Anticoagulants compared with anti-inflammatory drugs or placebo for treating people who have venous blood clots

A blood clot can block a venous blood vessel to cause what is known as a thromboembolism. This most often occurs in a leg (deep vein thrombosis) or in the lungs (pulmonary embolism), which can be fatal. Once formed, a blood clot in a leg can increase in size or can move to the lungs and the recommended treatment is to give drugs that thin the blood (anticoagulants). These include heparins and drugs that inhibit the action of vitamin K (warfarin, phenprocoumon, and acenocoumarol). The possible harms caused by anticoagulants include bleeding in the gut or brain and anticoagulant-induced clotting. The review authors made a thorough search of the medical literature looking for controlled studies on people with blood clots in their veins comparing blood thinning drugs (anticoagulants) with drugs to reduce inflammation (non-steroidal anti-inflammatory drugs) or dummy treatment (placebo). Only two small studies with a total of 113 participants treated over three months were identified, which gave inconclusive results. Since the use of anticoagulants is widely accepted in clinical practice, designing and implementing other similar studies would not be ethical.