Aspirin for primary prevention of cardiovascular events

The implications of competing risks and direct treatment disutility in cardiovascular disease and osteoporotic fracture: risk prediction and cost effectiveness analysis

Background

Clinical guidelines commonly recommend preventative treatments for people above a risk threshold. Therefore, decision-makers must have faith in risk prediction tools and model-based cost-effectiveness analyses for people at different levels of risk. Two problems that arise are inadequate handling of competing risks of death and failing to account for direct treatment disutility (i.e. the hassle of taking treatments). We explored these issues using two case studies: primary prevention of cardiovascular disease using statins and osteoporotic fracture using bisphosphonates.

Objectives

Externally validate three risk prediction tools [QRISK®3, QRISK®-Lifetime, QFracture-2012 (ClinRisk Ltd, Leeds, UK)]; derive and internally validate new risk prediction tools for cardiovascular disease [competing mortality risk model with Charlson Comorbidity Index (CRISK-CCI)] and fracture (CFracture), accounting for competing-cause death; quantify direct treatment disutility for statins and bisphosphonates; and examine the effect of competing risks and direct treatment disutility on the cost-effectiveness of preventative treatments.

Design, participants, main outcome measures, data sources

Discrimination and calibration of risk prediction models (Clinical Practice Research Datalink participants: aged 25-84 years for cardiovascular disease and aged 30-99 years for fractures); direct treatment disutility was elicited in online stated-preference surveys (people with/people without experience of statins/bisphosphonates); costs and quality-adjusted life-years were determined from decision-analytic modelling (updated models used in National Institute for Health and Care Excellence decision-making).

Results

CRISK-CCI has excellent discrimination, similar to that of QRISK3 (Harrell's c = 0.864 vs. 0.865, respectively, for women; and 0.819 vs. 0.834, respectively, for men). CRISK-CCI has systematically better calibration, although both models overpredict in high-risk subgroups. People recommended for treatment (10-year risk of ≥ 10%) are younger when using QRISK-Lifetime than when using QRISK3, and have fewer observed events in a 10-year follow-up (4.0% vs. 11.9%, respectively, for women; and 4.3% vs. 10.8%, respectively, for men). QFracture-2012 underpredicts fractures, owing to under-ascertainment of events in its derivation. However, there is major overprediction among people aged 85-99 years and/or with multiple long-term conditions. CFracture is better calibrated, although it also overpredicts among older people. In a time trade-off exercise (n = 879), statins exhibited direct treatment disutility of 0.034; for bisphosphonates, it was greater, at 0.067. Inconvenience also influenced preferences in best-worst scaling (n = 631). Updated cost-effectiveness analysis generates more quality-adjusted life-years among people with below-average cardiovascular risk and fewer among people with above-average risk. If people experience disutility when taking statins, the cardiovascular risk threshold at which benefits outweigh harms rises with age (≥ 8% 10-year risk at 40 years of age; ≥ 38% 10-year risk at 80 years of age). Assuming that everyone experiences population-average direct treatment disutility with oral bisphosphonates, treatment is net harmful at all levels of risk.

Limitations

Treating data as missing at random is a strong assumption in risk prediction model derivation. Disentangling the effect of statins from secular trends in cardiovascular disease in the previous two decades is challenging. Validating lifetime risk prediction is impossible without using very historical data. Respondents to our stated-preference survey may not be representative of the population. There is no consensus on which direct treatment disutilities should be used for cost-effectiveness analyses. Not all the inputs to the cost-effectiveness models could be updated.

Conclusions

Ignoring competing mortality in risk prediction overestimates the risk of cardiovascular events and fracture, especially among older people and those with multimorbidity. Adjustment for competing risk does not meaningfully alter cost-effectiveness of these preventative interventions, but direct treatment disutility is measurable and has the potential to alter the balance of benefits and harms. We argue that this is best addressed in individual-level shared decision-making.

Study registration

This study is registered as PROSPERO CRD42021249959.

Funding

This award was funded by the National Institute for Health and Care Research (NIHR) Health and Social Care Delivery Research programme (NIHR award ref: 15/12/22) and is published in full in Health and Social Care Delivery Research; Vol. 12, No. 4. See the NIHR Funding and Awards website for further award information.

Quantifying the impact of taking medicines for primary prevention: a time-trade off study to elicit direct treatment disutility in the UK

BACKGROUND

Direct treatment disutility (DTD) represents an individual's disutility associated with the inconvenience of taking medicine over a long period of time.

OBJECTIVES

The main aim of this study was to elicit DTD values for taking a statin or a bisphosphonate for primary prevention. A secondary aim was to understand factors which influence DTD values.

METHODS

Design: We used a cross-sectional study consisting of time-trade off exercises embedded within online surveys. Respondents were asked to compare a one-off pill ('Medicine A') assumed to have no inconvenience and a daily pill ('Medicine B') over 10 years (statins) or 5 years (bisphosphonates).Setting: Individuals from National Health Service (NHS) primary care and the general population were surveyed using an online panel company.Participants: Two types of participants were recruited. First, a purposive sample of patients with experience of taking a statin (n=260) or bisphosphonate (n=100) were recruited from an NHS sampling frame. Patients needed to be aged over 30, have experience of taking the medicine of interest and have no diagnosis of dementia or of using dementia drugs. Second, a demographically balanced sample of members of the public were recruited for statins (n=376) and bisphosphonates (n=359).Primary and secondary outcome measures: Primary outcome was mean DTD. Regression analysis explored factors which could influence DTD values.

RESULTS

A total of 879 respondents were included for analysis (514 for statins and 365 for bisphosphonates). The majority of respondents reported a disutility associated with medicine use. Mean DTD for statins was 0.034 and for bisphosphonates 0.067, respectively. Respondent characteristics including age and sex did not influence DTD. Experience of bisphosphonate-use reduced reported disutilities.

CONCLUSIONS

Statins and bisphosphonates have a quantifiable DTD. The size of estimated disutilities suggest they are likely to be important for cost-effectiveness, particularly in individuals at low-risk when treated for primary prevention.

Bleeding risk in patients prescribed dual antiplatelet therapy and triple therapy after coronary interventions: the ADAPTT retrospective population-based cohort studies

Background

Bleeding among populations undergoing percutaneous coronary intervention or coronary artery bypass grafting and among conservatively managed patients with acute coronary syndrome exposed to different dual antiplatelet therapy and triple therapy (i.e. dual antiplatelet therapy plus an anticoagulant) has not been previously quantified.

Objectives

The objectives were to estimate hazard ratios for bleeding for different antiplatelet and triple therapy regimens, estimate resources and the associated costs of treating bleeding events, and to extend existing economic models of the cost-effectiveness of dual antiplatelet therapy.

Design

The study was designed as three retrospective population-based cohort studies emulating target randomised controlled trials.

Setting

The study was set in primary and secondary care in England from 2010 to 2017.

