L. Bonneux

Estimating clinical morbidity due to ischemic heart disease and congestive heart failure : the future rise of heart failure

OBJECTIVES Many developed countries have seen declining mortality rates for heart disease, together with an alleged decline in incidence and a seemingly paradoxical increase in health care demands. This paper presents a model for forecasting the plausible evolution of heart disease morbidity. METHODS The simulation model combines data from different sources. It generates acute coronary event and mortality rates from published data on incidences, recurrences, and lethalities of different heart disease conditions and interventions. Forecasts are based on plausible scenarios for declining incidence and increasing survival. RESULTS Mortality is postponed more than incidence. Prevalence rates of morbidity will decrease among the young and middle-aged but increase among the elderly. As the milder disease states act as risk factors for the more severe states, effects will culminate in the most severe disease states with a disproportionate increase in older people. CONCLUSIONS Increasing health care needs in the face of declining mortality rates are no contradiction, but reflect a tradeoff of mortality for morbidity. The aging of the population will accentuate this morbidity increase.

Regression analysis of recent changes in cardiovascular morbidity and mortality in The Netherlands.

Abstract Objectives: To test whether recent declines in mortality from coronary heart disease were associated with increased mortality from other cardiovascular diseases. Design: Poisson regression analysis of national data on causes of death and hospital discharges. Setting and subjects: Population of the Netherlands, 1969-93. Main outcome measures: Annual changes in mortality from coronary heart disease, stroke, and other cardiovascular diseases and annual changes in hospital discharge rates for acute coronary events, stroke, and congestive heart failures. Results: Patterns of cardiovascular mortality changed abruptly in 1987-93. Annual decline in mortality from coronary heart disease increased sharply for women and men: from −1.9% (95% confidence interval −2.2% to −1.6%) and −1.7% (−1.9% to −1.4%) respectively in 1979-86 to −3.1% (−3.5% to −2.6%) and −4.2% (−4.6% to −3.9%) in 1987-93. The longstanding decline in mortality from stroke levelled off: from annual change of −3.3% (−3.7% to −2.8%) and −3.2% (−3.7% to −2.8%) in 1979-86 to −0.1% (−0.7% to 0.4%) and −1.1% (−1.7% to −0.5%) in 1987-93. Mortality from other cardiovascular diseases, however, started to increase: from −2.0% (−2.4% to −1.6%) and −0.2% (−0.5% to 0.2%) in 1979-86 to 1.5% (1.0% to 2.0%) and 1.9% (1.5% to 2.3%) in 1987-93. Hospital discharge rates for acute coronary heart disease, congestive heart failure, and stroke increased during 1980-6. During 1987-93 discharge rates for stroke and coronary heart disease stabilised but rates for congestive heart failure increased. Conclusion: Improved management of coronary heart disease seems to have reduced mortality, but some of the gains are lost to deaths from stroke and other cardiovascular diseases. The increasing numbers of patients with coronary heart disease who survive will increase demands on health services for long term care.

Stroke trends in an aging population. The Technology Assessment Methods Project Team.

BACKGROUND AND PURPOSE Trends in stroke incidence and survival determine changes in stroke morbidity and mortality. This study examines the extent of the incidence decline and survival improvement in the Netherlands from 1979 to 1989. In addition, it projects future changes in stroke morbidity during the period 1985 to 2005, when the countrys population will be aging. METHODS A state-event transition model is used, which combines Dutch population projections and existing data on stroke epidemiology. Based on the clinical course of stroke, the model describes historical national age- and sex-specific hospital admission and mortality rates for stroke. It extrapolates observed trends and projects future changes in stroke morbidity rates. RESULTS There is evidence of a continuing incidence decline. The most plausible rate of change is an annual decline of -1.9% (range, -1.7% to -2.1%) for men and -2.4% (range, -2.3% to -2.8%) for women. Projecting a constant mortality decline, the model shows a 35% decrease of the stroke incidence rate for a period of 20 years. Prevalence rates for major stroke will decline among the younger age groups but increase among the oldest because of increased survival in the latter. In absolute numbers this results in an 18% decrease of acute stroke episodes and an 11% increase of major stroke cases. CONCLUSIONS The increase in survival cannot fully explain the observed mortality decline and, therefore, a concomitant incidence decline has to be assumed. Aging of the population partially outweighs the effect of an incidence decline on the total burden of stroke. Increase in cardiovascular survival leads to a further increase in major stroke prevalence among the oldest age groups.

