BOSTON — Taller men appear to have a twofold greater risk for venous thromboembolic events than do men of more modest height, Norwegian investigators reported.
Men taller than 181 cm (about 5 feet 11 inches) had double the risk of either provoked or unprovoked venous thromboembolic events (VTEs), compared with men 173 cm (about 5 feet 8 inches) or shorter, reported Dr. Knut H. Borch of the Center for Atherothrombotic Research in Tromsø, Norway, and his colleagues.
In men, each 10-cm increase in height was associated with a significant hazard ratio of 1.34. In women, height was not a significant risk factor for VTE (HR 1.13), he said at a meeting of the International Society on Thrombosis and Haemostasis.
“We suggest that body height should be considered in risk stratification of VTE,” Dr. Borch said. More research is needed to determine how height interacts with other risk factors for VTE.
A 2005 analysis of data from the Physicians' Health Study (Am. J. Epidemiol. 2005;162:975-82) found that every 10 cm of height was associated with about a 36% increase in risk in men. In a separate study, Swedish researchers also found a positive association between body height and VTE risk in men (J. Thromb. Haemost. 2008;6:558-64).
Dr. Borch and his colleagues drew data from the Tromsø Study, a prospective population-based study of men and women aged 25 years and older in the town of Tromsø, in northern Norway. The study included 26,727 residents. The researchers recorded all first lifetime VTEs from the date of study enrollment (1994-1995) through Sept. 1, 2007. Cases were identified by discharge diagnosis, autopsy registry, and radiology procedure registry. VTE was confirmed by diagnostic procedure or autopsy, and the data collected included diagnosis of deep vein thromboembolism (DVT) or pulmonary embolism, signs and symptoms consistent with VTE, and VTE treatment.
During the median follow-up of 12.5 years, there were 462 VTEs, 193 (41.8%) of which were classified as provoked (associated with major surgery or an acute medical condition within 8 weeks of the event, cancer at the time of the event, prolonged immobilization, or other known risk factors). Of the provoked VTEs, 64.3% were DVTs. Overall, the incidence of VTE was 1.6 per 1,000 person-years.
Among men, there were 219 VTEs. Men in the tallest quartile (181 cm and taller) had a significantly increased risk for VTE, vs. men in the lowest height quartile (less than 173 cm). In a multivariate analysis that adjusted for other risk factors, the hazard ratio for the tallest men was 1.99. The hazard ratio for each 10 cm of height was 1.34. Height had no effect on total VTE risk among women. In both men and women, the risks for provoked vs. unprovoked VTE were similar.
Possible explanations for the sex difference in the VTE-height relationship include unidentified sex-specific differences in venous architecture, or differences in pressure dynamics or stasis, Dr. Borch said.
The funding source for the study was not disclosed. Dr. Borch declared that neither he nor his coauthors had relevant financial disclosures.