Are lipid-lowering guidelines evidence-based?

The benefits of statins in people without established cardiovascular disease but with cardiovascular risk factors: meta-analysis of randomised controlled trials

OBJECTIVES

To investigate whether statins reduce all cause mortality and major coronary and cerebrovascular events in people without established cardiovascular disease but with cardiovascular risk factors, and whether these effects are similar in men and women, in young and older (>65 years) people, and in people with diabetes mellitus.

DESIGN

Meta-analysis of randomised trials.

DATA SOURCES

Cochrane controlled trials register, Embase, and Medline. Data abstraction Two independent investigators identified studies on the clinical effects of statins compared with a placebo or control group and with follow-up of at least one year, at least 80% or more participants without established cardiovascular disease, and outcome data on mortality and major cardiovascular disease events. Heterogeneity was assessed using the Q and I(2) statistics. Publication bias was assessed by visual examination of funnel plots and the Egger regression test.

RESULTS

10 trials enrolled a total of 70 388 people, of whom 23 681 (34%) were women and 16 078 (23%) had diabetes mellitus. Mean follow-up was 4.1 years. Treatment with statins significantly reduced the risk of all cause mortality (odds ratio 0.88, 95% confidence interval 0.81 to 0.96), major coronary events (0.70, 0.61 to 0.81), and major cerebrovascular events (0.81, 0.71 to 0.93). No evidence of an increased risk of cancer was observed. There was no significant heterogeneity of the treatment effect in clinical subgroups.

CONCLUSION

In patients without established cardiovascular disease but with cardiovascular risk factors, statin use was associated with significantly improved survival and large reductions in the risk of major cardiovascular events.

Benefit of statins in daily practice? A six-year retrospective observational study

This observational retrospective study analysed the association of adherence to statins with the achievement of a target total cholesterol level (CL, <200mg/dl), and any association of adherence with the time to first hospital admission for coronary event in hypercholesterolemic patients treated with statins, in one Italian Local Health Authority between 1998 and 2003. The study population consisted of 3516 patients who were prescribed statins and for whom full cholesterol results were available. After three months of treatment, there were significant reductions in CL (p<0.001) in the three treatment groups stratified by adherence (good adherents -24%, poor adherents -22%, and nonadherents -14%). Patients more likely to achieve the target CL were older, male and more adherent to the statins. The risk of first hospitalization was associated positively with increased age and male gender. Patients with co-treatments were more likely to be hospitalized. Surprisingly, better adherence to statin treatment increased the risk of hospitalization.

Women and statin use: a women's health advocacy perspective

This paper is based on a longer report on the benefits, safety and modalities of information representation with regard to women and statin use, situated within the historical context of Women's Health Movement which has advocated for unbiased, appropriate medical research and prescribing for women based on the goals of full-disclosure, informed consent, evidence-based medicine and gender-based analysis. The evidence base for prescribing statins for women, especially for primary prevention is weak, yet Canadian data suggest that half of all prescriptions are for women. Safety meta-analyses do not disaggregate for women; do not consider female vulnerability to statin induced muscle problems, and women-centred concerns such as breast-cancer, miscarriage or birth defects are under-researched. Many trials have not published their non-cardiac serious adverse event data. These factors suggest that the standards of full-disclosure, informed consent, evidence-based prescribing and gender-based analysis are not being met and women should proceed with caution.

Use of Framingham risk score and new biomarkers to predict cardiovascular mortality in older people: population based observational cohort study

OBJECTIVES

To investigate the performance of classic risk factors, and of some new biomarkers, in predicting cardiovascular mortality in very old people from the general population with no history of cardiovascular disease.

DESIGN

The Leiden 85-plus Study (1997-2004) is an observational prospective cohort study with 5 years of follow-up.

SETTING

General population of the city of Leiden, the Netherlands.

PARTICIPANTS

Population based sample of participants aged 85 years (215 women and 87 men) with no history of cardiovascular disease; no other exclusion criteria. Main measurements Cause specific mortality was registered during follow-up. All classic risk factors included in the Framingham risk score (sex, systolic blood pressure, total and high density lipoprotein cholesterol, diabetes mellitus, smoking and electrocardiogram based left ventricular hypertrophy), as well as plasma concentrations of the new biomarkers homocysteine, folic acid, C reactive protein, and interleukin 6, were assessed at baseline.