Health expectancy: an indicator for change? Technology Assessment Methods Project Team.

STUDY OBJECTIVE--Health expectancy is an increasingly used indicator of population health status. It collapses both mortality and morbidity into a single indicator, and is therefore preferred to the total life expectancy index for populations with low mortality but high morbidity rates. Three methods of calculation exist: the Sullivan, double decrement, and multi-state methods. This report aims to describe their relative advantages and limitations when used to monitor changes in population health status over time. DESIGN--The differences between the three methods are explained. Using a dynamic model of heart disease, the effect of the introduction of thrombolytic treatment on the survival of patients with acute myocardial infarction is calculated. The resulting changes in health expectancy are calculated according to the Sullivan and multi-state methods. MAIN RESULTS--As opposed to the double decrement and the multi-state methods, the Sullivan method produces spurious trends in health expectancy in response to the change in survival. CONCLUSIONS--Estimates of health expectancy in a dynamic situation can be very misleading when based on the Sullivan method, with its attractively moderate data requirements. The multi-state method, which requires longitudinal studies of population health status, is often indispensable.

An indirect estimate of the incidence of non-insulin-dependent diabetes mellitus.

Our goal was to estimate non-insulin-dependent diabetes mellitus incidence in the Netherlands in the absence of equivocal empirical data. Incidence can be expressed as a function of age, sex, prevalence, and mortality. We obtained prevalence data from a study that pooled existing prevalence estimates. We calculated diabetes-related mortality using relative risks on all-cause mortality. Sensitivity for the rate of excess mortality was determined using the 95% confidence intervals (95% CI) of the relative risks. The estimated incidence increases exponentially with age, with a doubling time of 10 years for men and 9 years for women. The rate increases from 8.1 per 10,000 (95% CI = 7.7-8.8) for men ages 40-44 years and 7.0 (95% CI = 6.8-8.0) for women to 79.7 per 10,000 (95% CI = 69.5-90.9) for men ages 75-79 years and 85.8 (95% CI = 80.6-91.0) for women. When empirical estimates of incidence are largely lacking, the methodology described offers a useful alternative, in particular for the assessment of potential intervention effects.

The burden of mortality of diabetes mellitus in The Netherlands

Our objective was to estimate the excess mortality and the reduction in life expectancy related to diabetes mellitus. We developed a life table to describe the Dutch population in two states, diabetic and non-diabetic, using age- and sex-specific prevalence of diabetes mellitus and risks of dying for diabetic subjects. We compared the calculated excess deaths with registered deaths. The cause-of-death registration practice underestimates diabetes-related mortality. The method used in this study, combining mortality data with data from epidemiologic studies, provides an assessment of the impact of diabetes on the Dutch population.

Ischaemic heart disease and cholesterol There's more to heart disease than cholesterol

