The association of low income with poor health is widely recognized, but why some low-income individuals do not experience poor health remains unclear. The aim of this study was to determine whether greater positive personality trait scores modify the association between income and oral and general health-related quality of life (OHRQoL and HRQoL) among a representative sample of the South Australian population. Cross-sectional self-rated questionnaire data from a sample of 3645 adults in 2015-2016 were used for secondary analysis. In four factorial ANOVA models, the main effects, interaction, and effect modification of personality traits [measured using the Ten-Item Personality Inventory (TIPI)] on the association between income and OHRQoL [measured using the Oral Health Impact Profile (OHIP-14)] and HRQoL [measured using the European Quality of Life indicator (EQ-5D-3L)] were assessed. In the low-income group, participants with greater TIPI scale scores had lower means for the OHIP-14 and the EQ-5D-3L (better OHRQoL and HRQoL). Greater emotional stability scores modified the association between low income and HRQoL and OHRQoL. Stronger positive personality traits, such as emotional stability, appear to ameliorate the adverse effect of income inequalities in health.
