title: A nationwide family study of pulmonary embolism: identification of high risk families with increased risk of hospitalized and fatal pulmonary embolism.
abstract: BACKGROUND
  Family history is an important risk factor for deep venous thrombosis. However, few studies have determined the importance of family history of pulmonary embolism (PE).
  
  
  OBJECTIVE
  This nationwide study aimed to determine the familial risks of fatal and hospitalized PE.
  
  
  METHODS
  The Swedish Multi-Generation Register for subjects aged 0 to 76 years old born since 1932 were linked to the Hospital Discharge Register and Cause of Death Register for the period 1964-2008. Standardized incidence ratios (SIRs) for first hospitalization or death (without previous hospitalization for PE) with a main diagnosis of PE were calculated for individuals whose parent or siblings were hospitalized with or died from PE, compared to those whose parent or siblings were not affected by PE.
  
  
  RESULTS
  A total of 20,860 individuals were hospitalized for PE and 862 died due to primary fatal PE (without previous hospitalization for PE). The familial SIR for individuals with one sibling with hospitalized PE was 2.49 (95% CI 1.62-3.83). The familial SIR for siblings with two affected probands was 114.29 (95% CI 56.57-223.95). The familial SIRs for individuals with a parent or sibling hospitalized for PE were significantly increased for fatal PE (1.76; 95% CI 1.38-2.21) and hospitalized PE (2.13; 95% CI 2.04-2.23). Spouses had low overall familial risk for PE (1.09; 95% CI, 1.03-1.14).
  
  
  CONCLUSIONS
  The high familial risk in multiplex sibling families suggests the existence of strong genetic risk factors for PE. Familial factors and possibly genetic factors are important risk factors for primary fatal pulmonary embolism.
authors.affiliation: Center for Primary Health Care Research, Lund University/Region Skåne, Malmö, Sweden. bengt.zoller@med.lu.se
authors.forename: Bengt
authors.initials: B
authors.lastname: Zöller
authors.forename: Xinjun
authors.initials: X
authors.lastname: Li
authors.forename: Jan
authors.initials: J
authors.lastname: Sundquist
authors.forename: Kristina
authors.initials: K
authors.lastname: Sundquist
mesh_terms: D000328:Adult; D005260:Female; D020022:Genetic Predisposition to Disease; D006760:Hospitalization; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D010290:Parents; D010375:Pedigree; D011655:Pulmonary Embolism / Q000453:epidemiology* / Q000235:genetics; D012042:Registries; D012307:Risk Factors; D035781:Siblings; D018454:Spouses; D013548:Sweden