Physicians' attitudes toward post-MI aspirin prophylaxis: findings from an online questionnaire in Asia-Pacific

Histamine H2 receptor antagonists for decreasing gastrointestinal harms in adults using acetylsalicylic acid: systematic review and meta-analysis

BACKGROUND

It is unclear if histamine H2 receptor antagonists (H2 blockers) prevent a variety of gastrointestinal harms among patients taking acetylsalicylic acid (ASA) over long periods.

METHODS

Electronic databases (e.g., MEDLINE, Embase and Cochrane Central Register of Controlled Trials; from inception to November 2010) and reference lists of retrieved articles were searched. Randomized placebo-controlled trials (RCTs) assessing the efficacy of H2 blockers in reducing gastrointestinal harms (bleeding, ulcers) among adults taking ASA for 2 weeks or longer were included. Two reviewers independently abstracted study and patient characteristics and appraised study quality using the Cochrane risk-of-bias tool. Peto odds ratio (OR) meta-analysis was performed, 95% confidence intervals (CIs) were calculated, and statistical heterogeneity was assessed using the I (2) and χ(2) statistics.

RESULTS

Six RCTs (4 major publications and 2 companion reports) with a total of 498 participants (healthy volunteers or patients with arthritis, cardiovascular or cerebrovascular disease, or diabetes mellitus) were included. One trial adequately reported allocation concealment and sequence generation, with the other 3 trials being judged as unclear for both aspects. In one RCT, no statistically significant differences for gastrointestinal hemorrhage requiring admission to hospital (p = 0.14) or blood transfusion (p = 0.29) were observed between the group receiving concomitant famotidine and ASA and the group receiving concomitant placebo and ASA. After a median of 8 weeks' follow-up, H2 blockers were more effective than placebo in reducing gastrointestinal hemorrhage (2 RCTs, total of 447 patients, OR 0.07, 95% CI 0.02-0.23) and peptic ulcers (3 RCTs, total of 465 patients, OR 0.21, 95% CI 0.12-0.36) among patients taking ASA for 2 weeks or longer. Despite substantial clinical heterogeneity across the studies, including types of H2 blockers, dosing of ASA and underlying conditions, no statistical heterogeneity was observed.

INTERPRETATION

H2 blockers reduced gastrointestinal harm among patients taking ASA for 2 weeks or longer. These results should be interpreted with caution, because of the small number of studies identified for inclusion.

Compliance as the major effectiveness determinant in preventive acetylsalicylic acid therapy

Acetylsalicylic acid (ASA) treatment of patients with cardiovascular disease (CVD) is one of the most effective methods for CVD event prevention. In a substantial proportion of the patients, however, long-term preventive ASA treatment compliance is low (44-71%). Low compliance is associated with reduced antiplatelet effects of ASA and a 2-3-fold increase in the risk of myocardial infarction (MI), ischemic stroke (IS), and other cardiovascular events. ASA therapy compliance could be improved by achieving better collaboration between doctors and patients, while educating patients and explaining the importance of following the doctors’ advice. In addition, enteric-coated ASA forms could play an important role in improving treatment tolerability and, therefore, increasing compliance. Other potentially effective measures include the use of modern packaging (calendar blisters) and information technologies (telephone communication, MGMM).

Risk assessment and aspirin use in Asian and Western populations

Objective

The aim of this review was to examine aspirin utilization, cardiovascular risk estimation, and clinical evidence for aspirin prophylaxis in Asian versus Western countries.

Methods

A literature search was performed using PubMed and the key terms “aspirin” and “Asia” or “Western”.

Results

Despite the growing burden of cardiovascular disease (CVD), aspirin is underutilized in high-risk patients in both Asian and Western countries. A number of risk estimation scores are available; however, validation is needed in countries such as Japan, India, and in South Asia. Underutilization of aspirin in Asia may be linked to an overestimation of bleeding risks. It is possible that a higher prevalence of Helicobacter pylori infection and genetic differences may make Asians more susceptible to gastrointestinal bleeding. Very low aspirin doses and even the wider use of gastroprotective agents may be the optimal approach to high-risk patients in Asia.

Conclusions

Based on the current evidence, aspirin should be used for CVD prevention when the risk:benefit ratio is favorable. A number of trials are underway, including the Diabetic Atherosclerosis Prevention by Cilostazol and Japanese Primary Prevention Project, which will provide key data on the benefits of aspirin in Asian patients at risk of CVD, and may improve aspirin utilization and risk estimation.