SynthesisCMAJ : Canadian Medical Association journal = journal de l'Association medicale canadienne2008
Anticoagulation intensity and outcomes among patients prescribed oral anticoagulant therapy: a systematic review and meta-analysis.
Synthesis in CMAJ : Canadian Medical Association journal = journal de l'Association medicale canadienne, 2008. The graph could read no effect estimate from its abstract, so it casts no vote on the map. It is linked to trial NCT00990158 (A Multicentre Study of Low Dose Oral Vitamin K for INR Control in Patients Receiving Warfarin), which is not on this map. Cited by 56 papers, 5 of them syntheses that pooled it.
What it found
Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.
The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
A Multicentre Study of Low Dose Oral Vitamin K for INR Control in Patients Receiving Warfarin
Who cites it
56 citing papers in PubMed, 5 syntheses or guidelines pooled it, 171 citations in OpenAlex.
- Influence ofCardiovascular therapeutics · 2021Pooled it
- CYP2C9, VKORC1, and CYP4F2 polymorphisms and pediatric warfarin maintenance dose: a systematic review and meta-analysis.The pharmacogenomics journal · 2020Pooled it
- Guideline
- Two monitoring methods of oral anticoagulant therapy in patients with mechanical heart valve prothesis: a meta-analysis.Journal of thrombosis and thrombolysis · 2012Pooled it
- Thromboembolism.BMJ clinical evidence · 2011Pooled it
- Supplying Pharmacist Home Visit and Anticoagulation Professional Consultation During Transition of Care for Patients With Venous Thromboembolism.Journal of patient safety · 2020Trial
- Trial
- Low-intensity adjusted-dose warfarin for the prevention of hemodialysis catheter failure: a randomized, controlled trial.Clinical journal of the American Society of Nephrology : CJASN · 2011Trial
- Nontherapeutic INR After Hospital Discharge: A Repeated-Measures Analysis of Warfarin-Treated Patients and Potential Drug-Drug Interactions.Clinics and practice · 2026Article
- Pooled estimate of anticoagulation control with warfarin therapy among adult patients in Ethiopia: a systematic review and meta-analysis.Thrombosis journal · 2026Review
- Burden and Determinants of Drug-Drug Interactions at Hospital Discharge: Warfarin as a Model for High-Risk Medication Safety.Clinics and practice · 2025Article
- Α 6-month, multicenter, observational study investigating the treatment of venous thromboembolism in Greece (VICTORIA study).Thrombosis journal · 2025Article
- Patient self-management of warfarin therapy - a long-term follow up study.Thrombosis journal · 2025Article
- Warfarin and bisphosphontes interaction in patients undergoing total knee arthroplasty.Journal of orthopaedics · 2024Article
- Propensity matched analysis examining the effect of passive reversal of direct oral anticoagulants on blood loss and the need for transfusions among traumatic geriatric hip fractures.European journal of medical research · 2023Article
- A regional anticoagulation program improves safety and outcomes for both children and adults.Journal of thrombosis and thrombolysis · 2023Article
- Adherence to rivaroxaban for the treatment of venous thromboembolism-Results from the FIRST registry.Research and practice in thrombosis and haemostasis · 2021Article
- Acenocoumarol Pharmacogenetic Dosing Algorithm versus Usual Care in Patients with Venous Thromboembolism: A Randomised Clinical Trial.Journal of clinical medicine · 2021Article
- Partial warfarin reversal prior to hip fracture surgical intervention in geriatric trauma patients effects on blood loss and transfusions.Journal of clinical orthopaedics and trauma · 2021Article
- Warfarin therapy in atrial fibrillation: assessment of patient knowledge of risks and benefits.Journal of community hospital internal medicine perspectives · 2020Article
Corrections and comments
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Authors and funding
6 authors at 2 institutions in 1 country.
Funding
No grant is acknowledged in the PubMed record.
Abstract
backgroundPatients taking oral anticoagulant therapy balance the risks of hemorrhage and thromboembolism. We sought to determine the association between anticoagulation intensity and the risk of hemorrhagic and thromboembolic events. We also sought to determine how under-or overanticoagulation would influence patient outcomes.
methodsWe reviewed the MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials and CINAHL databases to identify studies involving patients taking anticoagulants that reported person-years of observation and the number of hemorrhages or thromboemboli in 3 or more discrete ranges of international normalized ratios. We estimated the overall relative and absolute risks of events specific to anticoagulation intensity.
resultsWe included 19 studies. The risk of hemorrhage increased significantly at high international normalized ratios. Compared with the therapeutic ratio of 2-3, the relative risk (RR) of hemorrhage (and 95% confidence intervals [CIs]) were 2.7 (1.8-3.9; p < 0.01) at a ratio of 3-5 and 21.8 (12.1-39.4; p < 0.01) at a ratio greater than 5. The risk of thromboemboli increased significantly at ratios less than 2, with a relative risk of 3.5 (95% CI 2.8-4.4; p < 0.01). The risk of hemorrhagic or thromboembolic events was lower at ratios of 3-5 (RR 1.8, 95% CI 1.2-2.6) than at ratios of less than 2 (RR 2.4, 95% CI 1.9-3.1; p = 0.10). We found that a ratio of 2-3 had the lowest absolute risk (AR) of events (AR 4.3%/yr, 95% CI 3.0%-6.3%).
conclusionsThe risks of hemorrhage and thromboemboli are minimized at international normalized ratios of 2-3. Ratios that are moderately higher than this therapeutic range appear safe and more effective than subtherapeutic ratios.
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What OpenQuestion holds
Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.