Do social inequalities in health widen or converge with age? Longitudinal evidence from three cohorts in the West of Scotland

Michaela Benzeval,Alastair H Leyland,Michael J Green

doi:10.1186/1471-2458-11-947

Michaela Benzeval, Alastair H Leyland + Show 1 more

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https://doi.org/10.1186/1471-2458-11-947

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Abstract

BackgroundExisting studies are divided as to whether social inequalities in health widen or converge as people age. In part this is due to reliance on cross-sectional data, but also among longitudinal studies to differences in the measurement of both socioeconomic status (SES) and health and in the treatment of survival effects. The aim of this paper is to examine social inequalities in health as people age using longitudinal data from the West of Scotland Twenty-07 Study to investigate the effect of selective mortality, the timing of the SES measure and cohort on the inequality patterns.MethodsThe Twenty-07 Study has followed three cohorts, born around 1932, 1952 and 1972, from 1987/8 to 2007/8; 4,510 respondents were interviewed at baseline and, at the most recent follow-up, 2,604 were interviewed and 674 had died. Hierarchical repeated-measures models were estimated for self-assessed health status, with and without mortality, with baseline or time-varying social class, sex and cohort.ResultsSocial inequalities in health emerge around the age of 30 after which they widen until the early 60s and then begin to narrow, converging around the age of 75. This pattern is a result of those in manual classes reporting poor health at younger ages, with the gap narrowing as the health of those in non-manual classes declines at older ages. However, employing a more proximal measure of SES reduces inequalities in middle age so that convergence of inequalities is not apparent in old age. Including death in the health outcome steepens the health trajectories at older ages, especially for manual classes, eliminating the convergence in health inequalities, suggesting that healthy survival effects are important. Cohort effects do not appear to affect the pattern of inequalities in health as people age in this study.ConclusionsThere is a general belief that social inequalities in health appear to narrow at older ages; however, taking account of selective mortality and employing more proximal measures of SES removes this convergence, suggesting inequalities in health continue into old age.

Highlights

Existing studies are divided as to whether social inequalities in health widen or converge as people age
This paper aims to investigate this question addressing some of the limitations in the literature by: including mortality-’the final health status’ [23] - with self-assessed health in the health trajectories; investigating cohort effects directly; and, employing both time-invariant and time-varying measures of socioeconomic status
Examining baseline data at each wave shows that men, people from manual classes and those with poor starting health were less likely to remain in the study, and in each case this was true of the 1930s cohort

Summary

Introduction

Existing studies are divided as to whether social inequalities in health widen or converge as people age In part this is due to reliance on cross-sectional data, and among longitudinal studies to differences in the measurement of both socioeconomic status (SES) and health and in the treatment of survival effects. Social inequalities in health have been demonstrated at most ages and across time [1,2,3], studies frequently show that they tend to narrow at older ages [4,5] Often evidence for these patterns has been based on cross-sectional data, thereby relying on comparisons of different individuals at different ages. Using more proximal measures of social class has been shown to dilute the effect of (SES) on health [19]

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