Invited Commentary: Biomarkers for Mortality Among Individuals With a History of Out-of-Home Care-Implications for Study Design and Conceptualizations of Risk.

Out-of-home care in childhood and adolescence has been shown to be associated with elevated risk for all-cause mortality in adulthood, with adverse socioeconomic, psychosocial, and health-related trajectories hypothesized to mediate this relationship. In the research letter by Batty and Hamer (Am J Epidemiol. 2021;190(1):176-178), the authors used data from the 1970 British birth cohort (n = 8,581) to examine risk of biomarkers for mortality in adults with a history of out-of-home care. While markers of inflammation, glucose metabolism, and lipids were less favorable in the exposed versus unexposed, differences between groups were small and were completely attenuated after adjustment. This study raises important issues regarding the design and conceptualization of future studies on the long-term outcomes of out-of-home care recipients. Such studies require more detailed information on duration of care, type of care setting, and reasons for care, all of which could affect outcome risk. Because the duration of follow-up is long, and attrition likely, authors should consider use of novel analytical techniques to account for selection bias, such as inverse probability weighting. Finally, a "chain-of-risk" approach to understanding outcomes might be warranted, given that risk is likely explained by accumulation of and prolonged exposure to adverse socioeconomic, psychosocial, and health risks.