Differences in coronary heart disease, stroke and cancer mortality rates between England, Wales, Scotland and Northern Ireland: the role of diet and nutrition

Abstract

Introduction

It is unclear how much of the geographical variation in coronary heart disease (CHD), stroke and cancer mortality rates within the UK is associated with diet. The aim of this study is to estimate how many deaths from CHD, stroke and cancer would be delayed or averted if Wales, Scotland and Northern Ireland adopted a diet equivalent in nutritional quality to the English diet.

Methods

Mortality data for CHD, stroke and 10 diet-related cancers for 2007–2009 were used to calculate the mortality gap (the difference between actual mortality and English mortality rates) for Wales, Scotland and Northern Ireland. Estimates of mean national consumption of 10 dietary factors were used as baseline and counterfactual inputs in a macrosimulation model (DIETRON). An uncertainty analysis was conducted using a Monte Carlo simulation with 5000 iterations.

Results

The mortality gap in the modelled scenario (achieving the English diet) was reduced by 81% (95% credible intervals: 62% to 108%) for Wales, 40% (33% to 51%) for Scotland and 81% (67% to 99%) for Northern Ireland, equating to approximately 3700 deaths delayed or averted annually. For CHD only, the mortality gap was reduced by 88% (69% to 118%) for Wales, 58% (47% to 72%) for Scotland, and 88% (70% to 111%) for Northern Ireland.

Conclusion

Improving the average diet in Wales, Scotland and Northern Ireland to a level already achieved in England could have a substantial impact on reducing geographical variations in chronic disease mortality rates in the UK. Much of the mortality gap between Scotland and England is explained by non-dietary risk factors.

Article summary

Article focus

• Scotland, Wales and Northern Ireland experience excess cardiovascular and cancer mortality compared to England.

• How much of this excess mortality is associated with differences in diet and nutrition in the four countries of the UK?

Key messages

• Modelled results suggest that if Wales and Northern Ireland achieved an average diet equivalent in nutritional quality to the average diet in England, then 81% of the excess cardiovascular and cancer mortality experienced in these countries would be removed.

• If Scotland achieved an average diet equivalent in nutritional quality to the average diet in England, then 40% of the excess cardiovascular and cancer mortality would be removed.

• For Wales, Scotland and Northern Ireland, changes in diet would have the biggest impact on inequalities in coronary heart disease mortality.

Strengths and limitations of this study

• The macrosimulation model used for the analysis is parameterised using meta-analyses of cohort and case–control studies, and considers 10 different dietary factors and 10 mortality outcomes.

• Uncertainty analysis, allowing parameter estimates to vary stochastically according to distributions reported in the literature, allow for an assessment of the uncertainty of the presented results.

• The model is parameterised from meta-analyses of observational studies, and therefore it is not possible to exclude the possibility of residual confounding.