Life-years gained from coronary heart disease mortality reduction in Scotland: Prevention or treatment?
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.
References (66)
- et al.
Alternative projections of mortality and disability by cause 1990–2020: Global Burden of Disease Study
Lancet
(1997) - et al.
Estimation of contribution of changes in classic risk factors to trends in coronary-event rates across the WHO MONICA Project
Lancet
(2000) - et al.
Meta-analysis of randomized trials comparing coronary angioplasty with bypass-surgery
Lancet
(1995) - et al.
Blood pressure, stroke, and coronary heart diseasePart 1, Prolonged differences in blood pressure: prospective observational studies corrected for the regression dilution bias
Lancet
(1990) - et al.
General pharmacologic treatment of acute myocardial infarction
Emerg Med Clin North Am
(2001) - et al.
Blood-pressure reduction and cardiovascular risk in HOPE study
Lancet
(2001) - et al.
Effect of coronary artery bypass graft surgery on survival: overview of 10-year results from randomised trials by the Coronary Artery Bypass Graft Surgery Trialists Collaboration
Lancet
(1994) - et al.
Blood pressure, stroke and coronary heart diseasePart 2, short term reductions in blood pressure: overview of randomised drug trials in their epidemiological context
Lancet
(1990) “Saving lives” our healthier nation
(1999)- General Register Office for Scotland. Scotland's Census; 2001....
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)
Cited by (31)
Trends in the diversity of mortality causes and age-standardised mortality rates among subpopulations within Scotland, 2001–2019
2022, SSM - Population HealthCitation Excerpt :For example, reducing the prevalence of heart attacks and strokes has been a priority of the Scottish Government for many years (Scottish Government, 2014) because relative rates of these diseases in Scotland are higher than comparable areas of the rest of the UK and Europe (Mitchell et al., 2005) and the resultant decrease may have had the effect of creating a more even and diverse distribution of mortality causes. Treatment for heart attacks and strokes and ongoing management of related conditions, as well as cancer treatment, have also improved significantly over the period (Critchley et al., 2003). In contrast, a number of causes of mortality have become more prevalent despite public health measures, with mortality rates increasing during the study period.
Making a Case for Quantitative Assessment of Cardiovascular Risk
2007, Journal of Clinical LipidologyCitation Excerpt :In a Scottish population-based study, a mortality model was used to estimate life-years gained attributable to cardiovascular treatments over a 19-year period. During 1994, the last year of the study, medical and surgical treatment and lifestyle modification resulted in >48,000 life-years gained, of which reductions in smoking, cholesterol, and blood pressure accounted for ∼36,000 (Fig. 2).40 Relating such data to the experience of a given patient remains challenging.
Preventing chronic diseases: Taking stepwise action
2005, LancetCitation Excerpt :This reduction would result in 36 million deaths averted over this period, of which 28 million would be averted in low-income and middle-income countries. The target is based on the achievements of several countries over the past three decades in which comprehensive chronic disease prevention programmes have been introduced.10–14 Subsequently, a vast amount of published work has accumulated to show that health gains can be obtained over a relatively short period of time, especially in the area of tobacco control, in which benefits accrue almost immediately.
Small changes in United Kingdom cardiovascular risk factors could halve coronary heart disease mortality
2005, Journal of Clinical EpidemiologyCitation Excerpt :First, it considers only mortality, and not years of life lost or morbidity. However, our estimates of deaths prevented or postponed could easily be translated into ∼20 times as many life-years gained [42]. Second, it considers only deaths from CHD.
Smoking combined with overweight or obesity markedly elevates cardiovascular risk factors
2006, European Journal of Preventive Cardiology