Biological Influences on Health-Ratings: The Relationship of Biomarkers and Self-Rated Health and How It Differs across Groups

Self-ratings of health are the most widely used single-indicator of health in many scientific disciplines. Accordingly, many researchers rely on these self-ratings in the description and explanation of social inequalities in health. How these ratings come about, however, is still partly unknown and self-rated health is treated like a valid measurement of 'true health' when it is actually a black box. This would prove especially problematic if there were differences in how respondents from different social groups (e.g., age-groups, men and women, socio-economic groups, or ethnicities) rate their health because this would mean that self-rated health measures a different concept in each group. In order to investigate these possible group differences, researchers need to have a wide array of health-related information which respondents might use to base their appraisal on. Physical measurements and biomarkers play a rather interesting role in this regard since they potentially give objective and highly relevant health information beyond what a respondent is willing - or even able - to tell. Their relevance for rating ones' health, though, is still basically unknown.

This paper contributes to the state of research by analyzing data from the Canadian Health Measures Survey (CHMS). Additionally to a health questionnaire the CHMS comprises, among others, physical measures like grip strength, blood measures like infection markers, and urine measures like creatinine levels. With these data cross-sectional analyses are conducted in order to determine the relative contribution of different types of health information for several groups in explaining self-rated health and whether physical measures and biomarkers can contribute to this explanation beyond information typically collected in questionnaire-only health surveys. All in all, this research evaluates the relevance of collecting this information in explaining self-rated health and whether self-rated health is invariantly measured in different groups.