Therapeutic Oral Anticoagulation Research Articles

Randomized Trial of Warfarin Nomograms

Letters16 March 2004Randomized Trial of Warfarin NomogramsMichael J. Kovacs, MD, FRCPC and Philip S. Wells, MD, FRCPC, MScMichael J. Kovacs, MD, FRCPCFrom London Health Sciences Centre, London, Ontario N6A 4G5, Canada, and Ottawa Hospital—Civic Campus; Ottawa, Ontario K1Y 4E9, Canada.Search for more papers by this author and Philip S. Wells, MD, FRCPC, MScFrom London Health Sciences Centre, London, Ontario N6A 4G5, Canada, and Ottawa Hospital—Civic Campus; Ottawa, Ontario K1Y 4E9, Canada.Search for more papers by this authorAuthor, Article, and Disclosure Informationhttps://doi.org/10.7326/0003-4819-140-6-200403160-00030 SectionsAboutFull TextPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinkedInRedditEmail IN RESPONSE:We thank all of the correspondents for the interest in our article, which has initiated a strong and emotional debate. Given the strong shift, however, of treatment of acute thromboembolism to an outpatient setting using low-molecular-weight heparin, it is imperative to have a simple means to achieve therapeutic oral anticoagulation in an efficient, timely, and predictable fashion.Much press has been given to the fact that the INR may predominantly reflect factor VII levels during initiation of oral anticoagulant therapy, but with concomitant primary therapy (that is, therapy with low-molecular-weight heparin), no clinical consequences have been reported. Perhaps ...

Perioperative management of patients receiving oral anticoagulants: a systematic review.

The safety and efficacy of various management strategies for patients receiving oral anticoagulants (OACs) who need to undergo surgery or invasive procedures are unknown. We performed a systematic review and synthesis of the English-language literature examining the perioperative management and outcomes of patients receiving long-term OAC therapy. Thirty-one reports were identified. The quality of the identified reports was generally poor; no randomized controlled trials have been performed and duration of follow-up was typically not stated. Overall, 29 thromboembolic events occurred amont 1868 patients (1.6%; 95% confidence interval, 1.0%-2.1%), including 7 strokes (0.4%; 95% confidence interval, 0%-0.7%). Thromboembolic event rates by management strategy were 0.4% (1 of 237) for continuation of OAC, 0.6% (6 of 996) for discontinuation of OAC therapy without administration of intravenous heparin, 0% (0 of 166) for discontinuation of OAC therapy with administration of intravenous heparin, 0.6% (1 of 180) for discontinuation of OAC therapy with administration of low-molecular-weight heparin, and 8.0% (21 of 263) for unspecified or unclear strategies. Major bleeding while receiving therapeutic OAC was rare for dental procedures (0.2% [4 of 2014]), arthrocentesis (0% [0 of 32]), cataract surgery (0% [0 of 203]), and upper endoscopy or colonoscopy with or without biopsy (0% [0 of 111]). Most patients can undergo dental procedures, arthrocentesis, cataract surgery, and diagnostic endoscopy without alteration of their regimen. For other invasive and surgical procedures, oral anticoagulation needs to be withheld, and the decision whether to pursue an aggressive strategy of perioperative administration of intravenous heparin or subcutaneous low-molecular-weight heparin should be individualized. The current literature is substantially limited in its ability to help choose an optimal strategy. Further and more rigorous studies are needed to better inform this decision.

Primary axillary-subclavian venous thrombosis: is aggressive surgical intervention justified?

Multimodal (thrombolysis, surgical decompression, venous reconstruction, oral anticoagulation) treatment of primary axillary-subclavian venous thrombosis was reviewed to assess the impact of venous patency on functional outcome. Since 1996, 7 patients (6 men, 1 woman) of ages 16-53 years (mean 33 years) presented with symptomatic acute axillosubclavian venous thrombosis as a result of a recent athletic or strenuous arm activity. Five patients had undergone previous (>2 weeks) catheter-directed thrombolysis and venous angioplasty. Diagnostic contrast venography followed by repeat catheter-directed thrombolysis demonstrated abnormal (residual stenosis [n=6] or occlusion [n=1]) axillosubclavian venous segments in all patients. Surgical intervention was performed at a mean interval of 7 days (range 1-19 days) after thrombolysis and consisted of thoracic outlet decompression with scalenectomy and 1st rib resection via a paraclavicular (n=4) or supraclavicular (n=3) approach. Medial claviculectomy or cervical rib resection was performed in 2 patients. Concomitant venous surgery was performed in all patients to restore normal venous patency by circumferential venolysis (n=7) and balloon catheter thrombectomy (n=3), or vein-patch angioplasty (n=2), or endovenectomy (n=5), or internal jugular transposition (n=2). Postoperative venous duplex testing beyond 1 month identified recurrent thrombosis in 4 patients despite therapeutic oral anticoagulation. Subsequent venous recanalization was documented in 3 patients. Poor functional outcome was associated with an occluded venous repair and extensive venous thrombosis on initial presentation. A patent or recanalized venous repair present in 6 of 7 patients was associated with good functional outcome and may justify multimodal intervention in patients with primary axillosubclavian effort thrombosis presenting with recurrent thrombosis and significant residual disease after thrombolysis.

Is the international normalised ratio (INR) reliable? A trial of comparative measurements in hospital laboratory and primary care settings.

AIM: To determine the reliability of international normalised ratio (INR) measurement in primary care by practice nurses using near patient testing (NPT), in comparison with results obtained within hospital laboratories...

Prolonged hospitalization because of inappropriate delay of warfarin therapy in deep venous thrombosis.

Current anticoagulation practices of physicians in an academic medical center were examined by retrospective review of records of 26 patients admitted for uncomplicated deep venous thrombosis (DVT) between 1978 and 1982. Patients received intravenous heparin for an average of 11.5 +/- 2.8 days. Warfarin therapy was started on day 8.3 +/- 3.1 and therapeutic oral anticoagulation was achieved by day 14.5 +/- 4.5. Total hospital stay averaged 16.8 +/- 5.1 days. No patient received concurrent initiation of heparin and warfarin therapy and only two patients received warfarin before day 5. These findings are in contrast to anticoagulation practices in Great Britain and Scandinavia where concurrent initiation of heparin and warfarin has been common practice for many years. Such a regimen is safe and usually requires fewer days of hospitalization for DVT. We conclude that failure to start warfarin therapy on the first hospital day resulted in a costly and unnecessarily prolonged hospital stay.