Influence of Psychosocial Factors on Socioeconomic Gradients in Self-Reported Oral Health

Abstract

The robust association between socioeconomic status (SES) and health is well established. The gradient between SES and health tends to be higher at lower levels of SES. Individuals from low-income families (low economic status) are more likely to be affected by a wide range of health problems. Also, low-income people are more likely to experience chronic stress due to their income level (leading to many life challenges). Psychosocial factors are crucial resources for low-income groups in coping with stress and maintaining good health. Although studies have shown that protective psychosocial factors affect health, the influence of these factors on the association between income and health and quality of life requires further research. The aim of the thesis was to investigate the effects of protective psychosocial factors (i.e., sense of coherence (SOC) and personality traits) on income gradients in self-reported oral and general health and quality of life following Wilson and Cleary's conceptual model of health-related quality of life (HRQoL). Specifically, the main effect and interaction effect of these psychosocial factors and total household income on health and quality of life outcome measures were evaluated. A total of five studies were conducted in this thesis to explore the aim using outcome measures in the order of Wilson and Cleary's model: (i) studies 1 and 2 investigated the effects of protective psychosocial factors (SOC and "Big Five" personality traits, respectively) and income on functional health, (ii) studies 3 and 4 investigated effects of SOC and personality traits (respectively) and income on general health perceptions, (iii) study 5 investigated effects of personality traits and income on the overall quality of life. All studies used the baseline data from the Dental Care and Oral Health Study (DCOHS, 2015-2016) collected by self-reported surveys sent to a random cohort of 12,245 South Australian adults aged 18 years or older. Factorial ANOVA and multivariable Poisson regression models were used to conduct cross-sectional analyses. Findings showed that SOC and personality traits were positively associated with better self-rated oral and general health and quality of life. The protective effect of these factors against poor self-reported health and quality of life was found at all income levels. Also, these psychosocial factors modified the association between income and health and quality of life outcome measures. Their modifying effect was associated with lower levels of poor self-reported oral and general health and quality of life across all income levels. However, there were greater health and quality of life gains (in absolute terms) for lowincome individuals by having these protective psychosocial factors. The evidence provided by the current thesis suggests the possibility and importance of incorporating psychosocial factors into multidimensional programs to reduce health inequalities.