A pharmacoeconomic evaluation of aggressive cholesterol lowering in Sweden

A systematic literature review of methods of incorporating mortality in cost-effectiveness analyses of lipid-lowering therapies

AIMS

Cost effectiveness analysis (CEA) is a useful tool for estimating the value of an intervention in relation to alternatives. In cardiovascular disease (CVD), CEA is especially important, given the high economic and clinical burden. One key driver of value is CVD mortality prevention. However, data used to inform CEA parameters can be limited, given the difficulty in demonstrating statistically significant mortality benefit in randomized clinical trials (RCTs), due in part to the frequency of fatal events and limited trial durations. This systematic review identifies and summarizes whether published CVD-related CEAs have incorporated mortality benefits, and the methodology among those that did.

MATERIALS AND METHODS

A systematic literature review was conducted of CEAs of lipid-lowering therapies published between 2000-2017. Health technology assessments (HTA) and full-length manuscripts were included, and sources of mortality data and methods of applying mortality benefits were extracted. Results were summarized as proportions of articles to articulate common practices in CEAs of CVD.

RESULTS

This review identified 100 studies for inclusion, comprising 93 full-length manuscripts and seven HTA reviews. Among these, 99% assumed a mortality benefit in the model. However, 87 of these studies that incorporated mortality differences did so despite the trials used to inform model parameters not demonstrating statistically significant differences in mortality. None of the 12 studies that used statistically significant findings from an individual RCT were based on active control studies. In a sub-group analysis considering the 60 CEAs that incorporated a direct mortality benefit, 48 (80%) did not have RCT evidence for statistically significant benefit in CVD mortality.

LIMITATIONS AND CONCLUSIONS

The finding that few CEA models included mortality inputs from individual RCTs of lipid-lowering therapy may be surprising, as one might expect that treatment efficacy should be based on robust clinical evidence. However, regulatory requirements in CVD-related RCTs often lead to insufficient sample sizes and observation periods for detecting a difference in CVD mortality, which results in the use of intermediate outcomes, composite end-points, or meta-analysis to extrapolate long-term mortality benefit in a lifetime CEA.

Projected cost-effectiveness of ezetimibe/simvastatin compared with doubling the statin dose in the United Kingdom: findings from the INFORCE study

OBJECTIVE

To evaluate the incremental cost-effectiveness ratio (ICER) of switching to ezetimibe/simvastatin (Eze/Simva) compared with doubling the submaximal statin doses, in patients with acute coronary syndrome (ACS) events in the INFORCE study.

METHODS

Lifetime treatment costs and benefits were computed using a Markov model. Model inputs included each patient's cardiovascular risk factor profile and actual lipid values at baseline and 12 weeks (endpoint). Cardiovascular event and drug costs were discounted at 3.5%. Age-specific utilities were based on UK literature values and non-coronary heart disease mortality rates on the Office of National Statistics data. In the INFORCE study, 384 patients taking statins at stable doses for ≥6 weeks before hospital admission were stratified by statin dose/potency (low, medium, and high) and then randomized to doubling the statin dose or switching to Eze/Simva 10/40mg for 12 weeks.

RESULTS

The Eze/Simva group (n=195) had a higher mean baseline total cholesterol than the double-statin group (n=189). Analyses were adjusted for baseline characteristics. In the INFORCE study, Eze/Simva reduced low-density lipoprotein cholesterol (LDL-C) by ∼30% (vs. 4% with doubling statin doses) and significantly enhanced LDL-C goal attainment. In the cost-effectiveness analysis, Eze/Simva conferred 0.218 incremental discounted quality-adjusted life year (QALY) at a discounted incremental cost of £2524, for an ICER of £11,571/QALY (95% confidence interval=£8181-£18,600/QALY). The ICER was £13,552/QALY, £11,930/QALY, and £10,148/QALY in the low-, medium-, and high-potency strata, respectively.

