European Heart Journal (1992) 13, 1602-1605
Height: a risk marker for ischaemic heart disease: prospective results from the Caerphilly and Speedwell Heart Disease Studies J. W. G. YARNELL*, E. S. LIMB*, J. M. LAYZELL* AND I. A.
* Medical Research Council Epidemiology Unit, Llandough Hospital, Penan h CF6 IXX, South Glamorgan, U.K.; tBristol and Weston Health Authority, Bristol, U.K. KEY WORDS: Ischaemic heart disease, height, social factors. The predictive power of height for future ischaemic heart disease (IHD) was examined in 4860 men from two communities in South Wales and the West of England. At follow-up, men in the shortest fifth of the height distribution had experienced twice as many incident IHD events (fatal and non-fatal myocardial infarction) as was the case for men from the tallest fifth. Adjustment for age, social class and smoking habit failed to alter these relationships significantly. In the data from South Wales, determinants of height were examined; birth rank and number of siblings showed a trend with height. This trend was found only in men whose fathers were manual workers and may be related to inadequate nutrition in the higher birth ranks and larger families. These results support the suggestion that early childhood factors may be relevant to IHD in middle age and possible mechanisms are discussed.
Introduction
Social factors have been associated with disease prevalence and incidence since the beginning of epidemiology, and ischaemic heart disease (IHD) is no exception. In the 1940s and '50s deaths in Britain certified as from IHD were highest in the professional classes and white collar workers. But by the early 1970s the trend had reversed in men under 55 years of age and there is now a 32% excess of IHD mortality among manual workers of all ages1'1. Several recent studies'2^*' have focused on social factors operating in childhood in order to explain the current social distribution of IHD. Height has been suggested151 as a marker for adverse environmental conditions in childhood, which are believed to be mainly nutritional'61. Recently, however, these studies have been questioned with data'71 which show that present day socio-economic circumstances appear to be equally as important as the early childhood factors. The British Regional Heart Study recently reported a relationship between height and IHD but they concluded that the effect could be largely attributed to a closely correlated variable; lung function'8'. In the present paper we examine the relationship between height and IHD, the influence of lung function, and childhood circumstances which contribute to the relationship. Methods STUDY POPULATIONS
A total sample of men was selected from within a defined area (total population, 40 000) of Caerphilly Submitted for publication on 5 March 1992, and in revised form 8 July 1992. Correspondence. DrJ Yarnell, MRC Epidemiology Unit. Llandough Hospital. PenarthCF6 IXX. U.K.. 0I95-668X 92 121602 + 04 SOS 00 0
town and several surrounding villages using the electoral registers and general practitioner records. They were aged between 45 and 59 years when first examined. A total of 2512 men were seen —89% of the 2818 found to be eligible. In Speedwell, a 100% sample of men was selected from the age-sex registers of 16 general practitioners working from two neighbouring health centres. These men were aged between 45 and 63 years when first examined. A total of 2348 men were seen — 92% of those found to be eligible. The combined cohort thus numbers 4860 men. SURVEY METHODS AND FOLLOW-UP PROCEDURE
The two studies had a common core protocol and common methodologies. These have been described in detail elsewhere'9101. At recruitment, the men attended an afternoon or evening clinic at which a standard medical and smoking history was obtained. The London School of Hygiene and Tropical Medicine Chest Pain Questionnaire was administered, height, weight and blood pressure were measured and a 12-lead ECG was recorded. Lung function was measured in Caerphilly men only, by the use of a McDermott spirometer. Two practice attempts were made and mean values calculated from a further three readings. Values for FEV, (forced expiratory volume) and FVC (forced vital capacity) were automatically standardized for ambient temperature and pressure. The initial questionnaire in the Caerphilly study included questions on the number of siblings, birth rank, father's occupation and any unemployment of the father when the subject was under 10 years of age, birthweight and history of breast feeding. Where possible, subjects were asked to obtain the information on the latter two items from their mother or other close relative. This questionnaire was not given to the subjects in Speedwell. >1992 The European Society of Cardiology
Height: a risk marker for IHD 1603
The subject's present social class and that of his father was coded by the Registrar General's Classification of Occupations, 1970. This paper reports the first follow-up of the men; in Caerphilly, this was at a nearly constant interval of 61 months (SD = 5), whilst in Speedwell the mean follow-up period was 38 months (SD = 3). At follow-up, the Chest Pain Questionnaire was administered again, and a second ECG recorded. The Chest Pain Questionnaire was extended to include questions about hospitalization for severe chest pain. Those, together with Hospital Activity Analysis notifications of admissions coded as 410-414 (ischaemic heart disease) on the International Classification of Diseases, were used as the basis for a search of hospital notes for events which satisfied the World Health Organisation criteria for definite acute myocardial infarction. For men who had died before the follow-up, a copy of the death certificate was automatically received from the National Health Service Central Registry. From this information, three categories of incident ischaemic heart disease events were defined: ischaemic heart disease death (cause of death coded as 410-414 on the International Classification of Diseases), clinical non-fatal myocardial infarction (an event satisfying the World Health Organisation criteria) and electrocardiographic myocardial infarction (appearance of major or moderate Q/QS waves, Minnesota codes 1-1-1 through 1-2-5 or 1-2-7 on the follow-up electrocardiogram when there were no Q/QS waves, Minnesota codes 1 -1 -any or 1 -2-any or 1-3-any, on the recruitment electrocardiogram). All electrocardiograms were read by experienced observers. The same observers read, independently, baseline and follow-up electrocardiograms for both studies.
