Education and adult cause-specific mortality--examining the impact of family factors shared by 871 367 Norwegian siblings.
OBJECTIVE
To estimate the impact family factors shared by siblings has on the association between length of education and cause-specific mortality in adulthood.


METHODS
The study population (n = 871 367) was all Norwegians born 1940-59 having one or more sibling within the cohort and alive in 1990. Length of education was obtained in 1990. Follow-up of deaths was from 1991 to 2008 when participants were aged 32-68 years.


RESULTS
Sixty-five per cent of participants had one or more siblings who had completed a different number of years of formal education. A one-category difference in education was associated with a 30% increase in the hazard rate of death by all causes among men in the cohort analysis and 23% in within siblings analysis, and in women, increases were 22% and 14%, respectively. For cardiovascular disease, increases were 36% and 25% in men and 51% and 36% in women. For lung cancer, they were 48% and 29% in men and 53% and 22% in women. External causes and alcohol-related causes in men were generally similar in both analyses.


CONCLUSIONS
This study suggests that at least some of the educational inequalities in all-cause, cardiovascular disease and lung cancer, external and alcohol-related mortality are explained by factors shared by siblings.
Division of Epidemiology, National Institute of Public Health, University of Oslo, Oslo, Norway.
Oyvind
O
Næss
Dominic A
DA
Hoff
Debbie
D
Lawlor
Laust H
LH
Mortensen
D000328:Adult; D000368:Aged; D002423:Cause of Death; D004522:Educational Status; D005191:Family Characteristics; D005260:Female; D054624:Health Status Disparities; D006801:Humans; D008297:Male; D008875:Middle Aged; D009026:Mortality / Q000639:trends*; D009664:Norway / Q000453:epidemiology; D017678:Sex Distribution; D035781:Siblings