Does Self-Rated Health Mean the Same Thing Across Socioeconomic Groups? Evidence From Biomarker Data

Purpose

Self-rated health (SRH) is widely used to study health inequalities by socioeconomic status (SES), but concern has arisen that SRH may not correspond to objective health in the same way for different SES groups. We test whether levels of biological risk differ by SES for those with the same SRH.

Methods

We analyzed a U.S. nationally representative sample of 13,877 adults aged 25 to 80 years. We tested whether education modifies the association between SRH and 14 biomarkers representing metabolic, cardiovascular, inflammatory, and organ function using both interaction models and models stratified by four levels of SRH. Estimated education coefficients in the stratified models indicated whether biomarker levels varied by educational attainment within a given self-rated health category.

Results

Significant variation in biological risk by education within the same self-rated health category was found, especially at higher levels of SRH. In general, respondents with more education had healthier levels of biomarkers for the same level of SRH.

Conclusions

The results suggest that the relation of self-reported health to objective health, as measured by biological risk factors, differs by socioeconomic status. Caution should be exercised when using SRH to compare health risks across SES groups.

Key Words: Biomarkers, Education, NHANES, Self-Rated Health, Socioeconomic Status

Selected Abbreviations and Acronyms: SRH, self-rated health, SES, socioeconomic status, BMI, body mass index, NHANES, National Health and Nutrition Examination Survey, BP, blood pressure, HDL, high-density lipoprotein, HbA1c, glycated haemoglobin, CRP, C-reactive protein, PEV, peak expiratory flow, FVC, forced vital capacity, GFR, glomerular filtration rate