Physicians' interpretation of "class effects": a need for thoughtful re-evaluation

Dihydropyridine calcium channel blockers and cardiovascular outcomes in elderly patients: a population-based study

BACKGROUND

Dihydropyridine calcium channel blockers are widely used for the treatment of hypertension and angina. Despite safety concerns associated with short-acting agents, increasing evidence supports the safety of long-acting dihydropyridines. Although amlodipine is the best studied of these, there are few studies comparing it with nifedipine.

OBJECTIVE

To examine the association between hospitalization for acute coronary syndromes and treatment with amlodipine or extended-release nifedipine in patients 65 years of age and older. The primary objective was a composite of hospital admission for angina or acute myocardial infarction.

METHODS

The present population-based, retrospective cohort study used linked health care databases from Ontario. Propensity scores were used to identify highly similar patients started on amlodipine or extended-release nifedipine between April 1997 and March 2002. Time-to-event analysis was conducted using Cox proportional hazards models.

RESULTS

The analysis included 24,190 patients (44% male; mean age 75 years) treated with amlodipine or extended-release nifedipine (n=12,095 each). The number of patients reaching the primary end point was 362 (3%) and 294 (2.4%) in the amlodipine and nifedipine groups, respectively. The groups were similar in a large number of demographic and clinical characteristics. No significant differences were observed among users of extended-release nifedipine (adjusted hazard ratio 0.91, 95% CI 0.74 to 1.13) relative to amlodipine.

CONCLUSIONS

These findings suggest that amlodipine and extended-release nifedipine are not associated with differential rates of acute coronary events in older patients.

Effectiveness of statins for secondary prevention in elderly patients after acute myocardial infarction: an evaluation of class effect

BACKGROUND

Clinical trials have shown the benefits of statins after acute myocardial infarction (AMI). However, it is unclear whether different statins exert a similar effect in reducing the incidence of recurrent AMI and death when used in clinical practice.

METHODS

We conducted a retrospective cohort study (1997-2002) to compare 5 statins using data from medical administrative databases in 3 provinces (Quebec, Ontario and British Columbia). We included patients aged 65 years and over who were discharged alive after their first AMI-related hospital stay and who began statin treatment within 90 days after discharge. The primary end point was the combined outcome of recurrent AMI or death from any cause. The secondary end point was death from any cause. Adjusted hazard ratios (HRs) for each statin compared with atorvastatin as the reference drug were estimated using Cox proportional hazards regression analysis.

RESULTS

A total of 18,637 patients were prescribed atorvastatin (n = 6420), pravastatin (n = 4480), simvastatin (n = 5518), lovastatin (n = 1736) or fluvastatin (n = 483). Users of different statins showed similar baseline characteristics and patterns of statin use. The adjusted HRs (and 95% confidence intervals) for the combined outcome of AMI or death showed that each statin had similar effects when compared with atorvastatin: pravastatin 1.00 (0.90-1.11), simvastatin 1.01 (0.91-1.12), lovastatin 1.09 (0.95-1.24) and fluvastatin 1.01 (0.80-1.27). The results did not change when death alone was the end point, nor did they change after adjustment for initial daily dose or after censoring of patients who switched or stopped the initial statin treatment.

INTERPRETATION

Our results suggest that, under current usage, statins are equally effective for secondary prevention in elderly patients after AMI.

Statins and liver toxicity: a meta-analysis

STUDY OBJECTIVE

To assess the risk of liver function test (LFT) abnormalities with the use of 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) for the treatment of hyperlipidemia.

DESIGN

Meta-analysis of randomized, placebo-controlled trials of statins used for the treatment of hyperlipidemia or for primary or secondary prevention of cardiovascular disease.

SETTING

University research center.

PATIENTS

A total of 49,275 patients from 13 trials.

INTERVENTION

A literature search of published clinical trials was performed in MEDLINE (January 1966-March 2003) and the Cochrane Controlled Trials Registry (first quarter 2003). Studies also were identified from the references of the trials and of published systematic reviews.

MEASUREMENTS AND MAIN RESULTS

For a trial to be included in the meta-analysis, its duration of follow-up had to be at least 48 weeks and the trial had to include at least 400 patients, with at least 200 treated with a statin. Trials conducted in transplant recipients were excluded. The proportion of patients having LFT abnormalities was low in both groups (statins 1.14% vs placebo 1.05%, odds ratio [OR] 1.26, 95% confidence interval [CI] 0.99-1.62, p=0.07). Only fluvastatin was associated with a significant increase in the odds of having LFT abnormalities (fluvastatin 1.13% vs placebo 0.29%, OR 3.54, 95% CI 1.1-11.6, p=0.04) compared with placebo, although this finding was based on only two trials.

CONCLUSIONS

Our results support previous observations that pravastatin, lovastatin, and simvastatin at low-to-moderate doses are not associated with a significant risk of LFT abnormalities. Additional data are required to determine whether other statins have a similar safety profile.

