High on high-dose aspirin: Bleeding risk influences dosing only slightly

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Aspirin dosing patterns after MI seem to favor high doses, regardless of bleeding risks, according to a study published online Aug. 12 in Circulation: Cardiovascular Quality & Outcomes.

Hurst M. Hall, MD, of the University of Texas Southwestern Medical Center in Dallas, and colleagues wrote that their study was driven by a desire to understand how aspirin was being prescribed to MI patients and ultimately the implications of recommendations on aspirin use.

Utilizing the National Cardiovascular Data Registry’s databases, they evaluated both patient and hospital level factors that went into aspirin dosing between January 2007 and March 2011. They defined high-dose and low dose aspirin as 325 mg and 81 mg, respectively.

Hall et al found that 60.9 percent of acute MI patients were discharged with prescriptions for high-dose aspirin. Of PCI patients, 73 percent of bare-metal stent and 73.7 percent of drug-eluting stent patients were given high-dose aspirin. Among patients being treated with warfarin, thienopyridine and aspirin, 44 percent were prescribed high-dose aspirin. High-dose aspirin was prescribed to 68.6 percent of patients in tandem with the blood thinner clopidogrel (Plavix, Bristol Myers-Squibb/Sanofi Aventis).

This information, coupled with the fact that 56.7 percent of patients discharged on high-dose aspirin also experienced major in-hospital bleeding events, calls into question the practice in MI patients with high risks for bleeding. In short, Hall et al, recommended major changes in practice, regardless of PCI approach.

According to Hall et al, habit appeared to play a key role as to why high-dose aspirin was continuing to be prescribed to patients rather than individualized patient risk/benefit examination. “[P]aradoxically, the majority of CABG patients were treated with low-dose aspirin, despite guidelines to the contrary,” Hall et al wrote. High-dose aspirin prescriptions represented 47.8 percent of CABG discharges.

“We observed a 25-fold variance among hospitals in the proportion of patients discharged on high-dose aspirin, with some hospitals discharging less than 10 percent of patients on high-dose aspirin and other hospitals discharging 100 percent of patients on high-dose aspirin,” they observed.