Randomised trial of prophylactic daily aspirin in British male doctors

The role of aspirin in the prevention of cardiovascular disease

Aspirin therapy is well-accepted as an agent for the secondary prevention of cardiovascular events and current guidelines also define a role for aspirin in primary prevention. In this review, we describe the seminal trials of aspirin use in the context of current guidelines, discuss factors that may influence the effectiveness of aspirin therapy for cardiovascular disease prevention, and briefly examine patterns of use. The body of evidence supports a role for aspirin in both secondary and primary prevention of cardiovascular events in selected population groups, but practice patterns may be suboptimal. As a simple and inexpensive prophylactic measure for cardiovascular disease, aspirin use should be carefully considered in all at-risk adult patients, and further measures, including patient education, are necessary to ensure its proper use.

Aspirin for primary prevention of cardiovascular events: meta-analysis of randomized controlled trials and subgroup analysis by sex and diabetes status

OBJECTIVE

To evaluate the benefits and harms of aspirin for the primary prevention of CVD and determine whether the effects vary by sex and diabetes status.

METHODS

We searched Medline, Embase, and Cochrane databases for randomized controlled trials comparing the effects of aspirin with placebo or control in people with no pre-existing CVD. Two investigators independently extracted data and assessed the study quality. Analyses were performed using Stata version 12.

RESULTS

Fourteen trials (107,686 participants) were eligible. Aspirin was associated with reductions in major cardiovascular events (risk ratio, 0.90; 95% confidence interval, 0.85-0.95), myocardial infarction (0.86; 0.75-0.93), ischemic stroke (0.86; 0.75-0.98) and all-cause mortality (0.94; 0.89-0.99). There were also increases in hemorrhagic stroke (1.34; 1.01-1.79) and major bleeding (1.55; 1.35-1.78) with aspirin. The number needed to treat to prevent 1 major cardiovascular event over a mean follow-up of 6.8 years was 284. By comparison, the numbers needed to harm to cause 1 major bleeding is 299. In subgroup analyses, pooled results demonstrated a reduction in myocardial infarction among men (0.71; 0.59-0.85) and ischemic stroke among women (0.77; 0.63-0.93). Aspirin use was associated with a reduction (0.65; 0.51-0.82) in myocardial infarction among diabetic men. In meta-regression analyses, the results suggested that aspirin therapy might be associated with a decrease in stroke among diabetic women and a decrease in MI among diabetic men and risk reductions achieved with low doses (75 mg/day) were as large as those obtained with higher doses (650 mg/day).

CONCLUSIONS

The use of low-dose aspirin was beneficial for primary prevention of CVD and the decision regarding an aspirin regimen should be made on an individual patient basis. The effects of aspirin therapy varied by sex and diabetes status. A clear benefit of aspirin in the primary prevention of CVD in people with diabetes needs more trials.

Gastrointestinal comorbidities associated with atrial fibrillation

This observational study was conducted to describe the risk of gastrointestinal (GI) events among patients with atrial fibrillation (AF). We analyzed Thomson Reuters MarketScan® data from 2005 to 2009. Subjects aged ≥18 years with ≥ 1 AF diagnosis were selected. GI events were identified from claims with a primary or secondary diagnosis code for any GI condition. The risk of GI events was assessed using cumulative incidence (new GI events/patients with AF without GI condition at baseline) and incidence rates (IRs), calculated as the number of patients with new GI events divided by patient-years of observation. In addition, the CHADS₂ score was evaluated at baseline to determine the patient’s risk of stroke. A total of 557,123 AF patients were identified. The mean (median) AF patient age was 68.2 years (70); 45% were female. The cumulative incidences of any GI event and dyspepsia were 40% and 19%, respectively. The corresponding IRs were 38.8 and 14.7 events per 100 patient–years. IRs of any GI events for female and male patients were 43.6 and 35.5; for patients in the age groups <65, 65–74, 75–84, and ≥85 years, IRs were 32.3, 38.9, 44.6, and 52.7; for patients with a CHADS₂ score of 0, 1–2, 3–4, and 5–6, IRs were 30.3, 41.6, 56.9, and 74.5, respectively. In this large claims database, 40% of AF patients experienced a GI event, predominantly dyspepsia. Physicians should take age and comorbidities into consideration when managing AF patients.

Aspirin therapy in primary cardiovascular disease prevention: a position paper of the European Society of Cardiology working group on thrombosis

Although the use of oral anticoagulants (vitamin K antagonists) has been abandoned in primary cardiovascular prevention due to lack of a favorable benefit-to-risk ratio, the indications for aspirin use in this setting continue to be a source of major debate, with major international guidelines providing conflicting recommendations. Here, we review the evidence in favor and against aspirin therapy in primary prevention based on the evidence accumulated so far, including recent data linking aspirin with cancer protection. While awaiting the results of several ongoing studies, we argue for a pragmatic approach to using low-dose aspirin in primary cardiovascular prevention and suggest its use in patients at high cardiovascular risk, defined as ≥2 major cardiovascular events (death, myocardial infarction, or stroke) projected per 100 person-years, who are not at increased risk of bleeding.

