Socioeconomic Variation in the Magnitude of the Association between Self-Rated Health and Mortality

doi:10.1016/j.annepidem.2010.01.007

Annals of Epidemiology

Volume 20, Issue 5, May 2010, Pages 395-400

https://doi.org/10.1016/j.annepidem.2010.01.007 Get rights and content

Purpose

To assess socioeconomic variation in the association between self-rated health (SRH) and mortality and to determine whether socioeconomic inequalities in SRH and socioeconomic inequalities in mortality differ in magnitude.

Methods

We used data from a cohort of Spanish people 60 years of age and older with an 8-year follow-up of mortality. The association between SRH at baseline and mortality was estimated by the age-adjusted relative risk of mortality in people with low, medium, and high education. The measures of health inequalities were the prevalence ratio of poor SRH and the age-adjusted relative risk of mortality according to educational level. The validity of SRH to reflect life-threatening and non–life-threatening health conditions was summarized with the likelihood ratio for poor SRH in each educational category.

Results

The relative risk of mortality according to SRH in subjects with high and low education was 3.24 and 1.62 in men and 2.25 and 1.50 in women, respectively. Inequalities in poor self-rated health were larger than inequalities in mortality: –1.63 versus 1.07 in men and 1.45 versus 1.30 in women. The highest likelihood ratio for SRH was seen in persons with high education in the case of life-threatening conditions, and for those with low education, in the case of non–life-threatening conditions.

Conclusions

Socioeconomic variation in the validity of SRH to reflect life-threatening and non–life-threatening conditions could explain the greater ability of SRH to predict mortality in persons with high education and why inequalities in poor SRH are larger than inequalities in mortality.

Introduction

Many investigations have shown a strong association between self-rated health (SRH) and mortality 1, 2. In contrast, only a few studies have evaluated whether this relation varies by socioeconomic position. Four of five studies on this issue found a socioeconomic variation in the relation between SRH and mortality 3, 4, 5, 6, 7. Three studies in the general population of Sweden, The Netherlands, and the United States, respectively, observed that the relative risk of mortality according to SRH was highest in subjects in the highest socioeconomic position 3, 4, 5. However, another study, conducted in an occupational cohort in France, found the highest relative risk for mortality in those with the lowest socioeconomic position (6). Since the results in the French cohort could have been affected by different selection biases (8), the consistency of the findings of the other three studies suggests that the validity of SRH to reflect life-threatening conditions may be higher in subjects with high socioeconomic position.

These findings are also relevant to the debate about whether the use of SRH, rather than mortality, leads to an underestimate or overestimate of socioeconomic inequalities in health 8, 9, 10, 11, 12. In theory, if there is socioeconomic variation in the validity of SRH to reflect life-threatening conditions, the magnitude of socioeconomic inequalities in health should be different depending on whether SRH or mortality is used. However, the information available is not conclusive. In one study, socioeconomic inequalities in health showed the same magnitude for SRH and for mortality (9). In addition, in other studies, inequalities using one or another measure of health gave different results depending on the indicator of socioeconomic position used or the SRH cut-off point 10, 11. In any case, results for SRH and for mortality are not comparable because SRH reports were obtained at the end of a follow-up period. SRH was reported only by those who were alive at the end of this period—a highly health-selected group; thus, SRH and mortality were measured in different samples.

The present work uses information from a cohort of older residents in Spain: first, to assess the socioeconomic variation in the association between SRH and mortality after an 8-year follow-up period and second, to determine whether the magnitude of socioeconomic inequalities in SRH is different from the magnitude of socioeconomic inequalities in mortality.

Section snippets

Study Population

A cohort of 4,008 persons, representative of the non-institutionalized Spanish population 60 years of age or older, was selected between 1 October 2000 and 31 March 2001 and was followed prospectively up to 31 October 2008. At baseline subjects were selected using probabilistic sampling with multistage clusters. The clusters were obtained according to region of residence and size of municipality. Census sections were then chosen randomly within each cluster, and the households in which

Results

Table 1 shows the distribution of baseline SRH by education and of mortality by SRH and education. In persons with good SRH the highest mortality is found in those with low education, and the lowest mortality is found in those with high education. In subjects with poor SRH, however, no clear pattern is observed in the percentage of deaths by educational level.

