Risk of deep vein thrombosis and pulmonary embolism after acute infection in a community setting.
BACKGROUND
Acute infection increases the risk of arterial cardiovascular events, but effects on venous thromboembolic disease are less well established. Our aim was to investigate whether acute infections transiently increase the risk of venous thromboembolism.


METHODS
We used the self-controlled case-series method to study the risk of first deep vein thrombosis (DVT) (n=7278) and first pulmonary embolism (PE) (n=3755) after acute respiratory and urinary tract infections. Data were obtained from records from general practices who had registered patients with the UK's Health Improvement Network database between 1987 and 2004.


RESULTS
The risks of DVT and PE were significantly raised, and were highest in the first two weeks, after urinary tract infection. The incidence ratio for DVT was 2.10 (95% CI 1.56-2.82), and that for PE 2.11 (1.38-3.23). The risk gradually fell over the subsequent months, returning to the baseline value after 1 year. The risk of DVT was also higher after respiratory tract infection, but possible diagnostic misclassification precluded a reliable estimate of the risk of PE after respiratory infection.


CONCLUSIONS
Acute infections are associated with a transient increased risk of venous thromboembolic events in a community setting. Our results confirm that infection should be added to the list of precipitants for venous thromboembolism, and suggest a causal relation.
Departments of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK. Electronic address: liam.smeeth@lshtm.ac.uk.
Liam
L
Smeeth
Departments of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK.
Claire
C
Cook
Departments of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK.
Sara
S
Thomas
Departments of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK.
Andrew J
AJ
Hall
Division of Respiratory Medicine, University of Nottingham, UK.
Richard
R
Hubbard
Centre for Clinical Pharmacology, British Heart Foundation Laboratories, University College London, UK.
Patrick
P
Vallance
D000208:Acute Disease; D000328:Adult; D000368:Aged; D016208:Databases, Factual; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D011655:Pulmonary Embolism / Q000453:epidemiology / Q000209:etiology*; D012141:Respiratory Tract Infections / Q000150:complications*; D012307:Risk Factors; D012621:Seasons; D013548:Sweden / Q000453:epidemiology; D014481:United States / Q000453:epidemiology; D014552:Urinary Tract Infections / Q000150:complications*; D020246:Venous Thrombosis / Q000453:epidemiology / Q000209:etiology*