Aspirin in the primary prevention of cardiovascular disease: current knowledge and future research needs

In secondary prevention, among a very wide range of survivors of prior occlusive cardiovascular disease (CVD) events and those suffering acute myocardial infarction (MI) or occlusive stroke, aspirin decreases risks of MI, stroke, and CVD death. In these high risk patients, the absolute benefits are large and absolute risks are far smaller so aspirin should be more widely prescribed. In contrast, in primary prevention, aspirin reduces risks of first MI but the evidence on stroke and CVD death remain inconclusive. Based on the current totality of evidence from predominantly low risk subjects where the absolute benefits is low and side effects the same as in secondary prevention, any decision to prescribe aspirin for primary prevention should be an individual clinical judgment by the healthcare provider that weighs the absolute benefit in reducing the risk of a first MI against the absolute risk of major bleeding. If the ongoing trials of intermediate risks subjects show net benefits then general guidelines may be justified with several caveats. First, any decision to use aspirin should continue to be made by the healthcare provider. Second, therapeutic lifestyle changes and other drugs of life saving benefit such as statins should be considered with aspirin as an adjunct, not alternative. The more widespread and appropriate use of aspirin in primary prevention is particularly attractive, especially in developing countries where CVD is emerging as the leading cause of death. In addition, aspirin is generally widely available over the counter and is extremely inexpensive.

A short-term effect of low-dose aspirin on major hemorrhagic risks in primary prevention: a case-crossover design

BACKGROUND

Very few studies have examined the risk of short-term adverse hemorrhage of low-dose aspirin use in primary prevention. This case-crossover study examined the transient effect of low-dose aspirin use on major hemorrhagic risks.

METHODS

A representative database of 1,000,000 patients randomly sampled from the Taiwan's National Health Insurance Research Database in 2000 was analyzed. The study cohort consisted of a total of 501,946 individuals, aged 30-95 years old, at risk of a major bleeding event in 2000. A case-crossover study was used to retrieve data on 10,905 incident patients with major hemorrhagic complications (3,781 cerebral and 7,124 gastrointestinal) and prescribed low-dose aspirin (≤300 mg/day) from 2000-2008. A 56-day time window (∼2 months) was used as the case period for which the odds ratio (OR) was estimated using the ratio of patients exposed during the 56-day case period only (1-56 days before the index date) compared to its corresponding 56-day control period only (57-112 days before the index date).

RESULTS

Four hundred eighty-nine (4.5%) of the 10,905 hemorrhagic patients had used low-dose aspirin during the 56-day case only period; 294 (2.7%) of the same patients had used low-dose aspirin during control only period. Low-dose aspirin use increase the risk of developing a major hemorrhage 1.33-fold (95% CI = 1.13-1.55, P<0.0001). Significance was found prominent in 4,453 non-hypertensive and non-diabetic subjects (Adjusted odds ratio = 1.88, 95% CI = 1.21-2.91).

CONCLUSION

Transient low-dose aspirin use increases risk for major hemorrhagic events in Han Chinese.

Use of coronary artery calcium testing to guide aspirin utilization for primary prevention: estimates from the multi-ethnic study of atherosclerosis

BACKGROUND

Aspirin for the primary prevention of coronary heart disease (CHD) is only recommended for individuals at high risk for CHD although the majority of CHD events occur in individuals who are at low to intermediate risk.

METHODS AND RESULTS

To estimate the potential of coronary artery calcium (CAC) scoring to guide aspirin use for primary prevention of CHD, we studied 4229 participants from the Multi-Ethnic Study of Atherosclerosis who were not on aspirin at baseline and were free of diabetes mellitus. Using data from median 7.6-year follow-up, 5-year number-needed-to-treat estimations were calculated by applying an 18% relative CHD reduction to the observed event rates. This was contrasted to 5-year number-needed-to-harm estimations based on the risk of major bleeding reported in an aspirin meta-analysis. Results were stratified by a 10% 10-year CHD Framingham Risk Score (FRS). Individuals with CAC≥100 had an estimated net benefit with aspirin regardless of their traditional risk status (estimated 5-year number needed to treat of 173 for individuals <10% FRS and 92 for individuals ≥10% FRS, estimated 5-year number needed to harm of 442 for a major bleed). Conversely, individuals with zero CAC had unfavorable estimations (estimated 5-year number needed to treat of 2036 for individuals <10% FRS and 808 for individuals ≥10% FRS, estimated 5-year number needed to harm of 442 for a major bleed). Sex-specific and age-stratified analyses showed similar results.

CONCLUSIONS

For the primary prevention of CHD, Multi-Ethnic Study of Atherosclerosis participants with CAC≥100 had favorable risk/benefit estimations for aspirin use while participants with zero CAC were estimated to receive net harm from aspirin.

Management of cardiovascular disease risk factors in older adults with type 2 diabetes mellitus: 2002-2012 literature review

Type 2 diabetes mellitus (DM) is one of the most common chronic conditions in older adults and is often accompanied by comorbidities and geriatric syndromes. The management of cardiovascular disease risk factors in older adults with DM is important to clinicians. The literature was reviewed from 2002 to 2012 to provide an American Geriatrics Society expert panel with an evidence base for updating and making new recommendations for improving the care of older adults with type 2 DM. This review includes only the domains of the management of blood pressure, lipid control, glycemic control, and use of aspirin. Over the last 10 years, new randomized controlled trials (RCT) designed to study different blood pressure treatment targets did not find evidence that intensive systolic blood pressure control (<130 mmHg) resulted in lower rates of myocardial infarction and mortality than less-intensive control. There are risks of side effects with achieving systolic blood pressure of less than 120 mmHg. Lipid-lowering statins are effective in reducing cardiovascular events in middle-aged and older adults, but data on niacin and fibrates is limited. Trials of statins and other lipid-lowering agents do not evaluate the cardiovascular effects on outcomes from treating lipids to different low-density lipoprotein cholesterol targets. No RCTs of lipid-lowering drugs enrolled significant numbers of adults aged 80 and older with or without DM. Three major RCTs that investigated intensive glycemic control did not find reductions in primary cardiovascular endpoints, and one study reported greater mortality with glycosylated hemoglobin of less than 6%. Two recently published RCTs were designed to study the cardiovascular benefits of aspirin use by individuals with DM. Neither trial found significantly fewer primary cardiovascular endpoints with aspirin than in control groups. Overall, RCTs enrolled few adults aged 80 and older or with significant comorbidities. More research is needed for clinicians to effectively customize care to older adults with DM because of heterogeneity in health status, comorbidities, duration of disease, frailty and functional status, and differences in life expectancy.

