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Original research
Effect of bodyweight on VerifyNow Aspirin platelet function test: a retrospective review
  1. Melissa Sandler1,
  2. Cuong Hoang1,
  3. Hannah Y Mak1,
  4. Michael R Levitt2
  1. 1Harborview Medical Center, Seattle, Washington, USA
  2. 2Neurological Surgery, University of Washington School of Medicine, Seattle, Washington, USA
  1. Correspondence to Dr Cuong Hoang, Harborview Medical Center, Seattle, WA 98104, USA; hoangvic{at}


Background Antiplatelet therapy is used to prevent stent thrombosis in intracranial stents, but the optimal dose of aspirin is unknown. This study sought to determine whether the degree of platelet inhibition with aspirin is affected by bodyweight as observed through a platelet reactivity assay.

Methods This is a retrospective review of patients who underwent neurovascular stent placement and had a VerifyNow Aspirin assay result. The primary outcome was the correlation between the VerifyNow Aspirin result, bodyweight, and the initial dose of aspirin. Secondary outcomes included the impact of the VerifyNow P2Y12 result and of weight on the incidence of bleeding or a thrombotic event.

Results Of the 142 included patients, 62.7% weighed ≥70 kg and 88.7% were initiated on aspirin 300–325 mg daily. 83.8% achieved a therapeutic VerifyNow Aspirin result. There was minimal correlation between the VerifyNow Aspirin result, bodyweight, and aspirin dose (R2=0.02). Between patients who weighed <70 kg versus ≥70 kg, there was no difference in the mean aspirin reaction units (ARU) (449 vs 435, p=0.32) or in the incidence of bleeding (28% vs 17.1%, p=0.14) or a thrombotic event (4% vs 5.3%, p=0.59). No patient experienced stent thrombosis and eight patients experienced in-stent stenosis. In a multivariate analysis, only the VerifyNow P2Y12 result predicted the development of either bleeding or a thrombotic event (p<0.01).

Conclusions Bodyweight did not influence the likelihood of obtaining a therapeutic VerifyNow Aspirin result. The clinical utility of obtaining VerifyNow Aspirin assays for this patient population is unknown.

  • pharmacology
  • platelets
  • aneurysm
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  • Contributors MS designed the trial, collected, analyzed, and interpreted the data, and drafted and revised the paper. She is the guarantor. CH and HM initiated the idea for the project, interpreted the data, and drafted and revised the paper. MRL interpreted the data and drafted and revised the paper.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests Dr Levitt reports grants from Stryker, Medtronic, and Philips Volcano and others from Metis Innovative, Synchron, Cerebrotech, and eLoupes outside the submitted work.

  • Patient consent for publication Not required.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data availability statement Data are available upon reasonable request. De-identified patient data are available from Melissa Sandler ( upon reasonable request.

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