Mark Woodward

Comparison of the prediction by 27 different factors of coronary heart disease and death in men and women of the Scottish Heart Health Study: cohort study.

Abstract Objective: To compare prediction by 27 different factors in men and women of coronary heart disease events, coronary deaths, and deaths from all causes. Design: Cohort study. Setting: Scottish population study. Subjects: In 1984-7 random sampling of residents aged 40-59 produced 11 629 men and women who generated survey clinic questionnaires, examination findings, and blood and urine specimens. Main outcome measures: Subsequent death, coronary artery surgery, and myocardial infarction. Risks were calculated for each category of factor or fifth of continuous variables. 27 factors were ranked by descending age adjusted hazard ratio of the top to bottom class in each factor, by sex and end point. Results: Follow up averaged 7.6 years, during which the 5754 men had 404 coronary events, 159 coronary deaths, and 383 deaths and the 5875 women 177, 47, and 208 respectively. The rankings for factors for the three end points were mainly similar in men and women, although hazard ratios were often higher in women. Classical risk factors ranked better for predicting coronary risk than newer ones. Yet strong prediction of coronary risk was no guarantee of significant prediction of all cause mortality. Findings included an anomalous coronary protective role for type A behaviour in women; raised plasma fibrinogen as a strong predictor of all end points; and an unexpectedly powerful protective relation of dietary potassium to all cause mortality. Conclusions: These initial unifactorial rankings and comparisons must be interpreted with caution until potential interaction, confounding, and problems of measurement and causation are further explored. Key messages Among Scottish men and women studied for 27 risk factors for coronary heart disease and followed up for eight years classical risk factors scored strongly in predicting coronary risk but the performance of new ones was more variable Risk factors for coronary disease, and also for death, showed few, albeit interesting, differences between men and women Relative risk was often higher for risk factors in women but they had low levels of absolute risk when risk factor levels were low Smoking, blood pressure, and fibrinogen predicted coronary disease and also death, but other factors are less consistent Unifactorial results should not be overinterpreted, but the protective effect of potassium consumption is of particular interest

Nutrient intakes of different social-class groups : results from the Scottish Heart Health Study (SHHS)

Food frequency questionnaire and socio-demographic data were collected from over 10,000 Scottish men and women aged 40-59 years in a cross-sectional study of coronary heart disease (CHD) risk factors. Dietary intake, including the antioxidant vitamins C and E and beta-carotene, was assessed for different socio-economic groups. Trends in nutrient intakes were found with social-class (occupational) groups I-V. The non-manual-manual distinctions were clear even after standardizing for serum cotinine, and alternative classification by housing tenure and level of education did not confound the social-class effect. Total energy intake was significantly higher in the manual (men 10,363 KJ, women 7507 KJ) than in the non-manual (men 9156 KJ, women 7169 KJ) groups, and all nutrient amounts except for vitamin C, vitamin E, beta-carotene and fibre were significantly higher in the manual than the non-manual groups. Alcohol intake was lower in manual women, but higher in manual men compared with their respective non-manual groups. Sex and social-class differences were maintained after adjusting for total energy. Women in general, and manual women in particular, had the highest percentage energy from total fat (40.2) and saturated fat (18.2), while the percentage energy from polyunsaturated fat was lower in men than women, and lowest in manual men (4.4). The polyunsaturated:saturated fat (P:S) ratios were, for non-manual and manual men 0.32 and 0.31, and for non-manual and manual women 0.31 and 0.28. Fibre and antioxidant vitamin intakes, when expressed as nutrient densities, were lower in men than women, and lowest in manual men. Overall, men and women in manual occupations had a poorer-quality diet than did those in non-manual occupations. The coincident low P:S ratios and low antioxidant vitamin intakes in manual groups may contribute to an increased risk of CHD. Thus, the findings are compatible with the view that poor diet may be a contributory factor to the higher mortality rates for CHD which occur in the lower socio-economic groups.

Social status and coronary heart disease: Results from the Scottish heart health study☆