Aspirin in primary prevention of cardiovascular disease and cancer: a systematic review of the balance of evidence from reviews of randomized trials

Background

Aspirin has been recommended for primary prevention of cardiovascular disease (CVD) and cancer, but overall benefits are unclear. We aimed to use novel methods to re-evaluate the balance of benefits and harms of aspirin using evidence from randomised controlled trials, systematic reviews and meta-analyses.

Methods and Findings

Data sources included ten electronic bibliographic databases, contact with experts, and scrutiny of reference lists of included studies. Searches were undertaken in September 2012 and restricted to publications since 2008. Of 2,572 potentially relevant papers 27 met the inclusion criteria. Meta-analysis of control arms to estimate event rates, modelling of all-cause mortality and L'Abbé plots to estimate heterogeneity were undertaken. Absolute benefits and harms were low: 60-84 major CVD events and 34-36 colorectal cancer deaths per 100,000 person-years were averted, whereas 46-49 major bleeds and 68-117 gastrointestinal bleeds were incurred. Reductions in all-cause mortality were minor and uncertain (Hazard Ratio 0.96; 95% CI: 0.90-1.02 at 20 years, Relative Risk [RR] 0.94, 95% CI: 0.88-1.00 at 8 years); there was a non-significant change in total CVD (RR 0.85, 95% CI: 0.69-1.06) and change in total cancer mortality ranged from 0.76 (95% CI: 0.66-0.88) to 0.93 (95% CI: 0.84-1.03) depending on follow-up time and studies included. Risks were increased by 37% for gastrointestinal bleeds (RR 1.37, 95% CI: 1.15-1.62), 54%-66% for major bleeds (Rate Ratio from IPD analysis 1.54, 95% CI: 1.30-1.82, and RR 1.62, 95% CI: 1.31-2.00), and 32%-38% for haemorrhagic stroke (Rate Ratio from IPD analysis 1.32; 95% CI: 1.00-1.74; RR 1.38; 95% CI: 1.01-1.82).

Conclusions

Findings indicate small absolute effects of aspirin relative to the burden of these diseases. When aspirin is used for primary prevention of CVD the absolute harms exceed the benefits. Estimates of cancer benefit rely on selective retrospective re-analysis of RCTs and more information is needed.

Use of antiplatelet agents in patients with atherosclerotic disease

Platelets play a key role in the initiation of hemostatic mechanisms during vascular injury. When contemplating prescription of antiplatelet agents (APAs) for patients as primary prevention for cardiovascular events, the physician should carefully weigh the potential benefits of cardiovascular risk reduction with the likelihood of harm, related mostly to hemorrhagic complications. The role of APAs in secondary prevention of atherosclerosis and coronary artery disease is well established, however, optimal duration of therapy and intensity of patient treatment are not settled and probably need to be individualized per patient. We describe the data emerging from contemporary trials on the efficacy and safety of the use of oral APAs in various patient subpopulations. We also discuss the advantages and potential roles of new APAs during and following acute coronary syndromes, percutaneous coronary interventions, and symptomatic atherosclerosis. We propose certain strategies and directions for future research to enhance the safety and efficacy prevention by optimizing the beneficial effects of APAs along with other contemporary treatment modalities of primary and secondary prevention.

Low-dose aspirin and upper gastrointestinal bleeding in primary versus secondary cardiovascular prevention: a population-based, nested case-control study

BACKGROUND

The benefit-risk profile of low-dose aspirin in primary prevention of cardiovascular disease is unclear. We sought to quantify upper gastrointestinal bleeding (UGIB) risk associated with low-dose aspirin in secondary versus primary prevention patients.

METHODS AND RESULTS

We performed a population-based nested case-control study using The Health Improvement Network (THIN) Database between 2000 and 2007. We identified 2049 cases of UGIB and 20,000 controls, frequency-matched to the cases on age, sex, and calendar year, who were subdivided into primary (without previous cardiovascular disease) and secondary (with previous cardiovascular disease) prevention populations. We estimated the relative risk of UGIB associated with the use of low-dose aspirin by multivariate logistic regression. The UGIB risk in patients taking low-dose aspirin relative to nonusers was significantly higher in the primary (adjusted relative risk, 1.90; 95% confidence interval, 1.59-2.26) than in the secondary (relative risk, 1.40; 95% confidence interval, 1.14-1.72; P value for the difference=0.0014) prevention cohort. However, as the baseline risk of UGIB was lower in the primary than in the secondary prevention cohort, numbers needed to harm per 1 year of low-dose aspirin use were 601 and 391 for primary and secondary prevention, respectively.

CONCLUSIONS

The relative risk of UGIB in patients taking low-dose aspirin is higher when used for primary than for secondary cardiovascular disease prevention, but this difference is more than compensated by the lower baseline risk in the primary prevention population. Such estimates are important for an assessment of the net clinical benefit in primary prevention.