Participants

Participants were patients aged ≥ 18 years undergoing coronary artery bypass grafting or emergency percutaneous coronary intervention (for acute coronary syndrome), or conservatively managed patients with acute coronary syndrome.

Data sources

Data were sourced from linked Clinical Practice Research Datalink and Hospital Episode Statistics.

Interventions

Coronary artery bypass grafting and conservatively managed acute coronary syndrome: aspirin (reference) compared with aspirin and clopidogrel. Percutaneous coronary intervention: aspirin and clopidogrel (reference) compared with aspirin and prasugrel (ST elevation myocardial infarction only) or aspirin and ticagrelor.

Main outcome measures

Primary outcome: any bleeding events up to 12 months after the index event. Secondary outcomes: major or minor bleeding, all-cause and cardiovascular mortality, mortality from bleeding, myocardial infarction, stroke, additional coronary intervention and major adverse cardiovascular events.

Results

The incidence of any bleeding was 5% among coronary artery bypass graft patients, 10% among conservatively managed acute coronary syndrome patients and 9% among emergency percutaneous coronary intervention patients, compared with 18% among patients prescribed triple therapy. Among coronary artery bypass grafting and conservatively managed acute coronary syndrome patients, dual antiplatelet therapy, compared with aspirin, increased the hazards of any bleeding (coronary artery bypass grafting: hazard ratio 1.43, 95% confidence interval 1.21 to 1.69; conservatively-managed acute coronary syndrome: hazard ratio 1.72, 95% confidence interval 1.15 to 2.57) and major adverse cardiovascular events (coronary artery bypass grafting: hazard ratio 2.06, 95% confidence interval 1.23 to 3.46; conservatively-managed acute coronary syndrome: hazard ratio 1.57, 95% confidence interval 1.38 to 1.78). Among emergency percutaneous coronary intervention patients, dual antiplatelet therapy with ticagrelor, compared with dual antiplatelet therapy with clopidogrel, increased the hazard of any bleeding (hazard ratio 1.47, 95% confidence interval 1.19 to 1.82), but did not reduce the incidence of major adverse cardiovascular events (hazard ratio 1.06, 95% confidence interval 0.89 to 1.27). Among ST elevation myocardial infarction percutaneous coronary intervention patients, dual antiplatelet therapy with prasugrel, compared with dual antiplatelet therapy with clopidogrel, increased the hazard of any bleeding (hazard ratio 1.48, 95% confidence interval 1.02 to 2.12), but did not reduce the incidence of major adverse cardiovascular events (hazard ratio 1.10, 95% confidence interval 0.80 to 1.51). Health-care costs in the first year did not differ between dual antiplatelet therapy with clopidogrel and aspirin monotherapy among either coronary artery bypass grafting patients (mean difference £94, 95% confidence interval -£155 to £763) or conservatively managed acute coronary syndrome patients (mean difference £610, 95% confidence interval -£626 to £1516), but among emergency percutaneous coronary intervention patients were higher for those receiving dual antiplatelet therapy with ticagrelor than for those receiving dual antiplatelet therapy with clopidogrel, although for only patients on concurrent proton pump inhibitors (mean difference £1145, 95% confidence interval £269 to £2195).

Conclusions

This study suggests that more potent dual antiplatelet therapy may increase the risk of bleeding without reducing the incidence of major adverse cardiovascular events. These results should be carefully considered by clinicians and decision-makers alongside randomised controlled trial evidence when making recommendations about dual antiplatelet therapy.

Limitations

The estimates for bleeding and major adverse cardiovascular events may be biased from unmeasured confounding and the exclusion of an eligible subgroup of patients who could not be assigned an intervention. Because of these limitations, a formal cost-effectiveness analysis could not be conducted.

Future work

Future work should explore the feasibility of using other UK data sets of routinely collected data, less susceptible to bias, to estimate the benefit and harm of antiplatelet interventions.

Trial registration

This trial is registered as ISRCTN76607611.

Funding

This project was funded by the National Institute for Health and Care Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 27, No. 8. See the NIHR Journals Library website for further project information.

Stroke of antiplatelet and anticoagulant therapy in patients with coronary artery disease: a meta-analysis of randomized controlled trials

BACKGROUND

We performed a meta-analysis sought to investigate the risk of stroke with antiplatelet and anticoagulant therapies among patients with coronary artery disease (CAD).

METHODS

We searched PubMed, EMBASE, and Cochrane Library for randomized controlled trials from January 1995 to March 2020. Studies were retrieved if they reported data of stroke for patients with CAD and were randomized to receive intensive versus conservative antithrombotic therapies, including antiplatelet and oral anticoagulant (OAC). Analyses were pooled by random-effects modeling. A total of 42 studies with 301,547subjects were enrolled in this analysis.

RESULTS

Intensive antithrombotic therapy significantly reduced risk of all stroke (RR 0.86, 95% CI 0.80-0.94) and ischemic stroke (RR 0.80, 95% CI 0.71-0.91), but increased risk of hemorrhagic stroke (RR 1.36, 95% CI 1.00-1.86) and intracranial hemorrhage (RR 1.46, 95% CI 1.17-1.81). Subgroup analyses indicated that OAC yields more benefit to all stroke than antiplatelet therapy (OAC: RR 0.73, 95% CI 0.58-0.92; Antiplatelet: RR 0.90, 95% CI 0.83-0.97; Between-group heterogeneity P value = 0.030). The benefit of antiplatelet therapy on all stroke and ischemic stroke were mainly driven by the studies comparing longer versus shorter duration of dual antiplatelet therapy (All stroke: RR 0.86, 95% CI 0.78-0.95; ischemic stroke: RR 0.84, 95% CI 0.75-0.94).

CONCLUSIONS

Among CAD patients who have already received antiplatelet therapy, either strengthening antiplatelet or anticoagulant treatments significantly reduced all stroke, mainly due to the reduction of ischemic stroke, although it increased the risk of hemorrhagic stroke and intracranial hemorrhage. OAC yields more benefit to all stroke than antiplatelet therapy.

Weighing the potential late benefits versus early hazard associated with bioresorbable vascular scaffolds in percutaneous coronary interventions: a Markov decision analytic model

OBJECTIVE

Use of poly-L-lactic acid-based bioresorbable scaffolds (BRS) has been associated with increased risk of device thrombosis during the first 3 years after implantation as compared to metallic everolimus-eluting stents (EES). The long-term performance of BRS relative to EES remains unknown.

METHODS

We used a Markov decision analysis model to evaluate the effectiveness of BRS vs. EES over a lifetime horizon. In addition to one-way sensitivity analyses of key variables, we evaluated the impact of optimal implantation technique and limiting procedures to larger vessels (>2.6 mm in diameter) on model results.

