Acute infections may make two blood clotting conditions — deep vein thrombosis (DVT) and pulmonary embolism — more likely.
Researchers report the news in The Lancet. They reviewed the medical records from a large British database.
The study shows that while DVT and pulmonary embolism were rare, they were more common after acute infections. Acute infections should be considered a risk factor for DVT and pulmonary embolism, write Liam Smeeth, PhD, and colleagues.
Smeeth works at the London School of Hygiene and Tropical Medicine. He and his colleagues focused on acute infections of the urinary or respiratory tracts. Minor respiratory illnesses weren't included.
Increased Risk After Acute Infections
Out of millions of medical records, Smeeth's team found more than 7,200 people who had DVTs and more than 3,700 who had pulmonary embolism. DVT risk was about twice as high after either acute infection, the study shows.
Pulmonary embolism risk also doubled after acute urinary tract infection. Due to the risk of misdiagnosis, the researchers didn't estimate pulmonary embolism risk after acute respiratory tract infection.
DVT and pulmonary embolism risk was highest in the first two weeks after acute infection. The risk fell back to normal after a year, the study shows. Of course, the results don't mean that everyone with acute infections will get DVT or pulmonary embolism.
The researchers don't know exactly what caused the patients' DVT or pulmonary embolism. They write that patients possibly got more medical care while recovering from acute infection, giving doctors more chance to spot DVT and pulmonary embolism.
Immobility raises DVT risk. But most infections weren't rough enough to prompt long periods of bed rest, write Smeeth and colleagues. They say the next step is to figure out how acute infections raise DVT and pulmonary embolism risk.
By Miranda Hitti, reviewed by Louise Chang, MD
SOURCES: Smeeth, L. The Lancet, April 1, 2006; vol 367: pp 1075-1079. News release, The Lancet.