Current issues of ACP Journal Club are published in Annals of Internal Medicine


Clinical Prediction Guide

A model predicted the benefits of hyperlipidemia and hypertension therapy in high-risk primary prevention and secondary prevention

ACP J Club. 1998 Nov-Dec; 129:81. doi:10.7326/ACPJC-1998-129-3-081


Source Citation

Grover SA, Paquet S, Levinton C, Coupal L, Zowall H. Estimating the benefits of modifying risk factors of cardiovascular disease. A comparison of primary vs secondary prevention. Arch Intern Med. 1998 Mar 23;158:655-62.


Abstract

Question

Can a life-expectancy model predict survival benefits for risk-factor modification in primary and secondary prevention of cardiovascular disease (CVD)?

Design

A life-expectancy model was developed on the basis of data from the Lipid Research Clinics (LRC) cohort. The model was tested by using the results of 9 randomized controlled trials (RCTs).

Settings

The model used patient data from 10 clinics in North America. The model was tested in RCTs done in Scandinavia, Scotland, and North America.

Patients

A cohort of LRC study patients (mean age 47 y, 52% men). Exclusion criteria included use of digitalis, antiarrhythmic drugs, or lipid-altering drugs or pregnancy. 5% of patients had cardiovascular disease at entry.

Design of prediction guide

The yearly probability of death from coronary disease, stroke, or other causes and of developing nonfatal coronary or cerebrovascular disease were estimated for a hypothetical cohort of 1000 patients (age range 30 to 74 y) with and without CVD at baseline. The benefits of modifying lipid levels and treating hypertension were calculated on the basis of the life-expectancy model.

Main outcome measures

Risk for death from coronary disease, stroke, and other causes.

Main results

The predicted life-years saved for lowering lipid levels and blood pressure are presented in the Tables.

Conclusion

A life-expectancy model predicted that treating hyperlipidemia or hypertension would benefit most high-risk patients without CVD and those with existent CVD independent of other risk factors.

Sources of funding: Dairy Farmers of Canada and Merck Frosst Canada.

For correspondence: Dr. S.A. Grover, Centre for the Analysis of Cost-Effective Care, Montreal General Hospital, 1650 Cedar Avenue, Montreal, Quebec H3G 1A4, Canada. FAX 514-934-8293.


Table. Life-years saved from lipid lowering according to cardiovascular disease (CVD) risk

Sex Age CVD absent at baseline CVD present at baseline
Low-risk High-risk Low-risk High-risk
Men 40 y 2.50 4.74 3.84 4.65
Men 70 y 0.43 0.78 0.74* 0.65
Women 40 y 1.12 3.76 2.58 4.39
Women 70 y 0.25 0.80 0.58* 0.75

*Data supplied by author.


Table. Life-years saved from blood pressure lowering according to CVD risk

Sex Age CVD absent at baseline CVD present at baseline
Low-risk High-risk Low-risk High-risk
Men 40 y 0.85 1.19 1.00 1.08
Men 70 y 0.17 0.29 0.23 0.23
Women 40 y 0.59* 1.34* 0.91* 1.26*
Women 70 y 0.13* 0.33* 0.25* 0.28*

*Data supplied by author.


Commentary

More than 3 decades ago, the landscape of cardiovascular preventive care started to change. The Veterans Administration Cooperative Study (1) provided the first definitive evidence that antihypertensive drugs were efficacious in preventing major cardiovascular events. Since then, other classes of drugs for other risk factors have been tested and found to be valuable for preventing the occurrence or delaying progress of a wide variety of vascular diseases. Thus, β-blockers, aspirin, and angiotensin-converting enzyme inhibitors are now standard in the armamentarium of cardiovascular preventive care.

A massive database has substantiated the value of lipid-lowering therapy in primary and secondary prevention since 1994. The most recent primary prevention trial, the Air Force/Texas Coronary Atherosclerosis Prevention Study (AFCAPS/TexCAPS) (2), shows the value of treating healthy persons who have abnormal blood lipid levels.

The question that must be answered for the practice of preventive cardiology and public health policy is this: What are the boundaries of prescribing drug therapy to persons who are asymptomatic and have no signs of disease? Should we place the whole adult population on lifelong statin therapy?

The study by Grover and colleagues is of great importance to everyday clinical practice. It provides guidance on which patients are likely to derive a clinically meaningful benefit from primary and secondary prevention of coronary and cerebrovascular conditions. This study confirms that primary preventive interventions should be based on assessment of global CVD risk rather than on individual risk factors and that existing cardiovascular conditions are a clear indication for instituting preventive measures, regardless of risk factor status.

J. George Fodor, MD, PhD
Heart Institute Prevention andRehabilitation CentreOttawa, Ontario, Canada


References

1. Effects of treatment on morbidity in hypertension. Results in patients with diastolic blood pressures averaging 115 through 129 mm Hg. JAMA. 1967;202:1028-34.

2. Downs JR, Beere PA, Whitney E, et al. Design & rationale of the Air Force/Texas Coronary Atherosclerosis Prevention Study (AFCAPS/TexCAPS). Am J Cardiol. 1997;80:287-93.