RESULTS

Assuming no risk of target lesion revascularization for BRS after 3 years, we found a small increment in quality-adjusted life expectancy (QALE) of 0.02 with the use of BRS relative to EES, with benefit being observed after 21.8 years. Optimal implantation technique and limiting to larger vessels resulted in larger gains in QALE (0.08 and 0.06, respectively) with BRS and shorter times to equipoise (6.7 and 8.3 years, respectively). Model results were highly sensitive to variations in the relative risk of stent thrombosis (BRS vs. EES).

CONCLUSIONS

Based on currently available data, it would take approximately 21.8 years for the presumed late benefits of current BRS relative to EES to overcome the early hazard associated with their use under favorable assumptions. Optimal implantation technique and limiting procedures to larger vessels improved BRS performance and reduced time to equipoise. Eliminating the higher BRS thrombosis risk is necessary in developing future generations of BRS as an acceptable alternative to EES.

Cost-effectiveness analysis of short-duration dual antiplatelet therapy with newer drug-eluting stent platforms versus longer-duration dual antiplatelet therapy with a second-generation drug-eluting stent in elective percutaneous coronary intervention

BACKGROUND

The cost-effectiveness of newer drug-eluting stents (DES) such as biodegradable-polymer or polymer-free stents with shorter dual antiplatelet therapy (DAPT) duration is unknown. We evaluated the cost-effectiveness of treatment with newer DES that may allow for shorter DAPT duration.

PATIENTS AND METHODS

We performed a cost-effectiveness analysis of treatment with newer DES platforms followed by 1 or 3 months of DAPT compared with standard second-generation DES followed by 6 or 12 months of DAPT in patients with stable coronary disease. A Markov model simulated distinct health states over a lifetime. Probabilistic sensitivity analysis and one-way sensitivity analyses were performed. A high-risk bleeding scenario was also evaluated.

RESULTS

Among patients with typical bleeding risk, second-generation DES and 6 months of DAPT was less expensive and resulted in marginally higher quality-adjusted life years compared with other strategies. A newer DES platform and 3 months of DAPT was preferred when the risk of fatal bleeding was two times greater than baseline, or when bleeding increased long-term mortality by a factor of 1.5. In a probabilistic sensitivity analysis, second-generation DES and 6 months of DAPT was preferred in 58% of iterations, whereas in a high-risk bleeding patient scenario, a newer DES and 3 months of DAPT was preferred in 52% of iterations.

CONCLUSION

A DES that allows 3 months of DAPT without increasing stent-related events is likely to be cost-effective among patients at elevated risk of bleeding, but not in patients with average bleeding risk.

Universal versus platelet reactivity assay-driven use of P2Y12 inhibitors in acute coronary syndrome patients

Platelet reactivity assays (PRAs) can predict patients’ likely response to clopidogrel. As ticagrelor and prasugrel are typically considered first-line agents for acute coronary syndrome in Europe, we assessed the cost-effectiveness of universal compared to PRA-driven selection of these agents. A Markov model was used to calculate five-year costs (2013£/€), quality-adjusted life-years and incremental cost-effectiveness ratios (ICERs) for one-year of universal ticagrelor or prasugrel (given to all) compared to each agents’ corresponding PRA-driven strategy (ticagrelor/prasugrel in those with high platelet reactivity [HPR, >208 on the VerifyNow P2Y12 assay], others given generic clopidogrel). We assumed patients had their index event at 65–70 years of age and had a 42.7% incidence of HPR 24–48 hours post-revascularisation. The analysis was conducted from the perspective of six countries (France, Germany, Italy, Spain, the Netherlands and United Kingdom) and used a one-year cycle length. Event data for P2Y12 inhibitors were taken from multinational randomised trials and adjusted using country-specific epidemiologic data. Neither universal ticagrelor nor prasugrel were found to be cost-effective (all ICERs >40,250€ or £36,600/QALY) compared to their corresponding PRA-driven strategies in any of the countries evaluated. Results were sensitive to differences in P2Y12 Inhibitors costs and drug-specific relative risks of major adverse cardiac events. Monte Carlo simulation suggested universal ticagrelor or prasugrel were cost-effective in only 25–44% and 11–17% of 10,000 iterations compared to their respective PRA-driven strategies, when applying a willingness-to-pay threshold = €30,000 or £20,000/QALY. In conclusion, the universal use of newer P2Y12 inhibitors is not likely cost-effective compared to PRA-driven strategies.

Better guidelines for better care: accounting for multimorbidity in clinical guidelines – structured examination of exemplar guidelines and health economic modelling

Background

Multimorbidity is common but most clinical guidelines focus on single diseases.

Aim

To test the feasibility of new approaches to developing single-disease guidelines to better account for multimorbidity.

Design

Literature-based and economic modelling project focused on areas where multimorbidity makes guideline application problematic.

Methods

(1) Examination of accounting for multimorbidity in three exemplar National Institute for Health and Care Excellence guidelines (type 2 diabetes, depression, heart failure); (2) examination of the applicability of evidence in multimorbidity for the exemplar conditions; (3) exploration of methods for comparing absolute benefit of treatment; (4) incorporation of treatment pay-off time and competing risk of death in an exemplar economic model for long-term preventative treatments with slowly accruing benefit; and (5) development of a discrete event simulation model-based cost-effectiveness analysis for people with both depression and coronary heart disease.

Results

(1) Comorbidity was rarely accounted for in the clinical research questions that framed the development of the exemplar guidelines, and was rarely accounted for in treatment recommendations. Drug–disease interactions were common only for comorbid chronic kidney disease, but potentially serious drug–drug interactions between recommended drugs were common and rarely accounted for in guidelines. (2) For all three conditions, the trials underpinning treatment recommendations largely excluded older, more comorbid and more coprescribed patients. The implications of low applicability varied by condition, with type 2 diabetes having large differences in comorbidity, whereas potentially serious drug–drug interactions were more important for depression. (3) Comparing absolute benefit of treatments for different conditions was shown to be technically feasible, but only if guideline developers are willing to make a number of significant assumptions. (4) The lifetime absolute benefit of statins for primary prevention is highly sensitive to the presence of both the direct treatment disutility of taking a daily tablet and competing risk of death. (5) It was feasible to use a discrete event simulation-based model to represent the relevant care pathways to estimate the relative cost-effectiveness of pharmacological treatments of major depressive disorder in primary care for patients who are also likely to go on and receive treatment for coronary heart disease but the analysis was reliant on eliciting some parameter values from experts, which increases the inherent uncertainty in the results. The key limitation was that real-life use in guideline development was not examined.

Conclusions

Guideline developers could feasibly (1) use epidemiological data characterising the guideline population to inform consideration of applicability and interactions; (2) systematically compare the absolute benefit of long-term preventative treatments to inform decision-making in people with multimorbidity and high treatment burden; and (3) modify the output from economic models used in guideline development to examine time to benefit in terms of the pay-off time and varying competing risk of death from other conditions.

Future work

Further research is needed to optimise presentation of comparative absolute benefit information to clinicians and patients, to evaluate the use of epidemiological and time-to-benefit data in guideline development, to better quantify direct treatment disutility and to better quantify benefit and harm in people with multimorbidity.

