In a study of 400 healthy volunteers, researchers went looking for people who are truly resistant to the benefits of aspirin. They failed to find one case of aspirin resistance; rather, they found “pseudoresistance,” due to the coating found on most brands of aspirin, often preferred by patients for the protection it is claimed to provide the stomach. A urine biomarker of platelet stickiness was not able to find which volunteers were even pseudoresistant.