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

Background The WHO MONICA (monitoring trends and determinants in cardiovasc ular disease) Project monitored, from the early 1980s, trend over 10 years in coronary heart disease (CHD) across 37 populations in 21 countries. We a imed to validate trends in mortality, partitioning responsibility between c hanging coronary-event rates and changing survival. Methods Registers identified non-fatal definite myocardial infarction and d efinite, 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 r ates from population denominators to estimate trends in age-standardised ra tes and case fatality (percentage of 28-day fatalities=[100-survival percen tage]). Findings During 371 population-years, 166 000 events were registered. Offic ial 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 cr iteria, CHD mortality rates were higher, but felt 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]). Cont ribution to changing CHD mortality varied, but in populations in which mort ality decreased, coronary-event rates contributed two thirds and case fatal ity one third. Interpretation Over the decade studied, the 37 populations in the WHO MONIC A Project showed substantial contributions from changes in survival, but th e major determinant of decline in CHD mortality is whatever drives changing coronary-event rates.