title: Patients' time in therapeutic range on warfarin among US patients with atrial fibrillation: Results from ORBIT-AF registry.
abstract: BACKGROUND
  Time in therapeutic range (TTR) of international normalized ratio (INR) of 2.0 to 3.0 is important for the safety and effectiveness of warfarin anticoagulation. There are few data on TTR among patients with atrial fibrillation (AF) in community-based clinical practice.
  
  
  METHODS
  Using the US Outcomes Registry for Better Informed Treatment of Atrial Fibrillation (ORBIT-AF), we examined TTR (using a modified Rosendaal method) among 5,210 patients with AF on warfarin and treated at 155 sites. Patients were grouped into quartiles based on TTR data. Multivariable logistic regression modeling with generalized estimating equations was used to determine patient and provider factors associated with the lowest (worst) TTR.
  
  
  RESULTS
  Overall, 59% of the measured INR values were between 2.0 and 3.0, with an overall mean and median TTR of 65% ± 20% and 68% (interquartile range [IQR] 53%-79%). The median times below and above the therapeutic range were 17% (IQR 8%-29%) and 10% (IQR 3%-19%), respectively. Patients with renal dysfunction, advanced heart failure, frailty, prior valve surgery, and higher risk for bleeding (ATRIA score) or stroke (CHA2DS2-VASc score) had significantly lower TTR (P < .0001 for all). Patients treated at anticoagulation clinics had only slightly higher median TTR (69%) than those not (66%) (P < .0001).
  
  
  CONCLUSIONS
  Among patients with AF in US clinical practices, TTR on warfarin is suboptimal, and those at highest predicted risks for stroke and bleeding were least likely to be in therapeutic range.
authors.affiliation: Duke University Medical Center, Durham, NC; Duke Clinical Research Institute, Durham, NC.
authors.forename: Sean D
authors.initials: SD
authors.lastname: Pokorney
authors.affiliation: Duke Clinical Research Institute, Durham, NC.
authors.forename: DaJuanicia N
authors.initials: DN
authors.lastname: Simon
authors.affiliation: Duke Clinical Research Institute, Durham, NC.
authors.forename: Laine
authors.initials: L
authors.lastname: Thomas
authors.affiliation: Division of Cardiology, University of California, Los Angeles, Los Angeles, CA.
authors.forename: Gregg C
authors.initials: GC
authors.lastname: Fonarow
authors.affiliation: Lankenau Institute for Medical Research, Wynnewood, PA.
authors.forename: Peter R
authors.initials: PR
authors.lastname: Kowey
authors.affiliation: Janssen Scientific Affairs, Raritan, NJ.
authors.forename: Paul
authors.initials: P
authors.lastname: Chang
authors.affiliation: Harvard Medical School, Massachusetts General Hospital, Boston, MA.
authors.forename: Daniel E
authors.initials: DE
authors.lastname: Singer
authors.affiliation: Lenox Hill Hospital, New York, NY.
authors.forename: Jack
authors.initials: J
authors.lastname: Ansell
authors.affiliation: Duke Clinical Research Institute, Durham, NC.
authors.forename: Rosalia G
authors.initials: RG
authors.lastname: Blanco
authors.affiliation: Mayo Clinic, Rochester, MN.
authors.forename: Bernard
authors.initials: B
authors.lastname: Gersh
authors.affiliation: Department of Medicine, Stanford University School of Medicine, Palo Alto, CA.
authors.forename: Kenneth W
authors.initials: KW
authors.lastname: Mahaffey
authors.affiliation: Boston University School of Medicine, Boston, MA.
authors.forename: Elaine M
authors.initials: EM
authors.lastname: Hylek
authors.affiliation: Kaiser Permanente, Oakland, CA.
authors.forename: Alan S
authors.initials: AS
authors.lastname: Go
authors.affiliation: Duke University Medical Center, Durham, NC; Duke Clinical Research Institute, Durham, NC.
authors.forename: Jonathan P
authors.initials: JP
authors.lastname: Piccini
authors.affiliation: Duke University Medical Center, Durham, NC; Duke Clinical Research Institute, Durham, NC. Electronic address: eric.peterson@duke.edu.
authors.forename: Eric D
authors.initials: ED
authors.lastname: Peterson
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000627:therapeutic use*; D001281:Atrial Fibrillation / Q000150:complications / Q000188:drug therapy* / Q000453:epidemiology; D005260:Female; D016330:Frail Elderly; D006333:Heart Failure / Q000453:epidemiology; D019918:Heart Valve Prosthesis Implantation / Q000706:statistics & numerical data; D006470:Hemorrhage / Q000453:epidemiology; D006801:Humans; D019934:International Normalized Ratio; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D012042:Registries; D051436:Renal Insufficiency, Chronic / Q000453:epidemiology; D012307:Risk Factors; D020521:Stroke / Q000209:etiology / Q000517:prevention & control*; D013997:Time Factors; D016896:Treatment Outcome; D014481:United States; D014859:Warfarin / Q000627:therapeutic use*
chemical_list: D000925:Anticoagulants; D014859:Warfarin