Environmental and behavioural determinants of geographic variation in coronary heart disease in England: an ecological study

Thesis

Coronary heart disease rates show substantial geographic variation in England, which could be due to environmental variables (e.g. climate, air quality) or behavioural risk factors for coronary heart disease within populations. Previous work investigating this geographic variation has either used ecological analysis (i.e. areas as units of observation) or individual-level analysis. Ecological studies have been unable to account adequately for differences in behavioural risk factors within populations; individual-level studies have been under-powered at the area-level to include all potentially explanatory environmental variables. This thesis reports on ecological multi-level and spatial error regression analyses of coronary heart disease mortality and hospitalisation rates for all wards in England using environmental variables and synthetic estimates of the prevalence of behavioural risk factors as explanatory variables. Existing sets of synthetic estimates were subjected to studies of their validity. Validated synthetic estimates of the prevalence of smoking, low fruit and vegetable consumption, raised blood pressure, obesity and raised cholesterol were combined into a single index of unhealthy lifestyle to take account of collinearity between them. Final models successfully explained around 80% of large scale geographic variation (i.e. variation between wards in different areas of the country) in mortality rates for coronary heart disease and 60% in hospitalisation rates, and around 20% of the small scale geographic variation (i.e. variation between wards in close proximity) in mortality rates, and 30% in hospitalisation rates. The climate explained around 15% of large scale geographic variation in coronary heart disease rates after adjustment for the index of unhealthy lifestyle and socioeconomic deprivation. Urbanicity and air pollution explained a small amount of small scale geographic variation in coronary heart disease rates. The majority of explained geographic variation was due to the index of unhealthy lifestyle and deprivation. The results of this thesis confirm and extend findings from the British Regional Heart Study, report on the validity of synthetic estimates currently used to guide healthcare resource allocation, and introduce an index of unhealthy lifestyle that could be used in future ecological studies of chronic disease.

Authors: Scarborough, P; Pete Scarborough

• Publication date: 2009
• DOI: 10.5287/ora-2ny2dgzjb
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: Oxford University, UK
• Language: English
• Keywords: coronary heart disease; synthetic estimates; inequality; geographic variation
• Subjects: Cardiovascular disease