Life-years gained from coronary heart disease mortality reduction in Scotland: Prevention or treatment?

doi:10.1016/S0895-4356(03)00059-3

Journal of Clinical Epidemiology

Volume 56, Issue 6, June 2003, Pages 583-590

https://doi.org/10.1016/S0895-4356(03)00059-3 Get rights and content

Abstract

Coronary Heart Disease (CHD) death rates have fallen considerably in many countries. We estimated the life-years-gained (LYG) in Scotland between 1975 and 1994 attributable to cardiology treatments, and population reductions in major CHD risk factors, using a previously validated mortality model. This combines published effectiveness data with information on uptake of CHD treatments; risk factor trends; and median survival by age and sex. Compared with 1975, there were 4,536 fewer CHD deaths in 1994, resulting in approximately 48,016 LYG among those aged 45–84 (maximum estimate 53,317; minimum estimate 36,867). Medical and surgical treatments for CHD patients gained approximately 12,025 life-years; the largest contribution coming from pharmacologic secondary prevention. Population reductions in major risk factors (smoking, cholesterol, and blood pressure) accounted for some 35,991 LYG, reductions in smoking accounted for over 50% of this. Modern cardiologic treatments gained many thousands of life-years in Scotland, but modest reductions in risk factors gained almost three times as many life-years.

Introduction

Coronary heart disease (CHD) mortality rates have halved since the 1970s in the majority of industrialized countries. Life expectancy has also improved considerably [1], and in many countries, much of this can be attributed to reductions in CHD mortality. However, CHD mortality has not declined as much in the UK as in many other Western countries [2]. Scotland has a population of 5.1 million [3] (2001 Census). CHD mortality rates have declined by 25% over the last 2 decades, but CHD still accounts for over 20% of all deaths (11,914 in 2001) [4]. Scotland therefore remains high in the world CHD league table, and CHD remains a top Government priority [5]. It is thus vital to explain the observed declines in coronary mortality and associated improvements in life expectancy, and evaluate the potential for further gains.

Many researchers have used models of varying degrees of complexity to attempt to explain these observed declines in mortality. These fairly consistently suggest that improvements in treatment explain less of the mortality decline than do risk factor changes [6]. For example, it has been estimated that the proportion of mortality decline attributable to medical interventions was 40% in Auckland, New Zealand (between 1974 and 1981) [7], compared with 39.5% in the United States (from 1968 to 1976) [8], 40% in Scotland (between 1975 and 1994) [9], 48% in Auckland, New Zealand between 1982 and 1993 [10], and 57% for the United States (1980–1990) using a more complex simulation model [11].

These analyses concentrated solely on explaining mortality. To date, few researchers have attempted to examine longevity, and estimate the increased life years gained (LYG) by reductions in CHD mortality for an entire population. This article therefore estimates the life years gained due to improved treatments, and changes in risk factor levels, that occurred between 1975 and 1994 in Scotland.

Section snippets

Methods

The number of LYG in 1994 in each 10-year age and sex group, for each treatment category and risk factor change, was estimated as the product of the number of deaths prevented or postponed in Scotland in 1994, and the estimated median survival for that group.

LYG by treatments

Medical and surgical cardiological treatments together prevented or postponed approximately 1,862 deaths in 1994 in age groups 45–84. This resulted in an additional 12,025 LYG in 1994 (minimum estimate 8,689, maximum 14,461). Treatments for secondary prevention after myocardial infarction or CABG surgery or angioplasty gained the most life-years (36% of the treatment total), along with treatments for hypertension and angina (see Table 1).

Reductions in population risk factor levels

Reductions in population risk factors prevented or

Discussion

Nearly 50,000 life-years were gained in Scotland in 1994 compared with 1975 due to the reductions in CHD mortality. These 48,016 LYG came from an estimated 4,536 deaths prevented or postponed in Scotland in 1994—suggesting that, on average, each person gained over 10 years of extra life. Although medical and surgical treatments accounted for nearly half of the deaths prevented or postponed in 1994, they accounted for only one-quarter of the LYG. Nearly three times as many life years gained were

Acknowledgements

We thank Rebecca Teers, Health Survey for England, Mary Walker, British Regional Heart Study, UK Data Archive Centre, University of Essex. B.U. was funded by the NHS Executive North West R&D Directorate as a Research Training Fellow.

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Life-years gained from coronary heart disease mortality reduction in Scotland: Prevention or treatment?

Abstract

Introduction

Section snippets

Methods

LYG by treatments

Reductions in population risk factor levels

Discussion

Acknowledgements

Lancet

Lancet

Lancet

Lancet

Emerg Med Clin North Am

Lancet

Lancet

Lancet

“Saving lives” our healthier nation

Why model coronary heart disease?

Eur Heart J

Medical management and the decline in mortality from coronary heart disease

Br Med J Clin Res Ed

The decline in ischemic heart disease mortality rates. An analysis of the comparative effects of medical interventions and changes in lifestyle

Ann Intern Med

Contribution of modern cardiovascular treatment and risk factor changes to the decline in coronary heart disease mortality in Scotland between 1975 and 1994

Heart

Explaining the decline in Coronary Heart Disease Mortality in Auckland, New Zealand between 1982 and 1993

Circulation

The recent decline in mortality from coronary heart disease, 1980–1990. The effect of secular trends in risk factors and treatment

JAMA

Limitations of the Parsonnet score for measuring risk stratified mortality in the north west of England

Heart

By how much and how quickly does reduction in serum cholesterol concentration lower risk of ischaemic heart disease?

BMJ

The relation between blood pressure and mortality due to coronary heart disease among men in different parts of the world. Seven Countries Study Research Group

N Engl J Med

Is “saving lives” feasible? Estimating the potential for further reductions in UK coronary heart disease deaths

J Epidemiol Community Health

Association of the California Tobacco Control Program with declines in cigarette consumption and mortality from heart disease

N Engl J Med

Trends in case-fatality in 117 718 patients admitted with acute myocardial infarction in Scotland

Eur Heart J

Evidence of improving prognosis in heart failure. Trends in case fatality in 66 547 patients hospitalized between 1986 and 1995

Circulation

Survival after coronary artery bypass surgery. 1–5 year survival. Data obtained from the SMR20 scheme Scotland 1983–1990

Sex difference in myocardial infarction and coronary deaths in the Scottish MONICA population of Glasgow 1985 to 1991

Circulation

Mortality in patients of the glasgow blood pressure clinic

J Hypertens

Time-trends in survival and readmission following coronary artery bypass grafting in Scotland between 1981 and 1996: a retrospective observational study

BMJ

Long-term prognosis of different forms of coronary heart disease: the Reykjavik Study

Int J Epidemiol

The natural history of prevalent ischaemic heart disease in middle-aged men

Eur Heart J

Multiple risk factor interventions for primary prevention of coronary heart disease (Cochrane review)