title: Determinants of oral anticoagulation control in new warfarin patients: analysis using data from Clinical Practice Research Datalink.
abstract: BACKGROUND
  The safety and effectiveness of warfarin therapy depends critically on the quality of anticoagulation control, often assessed using the percentage time in therapeutic International Normalised Ratio (INR) range (TTR). We aimed to identify patient characteristics related to anticoagulation control with warfarin, measured by TTR.
  
  
  METHODS
  We carried out a population-based study using the Clinical Practice Research Datalink, including two cohorts of patients starting warfarin after a first diagnosis of atrial fibrillation (AF) or venous thromboembolism (VTE) between 2000 and 2013. We used multivariate mixed regression and logistic regression models to predict the fully-adjusted effect of each predictor variable upon TTR.
  
  
  RESULTS
  The study population comprised 29,717 incident AF and 19,113 incident VTE patients who initiated warfarin. In real world clinical practice a minority of patients achieve good anticoagulation control with warfarin (44% AF and 36% VTE patients had TTR≥70%). Poor anticoagulation control driven by subtherapeutic INRs was observed in younger patients (<45years) and in AF patients with increased number of hospitalisations. Poor anticoagulation control driven by sub and/or supratherapeutic INRs was seen in AF and VTE patients current smokers, in patients using medications for pain and in VTE patients with active cancer.
  
  
  CONCLUSIONS
  In a real world clinical practice there is a high amount of unpredictable inter-individual TTR variability and in some patients good anticoagulation control is more challenging than in others. These findings may help to identify patients who will require closer monitoring or innovative strategies to optimise the outcomes of oral anticoagulant therapy.
authors.affiliation: Market Access Pricing & Outcomes Research, Boehringer-Ingelheim, UK. Electronic address: filipa_macedopt@hotmail.com.
authors.forename: Ana Filipa
authors.initials: AF
authors.lastname: Macedo
authors.affiliation: Biometrics & Data Management, Boehringer-Ingelheim, UK.
authors.forename: James
authors.initials: J
authors.lastname: Bell
authors.affiliation: Market Access Pricing & Outcomes Research, Boehringer-Ingelheim, UK.
authors.forename: Ciaran
authors.initials: C
authors.lastname: McCarron
authors.affiliation: Medical Affairs - Cardiovascular, Boehringer-Ingelheim, UK.
authors.forename: Rachel
authors.initials: R
authors.lastname: Conroy
authors.affiliation: Medical Affairs - Cardiovascular, Boehringer-Ingelheim, UK.
authors.forename: James
authors.initials: J
authors.lastname: Richardson
authors.affiliation: Market Access Pricing & Outcomes Research, Boehringer-Ingelheim, UK.
authors.forename: Anna
authors.initials: A
authors.lastname: Scowcroft
authors.affiliation: Market Access Pricing & Outcomes Research, Boehringer-Ingelheim, UK.
authors.forename: Tom
authors.initials: T
authors.lastname: Sunderland
authors.affiliation: Medical Affairs - Cardiovascular, Boehringer-Ingelheim, UK. Electronic address: naj.rotheram@boehringer-ingelheim.com.
authors.forename: Naj
authors.initials: N
authors.lastname: Rotheram
mesh_terms: D000284:Administration, Oral; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D019934:International Normalized Ratio / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D016896:Treatment Outcome; D014859:Warfarin / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use*; D055815:Young Adult
chemical_list: D000925:Anticoagulants; D014859:Warfarin
keywords: international normalized ratio (INR); oral anticoagulants; predictors; real world data; time in therapeutic range (TTR); warfarin