Current overview of statin-induced myopathy

Statins are an efficacious and well-tolerated class of lipid-altering agents that have been shown to reduce the risk of initial and recurrent cardiovascular events. However, cerivastatin was withdrawn from the world market because of its potential for severe myotoxic effects. Since the benefits of statin treatment outweigh the small risk of adverse events, statins remain the first-line therapy for lipid lowering and preventing atherosclerotic cardiovascular diseases. The risk of myopathy may be minimized with the appropriate choice of agent and by identifying patients at risk of myotoxic effects. Elderly or female patients, or those with concomitant medications or impaired metabolic processes, may be at increased risk and should be monitored closely. The risk of myopathy may also be inferred from the pharmacologic and pharmacokinetic properties of the statin used. Since myotoxic events are more frequent at higher doses, statins that are effective in reducing cholesterol levels and helping patients to reach target levels at start doses may be useful. The lipophilicity of a statin and its potential for drug-drug interactions may also help to determine the likelihood of muscular effects. Drug-drug interactions may be avoided by selecting a statin that does not share the same metabolic pathway.

Cost effectiveness of ramipril in patients at high risk for cardiovascular events : economic evaluation of the HOPE (Heart Outcomes Prevention Evaluation) study for Germany from the Statutory Health Insurance perspective

BACKGROUND

In the HOPE (Heart Outcomes Prevention Evaluation) trial, ramipril (compared with placebo) significantly reduced cardiovascular death and all-cause mortality as well as the incidence of costly cardiovascular events, such as myocardial infarction, revascularisation, stroke, cardiac arrest, hospitalisation due to heart failure and worsening angina pectoris, new-onset diabetes mellitus and microvascular diabetic complications.

OBJECTIVE

Data from the HOPE study were used in a cost-effectiveness analysis to determine the additional cost per life-year gained (LYG) when the ACE inhibitor ramipril was added to the current medication of patients at high risk for cardiovascular events. The aim was to establish the incremental cost-effectiveness ratio (ICER) of ramipril versus placebo from the perspective of the Statutory Health Insurance (SHI) provider in Germany, for both the study population as a whole and for the subgroup of patients with diabetes.

DESIGN

A modelling approach was used, based on secondary analysis of published data and retrospective application of costs. In the base-case analysis, average case-related expenses of the SHI were applied and LYG were quantified using the average of the difference between the survival rates in the ramipril and placebo groups during the HOPE trial. LYG beyond the trial duration were estimated by the method of declining exponential approximation of life expectancy.

RESULTS

After a treatment period of 4.5 years, the ICER of ramipril versus placebo was Euros 4074/LYG and Euros 2486/LYG (discounted at 5% per annum and in 1998-2002 values; Euro 1 approximately USD 0.88; first quarter 2002 values) for the HOPE study population as a whole and the subgroup of patients with diabetes, respectively. To test the model's robustness, the influence of the model variables on the results was quantified using a deterministic model, and a best-case/worst-case scenario analysis. The effect of random variables was investigated in a Monte Carlo simulation. The acquisition cost for ramipril had the greatest impact on the ICER of ramipril (2.2-fold greater than the impact of the number of LYG). In 95% of the 10,000 simulation steps, the ICER of ramipril after 4.5 years of treatment was between Euros 1290 and Euros 9005 per LYG for the entire HOPE study population and between Euros 290 and Euros 6115 per LYG in the diabetic subgroup.

CONCLUSIONS

Results of this evaluation suggest that ramipril is likely to be cost effective in secondary prevention of cardiovascular events from the perspective of the SHI (third-party payer) in Germany. The estimated ICER of ramipril compares well with other ICERs of widely accepted treatments used for the management of cardiovascular diseases, such as HMG-CoA reductase inhibitors.

Modulating atherosclerosis through inhibition or blockade of angiotensin

Angiotensin-convertng enzyme (ACE) inhibitors are well recognized for their benefits in treating hypertension and congestive heart failure and preventing postmyocardial infarction heart failure or left ventricular (LV) dysfunction. Recently, blockade of the angiotensin II type 1 (AT1) receptor was shown to reduce cardiovascular events in hypertensive subjects with LV hypertrophy. Several lines of evidence are now converging to show that ACE inhibitors may affect the atherosclerotic process itself. Emerging clinical data indicate that angiotensin-receptor blockers (ARBs) may possibly modulate atherosclerosis as well. The antiatherogenic properties of ACE inhibitors and ARBs may derive from inhibition or blockade of angiotensin II, now recognized as an agent that increases oxidative stress.Angiotensin-converting enzyme inhibition and angiotensin-receptor blockade also increase endothelial nitric oxide formation, which improves endothelial function. In contrast to the effects of ARBs, the vascular effects of ACE inhibitors may, in part, be mediated by an increase in bradykinin. This article reviews some of the biologic mechanisms whereby ACE inhibitors and ARBs may modulate atherosclerosis.