The following is a recent international study: Recent studies in middle-aged women have shown that the risk of VTE after many different forms of surgery is much higher and also lasts longer than previously thought. The study’s findings are important because they found that the risk of VTE was highest during the first six weeks after surgery, with a peak about three weeks later. But the vast majority of patients only received prophylaxis during their hospital stay, which averaged about six days, as noted in a recent article in the BMJ by Dr. Sîan Sweetland of the University of Oxford and his co-author. The risk of VTE was also found to remain high at 12 months postoperatively, said Dr Alexander T Cohen, a vascular surgeon at the Royal University Hospital, adding that the study by Sweetland et al. clarifies and extends the findings of currently available studies on the progressive risk of VTE after surgery, while sounding alarm bells for all surgeons. The strength of the study is its large size and breadth, Dr. Jane Green of the University of Oxford told Heart Online. The key finding, she said, is that VTE risk duration is correlated, and previously we didn’t have reliable data, especially about the timing and duration of these very high risks. She believes these new data are credible enough when any VTE prevention measures are carefully considered. The highest risks are for knee and hip replacement surgery, cancer surgery, etc. Sweetland analyzed their results and found more accurate information about the manner and extent of the increased risk of VTE after many types of surgical procedures. Applying data from the prospective Million Women Study in the United Kingdom, they examined questionnaires from 947,454 middle-aged women linked to NHS hospitalization and death records between 1996 and 2001. Excluded were 207,302 patients who had a history of surgery in the previous year or who had been hospitalized for VTE before being enrolled, or who had a history of blood clots, or a previous history of cancer. During the follow-up period (mean 6.2 years), 239,614 patients were admitted to the hospital because they needed surgery, 5,419 were admitted for VTE, and 270 even died because of VTE. Compared to the risk in patients without surgery, the risk of being diagnosed with VTE within the first six weeks after surgery in hospitalized patients was nearly 70 times higher (relative risk ratio 69.1), and the peak time of occurrence was nearly 10 times higher after three weeks and one day after surgery (RR relative risk factor 9.6). Some investigators say that the fact that day surgery is associated with an increased and delayed risk of VTE, even though the risk is slightly lower compared to inpatient surgery, is important because prophylaxis for thrombosis in day surgery patients is not the normal application. The risk, although low, has been elevated from 7-12 weeks postoperatively. The risk of VTE was nearly 20 times higher in these women compared to women without surgery, (RR 19.6). The investigators noted that in the vast majority of cases, the increased risk persisted for at least 1 year. The risk also varies when considering the type of surgery. The risk was highest in the first six weeks after inpatient hip and knee replacement surgery and cancer surgery, with a risk factor of 220.6 for the former and 91.6 for the latter, Cohen said, adding that this also confirms in clinical practice the findings of previous clinical trials regarding the surgical group with the highest risk of VTE. Sweetland and his colleagues say this means that, in real terms, 1 in 140 middle-aged women in the UK are likely to be hospitalized for VTE within 12 weeks after any form of surgery, and 1 in 45 after knee and hip replacement surgery; 1 in 85 after cancer surgery are admitted for VTE. By comparison, only 1 in 815 after day surgery and 1 in 6,200 women without surgery presented within a 12-week period. The new data lower the threshold for long-term prophylaxis. In his comments, Cohen noted that the application of recommended VTE prophylaxis is a secondary option worldwide – only 59% of surgical patients receive the recommended treatment, and its application varies by country. Currently available evidence suggests that treatment is needed for inpatients undergoing many orthopedic, general surgery and cancer procedures and should be administered for at least 7-10 days. In addition, extended prophylaxis can last 4-5 weeks in those patients at high risk and a net clinical benefit can be obtained after surgery. It is also noted however that we currently have no studies in any group of patients to confirm whether prophylaxis needs to be extended beyond 5 weeks. However, Cohen spoke in Cardiac Online about the fact that in terms of thrombosis, this study by Sweetland et al. in many patients lowered the threshold for the application of extended prophylaxis. One reason for the poor adoption of prophylaxis is the relative inconvenience of injectable anticoagulants, such as low-molecular heparin sodium (LMWH), the currently recommended treatment, she said, adding that previous recommendations for oral warfarin alone were not effective enough to prevent VTE. Convenient access to oral anticoagulants is an important issue for prophylaxis that needs to be extended. Such products recommended for VTE prophylaxis after orthopaedic surgery in Europe include dabigatran (Boehringer Ingelheim, Germany) and rivaroxaban (Johnson & Johnson).