The problematic nature of existing explanations for differential immigrant mortality: Insights from a comparative cross-national systematic review and meta-analysis.

Empirical studies in multiple disciplines have frequently observed an immigrant mortality advantage. Yet, questions remain regarding the possible mechanisms underlying this phenomenon. We obtained data from 61 studies of relative immigrant mortality from single origin-destination country pairings, providing information on immigrants from 77 origin countries. We systematically review the arguments made in these studies about origin-country factors that might influence immigrant mortality and then use meta-analyses to examine the veracity of these arguments. We find that most existing origin-country explanations for immigrant mortality patterns (e.g., health behaviors, genetic characteristics, environmental conditions, and socioeconomic conditions) are problematic or insufficient when accounting for differential mortality by origin country. We identify non-comparative analyses and geographic aggregation as the two major obstacles to understanding the mechanisms underlying the immigrant mortality advantage. We conclude by advocating for a risk-factor-based, cross-national approach.