Multiplex sibling history of coronary heart disease is a strong risk factor for coronary heart disease.
OBJECTIVE
Familial risks for coronary heart disease (CHD) in families with multiple affected siblings have not been thoroughly studied. This nationwide cohort study aimed to determine familial risks for hospitalization or death due to CHD in families with multiple affected siblings.


RESULTS
The study is a nationwide follow-up study. The Swedish Multigeneration Register data on 0-76-year-old subjects were linked to Hospital Discharge Register and Cause of Death Register data for 1964-2008. Standardized incidence ratios (SIRs) were calculated for individuals whose siblings were hospitalized or died (without previous hospitalization, i.e., primary fatal cases) due to CHD compared with those whose siblings were not affected. The procedure was repeated for spouses. Among a total of 185 810 cases of hospitalization or death due to CHD, the SIRs for hospitalization and death in the siblings of affected probands were 1.82 (95% CI: 1.27-2.60) and 1.60 (95% CI: 1.10-2.36), respectively. The SIRs for hospitalization in siblings of two and three affected probands were 6.92 (95% CI: 4.77-10.03) and 7.88 (95% CI: 5.31-11.70), respectively. The SIRs for death in siblings of two and three affected probands were 7.31 (95% CI: 4.76-11.19) and 6.61 (95% CI: 3.91-11.10), respectively. Spouses had low overall familial risks (SIR = 1.05, 95% CI: 1.05-1.06).


CONCLUSIONS
Family history of multiple affected siblings increases the CHD risk. Family history is not a binary trait. There are degrees of risk associated with family history with more than one affected sibling.
Center for Primary Health Care Research, Lund University/Region Skåne, Skåne University Hospital, CRC, Building 28, Floor 11, Entrance 72, SE-205 02 Malmö, Sweden. bengt.zoller@med.lu.se
Bengt
B
Zöller
Xinjun
X
Li
Jan
J
Sundquist
Kristina
K
Sundquist
D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D003327:Coronary Disease / Q000235:genetics* / Q000401:mortality; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D015994:Incidence; D007223:Infant; D008297:Male; D008875:Middle Aged; D010375:Pedigree; D011379:Prognosis; D012307:Risk Factors; D035781:Siblings; D013548:Sweden / Q000453:epidemiology; D055815:Young Adult