CONCLUSIONS

Switching to Eze/Simva 10/40 mg is projected to be a cost-effective treatment (vs. double-statin) in UK patients with ACS.

Economic evaluation of high-dose (80 mg/day) atorvastatin treatment compared with standard-dose (20 mg/day to 40 mg/day) simvastatin treatment in Canada based on the Incremental Decrease in End-Points Through Aggressive Lipid-Lowering (IDEAL) trial

BACKGROUND

The Incremental Decrease in End-Points Through Aggressive Lipid-Lowering (IDEAL) trial demonstrated incremental cardiovascular benefit of treatment with high-dose atorvastatin (80 mg/ day) versus standard-dose simvastatin (20 mg/day to 40 mg/day) in 8888 patients with a previous myocardial infarction (MI) over a median follow-up period of 4.8 years.

OBJECTIVES

To assess the cost-effectiveness of high-dose atorvastatin versus standard-dose simvastatin treatment in patients with a history of MI from a Canadian societal perspective.

METHODS

In a within-trial analysis, end point-related events, resources used and productivity losses occurring during the IDEAL trial were aggregated by treatment arm on an intention-to-treat basis to calculate the incremental cost per event avoided. Additionally, quality-adjusted survival was projected using a lifetime Markov model. Transition probabilities, workdays lost, use of study medication and cardiovascular hospitalization rates were based on IDEAL trial data. Hospitalization, study medication and productivity costs were included. Probabilistic and deterministic sensitivity analyses were performed.

RESULTS

Compared with standard-dose simvastatin, atorvastatin 80 mg led to 0.099 fewer events per patient and cost savings over 4.8 years of treatment. Over a lifetime horizon, atorvastatin 80 mg led to 0.023 qualityadjusted life years (QALYs) gained per patient at an incremental cost of $26,795/QALY gained. The incremental cost-effectiveness ratio remained below $50,000/QALY in 78% of 1000 simulations. Exclusion of indirect costs resulted in an incremental cost-effectiveness ratio of $38,834/QALY. Results were relatively sensitive to baseline age, but robust with respect to sex, baseline low-density lipoprotein cholesterol levels, diabetes status and hospitalization costs.

CONCLUSION

From a Canadian societal perspective, high-dose atorvastatin is cost-effective compared with standard-dose simvastatin in patients with a previous MI.

Statin treatment improves cerebral more than systemic endothelial dysfunction in patients with arterial hypertension

BACKGROUND

The pleiotropic effects of statins on the endothelial function are well recognized. However, the effect of statins might not be equally pronounced in the cerebral and systemic circulation. We compared cerebral and systemic endothelial function by L-arginine cerebrovascular reactivity and flow-mediated dilatation (FMD), respectively, in patients with arterial hypertension (AH) and healthy controls before and after atorvastatin treatment.

METHOD

L-arginine reactivity and FMD were measured in patients with AH (29 patients, aged 61.1 +/- 6.2 years) and 21 healthy controls. The mean arterial velocity (v(m)) in both middle cerebral arteries was measured by transcranial Doppler sonography before, during, and after a 30-min intravenous infusion of L-arginine. FMD of the brachial artery after hyperemia was determined. The measurements were repeated after 3 months of treatment with atorvastatin.

RESULTS

L-arginine reactivity and FMD were decreased in patients with AH (12.5 +/- 8.7%; 2.7 +/- 5.0 %) compared with controls (21.3 +/- 10.9%; 8.5 +/- 5.9%) (P < 0.01). After atorvastatin treatment, L-arginine reactivity and FMD improved in patients with AH (19.5 +/- 10.6%; 4.6 +/- 4.1%) compared with the controls (20.2 +/- 10.2%; 9.7 +/- 3.9%). The use of statin restored the cerebral circulation reactivity, while there was little change in the systemic circulation measured by FMD.

CONCLUSION

The decreased L-arginine reactivity and FMD were found to improve after atorvastatin treatment in patients with AH, but the results suggest that statin therapy improved cerebral more than systemic endothelial function.

