Bleeding complications related to aspirin dose

Proton-Pump Inhibitors Reduce Gastrointestinal Events Regardless of Aspirin Dose in Patients Requiring Dual Antiplatelet Therapy

BACKGROUND

The COGENT (Clopidogrel and the Optimization of Gastrointestinal Events Trial) showed that proton-pump inhibitors (PPIs) safely reduced rates of gastrointestinal (GI) events in patients requiring dual antiplatelet therapy (DAPT). However, utilization of appropriate prophylactic PPI therapy remains suboptimal, especially with low-dose aspirin.

OBJECTIVES

The authors investigated the safety and efficacy of PPI therapy in patients receiving DAPT in low- and high-dose aspirin subsets.

METHODS

Randomized patients with available aspirin dosing information in COGENT (N = 3,752) were divided into "low-dose" (≤ 100 mg) and "high-dose" (>100 mg) aspirin groups. The primary GI and cardiovascular endpoints were composite upper GI events and major adverse cardiac events, respectively. All events were adjudicated by independent, blinded gastroenterologists and cardiologists.

RESULTS

Median duration of follow-up was 110 days. Low-dose aspirin users (n = 2,480; 66.1%) were more likely to be older, female, and have higher rates of peripheral artery disease, prior stroke, and hypertension, whereas high-dose aspirin users (n = 1,272; 33.9%) had higher rates of hyperlipidemia, smoking, a history of percutaneous coronary intervention, and were more than twice as likely to be enrolled from sites within the United States (80.4% vs. 39.8%). High-dose aspirin was associated with similar 180-day Kaplan-Meier estimates of adjudicated composite GI events (1.7% vs. 2.1%; adjusted hazard ratio: 0.88; 95% confidence interval: 0.46 to 1.66) and major adverse cardiac events (4.8% vs. 5.5%; adjusted hazard ratio: 0.73; 95% confidence interval: 0.48 to 1.11) compared with low-dose aspirin. Randomization to PPI therapy reduced 180-day Kaplan-Meier estimates of the primary GI endpoint in low-dose (1.2% vs. 3.1%) and high-dose aspirin subsets (0.9% vs. 2.6%; p for interaction = 0.80), and did not adversely affect the primary cardiovascular endpoint in either group.

CONCLUSIONS

Gastroprotection with PPI therapy should be utilized in appropriately selected patients with coronary artery disease requiring DAPT, even if the patients are on low-dose aspirin. (Clopidogrel and the Optimization of Gastrointestinal Events Trial [COGENT]; NCT00557921).

Gastrointestinal lesions and complications of low-dose aspirin in the gastrointestinal tract

Low dose aspirin (ASA) use has been associated with a wide range of adverse side effects in the upper gastrointestinal (GI) tract, which range from troublesome symptoms without mucosal lesions to more serious toxicity, including ulcers, GI bleeding, perforation and even death. Upper GI symptoms in low dose ASA users are common but often careless or misinterpreted and they are not always related to the presence of mucosal injury. Usually, low dose ASA related ulcers are reasonably small and asymptomatic, and probably heal over a period of weeks to a few months. But, the real clinical problem occurs when the ulcer results in a GI complication (mostly bleeding). The estimated average excess risk of symptomatic or complicated ulcer related to low dose ASA is five cases per 1000 ASA users per year. Death is the worst outcome of GI complications in low dose ASA users, but data about this aspect are scarce. Current evidence indicates that low dose ASA can damage the lower GI tract also, but the real size of the problem is still unknown.

Enhancement of anti-inflammatory property of aspirin in mice by a nano-emulsion preparation

Aspirin, a non-steroidal anti-inflammatory drug, widely used for its anti-inflammatory properties is associated with several systemic side effects including gastro-intestinal discomfort. Inflammation can be mediated by pro-inflammatory cytokines and, along with various other host factors eventually give rise to edema at the inflamed site. Because of the adverse side effects oftentimes associated with systemic exposure to aspirin, the aim of the present study was to investigate whether the anti-inflammatory property of aspirin would enhance if delivered as nano-emulsion preparation. Nano-emulsion preparations of aspirin prepared with a Microfluidizer Processor were evaluated in the croton-oil-induced ear edema CD-1 mouse model using ear lobe thickness and the accumulation of specific in situ cytokines as biomarkers of inflammation. The results showed that particle size (90 nm) populations of nano-emulsion preparations of aspirin compared to an aspirin suspension (363 nm), significantly decreased (p<0. 05) ear lobe thickness approximately 2 fold greater than the aspirin suspension. In addition, the aspirin nano-emulsion further reduced the auricular levels of IL-1alpha (-37%) and TNFalpha (-69%) compared to the aspirin suspension preparation (p<0.05). The reductions in ear lobe thickness were also significantly associated with accumulated tissue levels of IL-1alpha (r=0.5, p<0.009) and TNFalpha (r=0.7, p<0.0004), respectively. In conclusion, these studies indicate that a nano-emulsion preparation of aspirin significantly improved the anti-inflammatory properties of an aspirin suspension in a CD-1 mouse model of induced inflammation.

The dose of aspirin for the prevention of cardiovascular and cerebrovascular events

BACKGROUND

Low dose aspirin (ASA) (75-325 mg daily) is commonly used for the secondary prevention of cardiovascular and cerebrovascular events, as recommended by US national guidelines. Questions remain, however, as to whether there is a difference in the efficacy and safety across this low dose range.

SCOPE

Double-blind controlled studies, meta-analyses, and observational analyses were reviewed to assess the body of evidence regarding the safety and efficacy of aspirin dosing.

FINDINGS

Only one double-blind study directly compared two doses of aspirin within the recommended low dose range. No difference in efficacy or safety was observed, although there was a trend toward greater efficacy with ASA 325 mg vs. ASA 81 mg. Three meta-analyses did not find a difference in bleeding events within the low dose range, while one found that higher doses were associated with more events. One meta-analysis found ASA 75-150 mg was as effective as ASA 160-325 mg. Observational analyses of low dose (75-325 mg) ASA from two large controlled trials differed in their results. One study found no difference in the number of cardiovascular/cerebrovascular events, and a significant improvement in mortality with higher doses, while the other found that higher doses were associated with more events.

CONCLUSION

There does not appear to be a difference in safety across the low dose range of 75-325 mg based on randomized controlled trial data. Furthermore, ASA 325 mg daily appears to be at least as effective as 75 mg daily. Since the optimal dose of ASA for primary and secondary prevention of events in the broad population is uncertain, dosing considerations should include an evaluation of a patient's individual clinical status as well as an overall cardiovascular and cerebrovascular benefit vs. risk assessment.