Predicting international normalised ratio ≥ 4.5 in hospitalised patients using vitamin K antagonists
Vitamin K antagonists (VKAs) used for the prevention and treatment of thromboembolic disease, increase the risk of bleeding complications. This model was developed and validated to predict the risk of an international normalised ratio (INR) ≥4.5 during a hospital stay.

We developed and validated a clinical prediction model for an INR ≥4.5 in VKA-treated patients admitted to our hospital. The model includes factors that are collected during routine care and are extractable from electronic patient records, enabling easy use of this model to predict an increased bleeding
risk in clinical practice.
Research authors: Albert R. Dreijer, Joseph S. Biedermann, Jeroen Diepstraten, Anouk D. Lindemans, Marieke J.H.A. Kruip, Patricia M.L.A. van den Bemt, Yvonne Vergouwe
Details Formula Study characteristics Files & References
Model author
Model ID
Revision date
MeSH terms
  • International Normalized Ratio
  • Ratio, International Normalized
  • Bleeding
  • Model type
    Logistic regression (Calculation)
    No Formula defined yet
    Condition Formula

    Additional information

    Adult patients admitted to a tertiary hospital and treated with VKAs between 2006 and 2010 were analysed. Bleeding risk was operationalised as an INR value ≥4.5. Multivariable logistic regression analysis was used to assess the association between potential predictors and an INR ≥4.5 and validated in an independent cohort of patients from the same hospital between 2011 and 2014.

    8996 admissions of patients treated with VKAs were identified, of which 1507 (17%) involved an INR ≥4.5. The final model included the following predictors: gender, age, concomitant medication and several biochemical parameters. Temporal validation showed a c-statistic of 0.71.

    The development cohort constisted of 8996 patients, and the validation cohort consisted of 9018 patients. 

    Study Population

    Total population size: 8996
    Males: {{ model.numberOfMales }}
    Females: {{ model.numberOfFemales }}

    Continuous characteristics

    Name LL Q1 Median Q3 UL Unit
    Alanine amino transferase 16 25 44 u/l
    Aspartate amino transferase 22 30 44 u/l
    Gamma-glutamyl transferase 33 61 131 u/l
    Lactate dehydrogenase 357 442.5 589.8 u/l
    Albumin 31 36 41 g/l
    estimated Glomerular filtration rate 49 70 90 ml/min/1.73m2
    Haemoglobin 100 116 134 g/l
    Thyroid stimulation hormone 0.7 1.4 2.8 mu/l
    Triiodothyronine 1.0 1.4 1.8 nmol/l
    Thyroxin 83.5 104.5 132.0 nmol/l
    C-reactive protein 8 30 82 mg/l
    plateletcount 175 229 300.8 x10^9/l

    Categorical characteristics

    Name Subset / Group Nr. of patients
    INR ≥4.5 during a previous admission Yes 868
    No 8128
    VKA type acenocoumarol 7978
    Other 1018
    Ward type Medical ward 5497
    Ither 3499
    Use of concomitant medication Miconazole 153
    Cotrimoxazole 337
    Fluconazole 119
    Voriconazole 7
    Amiodarone 724
    Rifampicin 53
    Carbamazepine 73
    Phenytoin 89
    Colestyramin 17
    Anti-thyroid drugs 110
    Predicting international normalised ratio ≥ 4.5 in hospitalised patients using vitamin K antagonists
    Refer to Intended Use for instructions before use
    Evidencio B.V., Irenesingel 19, 7481 GJ, Haaksbergen, the Netherlands

    Related files

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    Supporting Publications

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    Predicted risk of INR ≥ 4.5

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    Outcome stratification

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    Conditional information

    Result interpretation

    The prediction model can help physicians to identify patients at the lower spectrum of thromboembolic risk and those for whom the risk of bleeding during vitamin K antagonist (VKA) therapy is high. Using the prediction model may also help
    when counselling and informing patients about their potential risk for haemorrhage while on anticoagulants, and in identifying those patients who might benefit from more careful management of anticoagulation. Alternatively, these patients can also be switched to direct oral anticoagulants (DOACs), which cause less major bleeding, such as intracranial haemorrhages, compared to VKAs

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    Calculations alone should never dictate patient care, and are no substitute for professional judgement. See our full disclaimer.

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