eLife assessment
This study presents a valuable analysis of the effects of covariates, such as age, sex, socio-economic status, or biomarker levels, on the predictive accuracy of polygenic scores for body mass index; it also presents approaches for improving prediction accuracy by accounting for such covariates. While the analyses are solid, the study falls short of providing a cogent interpretation of key findings, which could be of great interest and utility. The work will be of interest to people using and developing methods for phenotypic prediction based on polygenic scores.