Cost-effectiveness of aspirin treatment in the primary prevention of cardiovascular disease events in subgroups based on age, gender, and varying cardiovascular risk

Individual and population benefits of daily aspirin therapy: a proposal for personalizing national guidelines

BACKGROUND

Clinical practice guidelines that help clinicians and patients to understand the magnitude of expected individual risks and benefits would help with patient-centered decision-making and prioritization of care. We assessed the net benefit from taking daily aspirin to estimate the individual and public health implications of a more individualized decision-making approach.

METHODS AND RESULTS

We used data from the National Health and Nutrition Examination Survey representing all US persons aged 30 to 85 years with no history of myocardial infarction and applied a Markov model based on randomized evidence and published literature to estimate lifetime effects of aspirin treatment in quality-adjusted life years (QALYs). We found that treatment benefit varies greatly by an individual's cardiovascular disease (CVD) risk. Almost all adults have fewer major clinical events on aspirin, but for most, events prevented would be so rare that even a very small distaste for aspirin use would make treatment inappropriate. With minimal dislike of aspirin use (disutility, 0.005 QALY per year), only those with a 10-year cardiac event risk >6.1% would have a net benefit. A disutility of 0.01 QALY moves this benefit cut point to 10.6%. Multiple factors altered the absolute benefit of aspirin, but the strong relationship between CVD risk and magnitude of benefit was robust.

CONCLUSIONS

The benefits of aspirin therapy depend substantially on an individual's risk of CVD and adverse treatment effects. Understanding who benefits from aspirin use and how much can help clinicians and patients to develop a more patient-centered approach to preventive therapy.

Cost-utility of aspirin and proton pump inhibitors for primary prevention

BACKGROUND

Aspirin reduces myocardial infarction but increases gastrointestinal tract (GI) bleeding. Proton pump inhibitors (PPIs) may reduce upper GI bleeding. We estimate the cost-utility of aspirin treatment with or without a PPI for coronary heart disease (CHD) prevention among men at different risks for CHD and GI bleeding.

METHODS

We updated a Markov model to compare costs and outcomes of low-dose aspirin plus PPI (omeprazole, 20 mg/d), low-dose aspirin alone, or no treatment for CHD prevention. We performed lifetime analyses in men with different risks for cardiovascular events and GI bleeding. Aspirin reduced nonfatal myocardial infarction by 30%, increased total stroke by 6%, and increased GI bleeding risk 2-fold. Adding a PPI reduced upper GI bleeding by 80%. Annual aspirin cost was $13.99; the generic PPI cost was $200.00.

RESULTS

In 45-year-old men with a 10-year CHD risk of 10% and 0.8 per 1000 annual GI bleeding risk, aspirin ($17,571 and 18.67 quality-adjusted life-years [QALYs]) was more effective and less costly than no treatment ($18,483 and 18.44 QALYs). Compared with aspirin alone, aspirin plus PPI ($21,037 and 18.68 QALYs) had an incremental cost per QALY of $447,077. Results were similar in 55- and 65-year-old men. The incremental cost per QALY of adding a PPI was less than $50,000 per QALY at annual GI bleeding probabilities greater than 4 to 6 per 1000.

CONCLUSIONS

Treatment with aspirin for CHD prevention is less costly and more effective than no treatment in men older than 45 years with greater than 10-year, 10% CHD risks. Adding a PPI is not cost-effective for men with average GI bleeding risk but may be cost-effective for selected men at increased risk for GI bleeding.

Effect of daily aspirin on long-term risk of death due to cancer: analysis of individual patient data from randomised trials

BACKGROUND

Treatment with daily aspirin for 5 years or longer reduces subsequent risk of colorectal cancer. Several lines of evidence suggest that aspirin might also reduce risk of other cancers, particularly of the gastrointestinal tract, but proof in man is lacking. We studied deaths due to cancer during and after randomised trials of daily aspirin versus control done originally for prevention of vascular events.

METHODS

We used individual patient data from all randomised trials of daily aspirin versus no aspirin with mean duration of scheduled trial treatment of 4 years or longer to determine the effect of allocation to aspirin on risk of cancer death in relation to scheduled duration of trial treatment for gastrointestinal and non-gastrointestinal cancers. In three large UK trials, long-term post-trial follow-up of individual patients was obtained from death certificates and cancer registries.