Study design of ASPirin in Reducing Events in the Elderly (ASPREE): a randomized, controlled trial

Cost-effective strategies to maintain healthy active lifestyle in aging populations are required to address the global burden of age-related diseases. ASPREE will examine whether the potential primary prevention benefits of low dose aspirin outweigh the risks in older healthy individuals. Our primary hypothesis is that daily oral 100 mg enteric-coated aspirin will extend a composite primary endpoint termed 'disability-free life' including onset of dementia, total mortality, or persistent disability in at least one of the Katz Activities of Daily Living in 19,000 healthy participants aged 65 years and above ('US minorities') and 70 years and above (non-'US minorities'). ASPREE is a double-blind, randomized, placebo-controlled trial of oral 100mg enteric-coated acetyl salicylic acid (ASA) or matching placebo being conducted in Australian and US community settings on individuals free of dementia, disability and cardiovascular disease (CVD) events. Secondary endpoints are all-cause and cause specific mortality, fatal and non-fatal cardiovascular events, fatal and non-fatal cancer (excluding non-melanoma skin cancer), dementia, mild cognitive impairment, depression, physical disability, and clinically significant bleeding. To 20 September 2013 14,383 participants have been recruited. Recruitment and study completion are anticipated in July 2014 and December 2018 respectively. In contrast to other aspirin trials that have largely focused on cardiovascular endpoints, ASPREE has a unique composite primary endpoint to better capture the overall risk and benefit of aspirin to extend healthy independent lifespan in older adults in the US and Australia.

Pharmacological and dietary prevention for colorectal cancer

Background

Colorectal cancer (CRC) is a leading cause of cancer morbidity and mortality. People at higher risk are those individuals with a family history of CRC and familial adenomatous polyposis. Prevention and screening are two milestones for this disease. The aim of this study is to evaluate the chemopreventive role of non-steroidal anti-inflammatory drugs (NSAIDs), including aspirin and cyclooxygenase 2 inhibitors, some micronutrients (folic acid, calcium, selenium, antioxidants) and probiotics.

Discussion

The studies on aspiring reported promising results, but it is debatable whether aspirin should be used as chemoprevention, because of its side effects and because of poor efficacy evident in subjects at high risk. Similar results were reported for other non-aspirin NSAIDs, such as sulindac and celecoxib, which the potential adverse effects limit their use. Selenium role in prevention of various types of cancer as well as in colon adenomas are often inconclusive or controversial. Several studies suggested that calcium may have a possible chemopreventive effect on colon adenomas and CRC, although contrasting results are reported for the latter. A recent meta-analysis including 13 randomized trial suggested that folic acid supplementation had not a chemiopreventive action on CRC. Several studies investigated the association between antioxidants, administered alone or in combination, and CRC risk, both among general and at risk population, but only few of them supported statistically significant results.

Conclusion

The results of this literature review showed an unclear role in CRC prevention of both pharmacological and dietary intervention. Despite several options are available to prevent colon cancer, it is challenging to identify a correct strategy to prevent CRC through pharmacological and dietary intervention due to the long latency of cancer promotion and development. Since some of the drugs investigated may have uncertain individual effects, it can be suggested to potentiate such effects by adding them together.

Cardiovascular Pharmacology Core Reviews

Acetylsalicylic acid, or aspirin, is perhaps the most well-studied drug in human history, but controversy persists regarding both optimal dose and its use in the primary prevention of atherothrombotic events. This article reviews the following: the effect of aspirin upon the cyclooxygenase pathway; clinical trials of aspirin for both secondary and primary prevention; prospective and retrospective studies of aspirin dose; the potential interaction between aspirin and ticagrelor; and the concept of aspirin resistance. It concludes with a review of major society guidelines regarding aspirin and offers a perspective on the evidence-based use of aspirin in clinical practice.

Frequency-risk and duration-risk relationships between aspirin use and gastric cancer: a systematic review and meta-analysis

Background

Although previous meta-analyses have suggested an association between aspirin use and risk of gastric cancer, current evidence is inconsistent. Additionally, it remains unclear whether there are frequency-risk and duration-risk relationships and if a threshold of effect exists.

Methods

We identified studies by searching MEDLINE and PUBMED databases and reviewing relevant articles. We derived the summary risk estimates using fixed-effects or random-effects model based on homogeneity analysis. The dose-response meta-analysis was performed by linear trend regression and restricted cubic spline regression. Potential heterogeneity was tested using the Q statistic and quantified with the I² statistic. Subgroup analyses and Galbraith plots were used to explore the potential sources of heterogeneity. Publication bias was evaluated with funnel plots and quantified by the Begg's and Egger's test.

Results

Fifteen studies were included in this meta-analysis. There was an overall 29% reduced risk of gastric cancer corresponding to aspirin use (RR  = 0.71, 95% CI 0.60–0.82). We found there are nonlinear frequency-risk and linear duration-risk relations between aspirin use and gastric cancer. A monotonically decreasing relation was observed only for low-frequency (≤4.5 times/week) aspirin intake (10% decreased risk for once/week, 19% for twice/week and 29% for 4.5 times/week), and the frequency threshold of aspirin use is 4.5 times per week. Regarding those with duration of aspirin use, there was a tendency towards stronger risk reduction of gastric cancer for longer aspirin use (10% decreased risk for 4 years, 19% for 8 years and 28% for 12 years), and no duration threshold was observed.

Conclusion

Our findings suggest that long-term (≥4 years) and low-frequency (1–4.5 times per week) aspirin use is associated with a statistically significant, dose-dependent reduction in the risk of gastric cancer.

Lung cancer chemoprevention: current status and future prospects

Lung cancer is the leading cause of cancer death worldwide, making it an attractive disease for chemoprevention. Although avoidance of tobacco use and smoking cessation will have the greatest impact on lung cancer development, chemoprevention could prove to be very effective, particularly in former smokers. Chemoprevention is the use of agents to reverse or inhibit carcinogenesis and has been successfully applied to other common malignancies. Despite prior studies in lung cancer chemoprevention failing to identify effective agents, we now have the ability to identify high-risk populations, and our understanding of lung tumour and premalignant biology continues to advance. There are distinct histological lesions that can be reproducibly graded as precursors of non-small-cell lung cancer and similar precursor lesions exist for adenocarcinoma. These premalignant lesions are being targeted by chemopreventive agents in current trials and will continue to be studied in the future. In addition, biomarkers that predict risk and response to targeted agents are being investigated and validated. In this Review, we discuss the principles of chemoprevention, data from preclinical models, completed clinical trials and observational studies, and describe new treatments for novel targeted pathways and future chemopreventive efforts.

