Socioeconomic inequalities in functional somatic symptoms by social and material conditions at four life course periods in Sweden: a decomposition analysis

OBJECTIVE: Socioeconomic inequalities in health are deemed a worldwide public health problem, but current research is lacking on key points including determinants of socioeconomic differences in health, and not the least variations of these determinants over the life course. Using a 26-year prospective Swedish community-based cohort, we aim at decomposing socioeconomic inequalities in functional somatic symptoms by social and material life circumstances, at 4 periods of the life course. DESIGN: Repeated cross-sectional study. SETTING: Participants came from the Northern Swedish Cohort (n=1001), who completed questionnaires about occupational class, social and material living conditions, and symptoms at ages 16, 21, 30 and 42. Socioeconomic inequalities were estimated and decomposed using the Blinder-Oaxaca decomposition analysis. RESULTS: Inequalities in symptoms between blue-collar and white-collar socioeconomic groups increased along the life course in the sample. In the decomposition analysis, a high proportion of the gap between socioeconomic groups could be explained by social and material living conditions at ages 16 (84% explained), 30 (45%) and 42 (68%), but not at age 21. Specific social (parental illness at age 16 and violence at ages 30 and 42) and material (parental unemployment at age 16, and own unemployment and financial strain at ages 30 and 42) factors contributed jointly to the health gaps. CONCLUSIONS: Socioeconomic inequalities in functional somatic symptoms increased along the life course in this Swedish cohort. A considerable portion of the social gaps in health was explained by concurrent social and material conditions, and the importance of specific adversities was dependent on the life course stage. Our findings suggest that socioeconomic inequalities in functional somatic symptoms may be reduced by addressing both social and material living conditions of disadvantaged families, and also that the life course stage needs to be taken into consideration.