Health selection at out- and return migration in Manitoba, Canada. A retrospective matched cohort register study

• We examined heterogeneity in health selectivity at out- and return migration • Migration and remigration were generally associated with better health outcomes • Health selectivity varied between local population, internal and external migrants • It increased with the degree of migration (i.e., international vs interprovincial) • Ignoring birthplace groups and degree of migration may result in misleading conclusions