The aspirin controversy in primary prevention

PURPOSE OF REVIEW

Apparently conflicting meta-analysis results have led to renewed debate about the role of aspirin for the primary prevention of cardiovascular disease. We review the results of meta-analyses comparing aspirin with placebo or no aspirin for the primary prevention of cardiovascular disease and critically evaluate whether aspirin provides a net benefit.

RECENT FINDINGS

The results of four independently conducted meta-analyses between 2009 and 2012 involving between 95 000 and 102 621 individuals at low risk of cardiovascular disease are consistent with the results of the 2002 Antithrombotic Trialists' Collaboration meta-analysis, which found that aspirin reduces cardiovascular events primarily by reducing nonfatal myocardial infarction (MI). There is no convincing evidence that aspirin reduces cardiovascular mortality, but estimates from all of the meta-analyses suggest a modest reduction in all-cause mortality. Aspirin reduces ischaemic stroke but increases haemorrhagic stroke and major bleeding.

SUMMARY

The meta-analysis results consistently indicate that, in individuals at low risk for cardiovascular disease, aspirin reduces the risk of MI at the cost of an increase in major bleeding and produces a modest nominally significant reduction in total mortality. These results suggest that recommendations for primary prevention with aspirin should be individualized, taking into account the balance between benefits and risks and individual values and preferences.

Chemoprevention of lung cancer: Diagnosis and management of lung cancer, 3rd ed: American College of Chest Physicians evidence-based clinical practice guidelines

BACKGROUND

Lung cancer is the most common cause of cancer death in men and women in the United States. Cigarette smoking is the main risk factor. Former smokers are at a substantially increased risk of developing lung cancer compared with lifetime never smokers. Chemoprevention refers to the use of specific agents to reverse, suppress, or prevent the process of carcinogenesis. This article reviews the major agents that have been studied for chemoprevention.

METHODS

Articles of primary, secondary, and tertiary prevention trials were reviewed and summarized to obtain recommendations.

RESULTS

None of the phase 3 trials with the agents β-carotene, retinol, 13-cis-retinoic acid, α-tocopherol, N-acetylcysteine, acetylsalicylic acid, or selenium has demonstrated beneficial and reproducible results. To facilitate the evaluation of promising agents and to lessen the need for a large sample size, extensive time commitment, and expense, surrogate end point biomarker trials are being conducted to assist in identifying the most promising agents for later-stage chemoprevention trials. With the understanding of important cellular signaling pathways and the expansion of potentially important targets, agents (many of which target inflammation and the arachidonic acid pathway) are being developed and tested which may prevent or reverse lung carcinogenesis.

CONCLUSIONS

By integrating biologic knowledge, additional early-phase trials can be performed in a reasonable time frame. The future of lung cancer chemoprevention should entail the evaluation of single agents or combinations that target various pathways while working toward identification and validation of intermediate end points.

The aspirin cardiovascular/gastrointestinal risk calculator--a tool to aid clinicians in practice

BACKGROUND

Assessment of both GI and CV risks vs. the benefits of low-dose aspirin for individual patients can be difficult in clinical practice.

AIM

To develop a tool to estimate CV and GI risks to facilitate the clinical decision-making process.

METHODS

We constructed risk-ratio estimations and determined the incidence of CV events and upper GI complications according to the presence of different risk factors. For upper GI complications we assumed a baseline incidence of 1 case/1000-persons-year, a twofold increased risk with low-dose aspirin, and estimated a 60% GI risk reduction with proton pump inhibitors (PPI) co-therapy and a 60% risk reduction with H. pylori eradication in patients with a history of peptic ulcer.

RESULTS

The calculator can be found at http://www.asariskcalculator.com. In patients with low CV risk the number of GI complications induced by low-dose aspirin may be greater than the number of CV events prevented. In patients with high CV risk, low-dose aspirin is recommended, but the number of GI complications induced may still overcome the CV events saved. The use of PPI reduces the number of complication events induced by low-dose aspirin, but the number of CV events saved may still be offset by the number of GI complications induced in patients at very high GI risk.

CONCLUSIONS

There are many clinical situations where the number of potential upper GI complications induced by low-dose aspirin may exceed the number of potentially prevented CV events. A risk calculator should guide physicians in choosing appropriate therapy and maximise the aspirin benefit.

Randomized phase II trial of sulindac for lung cancer chemoprevention

INTRODUCTION

Sulindac represents a promising candidate agent for lung cancer chemoprevention, but clinical trial data have not been previously reported. We conducted a randomized, phase II chemoprevention trial involving current or former cigarette smokers (≥30 pack-years) utilizing the multi-center, inter-disciplinary infrastructure of the Cancer Prevention Network (CPN).

METHODS

At least 1 bronchial dysplastic lesion identified by fluorescence bronchoscopy was required for randomization. Intervention assignments were sulindac 150mg bid or an identical placebo bid for 6 months. Trial endpoints included changes in histologic grade of dysplasia (per-participant as primary endpoint and per lesion as secondary endpoint), number of dysplastic lesions (per-participant), and Ki67 labeling index.