RESULTS

In eight eligible trials (25 570 patients, 674 cancer deaths), allocation to aspirin reduced death due to cancer (pooled odds ratio [OR] 0·79, 95% CI 0·68-0·92, p=0·003). On analysis of individual patient data, which were available from seven trials (23 535 patients, 657 cancer deaths), benefit was apparent only after 5 years' follow-up (all cancers, hazard ratio [HR] 0·66, 0·50-0·87; gastrointestinal cancers, 0·46, 0·27-0·77; both p=0·003). The 20-year risk of cancer death (1634 deaths in 12 659 patients in three trials) remained lower in the aspirin groups than in the control groups (all solid cancers, HR 0·80, 0·72-0·88, p<0·0001; gastrointestinal cancers, 0·65, 0·54-0·78, p<0·0001), and benefit increased (interaction p=0·01) with scheduled duration of trial treatment (≥7·5 years: all solid cancers, 0·69, 0·54-0·88, p=0·003; gastrointestinal cancers, 0·41, 0·26-0·66, p=0·0001). The latent period before an effect on deaths was about 5 years for oesophageal, pancreatic, brain, and lung cancer, but was more delayed for stomach, colorectal, and prostate cancer. For lung and oesophageal cancer, benefit was confined to adenocarcinomas, and the overall effect on 20-year risk of cancer death was greatest for adenocarcinomas (HR 0·66, 0·56-0·77, p<0·0001). Benefit was unrelated to aspirin dose (75 mg upwards), sex, or smoking, but increased with age-the absolute reduction in 20-year risk of cancer death reaching 7·08% (2·42-11·74) at age 65 years and older.

INTERPRETATION

Daily aspirin reduced deaths due to several common cancers during and after the trials. Benefit increased with duration of treatment and was consistent across the different study populations. These findings have implications for guidelines on use of aspirin and for understanding of carcinogenesis and its susceptibility to drug intervention.

FUNDING

None.

Comparison of the racial/ethnic prevalence of regular aspirin use for the primary prevention of coronary heart disease from the multi-ethnic study of atherosclerosis

In 2002, the United States Preventive Services Task Force and the American Heart Association recommended aspirin for the primary prevention of coronary heart disease in patients with Framingham risk scores ≥ 6% and ≥ 10%, respectively. The regular use of aspirin (≥ 3 days/week) was examined in a cohort of 6,452 White, Black, Hispanic, and Chinese patients without cardiovascular disease in 2000 to 2002 and 5,181 patients from the same cohort in 2005 to 2007. Framingham risk scores were stratified into low (<6%), increased (6% to 9.9%), and high (≥ 10%) risk. In 2000 to 2002 prevalences of aspirin use were 18% and 27% for those at increased and high risk, respectively. Whites (25%) used aspirin more than Blacks (14%), Hispanics (12%), or Chinese (14%) in the increased-risk group (p <0.001). Corresponding prevalences for the high-risk group were 38%, 25%, 17%, and 21%, respectively (p <0.001). In 2005 to 2007 prevalences of aspirin use were 31% and 44% for those at increased and high risk, respectively. Whites (41%) used aspirin more than Blacks (27%), Hispanics (24%), or Chinese (15%) in the increased-risk group (p <0.001). Corresponding prevalences for the high-risk group were 53%, 43%, 38%, and 28%, respectively (p <0.001). Racial/ethnic differences persisted after adjustment for age, gender, diabetes, income, and education. In conclusion, regular aspirin use in adults at increased and high risk for coronary heart disease remains suboptimal. Important racial/ethnic disparities exist for unclear reasons.

Long-term effect of aspirin on colorectal cancer incidence and mortality: 20-year follow-up of five randomised trials

BACKGROUND

High-dose aspirin (≥500 mg daily) reduces long-term incidence of colorectal cancer, but adverse effects might limit its potential for long-term prevention. The long-term effectiveness of lower doses (75-300 mg daily) is unknown. We assessed the effects of aspirin on incidence and mortality due to colorectal cancer in relation to dose, duration of treatment, and site of tumour.

METHODS

We followed up four randomised trials of aspirin versus control in primary (Thrombosis Prevention Trial, British Doctors Aspirin Trial) and secondary (Swedish Aspirin Low Dose Trial, UK-TIA Aspirin Trial) prevention of vascular events and one trial of different doses of aspirin (Dutch TIA Aspirin Trial) and established the effect of aspirin on risk of colorectal cancer over 20 years during and after the trials by analysis of pooled individual patient data.

