Trends in socioeconomic inequalities in self-rated health and mental distress during four decades in a Norwegian population: a HUNT Study

Background Socioeconomic inequalities constitute an important focus area for public health, and it has long been established that higher educational level and longer lifespan are correlated. Little is known about decennial time trends in poor self-rated health and mental distress.Methods This study linked decennial cross-sectional survey data on self-rated health and mental distress from the Tr & oslash;ndelag Health Study (HUNT) from 1984 to 2019 with educational registry data using personal identification numbers. Survey participation ranged from 50 807 to 77 212. Slope index of inequality (SII) and relative index of inequality (RII) were calculated using generalized linear models in Stata. Analyses were stratified by sex and age, using the age categories of 30-59 years and 60-80 years.Results Absolute inequalities in self-rated health and mental distress between educational groups have stayed relatively stable throughout all rounds of HUNT. Relative inequalities in self-rated health and mental distress have generally increased, and both men and women with the lowest education level were more likely to experience poor self-rated health and mental distress relative to those with the highest education level. RII in self-rated health increased over time for both sexes and both age groups. RII for mental distress increased in both sexes and both age groups, except for men and women aged 60-80.Discussion This study shows that relative inequalities in self-rated and mental health in the Norwegian population are still persistent and have increased. Further knowledge about groups with a disadvantageous health situation should have implications for health care resource allocation.