The association between SRH and mortality across educational categories is presented in Table 2. In both sexes, the highest and lowest

Discussion

With regard to the first objective, our study showed that the association between SRH and mortality was strongest in persons with high education. Although the confidence intervals overlap for the relative risk of mortality in the different educational groups, and no interaction between SRH and education was found in predicting mortality in women, the consistency of our findings in men and women provides additional evidence of socioeconomic differences in the ability of SRH to predict mortality.

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Cited by (31)

The value of general health perception in health equity research: A community-based cohort study of long-term mortality risk (Finnmark cohort study 1987–2017)
2021, SSM - Population Health
Citation Excerpt :
The question has been to what extent the predictive power of SRH for mortality correlated with indicators of socioeconomic position. Cohort studies from different countries have given mixed answers to this question (Burstrom & Fredlund, 2001; Dalen et al., 2012; Dowd & Zajacova, 2007; Holseter et al., 2015; Huisman et al., 2007; McFadden et al., 2009; Regidor et al., 2010; Singh-Manoux et al., 2007; van Doorslaer & Gerdtham, 2003). Given that SRH predicts mortality equally well for high and low socioeconomic positions, the interpretation has been that this measure will function well as an indicator for use in health-equity studies.
General health perception as measured by self-rated health (SRH) is an individual's synthesis of personal overall health and has value in its own right. In addition, this subjective perspective has a unique predictive power of subsequent mortality and adds valuable information not captured by objective measures. We studied the relationship between SRH and subsequent mortality to demonstrate how simple self-ratings can enhance our understanding of health inequities.
Data from a population-based survey conducted in Finnmark 1987/1988 were linked to the Norwegian Cause of Death Registry for information on all deaths by the end of 2017. We used Cox proportional hazard regression modelling to estimate the relative effects of all-cause mortality separately for sex and age (30–49 and 50–62 years) with stepwise adjustment for socio-demographics and various other health status and behavioural measures.
The age-adjusted power of mortality prediction of SRH was strong (most pronounced in the youngest age-group) but markedly attenuated by other factors. Education inequality in mortality was most substantial in the youngest age-group, which might partly be due to a combination of selective mortality and historical changes in health inequality. In comparison, educational inequality in SRH was clearly pronounced regardless of age. Work disability pension appeared as the common key factor affecting the mortality prediction of SRH and educational inequity for both subsequent mortality and SRH.
SRH adds unique information to our understanding of health inequities. The consistency in shared predictors of educational inequity concerning both mortality and SRH underscores the correspondence of these measures. In addition to predicting the fatal effects of social selection mechanisms, SRH adds non-fatal effects and seems less prone to selective mortality. The results are relevant to approaches in health equity research and have important policy implications.
Cautionary tails of grip strength in health inequality studies: An analysis from the Canadian longitudinal study on aging
2020, Social Science and Medicine
Citation Excerpt :
On the other hand, the subjective assessment might bring biases in health inequality analyses if it varies systematically with characteristics of interest for inequality. Correlations between self-rated health and mortality vary across socioeconomic status, but with inconsistent directions (Huisman et al., 2007; Regidor et al., 2010). Studies also find both pessimistic (Adams and White, 2006; Dowd and Zajacova, 2010; Layes et al., 2012) or optimistic (Humphries and Van Doorslaer, 2000) assessments by the socioeconomically advantaged compared to the socioeconomically disadvantaged.
Self-rated health is widely used in studies of the socioeconomic gradient of health in community-based populations. Its subjectivity may lead to under- or over-estimation of a true underlying socioeconomic gradient and has increased interest in searching for alternative, objective measures of health. Grip strength has emerged as one such alternative for community-based older populations, yet no study has directly assessed the relationship between these two measures and compared their associations with socioeconomic status and health behaviours. Using 26,754 participants aged 45–85 years in the baseline data of the Canadian Longitudinal Study on Aging Comprehensive Cohort, we estimated adjusted-grip strength through indirect standardization using age, sex, height, weight, and their square terms and used ANOVA to assess the variance of adjusted-grip strength within and between each self-rated health category. We ran four separate logistic regression models, examining unhealthy tails (those reporting poor health vs. not and those at the bottom 8th percentile of adjusted-grip strength vs. above) and healthy tails (those reporting excellent health vs. not and those at the top 20th percentile of adjusted-grip strength vs. below). Stronger adjusted-grip strength correlated with better self-rated health, but only 2% of the total variance of adjusted-grip strength was explained by variance between the self-rated health categories. While self-rated health largely showed the expected socioeconomic gradients and positive relationships with health enhancing behaviours, adjusted-grip strength showed no clear, consistent associations with either socioeconomic or health behaviour variables. The results give caution about using grip strength as an objective alternative to self-rated health in studies of social inequalities in health. Empirical approaches demand careful considerations as to which dimensions of health and corresponding measures of health are most relevant to the context being studied.