RESULTS

Slower than anticipated recruitment led to trial closure after randomizing participants (n=31 and n=30 in the sulindac and placebo arms, respectively). Pre- and post-intervention fluorescence bronchoscopy data were available for 53/61 (87%) randomized, eligible participants. The median (range) of dysplastic lesions at baseline was 2 (1-12) in the sulindac arm and 2 (1-7) in the placebo arm. Change in dysplasia was categorized as regression:stable:progression for 15:3:8 (58%:12%:31%) subjects in the sulindac arm and 15:2:10 (56%:7%:37%) subjects in the placebo arm; these distributions were not statistically different (p=0.85). Median Ki67 expression (% cells stained positive) was significantly reduced in both the placebo (30 versus 5; p=0.0005) and sulindac (30 versus 10; p=0.0003) arms, but the difference between arms was not statistically significant (p=0.92).

CONCLUSIONS

Data from this multi-center, phase II squamous cell lung cancer chemoprevention trial do not demonstrate sufficient benefits from sulindac 150mg bid for 6 months to warrant additional phase III testing. Investigation of pathway-focused agents is necessary for lung cancer chemoprevention.

Low-dose acetylsalicylic acid use and the risk of upper gastrointestinal bleeding: a meta-analysis of randomized clinical trials and observational studies

BACKGROUND

Low-dose acetylsalicylic acid (LDA, 75 mg/day to 325 mg/day) is recommended for primary and secondary prevention of cardiovascular events, but has been linked to an increased risk of upper gastrointestinal bleeding (UGIB).

OBJECTIVE

To analyze the magnitude of effect of LDA use on UGIB risk.

METHODS

The PubMed and Embase databases were searched for randomized controlled trials (RCTs) reporting UGIB rates in individuals receiving LDA, and observational studies of LDA use in patients with UGIB. Studies were pooled for analysis of UGIB rates.

RESULTS

Eighteen studies were included. Seven RCTs reported UGIB rates in individuals randomly assigned to receive LDA (n=22,901) or placebo (n=22,923). Ten case-control studies analyzed LDA use in patients with UGIB (n=10,816) and controls without UGIB (n=30,519); one cohort study reported 207 UGIB cases treated with LDA only. All studies found LDA use to be associated with an increased risk of UGIB. The mean number of extra UGIB cases associated with LDA use in the RCTs was 1.2 per 1000 patients per year (95% CI 0.7 to 1.8). The number needed to harm was 816 (95% CI 560 to 1500) for RCTs and 819 (95% CI 617 to 1119) for observational studies. Meta-analysis of RCT data showed that LDA use was associated with a 50% increase in UGIB risk (OR 1.5 [95% CI 1.2 to 1.8]). UGIB risk was most pronounced in observational studies (OR 3.1 [95% CI 2.5 to 3.7]).

CONCLUSIONS

LDA use was associated with an increased risk of UGIB.

Antiplatelet agents for chronic kidney disease

BACKGROUND

Antiplatelet agents are widely used to prevent cardiovascular events. The risks and benefits of antiplatelet treatment may be different in people with chronic kidney disease (CKD) for whom occlusive atherosclerotic events are less prevalent, and bleeding hazards might be increased.

OBJECTIVES

To summarise the effects of antiplatelet treatment (antiplatelet agent versus control or other antiplatelet agent) for the prevention of cardiovascular and adverse kidney outcomes in individuals with CKD.

SEARCH METHODS

In January 2011 we searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE and the Cochrane Renal Group's Specialised Register without language restriction.

SELECTION CRITERIA

We selected randomised controlled trials of any antiplatelet treatment versus placebo or no treatment, or direct head-to-head antiplatelet agent studies in people with CKD. Studies were included if they enrolled participants with CKD, or included people in broader at-risk populations in which data for subgroups with CKD could be disaggregated.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data from primary study reports and any available supplementary information for study population, interventions, outcomes, and risks of bias. Risk ratios (RR) and 95% confidence intervals (CI) were calculated from numbers of events and numbers of participants at risk which were extracted from each included study. The reported RRs were extracted where crude event rates were not provided. Data was pooled using the random-effects model.

MAIN RESULTS

We included 50 studies, enrolling 27,139 participants; 44 studies (21,460 participants) compared an antiplatelet agent with placebo or no treatment, and six studies (5679 participants) directly compared one antiplatelet agent with another. Compared to placebo or no treatment, antiplatelet agents reduced the risk of myocardial infarction (17 studies; RR 0.87, 95% CI 0.76 to 0.99), but not all-cause mortality (30 studies; RR 0.93, 95% CI 0.81 to 1.06), cardiovascular mortality (19 studies; RR 0.89, 95% CI 0.70 to 1.12) or stroke (11 studies; RR 1.00, 95% CI 0.58 to 1.72). Antiplatelet agents increased the risk of major (27 studies; RR 1.33, 95% CI 1.10 to 1.65) and minor bleeding (18 studies; RR 1.49, 95% CI 1.12 to 1.97). In terms of dialysis access outcomes, antiplatelet agents reduced access thrombosis or patency failure but had no effect on suitability for dialysis. Meta-regression analysis indicated no differences in the relative benefit or harms of treatment (risk of all-cause mortality, myocardial infarction, or major bleeding) by type of antiplatelet agent or stage of CKD. Limited data were available for direct head-to-head comparisons of antiplatelet drugs, treatment in kidney transplant recipients, primary prevention, or risk of ESKD.

AUTHORS' CONCLUSIONS

Antiplatelet agents reduce myocardial infarction but increase major bleeding. Risks may outweigh harms among people with low annual risks of cardiovascular events, including those with early stages of CKD who do not have clinically-evident occlusive cardiovascular disease.

Reinitiating aspirin therapy for primary prevention of cardiovascular events in a patient post-aspirin-induced upper gastrointestinal bleed: a case report and review of literature

OBJECTIVE

To describe a case of continued aspirin use for primary prevention of a cardiovascular event in a patient post-aspirin-induced upper gastrointestinal (GI) bleed and evaluate published evidence to determine whether reinitiating aspirin therapy for this patient was appropriate.

