Temporal trends in socioeconomic inequalities in obesity prevalence among economically-active working-age adults in Scotland between 1995 and 2011: a population-based repeated cross-sectional study

Objectives Obesity has been an alarming public health issue in the UK. Socioeconomic inequalities in obesity have been well-studied, however limited studies addressed inequality trends over time and none of them in Scotland. Methods We used nationally-representative data from the Scottish Health Survey (SHeS) across four time points between 1995 and 2010/2011. Respondents were economically active adults aged 16–65 years (N=27 059, 12 218 men). Socioeconomic position (SEP) was assessed by highest educational qualification, occupational social class and household income (2003 and 2010/2011 only) as well as a composite SEP score. We carried out sex-stratified logistic regression analyses (adjusted for age, smoking status, alcohol consumption, self-rated general health and physical activity) and we computed the relative index of inequality (RII). Results Between 1995 and 2010/2011, obesity prevalence increased in both men (from 17% in 1995 to 30.2% in 2010/2011, 2010/2011 OR of obesity compared with 1995=2.07; 95% CI 1.83 to 2.34) and women (from 18.4% to 30.2%; OR=1.85; 95% CI 1.66 to 2.07). Increase in obesity prevalence was observed across all socioeconomic strata, within which the most rapid increase was among males from the highest socioeconomic groups. RII showed that educational inequalities in obesity narrowed for both men (p=0.007) and women (p=0.008). Income inequalities in obesity between 2003 and 2010/2011 in women were also reduced (p=0.046) on the relative scale. Conclusions Obesity prevalence in Scotland increased substantially between 1995 and 2010/2011, although socioeconomic inequalities have decreased due to the more rapid increase in the higher socioeconomic strata.