Evaluation and interpretation of latent class modelling strategies to characterise dietary trajectories across early life: a longitudinal study from the Southampton women's survey

In the SWS cohort continuous diet quality indices (DQIs) were derived using principal component analysis from an interviewer-administered food frequency questionnaire collected in the mother preconception and at 11 and 34 weeks’ gestation, and in the child at ages 6 months, 12 months, 3, 6–7 and 8–9 years. Each model was assessed using the following criteria for classifying and interpreting latent class analyses: the Bayesian information criteria, probability of class assignment, the ratio of the odds of a correct classification, group membership, and relative entropy. According to the classification criteria, the optimal model included 5-trajectories, with results from the GMM and GBTM being most similar for the 5-trajectory model (Spearman's correlation = 0.98).