Background:
Although the rate of death (mortality) from Coronary Heart Disease (CHD) has halved since the 1970s, CHD remains a major cause of all-cause mortality in the UK. Furthermore, population ageing plus recent increases in obesity and diabetes may soon increase total CHD deaths. Predictions of future CHD mortality are thus potentially problematic. Here we explore future projections of CHD mortality in England & Wales under two conventional but dramatically contrasting assumptions.
Materials and Methods:
In SCENARIO A, we used a conventional counterfactual, assuming that the last-observed CHD mortality rates (ONS) from 2011 would persist unchanged to 2030.The future number of deaths was then calculated by applying those rates onto 2012-2030 population estimates. In SCENARIO B, we assumed that the recent trend in CHD mortality rates would continue. We used a well-established hierarchical Bayesian Age Period Cohort (BAPC) model, which works under the assumption that variability in CHD mortality can be explained by a combination of age, period and cohort effects. We fitted this model to the observed CHD mortality from 1979 to 2011 and then continued the linear trends in age, period and cohort effects up to 2030. We then used the BAPC model to predict mortality rates in 2012-2030, and then applied these rates to population projections to compute future deaths.
Results:
In scenario A, by assuming that 2011 mortality rates would continue at that level, the number of CHD deaths would increase 61.5% (39,597 of 64,323) by 2030. In scenario B, by assuming recent trends continued, the number of deaths would decrease 56.7% (-36,500 of 64,323) by 2030. This substantial decrease would occur despite a predicted slowing of mortality decline in middle aged groups.
Conclusion:
The decline in CHD mortality has been reasonably continuous since 1979, and there is little reason to believe it will soon halt. The underlying assumption of a commonly used mortality counterfactual thus appears slightly dubious. By contrast, the BAPC model offers a far more plausible prediction of future trends by simultaneously considering age, period and cohort effects and projecting each into the future. Thus, despite population ageing, we estimated that the number of CHD deaths would halve again between 2011 and 2030. Even so, shifts in population risk factors might still cause CHD mortality to move away from a trajectory of decline. There is no room for complacency and the promotion of cardiovascular health remains a top policy priority.
The future impact of population growth and aging on coronary heart disease in China: projections from the Coronary Heart Disease Policy Model-China
