Are the educational differences in incidence of cardiovascular disease explained by underlying familial factors? A twin study.
To isolate the effect of education from the influence of potential underlying factors, we investigated the association of education with the risk of cardiovascular disease (CVD) and ischemic heart disease (IHD) using twin data to adjust for familial factors shared within twins, including genetic make-up and childhood environment. The study was based on data from the Danish Twin Registry linked to administrative and heath registers in Statistics Denmark. A total of 11,968 monozygotic and 20,464 dizygotic same sexed twins were followed from 1980 to 2009, including more than 8000 events of CVD. Unpaired and intra-pair analyses were compared. In the unpaired analyses, an inverse educational gradient in CVD- and IHD risk was observed. This association was not replicated in the intra-pair analyses that control for shared familial factors exploiting that twins share their intrauterine- and childhood environment and are matched partly or fully on genetic setup. The attenuation of association of education with CVD and IHD in the intra-pair analyses suggests that shared familial factors account for a substantial part of the observed association of education with CVD and IHD in Denmark.
Unit of Epidemiology, Biostatistics and Biodemography, University of Southern Denmark, J.B. Winsløwsvej 9B, 5000 Odense, Denmark; The Danish Twin Registry, University of Southern Denmark, J.B. Winsløwsvej 9B, Odense, Denmark; Danish Aging Research Center, University of Southern Denmark, J.B. Winsløwsvej 9B, Odense, Denmark. Electronic address: Mimadsen@health.sdu.dk.
Mia
M
Madsen
Department of Public Health, Section of Biostatistics, University of Copenhagen, Øster Farimagsgade 5, Copenhagen, Denmark. Electronic address: pkan@sund.ku.dk.
Per K
PK
Andersen
Unit of Epidemiology, Biostatistics and Biodemography, University of Southern Denmark, J.B. Winsløwsvej 9B, 5000 Odense, Denmark. Electronic address: mgerster@gmail.dk.
Mette
M
Gerster
Department of Public Health, Section of Social Medicine, University of Copenhagen, Øster Farimagsgade 5, Copenhagen, Denmark. Electronic address: amny@sund.ku.dk.
Anne-Marie N
AM
Andersen
Unit of Epidemiology, Biostatistics and Biodemography, University of Southern Denmark, J.B. Winsløwsvej 9B, 5000 Odense, Denmark; The Danish Twin Registry, University of Southern Denmark, J.B. Winsløwsvej 9B, Odense, Denmark; Danish Aging Research Center, University of Southern Denmark, J.B. Winsløwsvej 9B, Odense, Denmark; Department of Clinical Biochemistry and Pharmacology, Odense University Hospital, Sdr. Boulevard 29, Odense, Denmark; Department of Clinical Genetics, Odense University Hospital, Sdr. Boulevard 29, Odense, Denmark. Electronic address: kchristensen@health.sdu.dk.
Kaare
K
Christensen
Danish Aging Research Center, University of Southern Denmark, J.B. Winsløwsvej 9B, Odense, Denmark; Department of Public Health, Section of Social Medicine, University of Copenhagen, Øster Farimagsgade 5, Copenhagen, Denmark; Research Centre for Prevention and Health, Glostrup University Hospital, Nordre Ringvej 57, 84-85, Glostrup, Denmark. Electronic address: merete.osler@regionh.dk.
Merete
M
Osler
D000328:Adult; D002318:Cardiovascular Diseases / Q000235:genetics*; D003718:Denmark / Q000453:epidemiology; D004522:Educational Status; D004777:Environment; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D015994:Incidence; D008297:Male; D017202:Myocardial Ischemia / Q000235:genetics; D012307:Risk Factors; D012959:Socioeconomic Factors; D014429:Twins, Dizygotic; D014430:Twins, Monozygotic
Cardiovascular diseases; Education; Social class; Twin Study