Unfractionated or low-molecular weight heparin for induction of remission in ulcerative colitis.

BACKGROUND: There are a limited number of treatment options for patients with ulcerative colitis (UC). An increased risk of thrombosis in UC coupled with an observation that UC patients being treated with anticoagulant therapy for thrombotic events had an improvement in their bowel symptoms led to trials examining the use of unfractionated heparin (UFH) and low molecular weight heparins (LMWH) in patients with active UC.

OBJECTIVES: To review randomized trials examining the efficacy of unfractionated heparin (UFH) or low molecular weight heparins (LMWH) for remission induction in patients with ulcerative colitis.

SEARCH STRATEGY: The MEDLINE (PUBMED), and EMBASE databases, The Cochrane Central Register of Controlled Trials, the Cochrane IBD/FBD group specialized trials register, review papers on ulcerative colitis, and references from identified papers were searched up to June 2010 in an effort to identify all randomized trials studying UFH or LMWH use in patients with ulcerative colitis. Abstracts from major gastroenterological meetings were searched to identify research published in abstract form only.

SELECTION CRITERIA: Each author independently reviewed potentially relevant trials to determine their eligibility for inclusion based on the criteria identified above. The Cochrane Risk of Bias tool was used to assess study quality. Studies published in abstract form only were included if the authors could be contacted for further information.

DATA COLLECTION AND ANALYSIS: A data extraction form was developed and used to extract data from included studies. At least 2 authors independently extracted data. Any disagreements were resolved by consensus. Data were analyzed on an intention-to-treat basis. The primary outcome was induction of remission, as defined by the studies. Data were combined for analysis if they assessed the same treatments (UFH or LMWH versus placebo or other therapy).

MAIN RESULTS: LMWH administered subcutaneously showed no benefit over placebo for any outcome, including clinical remission, and clinical, endoscopic, or histological improvement. High dose LMWH administered via an extended colon-release tablet demonstrated benefit over placebo for clinical remission (OR 2.73; 95% CI 1.32 to 5.67; P = 0.007), clinical improvement (OR 2.99; 95% CI 1.30 to 6.87; P = 0.01), and endoscopic improvement (OR 2.25; 95%CI 1.01 to 5.01; P = 0.05) but not endoscopic remission or histologic improvement. LMWH was not beneficial when added to standard therapy for clinical remission, clinical improvement, endoscopic remission or endoscopic improvement. LMWH was well-tolerated but provided no significant benefit for quality of life. One study examining UFH versus corticosteroids for the treatment of severe UC demonstrated the inferiority of UFH for clinical improvement. More patients assigned to UFH had rectal hemorrhage as an adverse event.

AUTHORS' CONCLUSIONS: There is evidence to suggest that LMWH may be effective for the treatment of active UC. When administered by extended colon-release tablets, LMWH was more effective than placebo for treating outpatients with mild to moderate disease. This benefit needs to be confirmed by further randomized controlled studies. The same benefits were not seen when LMWH was administered subcutaneously at lower doses. There is no evidence to support the use of UFH for the treatment of active UC. A further trial of UFH in patients with mild disease may also be justified. Any benefit found would need to be weighed against a possible increased risk of rectal bleeding in patients with active UC.