RESULTS

During follow-up, 108 of the 302 participants died; 32% (35/108) of deaths were from cardiovascular causes. Classic risk factors did not predict cardiovascular mortality when used in the Framingham risk score (area under receiver operating characteristic curve 0.53, 95% confidence interval 0.42 to 0.63) or in a newly calibrated model (0.53, 0.43 to 0.64). Of the new biomarkers studied, homocysteine had most predictive power (0.65, 0.55 to 0.75). Entering any additional risk factor or combination of factors into the homocysteine prediction model did not increase its discriminative power.

CONCLUSIONS

In very old people from the general population with no history of cardiovascular disease, concentrations of homocysteine alone can accurately identify those at high risk of cardiovascular mortality, whereas classic risk factors included in the Framingham risk score do not. These preliminary findings warrant validation in a separate cohort.

Statin treatment in a cohort of 20 212 men and women in Norway according to cardiovascular risk factors and level of education

AIMS

To study the influence of patients' education and cardiovascular risk factors on the probability of statin treatment.

METHODS

A prospective cohort study of participants in regional health surveys in Norway 2000-2002 with statin use recorded in the Norwegian Prescription Database 2004-2006 as outcome measure. Information on history of cardiovascular disease (CVD) and diabetes, lipid levels, blood pressure, use of cardiovascular drugs, body mass index, family history, smoking, physical activity, marital status and place of residence was obtained at baseline. A total of 20,212 men and women aged 40-41, 45-46 and 59-61 years who reported never use of statins were included. Educational level was retrieved from Statistics Norway. Adjusted relative risks (RR) were estimated by Poisson regression.

RESULTS

Whereas 655 participants reported a history of CVD or diabetes, 19,557 reported no such history. In the non-CVD/diabetes group 1,620 persons (8%) became statin users and 222 persons (34%) in the CVD/diabetes group. RR of becoming a statin user for high vs. low education increased from 0.64 [95% confidence interval (CI) 0.55, 0.73] to 0.91 (95% CI 0.79, 1.05) after adjustment in the non-CVD/diabetes group and from 0.94 (95% CI 0.70, 1.26) to 1.35 (95% CI 1.00, 1.81) in the CVD/diabetes group.

CONCLUSIONS

Patients with no history of CVD/diabetes were prescribed statins according to cardiovascular risk independent of education. There was a tendency to a higher probability of statin treatment among highly educated compared with people of lower educational level in the group with a history of CVD or diabetes, after adjustment for other CVD risk factors, particularly in women.

Efficacy of statins in familial hypercholesterolaemia: a long term cohort study

OBJECTIVE

To determine the efficacy of statin treatment on risk of coronary heart disease in patients with familial hypercholesterolaemia.

DESIGN

Cohort study with a mean follow-up of 8.5 years.

SETTING

27 outpatient lipid clinics.

SUBJECTS

2146 patients with familial hypercholesterolaemia without prevalent coronary heart disease before 1 January 1990.

MAIN OUTCOME MEASURES

Risk of coronary heart disease in treated and "untreated" (delay in starting statin treatment) patients compared with a Cox regression model in which statin use was a time dependent variable.

RESULTS

In January 1990, 413 (21%) of the patients had started statin treatment, and during follow-up another 1294 patients (66%) started after a mean delay of 4.3 years. Most patients received simvastatin (n=1167, 33 mg daily) or atorvastatin (n=211, 49 mg daily). We observed an overall risk reduction of 76% (hazard ratio 0.24 (95% confidence interval 0.18 to 0.30), P<0.001). In fact, the risk of myocardial infarction in these statin treated patients was not significantly greater than that in an age-matched sample from the general population (hazard ration 1.44 (0.80 to 2.60), P=0.23).

CONCLUSION

Lower statin doses than those currently advised reduced the risk of coronary heart disease to a greater extent than anticipated in patients with familial hypercholesterolaemia. With statin treatment, such patients no longer have a risk of myocardial infarction significantly different from that of the general population.

