Age, period and cohort effects on body mass index in New Zealand, 1997–2038

Objective: To estimate the effects of age, period and birth cohort on observed trends, and to provide short- to medium-term projections of population BMI in New Zealand. Methods: Data were obtained from New Zealand national health surveys covering the period 1997 to 2015 (n=76,294 individuals). A Hierarchical Age-Period-Cohort (HAPC) model and an Age-Period model with interaction terms were specified for population groups defined by ethnicity...