Ethnic variation in self-rated health–mortality association: Results from a 17-year follow-up study in Estonia
2017, Medicina (Lithuania)
Citation Excerpt :
Apart from low personal income that invariably predicted higher mortality in men and women from both ethnic groups, the results also emphasize considerable ethnic differences in socioeconomic and health-related variables as predictors of mortality. Several studies [8,9,14] have emphasized the role of individual socioeconomic status as an important effect-modifier in SRH–mortality association. Previous research from Estonia [24] showed that Russians had higher odds for poor self-rated health compared to ethnic Estonians even after adjustment for educational level, occupation and income.
Previous research has highlighted the role of self-rated health (SRH) as an important predictor of mortality. With substantial ethnic differences in SRH and mortality reported in Estonia, this study aims to examine the ethnic variation in SRH–mortality association in this setting.
The baseline data come from the nationally representative 1996 Estonian Health Interview Survey. Individual records of 3983 respondents in the 25–79 age group were linked with mortality data with 17 years follow-up time. The association between SRH and all-cause mortality was analyzed using the Cox regression for two ethnic groups and separately for men and women.
Among ethnic Estonians, both men and women with bad or very bad SRH had about 60% higher mortality compared to those with good or very good SRH even after adjustment for age, socioeconomic and health-related variables. In contrast, SRH did not predict mortality among non-Estonian men and women. A strong and universal inverse association with mortality was found for personal income. Education (among men) and occupation (among women) predicted mortality only among non-Estonians, whereas ever smoking was associated with mortality in Estonian men and women. Overweight women had lower mortality risk compared to women in normal weight category.
We found considerable ethnic variation in SRH–mortality association and in socioeconomic predictors of mortality. Further research, preferably focusing on cause-specific mortality and reporting heterogeneity of SRH could potentially shed further light on ethnic differences in SRH–mortality association in Estonia and more generally on socioeconomic inequalities in mortality in Eastern Europe.
Age and gender differences in the relationship between self-rated health and mortality among middle-aged and elderly people in Taiwan - Results of a national cohort study
2016, International Journal of Gerontology
Citation Excerpt :
Although the actual underlying mechanism is still unclear, many studies and meta-analyses have reported that poor SRH was associated with increased mortality risk. The relationship still persisted even after adjusting for demographic, psychosocial, and lifestyle variables and other health indicators6–8. Although the association between SRH and mortality is quite consistent in different populations, its strength may differ between men and women, but also by age9.
Self-rated health (SRH) is known to be a valid indicator for the prediction of mortality among middle-aged and older adults, but findings regarding age and gender differences are inconsistent. This study aimed to determine the association of SRH with subsequent mortality risk among middle-aged and elderly people in Taiwan.
This study was based on data from the “Taiwan Longitudinal Survey on Aging” (TLSA). A total of 2553 men and 2192 women aged ≥ 50 years of age comprised the major analytic cohort (mean age, 66.8 ± 9.1 years). SRH was categorized into good, fair, and poor health. Cox regression methods were used to examine the association between SRH and mortality.
During the follow-up period (median: 10.1 years), 1644 deaths occurred. Participants with poor SRH were at higher risk of mortality [relative risk (RR), 1.35 95% confidence interval (CI), 1.16–1.55)] than those with good SRH. This SRH-mortality association was more pronounced among men (RR, 1.56, 95% CI, 1.30–1.87) than women (RR, 1.01, 95% CI, 0.80–1.27). The associations decreased with increasing age. The SRH-mortality associations were significant for the oldest age group among men, but among women, there was no significant SRH-mortality association across all age groups.
Low SRH was associated with increased risk of mortality among middle-aged and older adults. The association varied across different age and gender groups. The association was strongest in the group of men aged 50–59 years. The factors that might explain the differences in the associations warrant further research.
Black-white difference in long-term predictive power of self-rated health on all-cause mortality in United States
2016, Annals of Epidemiology
Despite the well-established association between self-rated health (SRH) and mortality, limited information exists on Black–White differences in this link. Using a nationally representative sample of adults in the United States, the present study had four aims: (1) to assess whether the association between baseline SRH and all-cause mortality over a long follow-up differs for blacks and whites, (2) to test whether any race difference in the SRH–mortality link depends on how the SRH variable is treated (e.g., nominal, dichotomous, continuous), (3) to test if the SRH–mortality link or any differences in the association by race are explained by differences in objective health measures (chronic medical conditions [CMC]), and (4) to assess whether these associations vary by gender.