Funding

The National Institute for Health Research Health Services and Delivery Research programme.

Cost-Effectiveness of a Statewide Campaign to Promote Aspirin Use for Primary Prevention of Cardiovascular Disease

BACKGROUND

The U.S. Preventive Services Task Force in 2009 recommended increased aspirin use for primary prevention of cardiovascular disease (CVD) in men ages 45 to 79 years and women ages 55 to 79 years for whom benefit outweighs risk. This study estimated the clinical efficacy and cost-effectiveness of a statewide public and health professional awareness campaign to increase regular aspirin use among the target population in Minnesota to reduce first CVD events.

METHODS AND RESULTS

A state-transition Markov model was developed, adopting a payer perspective and lifetime time horizon. The main outcomes of interest were quality-adjusted life years, costs, and the number of CVD events averted among those without a prior CVD history. The model was based on real-world data about campaign effectiveness from representative state-specific aspirin use and event rates, and estimates from the scholarly literature. Implementation of a campaign was predicted to avert 9874 primary myocardial infarctions in men and 1223 primary ischemic strokes in women in the target population. Increased aspirin use was associated with as many as 7222 more major gastrointestinal bleeding episodes. The cost-effectiveness analysis indicated cost-saving results for both the male and female target populations.

CONCLUSIONS

Using current U.S. Preventive Services Task Force recommendations, a state public and health professional awareness campaign would likely provide clinical benefit and be economically attractive. With clinician adjudication of individual benefit and risk, mechanisms can be made available that would facilitate achievement of aspirin's beneficial impact on lowering risk of primary CVD events, with minimization of adverse outcomes.

Quantifying the utility of taking pills for preventing adverse health outcomes: a cross-sectional survey

OBJECTIVES

The utility value attributed to taking pills for prevention can have a major effect on the cost-effectiveness of interventions, but few published studies have systematically quantified this value. We sought to quantify the utility value of taking pills used for prevention of cardiovascular disease (CVD).

DESIGN

Cross-sectional survey.

SETTING

Central North Carolina.

PARTICIPANTS

708 healthcare employees aged 18 years and older.

PRIMARY AND SECONDARY OUTCOMES

Utility values for taking 1 pill/day, assessed using time trade-off, modified standard gamble and willingness-to-pay methods.

RESULTS

Mean age of respondents was 43 years (19-74). The majority of the respondents were female (83%) and Caucasian (80%). Most (80%) took at least 2 pills/day. Mean utility values for taking 1 pill/day using the time trade-off method were: 0.9972 (95% CI 0.9962 to 0.9980). Values derived from the standard gamble and willingness-to-pay methods were 0.9967 (0.9954 to 0.9979) and 0.9989 (95% CI 0.9986 to 0.9991), respectively. Utility values varied little across characteristics such as age, sex, race, education level or number of pills taken per day.

CONCLUSIONS

The utility value of taking pills daily in order to prevent an adverse CVD health outcome is approximately 0.997.

Balancing the risks of bleeding and stent thrombosis: a decision analytic model to compare durations of dual antiplatelet therapy after drug-eluting stents

BACKGROUND

After coronary stent placement, whether dual antiplatelet therapy (DAPT) duration should be extended to prevent late stent thrombosis (ST) or adverse cardiovascular events is uncertain.

METHODS

To define the reduction in ischemic events required to outweigh increased bleeding with longer-duration DAPT, we developed a decision-analytic Markov model comparing DAPT durations of 6, 12, and 30 months after DES. Separate models were developed for patients presenting with and without an acute coronary syndrome (ACS). We used sensitivity analyses to identify the incremental benefit of longer-duration DAPT on either ST or the composite of cardiac death, myocardial infarction, and ischemic stroke (major adverse cardiovascular and cerebrovascular events [MACCEs]) required to outweigh the increased risk of bleeding associated with longer DAPT. The outcome from each strategy was quantified in terms of quality-adjusted life years.

RESULTS

In the non-ACS population, in order for 30 months of DAPT to be preferred over 12 months of therapy, DAPT would have to result in a 78% reduction in the risk of ST (relative risk [RR] 0.22, 3.1 fewer events per 1000) and only a 5% reduction in MACCE (RR 0.95, 2.2 fewer events per 1000) as compared with aspirin alone. For the ACS population, DAPT would have to result in a 44% reduction in the risk of ST (RR 0.56, 3.4 fewer events per 1000) but only a 2% reduction in MACCE (RR 0.98, 2.3 fewer events per 1000) as compared with aspirin alone, for 30 months of DAPT to be preferred for 12 months.

CONCLUSIONS

Small absolute differences in the risk of ischemic events with longer DAPT would be sufficient to outweigh the known bleeding risks.

Effect of patients' risks and preferences on health gains with plasma glucose level lowering in type 2 diabetes mellitus

IMPORTANCE

Type 2 diabetes mellitus is common, and treatment to correct blood glucose levels is standard. However, treatment burden starts years before treatment benefits accrue. Because guidelines often ignore treatment burden, many patients with diabetes may be overtreated.

OBJECTIVE

To examine how treatment burden affects the benefits of intensive vs moderate glycemic control in patients with type 2 diabetes.

DESIGN, SETTING, AND PARTICIPANTS

We estimated the effects of hemoglobin A1c (HbA1c) reduction on diabetes outcomes and overall quality-adjusted life years (QALYs) using a Markov simulation model. Model probabilities were based on estimates from randomized trials and observational studies. Simulated patients were based on adult patients with type 2 diabetes drawn from the National Health and Nutrition Examination Study.

INTERVENTIONS

Glucose lowering with oral agents or insulin in type 2 diabetes.

MAIN OUTCOMES AND MEASURES

Main outcomes were QALYs and reduction in risk of microvascular and cardiovascular diabetes complications.

RESULTS

Assuming a low treatment burden (0.001, or 0.4 lost days per year), treatment that lowered HbA1c level by 1 percentage point provided benefits ranging from 0.77 to 0.91 QALYs for simulated patients who received a diagnosis at age 45 years to 0.08 to 0.10 QALYs for those who received a diagnosis at age 75 years. An increase in treatment burden (0.01, or 3.7 days lost per year) resulted in HbA1c level lowering being associated with more harm than benefit in those aged 75 years. Across all ages, patients who viewed treatment as more burdensome (0.025-0.05 disutility) experienced a net loss in QALYs from treatments to lower HbA1c level.

CONCLUSIONS AND RELEVANCE

Improving glycemic control can provide substantial benefits, especially for younger patients; however, for most patients older than 50 years with an HbA1c level less than 9% receiving metformin therapy, additional glycemic treatment usually offers at most modest benefits. Furthermore, the magnitude of benefit is sensitive to patients' views of the treatment burden, and even small treatment adverse effects result in net harm in older patients. The current approach of broadly advocating intensive glycemic control should be reconsidered; instead, treating patients with HbA1c levels less than 9% should be individualized on the basis of estimates of benefit weighed against the patient's views of the burdens of treatment.

