panel auditInternal validity: low · scope of inference: Post-PCI DAPT patients, gastrointestinal bleeding only.Key limitations: prasugrel pooled with ticagrelor · GI bleeding only · small prasugrel subgroup · confounding by indication
Null for bleeding, but prasugrel pooled with ticagrelor in a chronic-coronary-syndrome PCI population — prasugrel not isolable.
“secondary outcomes including bleeding (adjHR 0.75, 95% CI: 0.46-1.21; p=0.23) on propensity score stratification analysis.”
Panel auditInternal validity: low · scope of inference: Chronic coronary syndrome patients undergoing PCI.Key limitations: prasugrel pooled with ticagrelor · chronic not acute coronary syndrome · observational channelling
Observational null, but prasugrel was channelled to lower-risk patients per label, biasing against detecting an excess.
“the primary end point of clinically relevant bleeding events (defined as the composite of Bleeding Academic Research Consortium, BARC, type 3, 4 or 5 bleeding) at 1 year, occurred at a similar rate in both patient groups (prasugrel/clopidogrel: 3.8%/5.5%).”
Panel auditInternal validity: low · scope of inference: Guideline-treated invasively managed ACS patients in Switzerland.Key limitations: observational channelling · label-restricted prasugrel use · not designed to compare safety head-to-head
4 of 18 papers shown. The full review lists all of them, with the panel’s arbitration →
Claims are graded at each quarterly release, and re-graded between releases only when a pivotal trial lands. Every change is a new version of the claim.
A large, directly on-claim RCT carries the verdict, but the significant signal rests essentially on the TRITON programme while independent corpus evidence is null, warranting Likely rather than Established.
Release 2026-q4 re-graded every claim from its corpus under protocol v0.19. An earlier release's grade is shown for the record; it came from an earlier protocol and is not a movement.
Assumptions that carry weight but are not themselves established.
The panel records the gap that would most move the claim, and the study that would close it.
Independent standard-dose head-to-head. The significant bleeding excess rests entirely on one trial programme [2][17]; no independent study here reproduces it at standard dose. The panel rates this the highest-importance open gap for the claim, and names the study design that would close it: A new randomised or rigorously confounder-adjusted prasugrel-versus-clopidogrel comparison at standard dose in ACS-PCI patients, powered for major bleeding.
Open question: Does standard-dose prasugrel increase major bleeding versus clopidogrel in an ACS-PCI population independent of the TRITON programme? Why it is still open: Only [2] and its subgroup [17] show a significant excess; all independent studies in the corpus are null.
Priors is a sceptical first reader, not peer review, and not medical advice.
Release 2026-q4 · graded 21 Oct 2026 · protocol v0.19