Education, Occupation and Income Inequalities in Obesity Among Portuguese Women and Men: Evidence from National Health Surveys (2005–2019)

Introduction : We aimed to examine socioeconomic inequalities in obesity among Portuguese women and men from 2005–2019 with data from National Health Surveys (NHSs). Methods : We analysed weighted data corresponding to 20–64-year-old adults from the 2005/2006 (N̂= 6,508,833), 2014 (N̂=6,227,041), and 2019 (N̂=6,073,178) NHS. Socioeconomic position (SEP) included education (no formal education, 6th, 9th, and 12th grades, postsecondary education, and higher education), occupation (unemployed, operations/trade, technical/administrative, and senior professional/managerial), and monthly household net income (quintiles). Obesity was defined as body mass index (BMI) ≥ 30 kg/m² from self-reported weight and height. Slope index of inequality (SII) and relative index of inequality (RII) were used to measure absolute and relative inequalities, respectively. Log-binomial regression model was used to examine the relationship between obesity and socioeconomic indicators, employing an identity link function to calculate SII (absolute differences in predicted obesity incidence between highest and lowest SEP) and a log link function to estimate RII (ratio of obesity prevalence between these groups). Trends and overall SII and RII were analysed by socioeconomic indicators and sex, with significance set at p < 0.05. Results : We found statistically significant socioeconomic inequalities in terms of obesity: SII consistently exhibited negative values, and RII was less than 1, indicating a concentration of obesity among adults with lower SEP. Overall, education-related SII and RII were greater for women [SII (95% CI)= -0.27(-0.29;-0.24); RII (95%CI) = 0.18(0.15;0.21)] than for men [SII= -0.16(-0.19;-0.13); RII = 0.35(0.29,0.44)]. Similarly, occupational and income-related SIIs and RIIs were greater among women, although they were smaller in magnitude than education was, and SIIs and RIIs were minimal in men. From 2005–2019, sex differences in absolute education-, occupation-, and income-related inequalities remained relatively stable, with slight variations in the SII values (education: -0.11 to -0.10; occupation: constant at 0.11; income: -0.09 to -0.08). Similarly, over the study period, sex differences in relative education-related inequalities remained stable (RII: constant at 0.16), while occupational-related inequalities decreased (RII:0.42 to 0.31), and income-related inequalities showed minimal changes (RII:0.32 to 0.31). Conclusion : Socioeconomic inequalities in obesity persist and disproportionately affect women. The gender gap in socioeconomic inequalities in obesity has remained largely unchanged.