Social status has frequently been found to be associated with the prevalence of coronary heart disease. Currently, in developed countries, it seems that the least advantaged social groups are at the greatest risk. This article addresses this issue in the Scottish population, using a cross-sectional sample of 10,359 men and women. Four measures of social status are used: level of education, years of education, housing tenure, and the Office of Population Censuses and Surveys definition of social class based on occupation. By each of these four criteria, and for both sexes, the least advantaged have a significantly higher coronary heart disease prevalence (P less than 0.01). The odds ratios for housing tenure are highest, being 1.63 and 1.55 for men and women, respectively, comparing those who live in rented accommodation with owner-occupiers. After adjustment for a number of coronary heart disease risk factors, which are possible confounding variables, most, if not all, of the significant effect of education and occupation on coronary heart disease is removed. Housing tenure is still highly significant (P less than 0.001), with odds ratios of 1.48 and 1.45 for men and women, respectively. Smoking and fibrinogen are the most important confounding variables for men, and body mass index, high-density lipoprotein cholesterol, and triglyceride levels, the most important for women. When relationships among the social factors themselves are investigated, housing tenure is found to remove the significant effects of education and occupation in men, and of education in women. No other social factor removes the significant effect of housing tenure (P less than 0.001). Housing tenure in Scotland is thus found to be the most discriminatory measure of social status in relation to coronary heart disease.

Smoking characteristics and inhalation biochemistry in the Scottish population

Data from a cross-sectional random population sample of 10,359 middle-aged Scottish men and women are used to investigate the relationships between self-reported tobacco consumption and three biochemical markers of tobacco inhalation: expired air carbon monoxide (CO), serum thiocyanate and serum cotinine. These data represent one of the largest samples of these biochemical markers yet analysed. The results show that, for each sex, the biochemical markers are highly correlated for smokers and for the entire sample of mixed smokers and non-smokers. CO is the preferred biochemical marker, in such groups, because it is the cheapest, is non-invasive and gives virtually instantaneous results. Self-reported daily cigarette consumption also correlates well with each of these biochemical markers, and so it appears that people are, in the context of population studies, mainly truthful about their smoking. The relationships with self-reported cigarette consumption are curvilinear with apparent levelling out of the gradient at around 25 cigarettes/day for cotinine and thiocyanate and at greater than 40 cigarettes/day for CO. Sex differences are small, although thiocyanate is generally higher and cotinine generally lower in women with the same self-reported cigarette consumption as men. Amongst non-smokers, only cotinine is able to discriminate between self-reported levels of exposure to passive smoking. CO and thiocyanate are not suitable for measuring low levels of smoke inhalation, such as found in passive smokers.

Tea drinking, passive smoking, smoking deception and serum cotinine in the Scottish heart health study

Following a recent claim that the use of cotinine in body fluids, to assess passive smoking and smoking deception, was confounded by metabolic individuality, and by non-tobacco sources of dietary nicotine, particularly tea, data were examined from a large cross-sectional survey in a tea-drinking population. In 3383 men and women aged 40-59 years from the Scottish Heart Health Study, defined as non-smokers, both by self-report and by low thiocyanate and expired air carbon monoxide levels, serum cotinine showed minimal association with self-reported daily average tea consumption. However, there was a strong correlation between degree of self-reported passive tobacco smoke exposure and median serum cotinine level. In the same survey, serum cotinine in 4144 self-reported non-smokers and in 3326 smokers showed entirely different distributions, but the same range, suggesting heavy nicotine intake in some non-smokers. These analyses confirm that cotinine levels in true non-smokers reflect far more the nicotine in inhaled ambient tobacco smoke than they do nicotine in tea. Some smoking deceivers have the same degree of exposure to nicotine as heavy smokers. Despite individual variability, the claim of confounding is poorly supported, and cotinine is confirmed as an indicator both of passive smoking and of smoking deception.

An iterative technique for identifying smoking deceivers with application to the scottish heart health study

BACKGROUNDnThe study population consists of 3,977 self-declared nonsmokers for whom complete data on smoking biochemistry were available. Data were obtained from the Scottish Heart Health Study, a random cross-sectional population sample of 40- to 59-year-old men and women.nnnMETHODSnThree biochemical markers of smoking (expired-air carbon monoxide, serum thiocyanate, and serum cotinine) are used together to derive optimum cut-points for distinguishing true nonsmokers from self-declared nonsmokers who are smoking deceivers, using an iterative procedure via a computer program.nnnRESULTSnThe cut-points derived are, for carbon monoxide, 6 ppm (sensitivity, 0.81, and specificity, 0.94, when compared with the other two biochemical markers combined), for thiocyanate, 63.4 mumol/liter (sensitivity, 0.75; specificity, 0.92), and, for cotinine, 17.5 ng/ml (sensitivity, 0.77; specificity, 0.98). These cut-points are generally lower than those reported previously, primarily because other studies have taken self-reported smoking status to be the truth. The presence of deceivers among declared nonsmokers would tend to raise the biochemical levels of this group and hence of the cut-points.nnnCONCLUSIONnThe prevalence of smoking deception in the Scottish population is low: the frequency of those at or above all three cut-points is 1.2%, at or above two or more (the preferred definition of a smoking deceiver) is 2.2%, and at or above at least one is 16.4%.