Development of a population-based microsimulation model of body mass index.

Background: The increasing prevalence of overweight and obesity has necessitated the development of body mass index (BMI) projection models such as the POpulation HEalth Model (POHEM). This study describes the POHEM-BMI model, a microsimulation tool that can be used to support evidence-based health policy making for obesity reduction. Methods: The National Population Health Survey, the Canadian Community Health Survey (CCHS),and the Canadian Health Measures Survey (CHMS) were used to develop and validate a predictive model of BMI for adults and childhood BMI history. Models were incorporated into POHEM and used to transition BMI over time in a fully dynamic simulated Canadian population. Results: POHEM-BMI projections of self-reported and measured adult BMI and childhood BMI history agreed well with CCHS and CHMS validation estimates. Among men and women, average BMI is projected to increase by more than one BMI unit between 2001 and 2030. Projections of self-reported BMI show that 59% of the adult population will be overweight or obese by 2030; projections of measured BMI show that the percentage will be 66%. Interpretation: Using empirically developed BMI prediction models for adults and childhood BMI history integrated into the POHEM framework, validated projections of BMI for the Canadian population can be produced. Projections of BMI trends could have important applications in tracking the prevalence of related diseases and in planning and comparing intervention strategies.