Effect of including cancer mortality on the cost-effectiveness of aspirin for primary prevention in men

BACKGROUND

Recent data suggest that aspirin may be effective for reducing cancer mortality.

OBJECTIVE

To examine whether including a cancer mortality-reducing effect influences which men would benefit from aspirin for primary prevention.

DESIGN

We modified our existing Markov model that examines the effects of aspirin among middle-aged men with no previous history of cardiovascular disease or diabetes. For our base case scenario of 45-year-old men, we examined costs and life-years for men taking aspirin for 10 years compared with men who were not taking aspirin over those 10 years; after 10 years, we equalized treatment and followed the cohort until death. We compared our results depending on whether or not we included a 22 % relative reduction in cancer mortality, based on a recent meta-analysis. We discounted costs and benefits at 3 % and employed a third party payer perspective.

MAIN MEASURE

Cost per quality-adjusted life year (QALY) gained.

KEY RESULTS

When no effect on cancer mortality was included, aspirin had a cost per QALY gained of $22,492 at 5 % 10-year coronary heart disease (CHD) risk; at 2.5 % risk or below, no treatment was favored. When we included a reduction in cancer mortality, aspirin became cost-effective for men at 2.5 % risk as well (cost per QALY, $43,342). Results were somewhat sensitive to utility of taking aspirin daily; risk of death after myocardial infarction; and effects of aspirin on stroke, myocardial infarction, and sudden death. However, aspirin remained cost-saving or cost-effective (< $50,000 per QALY) in probabilistic analyses (59 % with no cancer effect included; 96 % with cancer effect) for men at 5 % risk.

CONCLUSIONS

Including an effect of aspirin on cancer mortality influences the threshold for prescribing aspirin for primary prevention in men. If such an effect is real, many middle-aged men at low cardiovascular risk would become candidates for regular aspirin use.

Cost-effectiveness of universal and platelet reactivity assay-driven antiplatelet therapy in acute coronary syndrome

Assays monitoring P2Y12 platelet reactivity can accurately predict which patients will have a poor response to clopidogrel. We sought to determine the cost-effectiveness of using platelet reactivity assays (PRAs) to select a dual-antiplatelet regimen for patients with acute coronary syndrome. A hybrid decision tree Markov model was developed to determine the cost-effectiveness of universal clopidogrel, ticagrelor, or prasugrel (given to all patients) or PRA-driven ticagrelor or prasugrel (given to patients with high platelet reactivity, defined as >230 on the VerifyNow P2Y12 assay; the others received generic clopidogrel). We assumed a cohort of 65-year-old patients with acute coronary syndrome and an incidence of high platelet reactivity of 32% and 13% at ~24 to 48 hours after revascularization and 1 month, respectively. The 5-year costs, quality-adjusted life-years, and incremental cost-effectiveness ratios were calculated for PRA-driven ticagrelor and prasugrel compared with universal clopidogrel, ticagrelor, or prasugrel. PRA-driven ticagrelor and prasugrel were cost-effective compared with universal clopidogrel (incremental cost-effectiveness ratio $40,100 and $49,143/quality-adjusted life-year, respectively); however, universal ticagrelor and prasugrel were not (incremental cost-effectiveness ratio $61,651 and $96,261/quality-adjusted life-year, respectively). Monte Carlo simulation suggested PRA-driven ticagrelor, PRA-driven prasugrel, universal ticagrelor, and universal prasugrel would have an incremental cost-effectiveness ratio <$50,000/quality-adjusted life-year in 52%, 40%, 23%, and 2% of the iterations compared with universal clopidogrel, respectively. Universal ticagrelor and prasugrel were not cost-effective compared with their respective PRA-driven regimens (incremental cost-effectiveness ratio $68,182; $116,875/quality-adjusted life-year, respectively). Monte Carlo simulation suggested universal ticagrelor and prasugrel would have an incremental cost-effectiveness ratio <$50,000/quality-adjusted life-year in 26% and 4% of iterations compared with their respective PRA-driven regimens. The results were most sensitive to differences in agent costs and drug-specific relative risks of death. In conclusion, even with generic clopidogrel, PRA-driven selection of antiplatelet therapy appeared to be a cost-effective strategy with the potential to decrease the overall acute coronary syndrome-associated healthcare costs.

Ticagrelor versus genotype-driven antiplatelet therapy for secondary prevention after acute coronary syndrome: a cost-effectiveness analysis

BACKGROUND

Clopidogrel's effectiveness is likely reduced significantly for prevention of thrombotic events after acute coronary syndrome (ACS) in patients exhibiting a decreased ability to metabolize clopidogrel into its active form. A genetic mutation responsible for this reduced effectiveness is detectable by genotyping. Ticagrelor is not dependent on gene-based metabolic activation and demonstrated greater clinical efficacy than clopidogrel in a recent secondary prevention trial. In 2011, clopidogrel will lose its patent protection and likely will be substantially less expensive than ticagrelor.

OBJECTIVE

To determine the cost-effectiveness of ticagrelor compared with a genotype-driven selection of antiplatelet agents.

METHODS

A hybrid decision tree/Markov model was used to estimate the 5-year medical costs (in 2009 US$) and outcomes for a cohort of ACS patients enrolled in Medicare receiving either genotype-driven or ticagrelor-only treatment. Outcomes included life years and quality-adjusted life years (QALYs) gained. Data comparing the clinical performance of ticagrelor and clopidogrel were derived from the Platelet Inhibition and Patient Outcomes trial.

RESULTS

The incremental cost-effectiveness ratio (ICER) for universal ticagrelor was $10,059 per QALY compared to genotype-driven treatment, and was most sensitive to the price of ticagrelor and the hazard ratio for death for ticagrelor compared with clopidogrel. The ICER remained below $50,000 per QALY until a monthly ticagrelor price of $693 or a 0.93 hazard ratio for death for ticagrelor relative to clopidogrel. In probabilistic analyses, universal ticagrelor was below $50,000 per QALY in 97.7% of simulations.

CONCLUSION

Prescribing ticagrelor universally increases quality-adjusted life years for ACS patients at a cost below a typically accepted threshold.

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.

Cost-effectiveness of aspirin use among persons with newly diagnosed type 2 diabetes

OBJECTIVE

To assess the long-term cost-effectiveness of aspirin use among adults aged >or=40 years with newly diagnosed type 2 diabetes.

RESEARCH DESIGN AND METHODS

We used a validated cost-effectiveness model of type 2 diabetes to assess the lifetime health and cost consequences of use or nonuse of aspirin. The model simulates the progression of diabetes and accompanying complications for a cohort of subjects with type 2 diabetes. The model predicts the outcomes of type 2 diabetes along five disease paths (nephropathy, neuropathy, retinopathy, coronary heart disease, and stroke) from the time of diagnosis until age 94 years or until death.

