Elsevier

The Lancet

Volume 353, Issue 9164, 8 May 1999, Pages 1547-1557
The Lancet

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Contribution of trends in survival and coronar y-event rates to changes in coronary heart disease mortality: 10-year results from 37 WHO MONICA Project populations

https://doi.org/10.1016/S0140-6736(99)04021-0Get rights and content

Summary

Background

The WHO MONICA (monitoring trends and determinants in cardiovascular disease) Project monitored, from the early 1980s, trends over 10 years in coronary heart disease (CHD) across 37 populations in 21 countries. We aimed to validate trends in mortality, partitioning responsibility between changing coronary-event rates and changing survival.

Methods

Registers identified non-fatal definite myocardial infarction and definite, possible, or unclassifiable coronary deaths in men and women aged 35–64 years, followed up for 28 days in or out of hospital. We calculated rates from population denominators to estimate trends in age-standardised rates and case fatality (percentage of 28-day fatalities=[100-survival percentage]).

Findings

During 371 population-years, 166 000 events were registered. Official CHD mortality rates, based on death certification, fell (annual changes: men −4·0% [range −10·8 to 3·2]; women −4·0% [-12·7 to 3·0]). By MONICA criteria, CHD mortality rates were higher, but fell less (-2·7% [-8·0 to 4·2] and −2·1% [-8·5 to 4·1]). Changes in non-fatal rates were smaller (-2·1%, [-6·9 to 2·8] and −0·8% [-9·8 to 6·8]). MONICA coronary-event rates (fatal and non-fatal combined) fell more (-2·1% [-6·5 to 2·8] and −1·4% [-6·7 to 2·8]) than case fatality (-0·6% [-4·2 to 3·1] and −0·8% [-4·8 to 2·9]). Contribution to changing CHD mortality varied, but in populations in which mortality decreased, coronary-event rates contributed two thirds and case fatality one third.

Interpretation

Over the decade studied, the 37 populations in the WHO MONICA Project showed substantial contributions from changes in survival, but the major determinant of decline in CHD mortality is whatever drives changing coronary-event rates.

Introduction

The WHO MONICA (monitoring trends and determinants in cardiovascular disease) Project was designed to answer key questions arising from the 1978 Bethesda Conference on the Decline in Coronary Heart Disease Mortality.1 The continuing relevance of these questions was highlighted by results from the ARIC study.2 Are reported declines in coronary heart disease (CHD) mortality genuine? If they are, how much is attributable to improved survival rather than to declining coronary-event rates? Consequential hypotheses arise from the latter question about inter-relations of changes in coronary-event rates, survival (or case fatality), risk factors, and coronary care.

The WHO MONICA Project set out to measure, within defined populations over 10 years, trends in rates of events from CHD and their case fatality, trends in risk factors, and trends in acute coronary care.3, 4, 5 The protocol, developed between 1979 and 1982, identified six possible associations: between risk factors and incidence; medical care and case fatality; incidence and case fatality; medical care and incidence; risk factors and case fatality; and medical care and risk factors. The first two relations, between trends in risk factors and incidence (or event rates) and between trends in coronary care and case fatality, were the basis of the two major null hypotheses of the study, reflecting the continuing concerns of those involved in health promotion versus those involved in coronary care (WHO MONICA Project protocol available at: URL: www.ktl.fi/publications/monica/manual/part1/i-l.htm URN: NBN:fi-fe 19981147).

This report covers the first definitive 10-year results from 37 populations in 21 countries across four continents. It addresses the original Bethesda questions. The results of standardised measurement of trends are compared with the routine mortality statistics. We estimate the contribution to trends in validated CHD mortality of changing survival compared with changing coronary-event rates.

Section snippets

Registration of events

MONICA populations and registration procedures have been described with full specification of diagnostic criteria (for relevant section of MONICA Manual see URL: www.ktl.fi/publications/monica/manual/part4/iv-1.htm URN: NBN:fi-fe 19981154).5 Standard coding and criteria were applied throughout, with internal and external quality control, to validate all suspected coronary events in individuals aged 35–64 years of defined populations. MONICA coronary events were made up of specified non-fatal

Availability and quality of data

37 populations provided data for this report on men and women aged 35–64 years. Table 1 lists the populations, years of registration, and population sizes. Most populations provided data for 10 years (range 8–14), and all provided data for 1985–91. Table 1 shows centrally generated quality scores for the coronary-event and demographic data from which event rates and trends were calculated. In the WHO MONICA Project a full score is 2·0 and 0 denotes at least one serious problem with the data,

Discussion

The WHO MONICA Project arose from recognition in 1978 that the reported decline in mortality from CHD in the USA was neither validated nor explained.1 Collection of standard data, from many heterogeneous populations over 10 years, would facilitate general understanding. The protocol was, however, impracticable for less-developed countries without adequate diagnostic facilities or population denominators. It was also a challenge for more-developed countries, with some participants dropping out.

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