Family history of premature myocardial infarction, life course socioeconomic position and coronary heart disease mortality--A Cohort of Norway (CONOR) study.
OBJECTIVE
To investigate self-reported family history (FH) of premature myocardial infarction (MI) in first-degree relatives as a risk factor for coronary heart disease (CHD) mortality, and assess whether any observed effect could be explained by current or life course socioeconomic position.


METHODS
130,066 participants from Cohort of Norway were examined during 1994-2003. A subgroup (n=84,631) had additional life course socioeconomic data. Using Cox proportional hazard analyses, we calculated hazard ratios (HR) for CHD mortality, assessed by linkages to the Norwegian Cause of Death Registry through 2009. For subgroup analyses, we created an index of life course socioeconomic position, and assessed its role as a potential confounder in the association of FH with CHD.


RESULTS
For men, MI in parents and siblings were both a significant risk factor for CHD mortality after adjusting for established risk factors and current socioeconomic conditions; the highest risk was with MI in siblings (HR: 1.44 [1.19-1.75]). For women, FH constituted significant risk after similar adjustment only for those with MI in parents plus siblings (HR: 1.78 [1.16-2.73]). Adjusting for current and life course socioeconomic conditions only marginally lowered the estimates, and those with FH did not have worse life course socioeconomic position than those without.


CONCLUSIONS
FH of premature MI is an independent risk factor for CHD mortality that differs in magnitude of effect by the sex of the index person and type of familial relationship. Life course socioeconomic position has little impact on the association between FH and CHD, suggesting the effect is not confounded by this.
University of Oslo, Faculty of Medicine, PB 1078 Blindern, 0316 Oslo, Norway. Electronic address: b.s.fiska@studmed.uio.no.
Bendik S
BS
Fiskå
Division of Epidemiology, National Institute of Public Health, PB 4404, Nydalen, 0403 Oslo, Norway.
Inger
I
Ariansen
Division of Epidemiology, National Institute of Public Health, PB 4404, Nydalen, 0403 Oslo, Norway.
Sidsel
S
Graff-Iversen
Department of Global Public Health and Primary Care, University of Bergen, PB 7804, 5018 Bergen, Norway; Department of Health Registries, Norwegian Institute of Public Health, Kalfarveien 31, 5018 Bergen, Norway.
Grethe S
GS
Tell
Department of Global Public Health and Primary Care, University of Bergen, PB 7804, 5018 Bergen, Norway; Department of Health Registries, Norwegian Institute of Public Health, Kalfarveien 31, 5018 Bergen, Norway.
Grace M
GM
Egeland
University of Oslo, Faculty of Medicine, PB 1078 Blindern, 0316 Oslo, Norway; Division of Epidemiology, National Institute of Public Health, PB 4404, Nydalen, 0403 Oslo, Norway.
Øyvind
Ø
Næss
D000293:Adolescent; D000328:Adult; D000368:Aged; D015331:Cohort Studies; D003324:Coronary Artery Disease / Q000175:diagnosis* / Q000191:economics / Q000401:mortality*; D005260:Female; D005500:Follow-Up Studies; D006306:Health Surveys; D006801:Humans; D008297:Male; D008875:Middle Aged; D009026:Mortality / Q000639:trends; D061213:Mortality, Premature / Q000639:trends; D009203:Myocardial Infarction / Q000175:diagnosis* / Q000191:economics / Q000401:mortality*; D009664:Norway / Q000453:epidemiology; D012307:Risk Factors; D012959:Socioeconomic Factors; D055815:Young Adult
Coronary heart disease; Coronary heart disease mortality; Family history; Life course socioeconomic position; Myocardial infarction