Researchers ID risk factors for VTE in large-scale study

Older age, smoking and a higher body mass index (BMI) were consistently associated with a heightened risk of venous thromboembolism (VTE) in an analysis of 1.1 million individuals published in JAMA Cardiology.

The analysis featured more than 730,000 people from the Emerging Risk Factors Collaboration (ERFC), which enrolled 75 cohorts from 18 different countries from 1960 through 2008. About half of participants were from Europe and another 43.1 percent were enrolled in North America.  

For more contemporary data, lead author John Gregson, PhD, and colleagues also studied more than 420,000 participants enrolled from 2006 to 2010 in the prospective UK Biobank study.

All participants had no history of cardiovascular disease, but the authors analyzed results from these sources in a parallel (rather than pooled) fashion because the ERFC only recorded fatal VTE events while the UK Biobank captured both fatal and nonfatal events.

Even so, Gregson et al. found three factors were significantly associated with VTE in both groups:

  • Age: Each decade increase was linked to 2.67 times the risk of VTE in the ERFC cohorts and 1.81 times the risk in UK Biobank.
  • Current smoking: Linked to a 38 percent increased risk in ERFC and a 23 percent increased risk in UK Biobank.
  • BMI: Each standard deviation increase was associated with excess risks of 43 percent in ERFC and 37 percent in UK Biobank.

“We found that older age, smoking, and higher levels of adiposity were clearly associated with higher risk of VTE,” Gregson, with London School of Hygiene and Tropical Medicine, and co-authors wrote. “These findings suggest that there is overlap in at least some major population determinants of important venous and arterial thrombotic diseases.”

VTE, which encompasses deep vein thrombosis or pulmonary embolism, affects about 10 million people globally every year, according to the authors. That makes it the third leading vascular disease behind myocardial infarction and stroke.

Gregson et al. said adiposity was the only one of the three consistent VTE risk factors that was associated with the condition more strongly than coronary heart disease (CHD).

“Our study characterized dose-response associations between several clinical measures of adiposity (eg, waist circumference and BMI) and VTE risk and showed no evidence of a threshold below which leaner body habitus stopped being associated with lower VTE risk,” they wrote. “Furthermore, we found that associations of BMI and waist circumference were somewhat stronger with PE vs DVT and about twice as strong with VTE vs CHD. These data suggest that efforts to combat the entire spectrum of obesity and overweight should yield important benefits for VTE prevention.”

Higher systolic blood pressure and a history of diabetes were tied to heightened risk for VTE in ERFC but not in UK Biobank. Gregson and colleagues speculated this could be because UK Biobank captured mostly nonfatal outcomes while ERFC only recorded fatal events.

“Our exploratory analysis of UK Biobank data was consistent with this explanation, as it found differing results with blood pressure and diabetes for fatal VTE vs nonfatal VTE similar to those observed in comparisons across UK Biobank and the ERFC,” the authors wrote. “However, future studies with more detailed clinical information will be needed to understand these possible differences with greater confidence.”