Figure 1

Decision node and anticoagulation subtree. Decision analysis tree demonstrating two strategies: providing anticoagulant prophylaxis at 24 hours to an adult patient following head injury with intracranial hemorrhage (ICH), or withholding anticoagulant prophylaxis. A linkage term representing the complement of the effectiveness of anticoagulant prophylaxis for reducing the risk of DVT was used to link the main subtrees. This effectiveness term was calculated as follows: effectiveness of anticoagulant prophylaxis = ((probability of DVT without LMWH) - (probability of DVT with LMWH))/(probability of DVT without LMWH). The square node at the extreme left represents the decision node, the circles represent chance nodes, and the plus signs at the far right indicate the presence of additional branches. Numerical values under each branch are the baseline probabilities used at each chance node. CNS Bleed: progression of intracranial hemorrhage; DVT: deep vein thrombosis; PE: pulmonary embolism.