The 2006 Canadian dyslipidemia guidelines will prevent more deaths while treating fewer people--but should they be further modified?

BACKGROUND

When clinical guidelines affect large numbers of individuals or substantial resources, it is important to understand their benefits, harms and costs from a population perspective. Many countries' dyslipidemia guidelines include these perspectives.

OBJECTIVE

To compare the effectiveness and efficiency of the 2003 and 2006 Canadian dyslipidemia guidelines for statin treatment in reducing deaths from coronary artery disease (CAD) in the Canadian population.

METHODS

The 2003 and 2006 Canadian dyslipidemia guidelines were applied to data from the Canadian Heart Health Survey (weighted sample of 12,300,000 people), which includes information on family history and physical measurements, including fasting lipid profiles. The number of people recommended for statin treatment, the potential number of CAD deaths avoided and the number needed to treat to avoid one CAD death with five years of statin therapy were determined for each guideline.

RESULTS

Compared with the 2003 guidelines, 1.4% fewer people (20 to 74 years of age) are recommended statin treatment, potentially preventing 7% more CAD deaths. The number needed to treat to prevent one CAD death over five years decreased from 172 (2003 guideline) to 147 (2006 guideline).

CONCLUSIONS

From a population perspective, the 2006 Canadian dyslipidemia recommendations are an improvement of earlier versions, preventing more CAD events and deaths with fewer statin prescriptions. Despite these improvements, the Canadian dyslipidemia recommendations should explicitly address issues of absolute benefit and cost-effectiveness in future revisions.

An untold story?

This week’s headline story about antidepressants highlights the ongoing problem of how study results are often distorted by a failure to access full datasets. Jeanne Lenzer and Shannon Brownlee report

Efficacy of cholesterol-lowering therapy in 18,686 people with diabetes in 14 randomised trials of statins: a meta-analysis

BACKGROUND

Although statin therapy reduces the risk of occlusive vascular events in people with diabetes mellitus, there is uncertainty about the effects on particular outcomes and whether such effects depend on the type of diabetes, lipid profile, or other factors. We undertook a prospective meta-analysis to help resolve these uncertainties.

METHODS

We analysed data from 18 686 individuals with diabetes (1466 with type 1 and 17,220 with type 2) in the context of a further 71,370 without diabetes in 14 randomised trials of statin therapy. Weighted estimates were obtained of effects on clinical outcomes per 1.0 mmol/L reduction in LDL cholesterol.

FINDINGS

During a mean follow-up of 4.3 years, there were 3247 major vascular events in people with diabetes. There was a 9% proportional reduction in all-cause mortality per mmol/L reduction in LDL cholesterol in participants with diabetes (rate ratio [RR] 0.91, 99% CI 0.82-1.01; p=0.02), which was similar to the 13% reduction in those without diabetes (0.87, 0.82-0.92; p<0.0001). This finding reflected a significant reduction in vascular mortality (0.87, 0.76-1.00; p=0.008) and no effect on non-vascular mortality (0.97, 0.82-1.16; p=0.7) in participants with diabetes. There was a significant 21% proportional reduction in major vascular events per mmol/L reduction in LDL cholesterol in people with diabetes (0.79, 0.72-0.86; p<0.0001), which was similar to the effect observed in those without diabetes (0.79, 0.76-0.82; p<0.0001). In diabetic participants there were reductions in myocardial infarction or coronary death (0.78, 0.69-0.87; p<0.0001), coronary revascularisation (0.75, 0.64-0.88; p<0.0001), and stroke (0.79, 0.67-0.93; p=0.0002). Among people with diabetes the proportional effects of statin therapy were similar irrespective of whether there was a prior history of vascular disease and irrespective of other baseline characteristics. After 5 years, 42 (95% CI 30-55) fewer people with diabetes had major vascular events per 1000 allocated statin therapy.

INTERPRETATION

Statin therapy should be considered for all diabetic individuals who are at sufficiently high risk of vascular events.

How evidence-based are the recommendations in evidence-based guidelines?