CASE SUMMARY

A 65-year-old man had been taking chronic low-dose (81 mg/day) aspirin therapy since 2002 for primary prevention of a cardiovascular event. He developed an upper GI bleed with lowered hemoglobin (9 mg/dL) and hematocrit (26.3%) after concomitantly taking 2 doses of naproxen (220 mg each). An objective causality assessment with the Naranjo probability scale revealed a probable adverse reaction of an upper GI bleed associated with concomitant naproxen and aspirin use. No further naproxen was taken. Aspirin was discontinued and pantoprazole was started, with resolution of the bleeding. Aspirin was restarted 2.5 months after pantoprazole was initiated, and no further bleeding occurred.

DISCUSSION

Upper GI bleeds associated with aspirin therapy are well described in the literature. The management of cardiovascular event prophylaxis after a GI bleed is often controversial; consensus in regard to the optimal method of management does not exist. We evaluated GI protection strategies for patients with a history of aspirin-induced GI bleeding requiring cardiovascular prophylaxis. We found that the benefit of aspirin for the primary prevention of cardiovascular events needs to be carefully balanced with the risks associated with its use. The current literature supports that the best approach to prevent recurrent aspirin-induced GI bleeding is to administer a proton pump inhibitor with aspirin therapy.

CONCLUSIONS

The benefit of aspirin for primary prevention of cardiovascular events needs to be carefully balanced with the risks associated with its use. Based on the current literature, the best approach to preventing recurrent aspirin-induced GI bleeds is to administer a proton pump inhibitor concomitantly with aspirin therapy.

Aspirin in prevention of sporadic colorectal cancer: current clinical evidence and overall balance of risks and benefits

In addition to longstanding evidence from observational studies, evidence from randomised trials of the effectiveness of aspirin for chemoprevention of colorectal cancer has increased substantially in recent years. Trials have shown that daily aspirin reduces the risk of any recurrent colorectal adenoma by 17 % and advanced adenoma by 28 %, and that daily aspirin for about 5 years reduces incidence and mortality due to colorectal cancer by 30-40 % after 20 years of follow-up, and reduces the 20-year risk of all-cause cancer mortality by about 20 %. Recent evidence also shows that the risk of major bleeding on aspirin diminishes with prolonged use, suggesting that the balance of risk and benefit favours the use of daily aspirin in primary prevention of colorectal and other cancers. Updated clinical guidelines are currently awaited.

Review of guidelines on primary prevention of cardiovascular disease with aspirin: how much evidence is needed to turn a tanker?

AIMS

There are numerous national and international guidelines on the use of aspirin for the primary prevention of cardiovascular disease. Given the uncertainties about aspirin in primary prevention, our aim was to compare the recommendations and the reported evidence in guidelines for the treatment with aspirin of subjects free of cardiovascular disease with or without diabetes.

METHODS AND RESULTS

Guidelines were retrieved through Medline and other electronic databases and through a web-based search for guideline development organizations. The content of the recommendations and the underlying evidence were analysed with qualitative and bibliometric methods. In addition, we searched for recent studies to assess whether they underscore the current recommendations. We included 12 guidelines: six European, three North American, and one each from New Zealand, Australia, and the World Health Organization. Recommendations differ with regard to outcome (morbidity, mortality), time span (years of risk), cut-off percentage between high and low risk, and the dose of aspirin. Most guidelines are not in line with recent evidence, which show that aspirin is of uncertain net value as the reduction in absolute risk for occlusive CV events needs to be weighed against an increase in the risk of major bleeds.

CONCLUSION

We found conflicting recommendations in various guidelines about the use of aspirin for the primary prevention of cardiovascular events, which reflect differences in selection of the evidence and in the timing of publication. According to recent evidence, in general, the use of aspirin seems no longer justifiable in primary prevention in patients with or without diabetes.

Mechanistic and pharmacological issues of aspirin as an anticancer agent

Recent findings have shown that aspirin, taken for several years, reduces the long-term risk of some cancers, particularly colorectal cancer. The result that aspirin benefit is detectable at daily low-doses (at least 75mg), the same used for the prevention of cardiovascular disease, positions the antiplatelet action of aspirin at the center of its antitumor efficacy. At low-doses given every 24 h, aspirin is acting by a complete and persistent inhibition of cyclooxygenase (COX)-1 in platelets (in the pre-systemic circulation) while causing a limited and rapidly reversible inhibitory effect on COX-2 and/or COX-1 expressed in nucleated cells. Aspirin has a short half-life in human circulation (approximately 20 min); nucleated cells have the ability to resynthesize the acetylated COX-isozymes within a few hours, while platelets do not. COX-independent mechanisms of aspirin, such as the inhibition of Wnt/ β-catenin and NF-kB signaling and the acetylation of extra-COX proteins, have been suggested to play a role in its chemo-preventive effects, but their relevance remains to be demonstrated in vivo at clinical doses. In conclusion, the results of clinical pharmacology and the analysis of randomized and epidemiological studies suggest that colorectal cancer and atherothrombosis share a common mechanism of disease, i.e. enhanced platelet activation in response to injury at distinct sites.

