Early-childhood linear growth faltering in low- and middle-income countries: do alternative metrics tell a different story?

We previously found high levels of stunting incidence between birth and age 3 months and low levels of stunting reversal from birth to 15 months in an individual participant meta-analysis of longitudinal studies in low- and middle-income countries (LMICs). Roth and colleagues recently questioned the use of conventional metrics of linear growth faltering (binary indicators of incident stunting, incident changes in length-for-age Z-scores (LAZ)) in our study and in the field in general, arguing that these metrics have limitations that have implications for the timing of linear growth faltering in LMICs. Here, we re-analyzed data from the original study using height-age, one of their proposed alternative metrics. We show how height-age is closely correlated with mean LAZ at a given age, suggesting they provide nearly identical information. We discuss the utility of conventional metrics for generating rigorous evidence about early life linear growth trajectories in LMICs.