EDITOR, - We are impressed by the “cholesterol papers.”*RF 1-3* M R Law and colleagues prove that it is highly probable that lowering the serum cholesterol concentration in the population will reduce the risk of ischaemic heart disease without increasing the risk of other disease. The jump from epidemiological evidence to conclusions regarding public health is not, however, as evident as they suggest. Law and colleagues state that lowering serum cholesterol concentration is critical in reducing ischaemic heart disease. It certainly was not so in the past; why should it be in the future? Several Western populations have seen a steeply decreasing mortality from ischaemic heart disease in association with constant or even increasing cholesterol concentrations.4 If we compare the cohort of the British United Provident Association (BUPA), which was recruited in 1975-82, with the Whitehall cohort, which was recruited one decade earlier, we observe higher serum cholesterol concentrations in all the fifths of the BUPA population (fig 12). Despite this, the incidence of ischaemic heart disease was at least three times lower in the BUPA cohort. As far as we can see - the y axis varies tremendously - the incidence of ischaemic heart disease in the patients with the lowest fifth of serum cholesterol concentration in the Whitehall study was still higher than that in the patients with the highest fifth of cholesterol concentration in the BUPA cohort. In the Whitehall study serum cholesterol concentrations were lower in the lower classes, but the risk of ischaemic heart disease was four times higher than that in the highest.5 Differences in cholesterol concentrations may explain the international variation in mortality from ischaemic heart disease but do not explain the variation in middle aged employed men in London. Before it is concluded that cholesterol concentrations must be reduced …

Diverging trends in colorectal cancer morbidity and mortality. Earlier diagnosis comes at a price

In developed countries, time trends in the incidence of colorectal cancer differ markedly from trends in mortality. This study sought to explain simultaneously changes in both colorectal cancer incidence and mortality. Data on first admissions, interventions and outcome from the national hospital registry over the period 1978-1989 and data on mortality from Statistics Netherlands over the same period were analysed by age-period models and subsequently entered in a Markov chain model, simulating disease history from first admission to death. Over the period 1978-1989, age adjusted numbers of first admissions and interventions increased by 37% and 32%, respectively, while mortality declined by 8%. For every 100 patients admitted between 1987 and 1989, 13 more will survive compared with 1978-1980. Of these, 3 will be saved by improving results of primary treatment but the other 10 will survive their diagnosis for the subsequent 10 years. Although progress in treatment has been made, therapeutic improvement can account only for the smaller part of the divergence between morbidity and mortality. Increased diagnostic activity, raising incidence and lowering mortality simultaneously, is the most likely cause of the unexplained divergence.

The new old epidemic of coronary heart disease

OBJECTIVES This study quantified the consequences for prevalence of increased survival of coronary heart disease (CHD) in the Netherlands from 1980 to 1993. METHODS A multistage life table fitted observed mortality and registration rates from the nationwide hospital register. The outcome was prevalence by age, sex, period, and disease state. RESULTS The prevalence of CHD from 1980 to 1993 was 4.4% (men, aged 25 to 84 years) and 1.4% (women, aged 25 to 84 years). Between 1980-1983 and 1990-1993, the incidence changed little, but age-adjusted prevalence increased by 19% (men) and 59% (women). CONCLUSIONS Sharply decreasing mortality but near-constant attack rates of CHD caused distinct increases in prevalence, particularly among the elderly.

Improvements in treatment of coronary heart disease and the cessation of the stroke mortality rate decline

BACKGROUND AND PURPOSE Many countries observed rapidly declining stroke mortality rates during 1970-1990, followed by a slowing or a cessation of this decline. This slowing was seen for both sexes and all ages. Here we test the hypothesis that improvements in coronary heart disease (CHD) survival can explain this slowing through an increase in the number of CHD survivors at an increased risk for stroke. METHODS We created multistate life-table models based on the survival experience of 46 years of follow-up of the Framingham Heart Study cohort. Improvements in survival after CHD were modeled by decreasing mortality rates for those with CHD. We analyzed whether improved CHD survival could result in a >3% increase in annual stroke mortality rates, which would be enough to eliminate the previously observed decline. RESULTS CHD survival improvements led to an increase in the number of stroke deaths but also a concomitant increase in the total population size. Under no circumstances was there an annual increase in stroke mortality rates approaching 3% for both sexes and for younger and older age groups. CONCLUSIONS The hypothesis that increases in the numbers of people with CHD, as a consequence of improvements in CHD survival, explain the observed slowing of the stroke mortality rate decline must be rejected. The true explanation is also likely to be a factor that changed markedly around 1990, but with more direct effects on stroke mortality.