RESULTS

In the four trials of aspirin versus control (mean duration of scheduled treatment 6·0 years), 391 (2·8%) of 14 033 patients had colorectal cancer during a median follow-up of 18·3 years. Allocation to aspirin reduced the 20-year risk of colon cancer (incidence hazard ratio [HR] 0·76, 0·60-0·96, p=0·02; mortality HR 0·65, 0·48-0·88, p=0·005), but not rectal cancer (0·90, 0·63-1·30, p=0·58; 0·80, 0·50-1·28, p=0·35). Where subsite data were available, aspirin reduced risk of cancer of the proximal colon (0·45, 0·28-0·74, p=0·001; 0·34, 0·18-0·66, p=0·001), but not the distal colon (1·10, 0·73-1·64, p=0·66; 1·21, 0·66-2·24, p=0·54; for incidence difference p=0·04, for mortality difference p=0·01). However, benefit increased with scheduled duration of treatment, such that allocation to aspirin of 5 years or longer reduced risk of proximal colon cancer by about 70% (0·35, 0·20-0·63; 0·24, 0·11-0·52; both p<0·0001) and also reduced risk of rectal cancer (0·58, 0·36-0·92, p=0·02; 0·47, 0·26-0·87, p=0·01). There was no increase in benefit at doses of aspirin greater than 75 mg daily, with an absolute reduction of 1·76% (0·61-2·91; p=0·001) in 20-year risk of any fatal colorectal cancer after 5-years scheduled treatment with 75-300 mg daily. However, risk of fatal colorectal cancer was higher on 30 mg versus 283 mg daily on long-term follow-up of the Dutch TIA trial (odds ratio 2·02, 0·70-6·05, p=0·15).

INTERPRETATION

Aspirin taken for several years at doses of at least 75 mg daily reduced long-term incidence and mortality due to colorectal cancer. Benefit was greatest for cancers of the proximal colon, which are not otherwise prevented effectively by screening with sigmoidoscopy or colonoscopy.

FUNDING

None.

Aspirin for primary prevention of cardiovascular disease in diabetes mellitus

Aspirin is effective for the prevention of cardiovascular events in patients with a history of vascular disease, as so-called secondary prevention. In general populations with no history of previous myocardial infarction or stroke, aspirin also seems useful for primary prevention of cardiovascular events, although the absolute benefits are smaller than those seen in patients with previous cardiovascular disease. Patients with diabetes mellitus are at an increased risk of cardiovascular events, but new trials have raised questions about the benefit of aspirin for primary prevention in patients with this disorder. This Review comprehensively examines the basic pharmacology of aspirin and provides an overview of the randomized, controlled trials of aspirin therapy that have included patients with diabetes mellitus. On the basis of currently available evidence from primary prevention trials, aspirin is estimated to reduce the relative risk of myocardial infarction and stroke by about 10% in patients with diabetes mellitus; however, aspirin also increases the risk of gastrointestinal bleeding. As such, low-dose aspirin therapy (75-162 mg) is reasonable for patients with diabetes mellitus and a 10-year risk of cardiovascular events >10%. Results from upcoming large trials will help clarify the effects of aspirin with greater precision, including whether the benefits differ between men and women.

Potential economic impact of increasing low dose aspirin usage on CVD in the US

BACKGROUND

Cardiovascular disease (CVD) is a leading cause of death in the US and Western Europe, but regular use of preventive low-dose aspirin has proven effective in preventing CVD events. The purpose of this study was to explore the potential economic impact in the US if preventive aspirin usage were to be increased in line with clinical guidelines for primary and secondary prevention.

METHODS

The risk profile of the US population was characterized using NHANES data, and Framingham cardiovascular risk equations were applied to calculate risk for myocardial infarction, angina and ischemic stroke according to age and gender. Primary and secondary patients were considered separately. Using publicly available unit costs, a budget impact model calculated the annual impact of increased preventive aspirin usage considering gastrointestinal bleeding and hemorrhagic stroke adverse events and diminishing aspirin adherence over a 10-year time horizon.

RESULTS

In a base population of 1,000,000 patients, full implementation of clinical guidelines would potentially prevent an additional 1273 myocardial infarctions, 2184 angina episodes and 565 ischemic strokes in primary prevention patients and an additional 578 myocardial infarctions, and 607 ischemic strokes in secondary prevention patients. This represents a total savings of $79.6 million for primary prevention and $32.2 million for secondary and additional out-of-pocket expense to patients of $29.0 million for primary prevention and $2.6 million for secondary prevention for the cost of aspirin.