Data came from the Americans' Changing Lives Study, a nationally representative longitudinal cohort of U.S. adults 25 years and older with up to 25 years of follow-up. The study followed 3361 blacks or whites for all-cause mortality between 1986 and 2011. The predictor of interest was a single-item measure of SRH in 1986, treated as a nominal, dichotomous (fair/poor vs. excellent/very good/good), and continuous variable. Confounders included baseline age, education, income, depressive symptoms, and CMC. Race (black vs. white) was the focal effect modifier. We ran Cox proportional hazard models for the pooled sample and also stratified by race and gender, before and after adjusting for CMC.
Regardless of how SRH was treated and for both men and women, we found significant interactions between race and SRH, indicating a stronger predictive role of SRH for all-cause mortality among whites compared to blacks. Before adjustment for chronic medical conditions, lower SRH was associated with higher risk of mortality among blacks and whites, but after adjustment, the SRH–mortality association was no longer significant among blacks.
Baseline SRH continues to predict long-term mortality among white but not black Americans after adjustment for chronic medical conditions at baseline, and these patterns are similar for men and women. Future research should test whether the differential predictive validity of SRH across race groups arises because SRH reflects different aspects of health of black and white Americans.
Self-rated health and mortality: A follow-up study of a Spanish population
2013, Public Health
Citation Excerpt :
These results do not agree with those obtained by Huisman et al.34 in a Dutch cohort study, who found an association between SRH and educational level in men, whereby the predictive effect of SRH on mortality was higher in men with a higher education; this was not found in women. In Spain, Regidor et al.37 also found an association between SRH and education in men but not in women. The authors believe that the present results are consistent, in general, with a model in which SRH can be identified as a mediator between socio-economic, demographic and health conditions and mortality, remaining strongly predictive of mortality although the information provided by other variables, especially disability and chronic disease, can increase predictive ability.
Self-rated health (SRH) is known to be a valid indicator for the prediction of health outcomes. The aims of this study were to describe and analyse the associations between SRH and health status, socio-economic and demographic characteristics; and between SRH and mortality in a Spanish population.
Longitudinal study.
A sample of 5275 adults (age ≥21 years) residing in the Valencian Community (Spanish Mediterranean region) was surveyed in 2005 and followed for four years. SRH was categorized into good and poor health. The response variable was mortality (dead/alive), obtained from the local mortality register. Logistic regression models were adjusted in order to analyse the associations between SRH and health status, socio-economic and demographic characteristics; odds ratios were calculated to measure the associations. Poisson regression models were adjusted in order to analyse the associations between mortality and explanatory variables; the relative risk of death was calculated to measure the associations.
Poor SRH was reported by 25.9% of respondents, and the mortality rate after four years of follow-up was 3.6%. An association was found between SRH and the presence of chronic disease and disability in men and women. A perception of poor health vs good health led to a mortality risk of 3.0 in men and 2.7 in women. SRH was predictive of mortality, even after adjusting for all other variables. In men and women, the presence of disability provided additional predictive ability.
SRH was predictive of mortality in both men and women, and acted as a mediator between socio-economic, demographic and health conditions and mortality.

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Socioeconomic Variation in the Magnitude of the Association between Self-Rated Health and Mortality

Purpose

Methods

Results

Conclusions

Introduction

Section snippets

Study Population

Results

Discussion

Soc Sci Med

Gac Sanit

Lancet

J Clin Epidemiol

Self-rated health and mortality: a review of twenty-seven community studies

J Health Soc Behav

Mortality prediction with a single general self-rated health question: a meta-analysis

J Gen Intern Med

Self rated health: is it as good a predictor of subsequent mortality among adults in lower as well as in higher social classes?

J Epidemiol Community Health

The predictive ability of self-assessed health for mortality in different educational groups

Int J Epidemiol

Does the predictive power of self-rated health for subsequent mortality risk vary by socioeconomic status in the US?

Int J Epidemiol

The association between self-related health and mortality in different socioeconomic groups in the Gazel Cohort study

Int J Epidemiol

Self-rated health: caught in the crossfire of the quest for `true' health?

Int J Epidemiol

Is the use of self-rated measures to assess health inequalities misleading?

Int J Epidemiol

Is the use of self-rated measures to assess health inequalities misleading?

Int J Epidemiol