Intensive statin therapy in acute coronary syndromes and stable coronary heart disease: a comparative meta-analysis of randomised controlled trials

BACKGROUND

Intensive statin therapy reduces major adverse cardiovascular events (MACE), but the effect on mortality is unclear.

OBJECTIVE

To determine whether intensive statin therapy reduces all-cause mortality compared with moderate statin therapy in patients with recent acute coronary syndromes (ACS) and stable coronary heart disease (CHD).

METHODS

Medline, Embase, the Cochrane Database, the internet, and conference proceedings from 1966 to 2006 were searched to identify relevant trials. Selection criteria were randomised allocation to intensive statin therapy (atorvastatin 80 mg/day, simvastatin 80 mg/day, or rosuvastatin 20-40 mg/day) versus moderate statin therapy, recent ACS or stable CHD at the time of randomisation, and > or =6 months of follow-up.

RESULTS

Six trials, encompassing 110 271 patient-years, were pooled. In patients with recent ACS, intensive statin therapy reduced all-cause mortality from 4.6% to 3.5% over 2.0 years (OR = 0.75, 95% CI 0.61 to 0.93). In patients with stable CHD, intensive statin therapy had no effect on all-cause mortality over 4.7 years (OR = 0.99, 95% CI 0.89 to 1.11). Overall, intensive statin therapy was associated with a reduction in MACE (OR = 0.84, 95% CI 0.77 to 0.91) and admissions to hospital for heart failure (OR = 0.72, 95% CI 0.62 to 0.83). Intensive statin therapy was also associated with an increase in hepatic transaminases >3 times normal (OR = 3.73, 95% CI 2.11 to 6.58) and a trend towards increased creatine kinase >10 times normal and/or rhabdomyolysis (OR = 1.96, 95% CI 0.50 to 7.63).

CONCLUSIONS

Compared with moderate statin therapy, intensive statin therapy reduces all-cause mortality in patients with recent ACS but not in patients with stable CHD.

Economic evaluations of cholesterol-lowering drugs: a critical and systematic review

The wide availability of economic evaluations and their increasing importance for decision making emphasises the need for economic evaluations that are methodologically sound. The aim of this review was to provide users of economic evaluations of cholesterol-lowering drugs with an insight into the quality of these evaluations. By focusing on the most relevant studies, the gap between research and policy making may be narrowed. A systematic review was conducted. All Dutch and English publications on economic evaluations of cholesterol-lowering drugs were identified by searching PubMed, the Centre for Reviews and Dissemination database (CRD), the NHS Economic Evaluation Database (NHS EED), the Health Technology Assessment database (HTA) and the Database of Abstracts of Reviews of Effects (DARE). A search strategy was set up to identify the articles to be included. The quality of these articles was assessed using Drummond's checklists. The scoring was performed by at least two reviewers. When necessary, disagreement between these reviewers was decided upon in a consensus meeting. We calculated an average quality score for the included articles. The search identified 1390 articles, of which 23 were included. Most studies measured the costs per life-year gained. The overall score per study was disappointing and varied between 2.7 and 7.7, with an average of 5.5. Most studies scored high on the measurement of costs and consequences, whereas the establishment of effectiveness left room for improvement. Only two studies included a well performed incremental analysis. This study noted an increase of quality of economic evaluations over time, suggesting the value of cost-effectiveness studies for policy decisions increases over time. In general, piggy-back evaluations tended to score higher on quality and may therefore be more valuable in decision making.

Pharmacoeconomic evaluation of the effects of atorvastatin on early recurrent ischemic events in acute coronary syndromes

An economic analysis was conducted using clinical outcomes in the MIRACL trial that evaluated high-dose atorvastatin versus placebo for 16 weeks after acute coronary syndrome. The direct cost of atorvastatin was largely offset by the associated decrease in cardiovascular events. The net incremental cost of atorvastatin treatment was 157 dollars/patient with a cost-effectiveness ratio of 4,086 dollars/event avoided.