RESULTS

Over a lifetime, aspirin users gained 0.31 life-years (LY) or 0.19 quality-adjusted LYs (QALYs) over nonaspirin users, at an incremental cost of $1,700; the incremental cost-effectiveness ratio (ICER) of aspirin use was $5,428 per LY gained or $8,801 per QALY gained. In probabilistic sensitivity analyses, the ICER was <$30,000 per QALY in all of 2,000 realizations in two scenarios.

CONCLUSIONS

Regular use of aspirin among people with newly diagnosed diabetes is cost-effective.

Aspirin for the primary prevention of adverse cardiovascular events

There is consideration controversy regarding the use of aspirin for the prophylaxis of certain cardiovascular conditions, such as coronary thrombosis and stroke. An exploration of current literature suggests that the decision to adopt a routine aspirin regimen must follow a careful analysis of potential risks as well as benefits. Nurses share a vital role in patient education related to aspirin regimens, to guard against potential complications of low-dose aspirin therapy, including gastrointestinal bleeding and stroke.

Use of Antiplatelet Agents for Primary and Secondary Prevention of Cardiovascular Disease Amongst Type 2 Diabetic Patients

Background. A retrospective observational study was conducted to study the use of antiplatelet agents for primary and secondary prevention of cardiovascular disease among hospitalized type 2 diabetes mellitus patients.

Method. A total of 355 patients were included in the study. The compliance with the American Diabetes Association recommendation on the use of antiplatelet therapy for prevention of cardiovascular disease was studied.

Results. For the primary prevention group, type 2 diabetes mellitus, patients with known dyslipidemia were more likely to receive antiplatelet therapy than those without dyslipidemia (P = 0.023). The rate of adherence to the American Diabetes Association recommendations on the use of antiplatelet therapy for secondary prevention of cardiovascular disease was higher than for primary prevention of cardiovascular disease (P = 0.001).

Conclusion. In conclusion, many of the eligible patients still do not receive antiplatelet therapy, particularly in primary prevention of cardiovascular disease. Measures should be taken to ensure that type 2 diabetes mellitus patients receive the antiplatelet therapy and hence prevent macrovascular complications.

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

BACKGROUND

Aspirin is effective for the primary prevention of cardiovascular events, but it remains unclear for which subgroups of individuals aspirin is beneficial. We assessed the cost-effectiveness of aspirin separately for men and women of different ages with various levels of cardiovascular disease risk.

METHODS AND RESULTS

A Markov model was developed to predict the number of cardiovascular events prevented, quality-adjusted life-years, and costs over a 10-year period. Event rates were taken from Dutch population data, and the relative effectiveness of aspirin was taken from a gender-specific meta-analysis. Sensitivity analyses and Monte Carlo simulations were conducted to evaluate the robustness of the results. In 55-year-old persons, aspirin prevented myocardial infarctions in men (127 events per 100,000 person-years) and ischemic strokes in women (17 events per 100,000 person-years). Aspirin implies a net investment and a quality-adjusted life-year gain in men 55 years of age; the incremental cost-effectiveness ratio was 111,949 euros per quality-adjusted life-year (1 euro=$1.27 as of June 2007). Aspirin was cost-effective for 55- and 65-year-old men with moderate cardiovascular risk and men 75 years of age (10-year cardiovascular disease risk >10%). Conversely, aspirin was beneficial for women 65 years of age with high cardiovascular risk and women 75 years of age with moderate cardiovascular risk (10-year cardiovascular disease risk >15%). Results were sensitive to drug treatment costs, effectiveness of aspirin treatment, and utility of taking aspirin.

CONCLUSIONS

Aspirin treatment for primary prevention is cost-effective for men with a 10-year cardiovascular disease risk of >10% and for women with a risk of >15%. This occurs much later in life for women than men. Therefore, opportunities for the primary prevention of aspirin seem limited in women, and a differentiated preventive strategy seems warranted.

Cardioprotective aspirin users and their excess risk of upper gastrointestinal complications

BACKGROUND

To balance the cardiovascular benefits from low-dose aspirin against the gastrointestinal harm caused, studies have considered the coronary heart disease risk for each individual but not their gastrointestinal risk profile. We characterized the gastrointestinal risk profile of low-dose aspirin users in real clinical practice, and estimated the excess risk of upper gastrointestinal complications attributable to aspirin among patients with different gastrointestinal risk profiles.

METHODS

To characterize aspirin users in terms of major gastrointestinal risk factors (i.e., advanced age, male sex, prior ulcer history and use of non-steroidal anti-inflammatory drugs), we used The General Practice Research Database in the United Kingdom and the Base de Datos para la Investigación Farmacoepidemiológica en Atención Primaria in Spain. To estimate the baseline risk of upper gastrointestinal complications according to major gastrointestinal risk factors and the excess risk attributable to aspirin within levels of these factors, we used previously published meta-analyses on both absolute and relative risks of upper gastrointestinal complications.

RESULTS

Over 60% of aspirin users are above 60 years of age, 4 to 6% have a recent history of peptic ulcers and over 13% use other non-steroidal anti-inflammatory drugs. The estimated average excess risk of upper gastrointestinal complications attributable to aspirin is around 5 extra cases per 1,000 aspirin users per year. However, the excess risk varies in parallel to the underlying gastrointestinal risk and might be above 10 extra cases per 1,000 person-years in over 10% of aspirin users.

CONCLUSION

In addition to the cardiovascular risk, the underlying gastrointestinal risk factors have to be considered when balancing harms and benefits of aspirin use for an individual patient. The gastrointestinal harms may offset the cardiovascular benefits in certain groups of patients where the gastrointestinal risk is high and the cardiovascular risk is low.

Management of high-risk patients on non-steroidal anti-inflammatory drugs or aspirin

Low-dose aspirin is increasingly used for the primary prevention of cardiovascular events. However, current evidence suggests that the gastrointestinal and other bleeding risks of aspirin probably outweigh its potential benefits in primary prevention. Various strategies have been proposed to reduce the gastrointestinal risk of aspirin, including gastroprotection with a proton pump inhibitor (PPI), eradication of Helicobacter pylori infection and replacing aspirin with other anti-platelet agents. Although co-therapy with a PPI and the eradication of H. pylori substantially reduce the risk of recurrent ulcer bleeding with aspirin, the replacement of aspirin by clopidogrel cannot be recommended to patients with a high gastrointestinal risk. Traditionally, strategies for the prevention of non-steroidal anti-inflammatory drug (NSAID)-induced ulcer complications included co-therapy with a gastroprotective agent and the substitution of cyclooxygenase (COX)-2 inhibitors for non-selective NSAID. Evidence emerged recently that COX-2 inhibitors and some non-selective NSAID increase cardiovascular risk. Before prescribing anti-inflammatory therapy, both gastrointestinal and cardiovascular risk factors of individual patients need to be evaluated. In patients with increased cardiovascular risk requiring anti-inflammatory analgesics, the combination of a non-selective NSAID, low-dose aspirin and a PPI is the preferred treatment.

