Describing and explaining time trends in coronary heart disease, stroke and type 2 diabetes
Lead Research Organisation:
University College London
Department Name: UNLISTED
Abstract
Coronary heart disease (CHD) and stroke mortality have fallen in the UK in recent years. In contrast, type 2 diabetes prevalence has increased rapidly. We seek to understand the reasons for these changes, to help prevent the conditions in future.
This is important because although death rates from CHD and stroke have fallen, together these conditions remain the leading cause of death in the UK, responsible for over 200,000 deaths in 2006. Meanwhile, type 2 diabetes is a growing health burden.
Previous studies have suggested that roughly half the decline in CHD mortality is due to improvements in medication, and half due to improvements in lifestyle. However, little research has been done to identify the causes of the fall in stroke mortality and increase in diabetes.
The research will use two data sources, a long-term follow-up study of middle-aged British men and a database from General Practice, to examine the contributions of changes in lifestyle, primary prevention initiatives and medical treatment to the changes in these three conditions which have occurred. It will also examine the paradox of the decline in CHD and stroke at the time of an increase in diabetes (which is a risk factor for both conditions).
This is important because although death rates from CHD and stroke have fallen, together these conditions remain the leading cause of death in the UK, responsible for over 200,000 deaths in 2006. Meanwhile, type 2 diabetes is a growing health burden.
Previous studies have suggested that roughly half the decline in CHD mortality is due to improvements in medication, and half due to improvements in lifestyle. However, little research has been done to identify the causes of the fall in stroke mortality and increase in diabetes.
The research will use two data sources, a long-term follow-up study of middle-aged British men and a database from General Practice, to examine the contributions of changes in lifestyle, primary prevention initiatives and medical treatment to the changes in these three conditions which have occurred. It will also examine the paradox of the decline in CHD and stroke at the time of an increase in diabetes (which is a risk factor for both conditions).
Technical Summary
Background During the last 25 years, time trends in chronic diseases have differed widely. Coronary heart disease (CHD) mortality rates have fallen since the late 1970s; stroke mortality has declined over a longer period. The prevalence of type 2 diabetes (T2DM), in contrast, has increased markedly. However, few attempts have been made to examine the extent to which these changes reflect changes in aetiological exposures, primary prevention and treatment use.
Aims and objectives I will use individual-level data to analyse the most recent trends in coronary heart disease, stroke and diabetes in the UK both in relation to changes in aetiological factors and treatment use and in relation to each other. Specific objectives are to; i) Examine the patterns of decline in CHD and stroke mortality, and the contribution of changes in relevant aetiological factors and treatment use; ii) Examine the patterns of increase in T2DM prevalence and the contribution of changes in relevant aetiological factors (particularly changes in adiposity); iii) Examine the paradox that CHD and stroke have declined while T2DM (a risk factor for both conditions) has increased.
Design Combination of observational cohort study and a routine primary care database
Methodology The British Regional Heart Study (BRHS), an established cohort study, has followed up 7735 British men for cardiovascular morbidity and mortality for over 25 years from 1978 and has obtained information on cardiovascular risk factors and treatment use at repeated intervals. The Health Improvement Network (THIN) comprises longitudinal GP records on over 5 million patients from GP practices across the UK from 1990 onwards and includes demographic information and information on all diagnoses and prescriptions. These data sources will be used to explore variations in trends in the three conditions by age, gender and socioeconomic status; age, period and cohort effects will be formally explored. Regression models with time-dependent covariates will be developed to analyse the contributions of changes in risk factors and treatment use to the disease trends.
Scientific and Medical Opportunities Analysing the contributions of changes in aetiological factors and treatment use to the decline in CVD and increase in diabetes will help us to understand the reasons for recent time trends and may help to inform future efforts to reduce stroke and CHD further and stem the rise in diabetes, both in the UK and in other locations. The models developed to analyse the trends may be applied more widely to other diseases.
Aims and objectives I will use individual-level data to analyse the most recent trends in coronary heart disease, stroke and diabetes in the UK both in relation to changes in aetiological factors and treatment use and in relation to each other. Specific objectives are to; i) Examine the patterns of decline in CHD and stroke mortality, and the contribution of changes in relevant aetiological factors and treatment use; ii) Examine the patterns of increase in T2DM prevalence and the contribution of changes in relevant aetiological factors (particularly changes in adiposity); iii) Examine the paradox that CHD and stroke have declined while T2DM (a risk factor for both conditions) has increased.
Design Combination of observational cohort study and a routine primary care database
Methodology The British Regional Heart Study (BRHS), an established cohort study, has followed up 7735 British men for cardiovascular morbidity and mortality for over 25 years from 1978 and has obtained information on cardiovascular risk factors and treatment use at repeated intervals. The Health Improvement Network (THIN) comprises longitudinal GP records on over 5 million patients from GP practices across the UK from 1990 onwards and includes demographic information and information on all diagnoses and prescriptions. These data sources will be used to explore variations in trends in the three conditions by age, gender and socioeconomic status; age, period and cohort effects will be formally explored. Regression models with time-dependent covariates will be developed to analyse the contributions of changes in risk factors and treatment use to the disease trends.
Scientific and Medical Opportunities Analysing the contributions of changes in aetiological factors and treatment use to the decline in CVD and increase in diabetes will help us to understand the reasons for recent time trends and may help to inform future efforts to reduce stroke and CHD further and stem the rise in diabetes, both in the UK and in other locations. The models developed to analyse the trends may be applied more widely to other diseases.