Table 1 Number of cases (non-fatal and fatal) of ischaemic heart disease and relative odds (95% Cl) by each fifth of height distribution in each study cohort Height (mm)
Caerphilly cohort
Height: a risk marker for ischaemic heart disease: prospective results from the Caerphilly and Speedwell Heart Disease Studies J. W. G. YARNELL*, E. S. LIMB*, J. M. LAYZELL* AND I. A.
* Medical Research Council Epidemiology Unit, Llandough Hospital, Penan h CF6 IXX, South Glamorgan, U.K.; tBristol and Weston Health Authority, Bristol, U.K. KEY WORDS: Ischaemic heart disease, height, social factors. The predictive power of height for future ischaemic heart disease (IHD) was examined in 4860 men from two communities in South Wales and the West of England. At follow-up, men in the shortest fifth of the height distribution had experienced twice as many incident IHD events (fatal and non-fatal myocardial infarction) as was the case for men from the tallest fifth. Adjustment for age, social class and smoking habit failed to alter these relationships significantly. In the data from South Wales, determinants of height were examined; birth rank and number of siblings showed a trend with height. This trend was found only in men whose fathers were manual workers and may be related to inadequate nutrition in the higher birth ranks and larger families. These results support the suggestion that early childhood factors may be relevant to IHD in middle age and possible mechanisms are discussed.
Introduction
Social factors have been associated with disease prevalence and incidence since the beginning of epidemiology, and ischaemic heart disease (IHD) is no exception. In the 1940s and '50s deaths in Britain certified as from IHD were highest in the professional classes and white collar workers. But by the early 1970s the trend had reversed in men under 55 years of age and there is now a 32% excess of IHD mortality among manual workers of all ages1'1. Several recent studies'2^*' have focused on social factors operating in childhood in order to explain the current social distribution of IHD. Height has been suggested151 as a marker for adverse environmental conditions in childhood, which are believed to be mainly nutritional'61. Recently, however, these studies have been questioned with data'71 which show that present day socio-economic circumstances appear to be equally as important as the early childhood factors. The British Regional Heart Study recently reported a relationship between height and IHD but they concluded that the effect could be largely attributed to a closely correlated variable; lung function'8'. In the present paper we examine the relationship between height and IHD, the influence of lung function, and childhood circumstances which contribute to the relationship. Methods STUDY POPULATIONS
A total sample of men was selected from within a defined area (total population, 40 000) of Caerphilly Submitted for publication on 5 March 1992, and in revised form 8 July 1992. Correspondence. DrJ Yarnell, MRC Epidemiology Unit. Llandough Hospital. PenarthCF6 IXX. U.K.. 0I95-668X 92 121602 + 04 SOS 00 0
town and several surrounding villages using the electoral registers and general practitioner records. They were aged between 45 and 59 years when first examined. A total of 2512 men were seen —89% of the 2818 found to be eligible. In Speedwell, a 100% sample of men was selected from the age-sex registers of 16 general practitioners working from two neighbouring health centres. These men were aged between 45 and 63 years when first examined. A total of 2348 men were seen — 92% of those found to be eligible. The combined cohort thus numbers 4860 men. SURVEY METHODS AND FOLLOW-UP PROCEDURE
The two studies had a common core protocol and common methodologies. These have been described in detail elsewhere'9101. At recruitment, the men attended an afternoon or evening clinic at which a standard medical and smoking history was obtained. The London School of Hygiene and Tropical Medicine Chest Pain Questionnaire was administered, height, weight and blood pressure were measured and a 12-lead ECG was recorded. Lung function was measured in Caerphilly men only, by the use of a McDermott spirometer. Two practice attempts were made and mean values calculated from a further three readings. Values for FEV, (forced expiratory volume) and FVC (forced vital capacity) were automatically standardized for ambient temperature and pressure. The initial questionnaire in the Caerphilly study included questions on the number of siblings, birth rank, father's occupation and any unemployment of the father when the subject was under 10 years of age, birthweight and history of breast feeding. Where possible, subjects were asked to obtain the information on the latter two items from their mother or other close relative. This questionnaire was not given to the subjects in Speedwell. >1992 The European Society of Cardiology
Height: a risk marker for IHD 1603
The subject's present social class and that of his father was coded by the Registrar General's Classification of Occupations, 1970. This paper reports the first follow-up of the men; in Caerphilly, this was at a nearly constant interval of 61 months (SD = 5), whilst in Speedwell the mean follow-up period was 38 months (SD = 3). At follow-up, the Chest Pain Questionnaire was administered again, and a second ECG recorded. The Chest Pain Questionnaire was extended to include questions about hospitalization for severe chest pain. Those, together with Hospital Activity Analysis notifications of admissions coded as 410-414 (ischaemic heart disease) on the International Classification of Diseases, were used as the basis for a search of hospital notes for events which satisfied the World Health Organisation criteria for definite acute myocardial infarction. For men who had died before the follow-up, a copy of the death certificate was automatically received from the National Health Service Central Registry. From this information, three categories of incident ischaemic heart disease events were defined: ischaemic heart disease death (cause of death coded as 410-414 on the International Classification of Diseases), clinical non-fatal myocardial infarction (an event satisfying the World Health Organisation criteria) and electrocardiographic myocardial infarction (appearance of major or moderate Q/QS waves, Minnesota codes 1-1-1 through 1-2-5 or 1-2-7 on the follow-up electrocardiogram when there were no Q/QS waves, Minnesota codes 1 -1 -any or 1 -2-any or 1-3-any, on the recruitment electrocardiogram). All electrocardiograms were read by experienced observers. The same observers read, independently, baseline and follow-up electrocardiograms for both studies.
Table 1 Number of cases (non-fatal and fatal) of ischaemic heart disease and relative odds (95% Cl) by each fifth of height distribution in each study cohort Height (mm)
Caerphilly cohort