Prevention of cardiovascular disease in patients with rheumatic diseases

Cardiovascular disease (CVD), the leading cause of death in the USA, has emerged as an important comorbidity in the rheumatic diseases. As disease-modifying therapies have resulted in better disease control and decreases in disease-associated mortality, it is now apparent that the prevalence of CVD and cardiovascular (CV) events is significantly increased in a number of rheumatic disorders when compared with age and gender-matched subjects from the general population. Investigations into the mechanisms of CVD in the general population have provided insights into potential mechanisms in rheumatic disease patients and possible aetiologies for their increased risk. Although there are no evidence-based guidelines for CV risk factor screening and interventions specific to patients with rheumatic disease, the best current approach utilizes evidence-based recommendations for the general population (and higher-risk subgroups) modified by what is known of CV risk factor and event prevalence in these patients.

Analysis of Aspirin-Associated Risks in Healthy Individuals

BACKGROUND:

Aspirin therapy is widely accepted for patients with documented cardiovascular disease, but there is a growing trend among healthy individuals to use aspirin as primary prevention for both cardiovascular disease and cancer.

OBJECTIVE:

To determine the impact of the complications of aspirin therapy on quality-adjusted life-years (QALYs) in healthy individuals.

METHODS:

A computer-based decision-analytic model was constructed. In this model, healthy individuals taking aspirin were assumed to receive no advantages from the aspirin, but were at risk of developing its associated complications. Individuals took 325 mg of enteric-coated aspirin every day until death, discontinuing therapy only if an aspirin-induced complication occurred. The analysis was performed from a societal perspective, starting at age 50 years. Extensive sensitivity analyses were performed.

RESULTS:

In the absence of any beneficial effect, aspirin reduced QALYs by 0.03 per individual. Unadjusted life expectancy was decreased by 0.04 years (2 wk). Lifetime aspirin use cost an average of $460/healthy person. The total complication rate over a lifetime of aspirin therapy was 6.79%, with a mortality rate of 0.18%. Alternatively stated, there was one complication for every 15 individuals treated and one death for every 556 individuals treated. Extensive sensitivity analysis showed the range of results possible when varying age, gender, length of follow-up, and other key parameters.

CONCLUSIONS:

Assuming no benefits, aspirin therapy in healthy individuals leads to a small reduction in QALYs at an overall low cost per person. However, approximately 1 in 15 individuals will experience an aspirin-induced complication and 1 in 556 individuals will die.

The cost-effectiveness of aspirin versus cyclooxygenase-2-selective inhibitors for colorectal carcinoma chemoprevention in healthy individuals

BACKGROUND

Aspirin therapy is accepted widely for secondary prevention in patients with documented cardiovascular disease, but there is a growing trend among healthy individuals to use aspirin as primary chemoprevention for both cardiovascular and oncologic diseases. Accruing evidence suggests that cyclooxygenase-2-selective inhibitors (coxibs) may be effective for colorectal carcinoma (CRC) chemoprevention but would not provide the primary cardiac benefit of aspirin.

METHODS

A computer-based Markov model simulated hypothetical cohorts of healthy men age 50 years who took either 325 mg of enteric-coated aspirin daily or celecoxib at a dose of 400 mg twice a day. Patients in both cohorts could develop drug-related complications that would lead to its discontinuation. The aspirin group also was modeled to have a decreased rate of coronary ischemic events; however, decreased CRC mortality was not modeled in either group based on the assumption that the two treatments were effective equally in this regard. Data sources included published literature and the Centers for Medicare and Medicaid Services. Endpoints used to compare the two strategies included quality-adjusted life years (QALYs), mortality and complication rates, and cost. The analysis was from a societal perspective with a time horizon of 10 years from age 50 years. Extensive sensitivity analyses were performed.

RESULTS

Aspirin therapy resulted in 0.03 more QALYs and cost $23,000 less than coxib therapy over a 10-year period. Compared with the aspirin group, the coxib group had 3.877% more complications and 0.17% more deaths. Alternatively stated, coxib therapy resulted in 1 patient complication or death for every 26 or 588 patients treated with coxibs, respectively.

CONCLUSIONS

Assuming equal efficacy in CRC prevention over a 10-year period, aspirin was both more effective and less costly than coxib therapy when used for primary chemoprevention of CRC.

Cost-effectiveness of aspirin chemoprevention for Barrett's esophagus

BACKGROUND

Recent data suggest that nonsteroidal anti-inflammatory drugs, including aspirin, may prevent the progression of Barrett's esophagus to adenocarcinoma. However, use of aspirin is associated with numerous potential complications, including gastrointestinal bleeding and hemorrhagic strokes. We used a modeling approach to determine and compare the effectiveness and cost-effectiveness of aspirin with and without endoscopic surveillance to prevent esophageal adenocarcinoma.

METHODS

A Markov Monte Carlo decision model was constructed to compare four strategies for management of Barrett's esophagus: aspirin therapy, endoscopic surveillance with biopsies, both, or neither. Patients who took a daily enteric-coated aspirin were modeled to have a 50% reduction in the incidence of esophageal adenocarcinoma but could have complications related to therapy, at which point the aspirin was discontinued. Potential cardiac benefits of aspirin and its role in the chemoprevention of other cancers were not included in the analysis. The analysis was from a societal perspective from age 55 years until death. Sensitivity analyses were performed to investigate the effects of changes in model parameters on estimated costs and effectiveness outcomes across a wide range of assumptions.

RESULTS

Aspirin therapy was more effective and less costly than no therapy, resulting in 0.19 more quality-adjusted life years (QALYs). The combination of aspirin and endoscopic surveillance produced 0.27 more QALYs than no therapy at a cost of 13,400 U.S. dollars more, for an associated incremental cost-effectiveness ratio of 49,600 U.S. dollars/QALY. Aspirin use in combination with endoscopic surveillance dominated endoscopic surveillance alone, resulting in 0.06 more QALYs and 11,400 U.S. dollars less cost. The model's results were sensitive to increasing age and to decreased benefit or delay in aspirin's chemopreventive efficacy.

CONCLUSION

Using published values of parameters, regardless of whether a patient undergoes endoscopic surveillance, aspirin use in the management of Barrett's esophagus appears to be a cost-effective strategy to prevent esophageal adenocarcinoma.

Aspirin use and counseling about aspirin among patients with diabetes

OBJECTIVE

Despite being a safe, effective therapy for lowering cardiovascular risk, only 20% of diabetic patients were using aspirin in the early 1990s. This study examines current physician practices and the use of aspirin therapy by individuals with diabetes.