Influence of Adrenergic Receptor Blockade on Aspirin-induced Inhibition of Platelet Function

Studies from our laboratory have demonstrated that epinephrine via alpha(2)-adrenoreceptor modulation can restore the sensitivity of aspirin-treated platelets to the action of agonists independent of secretion of granule contents or synthesis of prostanoids. The present study has evaluated the effects of full strength aspirin (take on alternate days) and low dose aspirin (taken daily) and sought to determine whether agents which antagonise alpha or beta adrenergic receptors can prevent the corrective influence of epinephrine on aspirin-treated platelets. Adult volunteers were given 325 mg aspirin every other day or 80 mg aspirin daily. After confirming the inhibitory effect of aspirin, these individuals were given yohimbine (5 mg), atenolol (100 mg), verapamil (160 mg) or ethanol (white wine 8 oz). Two hours later, blood was drawn for platelet studies. Cells exposed to aspirin did not aggregate when stirred with arachidonate (0.45 mM) or epinephrine (5 M) alone. Addition of epinephrine to aspirin treated platelets restored the sensitivity to the action of arachidonate and resulted in irreversible aggregation. Ethanol and verapamil at the concentrations tested did not potentiate the action of aspirin. Ingestion of yohimbine, an alpha(2)-adrenergic antagonist, or atenolol, a beta blocker, prevented the corrective influence of epinephrine on aspirin-treated refractory platelets. Results suggest that alpha and beta blockers may serve a useful role in reinforcing the antithrombotic influence of aspirin in vivo.

Primary and secondary prevention of cardiovascular disease in diabetes with aspirin

Diabetes is associated with an increased cardiovascular risk. The role for aspirin in diabetes is of high clinical interest. Guidelines recommend that primary prevention of cardiovascular disease (CVD) in diabetes with aspirin should be based on the individual risk for CVD. New mechanistic studies suggest that enhanced platelet turnover may partly contribute to the fact the primary prevention studies found unequivocal results in diabetes. There is initial evidence that a potential future modification of dosages in diabetes may counteract the enhancement in platelet turnover in diabetes. The use of aspirin in diabetic patients for secondary prevention of CVD is supported by key evidence. The aim of the review is to present recent studies on aspirin for prevention of CVD in diabetes and to highlight its role also in view of new mechanistic and clinical studies with aspirin. Novel aspects of aspirin, e.g. its potential role for the prevention of cancer, are also presented.

Acetylsalicylic acid for primary prevention of cardiovascular diseases in older patients with diabetes: do the benefits overcome the risks?

Cardiovascular diseases (CVDs) represent a huge health burden for older patients with diabetes. Acetylsalicylic acid (ASA) has long been used as a cardioprotective agent in primary and secondary prevention of CVD. However, there are important issues regarding the benefits and risks of ASA therapy in primary prevention of CVDs, for the older group in general and for individuals of all ages with diabetes. In this review, we summarize the benefits and risks related to ASA therapy by outlining the evidence for older patients and for patients with diabetes. There appear to be significant gaps in knowledge. The balance of benefits and risks is not well defined but ASA treatment seems to be unfavorable in many older patients.

Aspirin for primary prevention of cardiovascular disease events

Aspirin has been used for the prevention and treatment of cardiovascular disease (CVD) for several decades. The efficacy of aspirin for secondary prevention of cardiovascular disease is well established, but the clinical benefit of aspirin for primary prevention of CVD is less clear. The primary literature suggests that aspirin may provide a reduction in CVD events, but the absolute benefit is small and accompanied by an increase in bleeding. For aspirin to be beneficial for an individual patient, the risk of a future CVD event must be large enough to outweigh the risk of bleeding. The estimation of CVD risk is multifaceted and can involve numerous risk scores and assessments of concomitant comorbidities that confer additional CVD risk. Numerous guidelines provide recommendations for the use of aspirin for primary prevention, but they often contradict one another despite being based on the same clinical trials. Additional literature suggests that the presence of comorbidities that increase CVD risk, such as diabetes mellitus, asymptomatic peripheral arterial disease, or chronic kidney disease, does not ensure that aspirin therapy will be beneficial. Ongoing clinical trials may provide additional insight, but until more data are available, an individualized assessment of CVD risk with careful evaluation of risk and benefit should be performed before recommending aspirin therapy for primary prevention of CVD.

Aspirin for primary prevention of cardiovascular events in the elderly: current status and future directions

The role of aspirin in the secondary prevention of occlusive cardiovascular events has now been well established. Given this, aspirin in primary prevention has been the focus of several large trials and subsequent meta-analyses over the past 3 decades, and yet the issue remains controversial. Recent studies in populations with high baseline risk - such as diabetics and those with asymptomatic peripheral arterial disease - have not found the expected benefits of aspirin on cardiovascular endpoints, which contrasts with earlier studies that reported a reduced relative risk for outcomes such as myocardial infarction and ischaemic stroke, but not for mortality. Furthermore, in healthy populations, the absolute risk reduction conferred by aspirin is small and needs to be balanced against the risk of a major haemorrhage. Older adults have a higher risk for cardiovascular events and therefore might represent the group in which aspirin for primary prevention could deliver the greatest absolute benefit, yet at the same time, the elderly bear an increased vulnerability to major haemorrhage, including haemorrhagic stroke. It is also not known whether older adults experience the same risk reduction from aspirin as middle-aged individuals. The current evidence base does not sufficiently clarify whether aspirin for primary prevention confers a meaningful net benefit in the elderly.

[Primary prevention with aspirin]

The benefit of acetylsalicylic acid and other antiplatelet drugs in secondary prevention is well established, however it use in primary prevention continues to be controversial. On the one hand, the benefit obtained is very near the potential damage arising from its use (mainly gastrointestinal bleeding), and on the other, the net benefit is less, given that its aim is to prevent the occurrence of vascular events in situations with a lower baseline risk. Antiplatelet treatment with aspirin in primary prevention has been evaluated in clinical trials and several meta-analyses, comparing its efficacy with a placebo, and with results noted for their heterogeneity. The mechanisms of action of different antiplatelet drugs, as well as the existing evidence with aspirin in primary prevention, the directions for its use by different Scientific Societies, and the cost/benefit of the intervention are reviewed.