Purpose: Neuroticism, a personality trait associated with negative affect, is strongly related to perception of health, self-assessed health, and numerous measures of mental and physical health. The EQ-5D descriptive system is a generic form intended as an objective measure of health status. It has five dimensions (mobility, self-care, usual activities, pain/discomfort, and anxiety/depression), each with three levels (no, some, or extreme problems), describing 243 different combination health states. The objective of this study was to assess the association between neuroticism, as expressed by a trait measure, and self-descriptions of health state using the EQ-5D.
Method: We collected descriptions of own health on the EQ-5D and the 12-item neuroticism scale of the NEO Five Factor Inventory (NEO FFI) from a representative sample of 2279 persons from the adult Norwegian population. We calculated Pearson’s r between neuroticism (Z-scores based on Norwegian norms) and scores in the five EQ-5D dimensions. We then used multiple linear regression to predict US and Danish EQ-5D tariff values corresponding to the respondents’ EQ-5D profiles, using age, sex, and neuroticism scores as predictors.
Result: Neuroticism was significantly correlated with all five EQ-5D dimensions (mobility .174, self-care .151, usual activities .206, pain/discomfort .216, anxiety/depression .409 (p<.001 for all). When predicting US and Danish EQ-5D tariff values, age (+1 year = -.002 in both), female sex (-.042 and -.050, respectively) and neuroticism score (+1 SD = -.058 and -.071, respectively) were significant predictors (p<.001 for all).
Conclusion: Neuroticism was a strong predictor of EQ-5D tariff values. The association between neuroticism score and EQ-5D dimension scores was strongest for anxiety/depression. Our findings indicate that the personality trait (or, at least, the measure of it) is substantially influenced by health status, that self-ratings on the EQ-5D are influenced by neuroticism, or both. Our cross-sectional study is unsuited to determine the causal relationship between neuroticism and self-ratings of health. The bi-directional relationship should be investigated further using a longitudinal design, since it could prove important for the interpretation and validity of both individual level and patient-group level EQ-5D data.