Background: The value of parental history as a risk indicator for venous thromboembolism (VTE) has not been determined in a nationwide setting.
Objectives: To perform the first nationwide study of age-specific and sex-specific familial VTE risks in offspring of parents hospitalized for VTE.
Patients/methods: The Swedish Multigeneration Register of 0-75-year-old subjects was linked to the Hospital Discharge Register for 1987-2007. Standardized incidence ratios (SIRs) were calculated for individuals whose parents were hospitalized for VTE as compared with those whose parents were unaffected.
Results: Among 45,362 hospitalized offspring cases with VTE, 4865 offspring of affected parents were identified with a familial SIR of 2.00 (95% confidence interval [CI] 1.94-2.05). Familial SIR was slightly higher for male offspring than for female offspring (2.08, 95% CI 2.00-2.16 vs. 1.91, 95% CI 1.84-1.99). The risk in offspring was further increased when both parents were affected (3.97, 95% CI 3.40-4.61), with high familial risks at ages 20-29 years (10.00, 95% CI 5.91-15.84). The familial risks for VTE among offspring were increased from the age of 10 years up to 75 years, with familial SIRs of 3.96 (95% CI 3.13-4.94) at age 10-19 years and 1.48 (95% CI 1.17-1.84) at ages 70-75 years. However, the absolute incidence rate increased with age.
Conclusions: Parental history is potentially useful for risk assessments of VTE, although age needs to be considered. Our results support the use of an age-dependent multicausal model to estimate the risk of VTE.
© 2010 International Society on Thrombosis and Haemostasis.