Public Release: 

Nonhospitalized patients with active inflammatory bowel disease are 16 times more likely to suffer a blood clot than the general population

Lancet

Non-hospitalised patients with active inflammatory bowel disease (IBD) are 16 times more likely to suffer a blood clot (venous thromboembolism) than the non-hospitalised general population. These results suggest that active IBD in ambulatory patients might be a far greater risk factor for venous thromboembolism than previously recognised, and these patients could be a target for prophylaxis. These are the conclusions of an Article published Online First (www.thelancet.com) and in an upcoming edition of The Lancet--written by Dr Matthew J Grainge, University of Nottingham, UK, and colleagues.

Venous thromboembolism in the leg is associated with a short-term mortality rate of about 6%, whereas the rate after embolism in the pulmonary circulation is as high as 20%. Infection and inflammation are thought to predispose to this life-threatening disease, and people with IBD seem to be particularly at risk. Research suggests that most patients with IBD have active disease at the time of developing venous thromboembolism. The three-fold overall increase in risk has led to the use of thromboprophylaxis (anti-clotting drugs) as the standard of care for patients with active IBD admitted to hospital. However, the absolute and relative risks in people with active disease who are not admitted to hospital are not known. In this study, the authors assessed different potentially interacting periods to separate out the effects of hospital admission and active IBD on the risk of a blood clot.

The researchers used the UK General Practice Research Database from November, 1987, until July, 2001, to match patients with IBD with controls without the disease. There were 13 756 patients with IBD and 71 672 matched controls included in the analysis, and of these 139 patients and 165 controls developed a blood clot. Overall, patients with IBD had a higher risk of a blood clot than did controls (3•4 times increased risk). At the time of a flare*, however, this increase in risk was much more prominent (8 times). Although the absolute risk of clots was greater for patients in hospital, this relative risk at the time of a flare was higher during non-hospitalised periods (when patients were at 16 times the risk of their non-hospitalised controls) than during hospitalised periods (when the risk was 3 times that of other hospitalised patients).

The authors say: "Inflammatory bowel disease was associated with a roughly three-fold increase in the risk of venous thromboembolism. Compared with the general population while ambulatory, the risk of venous thromboembolism was increased about 16-fold for non-hospitalised patients with active inflammatory bowel disease. Despite the low absolute risks during non-hospitalised periods, these results suggest that active inflammatory bowel disease in ambulatory patients might be a far greater risk factor for venous thromboembolism than previously recognised."

They conclude: "We believe that the medical profession needs to recognise the increased risk in people with inflammatory bowel disease when assessing the likelihood of venous thromboembolism and to address the difficulty of reducing this risk in patients with a flare who are not admitted to hospital... Such strategies to achieve a reduction in risk might include those used for inpatients such as brief courses of low-molecular weight heparin or perhaps newly available oral anticoagulants."

In an accompanying Comment Dr Geoffrey C Nguyen, Mount Sinai Hospital Inflammatory Bowel Disease Centre, University of Toronto, Canada, and Johns Hopkins Division of Gastroenterology and Hepatology, Baltimore, MD, USA; and Dr Erik L Yeo, University Health Network Thrombosis Clinic, University of Toronto, Canada, say: "We believe that the clinical efficacy and cost-effectiveness of pharmacological prophylaxis in the population with inflammatory bowel disease should be proven before it is routinely recommended during acute flares [in the ambulatory setting]. The ascertainment of efficacy data through clinical trials might, however, be a formidable challenge given that the absolute risk of venous thromboembolism is low and a sample size of thousands of people with inflammatory bowel disease during active flares might be required."

They add: "A pragmatic initial approach to reduction of the rates of morbidity and mortality resulting from venous thromboembolism in ambulatory patients with inflammatory bowel disease would be non-pharmacological thromboprophylaxis, including patients' education and awareness of risk and signs and symptoms of venous thromboembolism, and use of support stockings."

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Media Relations, University of Nottingham, UK. T) +44 (0) 115 951 5793 E) communications@nottingham.ac.uk

Dr Geoffrey C Nguyen, Erik L Yeo, Mount Sinai Hospital Inflammatory Bowel Disease Centre, University of Toronto, Canada, and Johns Hopkins Division of Gastroenterology and Hepatology, Baltimore, MD, USA. T) +1 416-586-4800 ext 2819 E) geoff.nguyen@utoronto.ca

For full Article and Comment see: http://press.thelancet.com/ibdvte.pdf

Notes to editors: * A flare as defined in this study was a period of time during which patients with inflammatory bowel disease were prescribed a new course of oral corticosteroids and the 4 months after the prescription

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