Social Class Differences in Secular Trends in Established Coronary Risk Factors over 20 Years: A Cohort Study of British Men from 1978–80 to 1998–2000

Richard W. Morris,S. G. Wannamethee,Peter H. Whincup,Sarah L. Hardoon,Mike B. Gravenor,Lucy T. Lennon,Sheena E. Ramsay

doi:10.1371/journal.pone.0019742

Richard W. Morris, S. G. Wannamethee + Show 5 more

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https://doi.org/10.1371/journal.pone.0019742

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Abstract

BackgroundCoronary heart disease (CHD) mortality in the UK since the late 1970s has declined more markedly among higher socioeconomic groups. However, little is known about changes in coronary risk factors in different socioeconomic groups. This study examined whether changes in established coronary risk factors in Britain over 20 years between 1978–80 and 1998–2000 differed between socioeconomic groups.Methods and FindingsA socioeconomically representative cohort of 7735 British men aged 40–59 years was followed-up from 1978–80 to 1998–2000; data on blood pressure (BP), cholesterol, body mass index (BMI) and cigarette smoking were collected at both points in 4252 survivors. Social class was based on longest-held occupation in middle-age. Compared with men in non-manual occupations, men in manual occupations experienced a greater increase in BMI (mean difference = 0.33 kg/m2; 95%CI 0.14–0.53; p for interaction = 0.001), a smaller decline in non-HDL cholesterol (difference in mean change = 0.18 mmol/l; 95%CI 0.11–0.25, p for interaction≤0.0001) and a smaller increase in HDL cholesterol (difference in mean change = 0.04 mmol/l; 95%CI 0.02–0.06, p for interaction≤0.0001). However, mean systolic BP declined more in manual than non-manual groups (difference in mean change = 3.6; 95%CI 2.1–5.1, p for interaction≤0.0001). The odds of being a current smoker in 1978–80 and 1998–2000 did not differ between non-manual and manual social classes (p for interaction = 0.51).ConclusionSeveral key risk factors for CHD and type 2 diabetes showed less favourable changes in men in manual occupations. Continuing priority is needed to improve adverse cardiovascular risk profiles in socially disadvantaged groups in the UK.

Highlights

Coronary heart disease (CHD) mortality and incidence has declined since the late 1970s in the UK and other developed countries [1,2,3]
The proportion of non-manual and manual social classes was 41% and 59% at baseline, and 48% and 52% at the 20-year follow-up. 3324 (44%) men had died during the 20 year follow-up period (37% of non-manual and 50% of manual group); death rate was 20 per 1000 person years in non-manual groups and 28 per 1000 person years in manual groups. 4132 men alive at the 20-year follow-up with information on social class were eligible to be included in the analysis
There was an overall decline in systolic blood pressure, which was more marked in men in manual social classes (211.6 mmHg) than in men in non-manual groups (27.9 mmHg; p for social class*time interaction,0.0001)

Summary

Introduction

Coronary heart disease (CHD) mortality and incidence has declined since the late 1970s in the UK and other developed countries [1,2,3]. Improvements in established coronary risk factors (fall in blood pressure, cholesterol and cigarette smoking levels) are responsible for a substantial proportion of the overall fall in CHD rates [8,9]. Improvements in these coronary risk factors in the USA and Western Europe have not occurred uniformly in all socioeconomic groups, with more favourable reductions in adverse risk factors in higher socioeconomic groups [10,11,12,13,14]. This study examined whether changes in established coronary risk factors in Britain over 20 years between 1978–80 and 1998–2000 differed between socioeconomic groups

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