title: Does shared family background influence the impact of educational differences on early mortality?
abstract: The mechanisms behind social differences in mortality rates have been debated. The authors examined the extent to which shared family background and health in early life could explain the association between educational status and all-cause mortality rates using a sibling design. The study was register-based and included all individuals born in Denmark between 1950 and 1979 who had at least 1 full sibling born in the same time period (n = 1,381,436). All individuals were followed from 28 years of age until death, emigration, or December 2009. The authors used Cox regression analyses to estimate hazard ratios for mortality according to educational level. Conventional cohort and intersibling analyses were carried out and conducted separately for deaths occurring before and after the age of 45 years, respectively. The cohort analyses showed an inverse association between educational status and all-cause mortality that was strongest for males, increased with younger birth cohorts, and tended to be strongest in the analyses of death before 45 years of age. The associations were attenuated slightly in the intersibling analyses and after adjustment for serious health conditions in early life. Hence, health selection and confounding by factors shared by siblings explained only a minor part of the association between educational level and all-cause mortality.
authors.affiliation: Research Centre for Prevention and Health, Glostrup University Hospital, Glostrup, Germany. gsoe0038@regionh.dk
authors.forename: Grethe
authors.initials: G
authors.lastname: Søndergaard
authors.forename: Laust H
authors.initials: LH
authors.lastname: Mortensen
authors.forename: Anne-Marie
authors.initials: AM
authors.lastname: Nybo Andersen
authors.forename: Per Kragh
authors.initials: PK
authors.lastname: Andersen
authors.forename: Susanne Oksbjerg
authors.initials: SO
authors.lastname: Dalton
authors.forename: Mia
authors.initials: M
authors.lastname: Madsen
authors.forename: Merete
authors.initials: M
authors.lastname: Osler
mesh_terms: D000328:Adult; D000465:Algorithms; D002423:Cause of Death; D003718:Denmark / Q000453:epidemiology; D004522:Educational Status; D005190:Family; D005260:Female; D005500:Follow-Up Studies; D054624:Health Status Disparities; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000401:mortality; D016017:Odds Ratio; D011203:Poverty; D016016:Proportional Hazards Models; D012307:Risk Factors; D035781:Siblings; D015996:Survival Rate