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08-08-2011 | Cardiology | Article

Sibling history may predict VTE risk


Free abstract

MedWire News: A sibling history of venous thromboembolism (VTE) appears to be an important risk factor for developing the condition, researchers report.

Bengt Zöller (Lund University, Malmö, Sweden) and colleagues used data from the Swedish Multigeneration and Hospital Discharge Registers to determine age- and gender-specific familial risks in siblings hospitalized for VTE.

Between 1987 and 2007, 45,362 patients aged 0 to 75 years were hospitalized with VTE. Of these, 2393 had siblings who were also affected by the condition.

The researchers calculated that the standardized incidence ratio (SIR) for individuals whose siblings were hospitalized for VTE was 2.5, compared with those whose siblings were not affected, indicating that individuals with a sibling history were more than twice as likely to have VTE than those without such history.

When the team looked at individuals with more than one affected sibling, they observed significant increases in the SIRs; the SIR was 51.9 for individuals with two affected siblings and 53.7 for those with three or more affected siblings.

The total incidence rate was significantly higher for females (36.2 per 100,000 years) than for males (32.5 per 100,000 years). However, the gender difference was age-dependent, with a higher incidence observed among women than men from the ages of 10 to 40 years, but higher incidence among men than women aged 50 years and older.

The familial risks were significantly increased from the age of 10 to 69 years, but the highest SIR was observed among those aged 10 to 19 years, at 4.8. This fell to 2.1 for individuals aged 60 to 69 years, although the absolute risk increased with age.

Zöller and team found that the age difference among siblings had little impact on the SIRs. In addition, spouses had low familial risks (SIR=1.1), indicating that most of the familial risk is due to genetics rather than family environmental factors, the researchers say.

The authors explain that, the average familial risk in first-degree relatives is about doubled for many complex diseases, which is in agreement with the present study.

"Our data support the view that VTE is a multifactorial disease with familial risks comparable to those of many other complex disorders," they write in the journal Circulation.

"However, in a small fraction of siblings, the familial risk is very high, suggesting a segregation of rare but strong genetic risk factors," the team concludes.

By Laura Dean

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