AMSTERDAM, Sept 2: A new blood clot preventer from Daiichi Sankyo proved as effective as widely used warfarin in treating a dangerous condition known as venous thromboembolism and caused less bleeding, a large clinical trial found. The Japanese drugmaker hopes the finding will help it take on rivals including Bayer, Johnson & Johnson , Pfizer and Bristol-Myers Squibb in a growing market for novel pills to prevent blood clots, especially as the drug appears to work best in sicker patients. (agencies)