e of the three affiliated hospitals and were therefore excluded. As a result, the study population comprised 537 patients, of whom 223 were primarily diagnosed with pulmonary embolism, and 314 with deep vein thrombosis. All other patient characteristics at baseline are reported in Major bleeding During 180 days follow-up, 11/537 patients developed a major bleeding event. Median time to the occurrence of bleeding in those 11 patients was 61 days. Three of eleven bleeds were gastrointestinal, three intramuscular, one retroperitoneal, and four at other locations. Bleeding was fatal in none of the eleven patients experiencing a major bleeding complication. Mean INR during KU-55933 biological activity follow-up was 2.9 for patients developing a major bleeding event and 2.8 for those who did not. Test characteristics of the HAS-BLED score When high-risk of major bleeds was defined by a HAS-BLED score of 3 points or higher as is used for patients with atrial fibrillation, 13.6% of patients were identified as high-risk. Cumulative incidences of major bleeds were 1.3% in the non-high and 9.6% in the high-risk group, which resulted in a HR for major 
bleeds of 8.7 in high-risk patients. According to the predefined major bleeding risk cut-off of 7.3% for the definition of highrisk as indicated by previous studies within the VTE population, patients with a HAS-BLED score of 4 points or higher were classified as PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/19768259 high-risk of major bleeding events. The HAS-BLED score categorized 15/537 patients as highrisk of bleeding using this cut-off level. Two out of eleven patients who developed a major bleeding event were identified as high-risk by this cut-off point. The cumulative incidences of major bleeds were 2.0% in the non-high and 22.1% in the high-risk group,, with a HR of 10.8 for major bleeding in high-risk patients. 4 / 11 HAS-BLED Score in Patients with PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/19769788 Acute VTE Data are presented as n, % unless stated otherwise Abbreviations: VTE = venous thromboembolism, NSAIDS = non-steroidal anti-inflammatory drugs, TIA = transient ischemic attack, INR = international normalized ratio 1 2 3 4 5 6 Unknown in 39 patients, Blood pressure measurements missing in 169 patients, information on renal function lacking in 114 patients, Information on liver function lacking in 127 patients, 28 patients lacking information on previous stroke or TIA, Unknown in 331 patients doi:10.1371/journal.pone.0122520.t001 For both cut-offs on the HAS-BLED score, we reported the positive and negative predictive value, sensitivity and specificity for the endpoint of major bleeds in Risk factors for major bleeds Of the items in the HAS-BLED score, abnormal renal function and a history of bleeding events were independent predictors of major bleeds during follow-up with HRs of 10.8 and 10.4, respectively. Discussion We aimed to evaluate whether the HAS-BLED score predicts major bleeding complications in patients with acute VTE during VKA therapy. Our study demonstrates that patients with a HAS-BLED score 3 points are at 8-fold increased risk of major bleeding complications 5 / 11 HAS-BLED Score in Patients with Acute VTE Fig 1. Percent survival of major bleeding complications by Kaplan-Meier life table method, stratified to A) non-high or highrisk of major bleeds; p = 0.0007 by Log-Rank test, HR of 10.8 or B) non-high or high-risk of major bleeds; p <0.0001 by Log-Rank test, HR of 8.7. doi:10.1371/journal.pone.0122520.g001 during the first 180 days of VKA treatment. However, despite a good specificity and negative pre