Cost analysis of amlodipine versus enalapril in patients with coronary artery disease and normal blood pressure: findings from the CAMELOT economic substudy.
ABSTRACT To analyse 2-year hospitalization and cost data collected during a prospective, double-blind, randomized, controlled trial comparing amlodipine, enalapril and placebo in normotensive patients with coronary artery disease (CAD).
All patients who were enrolled in the CAMELOT study were included in this economic substudy. Patients with CAD and normal blood pressure were randomized to amlodipine, enalapril or placebo, and followed up for 24 months (between 1999 and 2004). Data on hospitalizations and medication use were obtained from the clinical trial. Costs were assigned from secondary sources. Total costs ($US, year 2004 values) were estimated as the sum of costs associated with cardiovascular hospitalizations, study medications and concomitant cardiovascular medications. Costs and resource use were analysed by treatment arm overall and for selected patient subgroups. Cost differences were evaluated using nonparametric bootstrap techniques.
Of 1991 patients enrolled, 663 were treated with amlodipine, 673 were treated with enalapril and 655 were treated with placebo. Significantly fewer patients were hospitalized for cardiovascular reasons in the amlodipine group (16.4%) than in the placebo group (22.7%; p < 0.01), but not compared with the enalapril group (20.1%; p = 0.09). The amlodipine group also had numerically fewer days in hospital per patient (1.1) than the enalapril (1.3) and placebo (1.5) groups. Mean 2-year per-patient costs in the amlodipine group were estimated to be $US 609 and $US 717 lower than for the placebo and enalapril groups, respectively.
These results suggest that use of amlodipine may reduce costs of care among CAD patients with normal blood pressure.
[Show abstract] [Hide abstract]
ABSTRACT: Cost-effectiveness ratios usually appear as point estimates without confidence intervals, since the numerator and denominator are both stochastic and one cannot estimate the variance of the estimator exactly. The recent literature, however, stresses the importance of presenting confidence intervals for cost-effectiveness ratios in the analysis of health care programmes. This paper compares the use of several methods to obtain confidence intervals for the cost-effectiveness of a randomized intervention to increase the use of Medicaid's Early and Periodic Screening, Diagnosis and Treatment (EPSDT) programme. Comparisons of the intervals show that methods that account for skewness in the distribution of the ratio estimator may be substantially preferable in practice to methods that assume the cost-effectiveness ratio estimator is normally distributed. We show that non-parametric bootstrap methods that are mathematically less complex but computationally more rigorous result in confidence intervals that are similar to the intervals from a parametric method that adjusts for skewness in the distribution of the ratio. The analyses also show that the modest sample sizes needed to detect statistically significant effects in a randomized trial may result in confidence intervals for estimates of cost-effectiveness that are much wider than the boundaries obtained from deterministic sensitivity analyses.Statistics in Medicine 07/1996; 15(13):1447-58. DOI:10.1002/(SICI)1097-0258(19960715)15:13<1447::AID-SIM267>3.0.CO;2-V · 2.04 Impact Factor
[Show abstract] [Hide abstract]
ABSTRACT: The effect of antihypertensive drugs on cardiovascular events in patients with coronary artery disease (CAD) and normal blood pressure remains uncertain. To compare the effects of amlodipine or enalapril vs placebo on cardiovascular events in patients with CAD. Double-blind, randomized, multicenter, 24-month trial (enrollment April 1999-April 2002) comparing amlodipine or enalapril with placebo in 1991 patients with angiographically documented CAD (>20% stenosis by coronary angiography) and diastolic blood pressure <100 mm Hg. A substudy of 274 patients measured atherosclerosis progression by intravascular ultrasound (IVUS). Patients were randomized to receive amlodipine, 10 mg; enalapril, 20 mg; or placebo. IVUS was performed at baseline and study completion. The primary efficacy parameter was incidence of cardiovascular events for amlodipine vs placebo. Other outcomes included comparisons of amlodipine vs enalapril and enalapril vs placebo. Events included cardiovascular death, nonfatal myocardial infarction, resuscitated cardiac arrest, coronary revascularization, hospitalization for angina pectoris, hospitalization for congestive heart failure, fatal or nonfatal stroke or transient ischemic attack, and new diagnosis of peripheral vascular disease. The IVUS end point was change in percent atheroma volume. Baseline blood pressure averaged 129/78 mm Hg for all patients; it increased by 0.7/0.6 mm Hg in the placebo group and decreased by 4.8/2.5 mm Hg and 4.9/2.4 mm Hg in the amlodipine and enalapril groups, respectively (P<.001 for both vs placebo). Cardiovascular events occurred in 151 (23.1%) placebo-treated patients, in 110 (16.6%) amlodipine-treated patients (hazard ratio [HR], 0.69; 95% CI, 0.54-0.88 [P = .003]), and in 136 (20.2%) enalapril-treated patients (HR, 0.85; 95% CI, 0.67-1.07 [P = .16]. Primary end point comparison for enalapril vs amlodipine was not significant (HR, 0.81; 95% CI, 0.63-1.04 [P = .10]). The IVUS substudy showed a trend toward less progression of atherosclerosis in the amlodipine group vs placebo (P = .12), with significantly less progression in the subgroup with systolic blood pressures greater than the mean (P = .02). Compared with baseline, IVUS showed progression in the placebo group (P<.001), a trend toward progression in the enalapril group (P = .08), and no progression in the amlodipine group (P = .31). For the amlodipine group, correlation between blood pressure reduction and progression was r = 0.19, P = .07. Administration of amlodipine to patients with CAD and normal blood pressure resulted in reduced adverse cardiovascular events. Directionally similar, but smaller and nonsignificant, treatment effects were observed with enalapril. For amlodipine, IVUS showed evidence of slowing of atherosclerosis progression.JAMA The Journal of the American Medical Association 11/2004; 292(18):2217-25. DOI:10.1001/jama.292.18.2217 · 30.39 Impact Factor
JAMA The Journal of the American Medical Association 11/2004; 292(18):2271-3. DOI:10.1001/jama.292.18.2271 · 30.39 Impact Factor