RESEARCH DESIGN AND METHODS

A random sample of diabetic patients receiving care in the Department of Veterans Affairs health care system were surveyed during January-March 2000. The association between aspirin counseling, aspirin use, and reported coronary vascular disease (CVD) and classical CVD risk factors were examined using logistic regression. The effect of increasing aspirin use on risk of myocardial infarction (MI) and cardiovascular mortality was demonstrated by simulation.

RESULTS

Seventy-one percent of respondents reported being counseled about aspirin use, and 66% were taking daily aspirin. Individuals with known CVD were more likely to be counseled (odds ratio [OR] 4.9, 95% CI 2.9-8.1) and to use aspirin (2.1, 1.2-3.7). The factor most strongly associated with aspirin use was having been counseled about aspirin therapy by a doctor. We estimate that for this population, increasing daily aspirin use to 90% could prevent an additional 11,000 MIs and potentially save >8,000 lives.

CONCLUSIONS

Compared with previous reports, a substantial proportion of these diabetic patients have been counseled about and use aspirin. Most clinicians recognize aspirin as an important treatment for patients with preexisting coronary disease. However, since diabetes is now considered a CVD equivalent, it is imperative that clinicians include counseling about aspirin therapy as a care priority for all their diabetic patients, as this simple intervention may prevent many cardiovascular events and deaths.

Chemoprevention of colorectal cancer by aspirin: a cost-effectiveness analysis

BACKGROUND & AIMS

The aim of the study is to compare the cost-effectiveness of aspirin and colonoscopy in the prevention of colorectal cancer.

METHODS

A Markov process is used to follow a hypothetical cohort of 100,000 subjects aged 50 years until death. Four strategies are compared: (1) no intervention, (2) colonoscopy once per 10 years and every 3 years in subjects with polyps, (3) chemoprevention with 325 mg of daily aspirin, and (4) combination of the second and third strategies. The various strategies are compared calculating incremental cost-effectiveness ratios (ICERs).

RESULTS

The expected number of colorectal cancers is 5904 per 100,000 subjects. Colonoscopy prevents 4428 colorectal cancers and saves 7951 life-years at an ICER of $10,983 per life-year saved compared with no intervention. Aspirin prevents 2952 colorectal cancers and saves 5301 life-years at an ICER of $47,249 per life-year saved compared with no intervention. The cost of aspirin therapy plus management of aspirin-related complications was reported to be $172 per year per patient. Varying the annual aspirin-related costs between $50 and $200 results in ICER changes between $4617 and $57,080, with the 2 strategies breaking even at $70. Applying aspirin chemoprevention plus colonoscopy screening concomitantly yields an ICER of $227,607 per life-year saved compared with screening colonoscopy alone.

CONCLUSION

As compared with colonoscopy once per 10 years, the use of aspirin to prevent colorectal cancer saves fewer lives at higher costs. The high complication cost and the lower efficacy of aspirin render screening colonoscopy a more cost-effective strategy to prevent colorectal cancer.

Health-related quality of life after stroke a comprehensive review

BACKGROUND AND PURPOSE

We performed a comprehensive review of all quality-of-life (QOL) estimates for stroke appearing in the peer-reviewed literature between 1985 and 2000. We examine variation in QOL weights and the rigor of methods used to assess QOL and discuss the implications for cost-utility assessment and resource allocation decisions.

METHODS

Through a systematic search, we identified 67 articles that met our inclusion criteria. A team of trained researchers read each article and followed detailed guidelines to extract QOL weights and other parameters. This effort yielded 161 QOL estimates for stroke-related health states. All estimates were measured on a 0 to 1 scale, with 0 representing the worst outcome and 1 representing the best.

RESULTS

QOL estimates range from -0.02 to 0.71 (n=67) for major stroke, from 0.12 to 0.81 (n=14) for moderate stroke, from 0.45 to 0.92 (n=38) for minor stroke, and from 0.29 to 0.903 (n=42) for general stroke. Although QOL should decrease with severity, there were many instances in which the QOL for major stroke as reported by one study exceeded the QOL for moderate stroke as reported by another. The same reversal was found for moderate and minor stroke, and it occurred even when both authors used similar assessment methods and subject populations. Authors of cost-utility and decision analyses rarely base their choice of QOL weights on their own primary data (19%). When obtaining weights from secondary sources, some authors (23%) chose QOL weights for a severity of stroke that did not match the severity for which they sought data.

CONCLUSIONS

QOL estimates for stroke vary greatly and are not always estimated in sound fashion. This impedes the comparability and quality of the cost-effectiveness studies that use these QOL weights and hampers good resource allocation decisions.

Patient preference-based treatment thresholds and recommendations: a comparison of decision-analytic modeling with the probability-tradeoff technique

BACKGROUND

Decision analysis (DA) and the probability-tradeoff technique (PTOT) are patient preference-based methods of determining optimal therapy for individuals. Using aspirin therapy for the primary prevention of stroke and myocardial infarction (MI) in elderly persons as an example, the objective of this study was to determine whether group-level treatment thresholds and individual-level treatment recommendations derived using PTOT are identical to those of DA incorporating the patients' own values.

METHODS

Persons in a pilot study of the efficacy of aspirin in the prevention of stroke and MI were asked to participate. Participant values and utilities for pertinent health states (e.g., minor and major stroke, MI, major bleeding episode) were determined. Then, in three hypothetical clinical situations in which the chance of stroke or MI was varied, PTOT was used to directly determine treatment thresholds for aspirin therapy (i.e., the smallest reduction in MI or stroke risk for which participants would be willing to take aspirin). Using DA modeling, with the same probabilities of events as in the PTOT exercise and incorporating participants' own values, treatment thresholds for the three clinical situations were determined. The thresholds determined by the two approaches were compared. Finally, based on these treatment thresholds, using the best estimates of the efficacy of aspirin to prevent first-time stroke and MI, PTOT and DA treatment recommendations for individual participants were compared.

RESULTS

The 42 participants reported that a major stroke was the least desirable health state, followed by MI, minor stroke, and major bleeding. The minimum risk reduction required to take aspirin was greater for MI prevention compared with stroke prevention. For the two clinical situations in which the hypothetical efficacy of aspirin to prevent stroke was varied, treatment thresholds for the PTOT versus DA approaches differed (p < 0.04), but this difference was not significant (p = 0.19) for the MI-based clinical situation. Using the best estimate of the efficacy of aspirin to prevent first-time stroke and MI, PTOT and DA treatment recommendations whether or not to take aspirin were discordant for 38% of participants (16 of 42) (p < 0.001).

CONCLUSIONS

Patient preference-based group-level treatment thresholds and individual-level treatment recommendations can differ significantly depending on whether PTOT or DA is used, apparently because the two emphasize different aspects of the decision-making process. DA theory assumes that effective therapeutic decision making should maximize both quality and quantity of life; with PTOT, the emphasis for effective clinical decision making allows patients to be fully engaged in the process, thus hopefully leading to fully informed decisions that may result in satisfaction and compliance.