CONCLUSIONS

This budgetary model suggests that there is a strong economic case, both for payers and society, to encourage aspirin use for patients at appropriate risk and per clinical guidelines. It also provides an example of how minimizing costs do not necessarily have to imply a rationing of care. Limitations include the exclusion of other CVD interventions in the analysis.

Lipid-lowering therapy for the primary prevention of cardiovascular disease in the elderly: opportunities and challenges

Although HMG-CoA reductase inhibitors (statins) have been shown to reduce the risk of cardiovascular events in patients aged 65-80 years who have clinical cardiovascular disease, fewer data are available for elderly patients without cardiovascular disease. Treatment guidelines recommend a low-density lipoprotein cholesterol goal of <100 mg/dL for those with cardiovascular disease or diabetes mellitus but vary in their recommendations for primary prevention. Moderate-dose statins have been shown to be effective and safe in properly selected elderly patients up to the age of 80 years. High-dose statins have also been shown to be effective and reasonably safe in patients without significant co-morbidities up to the age of 75 years. With advancing age, the potential for benefit from cholesterol-lowering treatment needs to be weighed against the increasing risk of muscle and hepatic toxicity, as well as competing causes of morbidity and mortality.

A review of international pharmacoeconomic models assessing the use of aspirin in primary prevention

PURPOSE

The aim of this narrative review was to summarise the cost analyses and supporting trial data for aspirin prophylaxis in primary prevention.

METHODS

A PubMed search using the term 'aspirin and cost-effective and primary prevention' was performed. Professional meetings (2009) were also searched for any relevant abstracts contacting the terms 'aspirin' and 'cost effectiveness'. Where possible, outcomes were discussed in terms of cost implications (expressed as quality-adjusted life-year [QALY], disability-adjusted life-year or incremental cost-effectiveness ratio) in relation to the annual risk of cardiovascular disease. Aspirin was included in cost-effectiveness models that determined direct cost savings.

RESULTS

A total of 67 papers were identified using PubMed, and 17 cost-effectiveness studies, which assessed aspirin in primary prevention (largely based on the key primary prevention studies), and two abstracts were included in the review. These analyses showed that low-dose aspirin was cost effective in a variety of scenarios. In the UK, Germany, Spain, Italy and Japan, the mean 10-year direct cost saving (including follow-up costs and aspirin costs) per patient was €201, €281, €797, €427 and €889 with aspirin use in patients with an annual coronary heart disease risk of 1.5%. Cost-effectiveness analyses were affected by age, risk level for stroke and myocardial infarction (MI), risk of bleeds and adherence to aspirin. Underutilisation is a major limiting factor, as the appropriate use of aspirin in an eligible population (n=301,658) based on the NHANES database would prevent 1273 MIs, 2184 angina episodes and 565 ischaemic strokes in patients without previous events; this would result in a direct cost saving of $79.6 million (€54.7 million; 2010 values), which includes aspirin costs.

CONCLUSIONS

Most analyses in primary prevention have shown that low-dose aspirin is a cost-effective option, and is likely to meet the willingness of a healthcare system to pay for any additional QALY gained in the majority of healthcare systems.

Prevention and management of stroke in very elderly patients

As the average human lifespan extends and medical care improves, there are more individuals above the age of 80 years who have a high quality of life. However, these very elderly individuals are particularly susceptible to stroke. Identifying ways to optimise the treatment and prevention of acute stroke in these much older people will increasingly be a priority for health-care providers, research funding agencies, and policy makers in years to come. Despite substantial advances in stroke research, with several therapeutic drugs being able to enhance clinical outcomes in people with stroke or who are at risk of stroke, the very elderly seem to receive fewer vascular protection interventions that have been shown to be effective in younger individuals. Although there has been an under-representation of the very elderly in studies of stroke therapy, these treatments might be of benefit to this group of patients. Indeed, emerging data indicate that the use of several of these therapies in routine clinical practice in the very elderly can be effective.

The German Coronary Artery Disease Risk Screening Model: development, validation, and application of a decision-analytic model for coronary artery disease prevention with statins

BACKGROUND

Coronary artery disease (CAD) is a major cause of death in industrial countries, leading to high health-related costs and decreased quality of life.

OBJECTIVE

To develop and validate a decision-analytic model for CAD risk screening in Germany (German Coronary Artery Disease Screening Model).

DESIGN

Markov model.

TARGET POPULATION

Age- and gender-specific cohorts of the German population.

