Body mass index inequities among adults in Spain: An intersectional multilevel analysis of individual heterogeneity and discriminatory accuracy of age, sex/gender, immigration status, and education

Purpose

We aimed to examine intersectional BMI inequities across age, sex/gender, immigration status, and education among adults in Spain.

Methods

We analyzed data from 61,844 adults aged ≥ 18 years from the 2014 and 2020 European Health Interview Surveys in Spain and the 2017 Spanish National Health Survey. Using intersectional multilevel analysis of individual heterogeneity and discriminatory accuracy (I-MAIHDA) via linear mixed models, we examined BMI inequities across 180 intersectional strata, defined by age, sex/gender, immigration status, education, and survey year, and quantified the contribution of their intersections to BMI inequities.

Results

The intersectional strata explained 9.6 % of BMI inequities, with 87.1 % of the between-strata variance explained by age, sex/gender, immigration status, education, and survey year. On average, BMI was higher in older adults, immigrants, and those with lower education but lower in women. Interaction effects revealed that immigrant women had a higher predicted BMI than Spanish-born women. BMI inequities between immigrant and Spanish-born women were greatest for those aged 55–64 with middle and high education.

Conclusion

Although most BMI inequities were explained by the social factors considered as inequity axes, interaction effects were present. The latter calls for a universal public health intervention proportionate to the needs of specific groups in the population. I-MAIHDA revealed complex patterns of BMI inequities in Spain, which may inform the interventions needed to address weight-related outcomes.