Caerphilly Heart Disease Study
The Caerphilly Heart Disease Study, also known as the Caerphilly Prospective Study (CaPS), is an epidemiological prospective cohort, set up in 1979 in a representative population sample drawn from Caerphilly, a typical small town in South Wales, UK.[1]
The initial aim was to examine relationships between a wide range of social, lifestyle, dietary and other factors with incident vascular disease. Opportunity was also taken, in collaboration with a range of clinical and laboratory colleagues, to collect data on a wide range of factors with possible relevance to diseases other than vascular, and at the same time to collect clinical information on incident disease events. The study was initiated by Professor Peter Elwood, Director of the Medical Research Council (MRC) Epidemiology Unit for South Wales. The work has so far led to over 400 publications in the medical press.
History
In 1948, an MRC epidemiological unit was set up in
The randomised controlled trial of
Detailed work was also completed on thrombosis and
At baseline, a 1:3 sample (668 men) completed a 7-day weighed dietary intake record. Data on the dietary intake of each subject in the cohort was collected during each phase of the study.
Ten years into the study a detailed package of
Major findings
Healthy lifestyles
The Caerphilly Study gave opportunity to study the relationship between lifestyle choices and health in a representative population sample drawn from a typical small town in the UK.[16] The participants were asked detailed questions at baseline and at subsequent examinations about lifestyle behaviours, enabling the men to be classified in terms of five healthy behaviours:
- Non-smoking
- A low body weight (BMI18–25)
- Regular exercise (30 minutes walking or equivalent, five days per week)
- A low fat diet, combined with daily intake of five portions of fruit and vegetables.
- An intake of alcohol within accepted guidelines (21 or less units of alcohol per week).
These healthy behaviours displayed significant negative associations with cognitive impairment and dementia, with participant disease outcomes falling as the number of healthy behaviours followed increased. Men who followed four or five of the healthy behaviours during 30 years of follow-up experienced on average a 73% reduction in diabetes, a 67% reduction in vascular disease, a 35% reduction in cancer (attributable to non-smoking alone) and a 64% reduction in cognitive impairment and dementia.[16]
Healthy behaviours are the responsibility of each individual,[17] and <1% of the men in the Caerphilly Study followed all five, with only 5% following four consistently.[16] Comparisons with data collected in the 2009 Welsh Health Survey indicate that while the pattern of behaviours has changed, the proportions of subjects following four or five of the healthy behaviours has scarcely altered over the past 30 years.[18]
The Caerphilly Study estimated the likely effect of increased healthy living within the community by supposing that each man in the Caerphilly cohort had each been urged at the start of the study in 1979 to adopt just one additional healthy behaviour. If only half of them had complied, then over the following 30 years 12% fewer would have developed diabetes; 6% fewer would have had a vascular disease event; 13% fewer would have developed dementia; and there would have been 5% fewer deaths.[16] A video summarising this work is available on YouTube.[19]
Cognitive function
Participants were asked to obtain from a close female relative the details of their own birth weight and how they had been fed as infants. Over half of the men obtained these details, and results showed that having been breast fed conferred some protection against the loss of cognitive function later in life, particularly in those whose birth weight had been low.[20]
Smoking, alcohol intake and leisure activities are lifestyle factors which were found to be predictive of cognitive function.
In diabetic subjects, it was found that poor control of blood sugar was associated with a lower cognitive function, and diabetes per se, but none of the components of metabolic syndrome, other than high blood pressure, were predictive of worse cognition.[24] Hearing loss was also found to be predictive of later cognitive impairment and incident dementia.[25]
Platelets and thrombosis
The main objective of the work on
No prediction for heart disease was shown by any aspect of platelet morphology nor any platelet test, nor by the bleeding time test. An unexpected finding was that the men who had had the most active platelets in two tests, based on platelet rich plasma and whole blood, had the lowest subsequent risk of an incident ischaemic stroke.[26]
Diet and dietary items
Detailed analyses of the dietary data identified a number of food items related to vascular disease risk. The consumption of fatty fish was associated with lower levels of blood lipids,[27] and a reduction in vascular disease mortality was confirmed in a randomised trial.[28]
Milk consumption was found to be associated with a small reduction in the metabolic syndrome,[29] and reductions in ischaemic heart disease, ischaemic stroke and diabetes,[30] and these findings were confirmed in later overviews and meta-analyses.[31] A reduction in blood pressure associated with milk consumption is well recognised, but new work in Caerphilly also identified a reduction in arterial stiffness associated with milk consumption.[8]
The consumption of fruit and vegetables was shown to be positively associated with blood antioxidant levels.[32] Detailed work with Serge Renaud on platelet activity showed a beneficial relationship between a low alcohol consumption and platelet aggregation, but an enhanced response to thrombin with binge drinking, confirming previous work in animals.[33]
Sleep
A detailed questionnaire of sleep pattern was included in one of the re-examinations of the men. In addition to the association with cognitive function already mentioned,[23] there was evidence of an increase in ischaemic stroke in men whose sleep is frequently disturbed, and an association between daytime sleepiness and a significant increase in ischaemic heart disease.[34]
Other studies
Many analyses of foods and dietary factors were conducted, as well as an examination of Helicobacter pylori and other infections, and vascular disease risk.[35][36][37] A reduction in vascular disease mortality was found in those subjects most sexually active.[38] Relationships between vascular disease and psychiatric symptoms,[39][40] noise exposure,[41][42] and hearing loss[25] were also identified.
References
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