DATA SOURCES

Mortality rates posted by the German Federal Statistical Office, the German Health Survey, social health insurance institutions, the MONICA Augsburg study, and the literature.

TIME HORIZON

Lifetime.

INTERVENTIONS

CAD risk screening for high-risk individuals using Framingham risk equation and use of statins as the primary preventive measure, compared with a setting without screening.

OUTCOME MEASURES

Life-years (LY) gained, quality-adjusted life-years (QALYs) gained.

RESULTS

The model-based CAD incidence corresponds well with empirical data from the MONICA Augsburg study. Health outcomes depend on the screening threshold (cutoff value of Framingham 10-year risk) and on the age and gender of the cohort screened (0.03 to 0.26 LYs and 0.06 to 0.42 QALYs gained per person screened in cohorts of 50- and 60-year-old men and women, respectively).

CONCLUSIONS

The model provides a valid tool for evaluating the long-term effectiveness of CAD risk screening in Germany. Using statins as a primary prevention intervention for CAD in high-risk individuals identified by screening could improve the long-term health of the German population.

Aspirin in the primary and secondary prevention of vascular disease: collaborative meta-analysis of individual participant data from randomised trials

BACKGROUND

Low-dose aspirin is of definite and substantial net benefit for many people who already have occlusive vascular disease. We have assessed the benefits and risks in primary prevention.

METHODS

We undertook meta-analyses of serious vascular events (myocardial infarction, stroke, or vascular death) and major bleeds in six primary prevention trials (95,000 individuals at low average risk, 660,000 person-years, 3554 serious vascular events) and 16 secondary prevention trials (17,000 individuals at high average risk, 43,000 person-years, 3306 serious vascular events) that compared long-term aspirin versus control. We report intention-to-treat analyses of first events during the scheduled treatment period.

FINDINGS

In the primary prevention trials, aspirin allocation yielded a 12% proportional reduction in serious vascular events (0.51% aspirin vs 0.57% control per year, p=0.0001), due mainly to a reduction of about a fifth in non-fatal myocardial infarction (0.18%vs 0.23% per year, p<0.0001). The net effect on stroke was not significant (0.20%vs 0.21% per year, p=0.4: haemorrhagic stroke 0.04%vs 0.03%, p=0.05; other stroke 0.16%vs 0.18% per year, p=0.08). Vascular mortality did not differ significantly (0.19%vs 0.19% per year, p=0.7). Aspirin allocation increased major gastrointestinal and extracranial bleeds (0.10%vs 0.07% per year, p<0.0001), and the main risk factors for coronary disease were also risk factors for bleeding. In the secondary prevention trials, aspirin allocation yielded a greater absolute reduction in serious vascular events (6.7%vs 8.2% per year, p<0.0001), with a non-significant increase in haemorrhagic stroke but reductions of about a fifth in total stroke (2.08%vs 2.54% per year, p=0.002) and in coronary events (4.3%vs 5.3% per year, p<0.0001). In both primary and secondary prevention trials, the proportional reductions in the aggregate of all serious vascular events seemed similar for men and women.

INTERPRETATION

In primary prevention without previous disease, aspirin is of uncertain net value as the reduction in occlusive events needs to be weighed against any increase in major bleeds. Further trials are in progress.

FUNDING

UK Medical Research Council, British Heart Foundation, Cancer Research UK, and the European Community Biomed Programme.

Cardiovascular prevention in clinical practice (ESC and German guidelines 2007)

Preventive efforts should be guided by the patient's global cardiovascular (CV) risk. A risk stratification should be done in every person > age 35 with more than a single risk factor. Recommendations for improved lifestyle are applicable to all persons with CV risk factors: smoking cessation, daily exercise, normal body mass index, Mediterranean diet, blood pressure < 140 mmHg systolic, and LDL cholesterol < 130 mg/dl are beneficial. If the 10-year risk is > or = 20% for CV events or > or = 5% for CV death, additional drug interventions are usually necessary: acetylsalicylic acid 100 mg daily, statins to lower LDL cholesterol to < 100 mg/dl or, in diabetics with coronary artery disease, to < 70 mg/dl, blood pressure should be < 130 mmHg systolic, e.g., in patients with diabetes or renal disease. After bare-metal stent implantation clopidogrel should be given for > or = 4 weeks and after drug-eluting stents for > or = 6 months. In patients after myocardial infarction with an ejection fraction of < 40%, ACE inhibitors and beta-blocker should be started. Influenza vaccination improves prognosis in high-risk patients.