Psychological factors related to physical, social, and mental dimensions of the SF-36: a population-based study of middle-aged women and men

BACKGROUND Measures of health-related quality of life (HRQoL) are increasingly used as patient-reported outcome measures in routine health care. Research on determinants and correlates of HRQoL has, therefore, grown in importance. Earlier studies have generally been patient-based and few of them have examined differences between women and men. The aim of this study was to explore the relationship between psychological factors and physical, social, and mental dimensions of HRQoL, as measured by the Medical Outcome Study Short Form-36 Health Survey (SF-36), in a normal population and to see if observed relations were the same for women and men. METHODS Relations between scale scores for the eight scales of SF-36 and scale scores for Self-esteem, Sense of Coherence, Perceived Control, Depressed Mood (CES-D), and Cynicism were assessed through partial correlation and multiple linear regression analyses on a sample of 505 women and 502 men (aged 45-69 years), stratified for sex and adjusted for effects of age, presence of disease, back pain, lifestyle, and social support. RESULTS All psychological factors tested, except Cynicism, were significantly correlated to all scales of the SF-36 for women and men (Pearson product-moment partial correlation coefficient, |r| = 0.11-0.63 and |r| = 0.11-0.60, respectively). The addition of psychological factors into regression models resulted in significant total explained variance (R(2)) changes in all scales of the SF-36 for both sexes. Any discrepancies between women and men pertained more to the strength of relationships rather than the significance of different psychological factors. CONCLUSION In this population-based study, psychological factors showed significant correlation, for women and men alike, with the physical and social scales of SF-36, as well as the mental scales. These findings suggest that assessments of HRQoL are not merely a measure of absolute function but are also dependent on people's perception of their ability.