Venous thromboembolism during active disease and remission in inflammatory bowel disease: a cohort study.
BACKGROUND
Patients with inflammatory bowel disease who develop deep vein thrombosis or pulmonary embolism often have active disease at the time of thromboembolism. We therefore aimed to quantify the risk of venous thromboembolism prospectively during different activity phases of inflammatory bowel disease.


METHODS
From the General Practice Research Database, we matched patients with prospectively recorded inflammatory bowel disease from November, 1987, until July, 2001 with up to five controls by age, sex, and general practice. A flare was defined as the period 120 days after a new corticosteroid prescription. We used Cox regression analysis with time-varying covariates to accommodate changes in the state of inflammatory bowel disease, and whether patients were at high risk of venous thromboembolism after hospitalisation.


RESULTS
13 756 patients with inflammatory bowel disease and 71 672 matched controls were included in the analysis, and of these 139 patients and 165 controls developed venous thromboembolism. Overall, patients with inflammatory bowel disease had a higher risk of venous thromboembolism than did controls (hazard ratio 3.4, 95% CI 2.7-4.3; p<0.0001; absolute risk 2.6 per 1000 per person-years). At the time of a flare, however, this increase in risk was much more prominent (8.4, 5.5-12.8; p<0.0001; 9.0 per 1000 person-years). This relative risk at the time of a flare was higher during non-hospitalised periods (15.8, 9.8-25.5; p<0.0001; 6.4 per 1000 person-years) than during hospitalised periods (3.2, 1.7-6.3; p=0.0006; 37.5 per 1000 person-years).


CONCLUSIONS
Trials of primary prophylaxis of venous thromboembolism are warranted to find out whether this important complication can be prevented.


BACKGROUND
National Association for Colitis and Crohn's Disease.
Division of Epidemiology and Public Health, University of Nottingham, Nottingham, UK. matthew.grainge@nottingham.ac.uk
Matthew J
MJ
Grainge
Joe
J
West
Timothy R
TR
Card
D000328:Adult; D000367:Age Factors; D000368:Aged; D016022:Case-Control Studies; D015331:Cohort Studies; D015986:Confounding Factors, Epidemiologic; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D015994:Incidence; D015212:Inflammatory Bowel Diseases / Q000150:complications / Q000453:epidemiology*; D008297:Male; D016555:Matched-Pair Analysis; D008875:Middle Aged; D016016:Proportional Hazards Models; D012306:Risk; D018570:Risk Assessment; D012307:Risk Factors; D012737:Sex Factors; D013923:Thromboembolism / Q000150:complications / Q000453:epidemiology*; D054556:Venous Thromboembolism / Q000150:complications / Q000453:epidemiology*; D020246:Venous Thrombosis / Q000150:complications / Q000453:epidemiology* / Q000209:etiology