BACKGROUND

Treatment recommendations for the same condition from different guideline bodies often disagree, even when the same randomized controlled trial (RCT) evidence is cited. Guideline appraisal tools focus on methodology and quality of reporting, but not on the nature of the supporting evidence. This study was done to evaluate the quality of the evidence (based on consideration of its internal validity, clinical relevance, and applicability) underlying therapy recommendations in evidence-based clinical practice guidelines.

METHODS AND FINDINGS

A cross-sectional analysis of cardiovascular risk management recommendations was performed for three different conditions (diabetes mellitus, dyslipidemia, and hypertension) from three pan-national guideline panels (from the United States, Canada, and Europe). Of the 338 treatment recommendations in these nine guidelines, 231 (68%) cited RCT evidence but only 105 (45%) of these RCT-based recommendations were based on high-quality evidence. RCT-based evidence was downgraded most often because of reservations about the applicability of the RCT to the populations specified in the guideline recommendation (64/126 cases, 51%) or because the RCT reported surrogate outcomes (59/126 cases, 47%).

CONCLUSIONS

The results of internally valid RCTs may not be applicable to the populations, interventions, or outcomes specified in a guideline recommendation and therefore should not always be assumed to provide high-quality evidence for therapy recommendations.

Eminence-based guidelines: a quality assessment of the second Joint British Societies' guidelines on the prevention of cardiovascular disease

The quality and independence of clinical practice guidelines developed by professional societies has previously been assessed as unsatisfactory. Calls for explicit methodological standards have lead to international consensus on standards for guideline development. The methodological quality of current British cardiovascular guidelines produced by six professional societies is assessed with reference to internationally recognised criteria (Appraisal of Guidelines Research and Evaluation) for evaluating the quality of clinical guidelines. When evaluated with reference to a recognised quality framework for guideline development, current Joint British Societies guidelines for the prevention and treatment of cardiovascular disease contain serious deficiencies, are of low quality and should not be recommended for clinical practice.

Comparing primary prevention with secondary prevention to explain decreasing coronary heart disease death rates in Ireland, 1985-2000

Background

To investigate whether primary prevention might be more favourable than secondary prevention (risk factor reduction in patients with coronary heart disease(CHD)).

Methods

The cell-based IMPACT CHD mortality model was used to integrate data for Ireland describing CHD patient numbers, uptake of specific treatments, trends in major cardiovascular risk factors, and the mortality benefits of these specific risk factor changes in CHD patients and in healthy people without recognised CHD.

Results

Between 1985 and 2000, approximately 2,530 fewer deaths were attributable to reductions in the three major risk factors in Ireland. Overall smoking prevalence declined by 14% between 1985 and 2000, resulting in about 685 fewer deaths (minimum estimate 330, maximum estimate 1,285) attributable to smoking cessation: about 275 in healthy people and 410 in known CHD patients. Population total cholesterol concentrations fell by 4.6%, resultingin approximately 1,300 (minimum estimate 1,115, maximum estimate 1,660) fewer deaths attributable to dietary changes(1,185 in healthy people and 115 in CHD patients) plus 305 fewer deaths attributable to statin treatment (45 in people without CHD and 260 in CHD patients). Mean population diastolic blood pressure fell by 7.2%, resulting in approximately 170 (minimum estimate 105, maximum estimate 300) fewer deaths attributable to secular falls in blood pressure (140 in healthy people and 30 in CHD patients), plus approximately 70 fewer deaths attributable to antihypertensive treatments in people without CHD.

Of all the deaths attributable to risk factor falls, some 1,715 (68%) occurred in people without recognized CHD and 815(32%) in CHD patients.

Conclusion

Compared with secondary prevention, primary prevention achieved a two-fold larger reduction in CHD deaths. Future national CHD policies should therefore prioritize nationwide interventions to promote healthy diets and reduce smoking.

Should women be offered cholesterol lowering drugs to prevent cardiovascular disease? No

Women in western countries are more likely to die from heart disease than from cancer. Scott M Grundy argues that the risks make preventive treatment essential, but Malcolm Kendrick believes the evidence of benefit is not strong enough