title: Gaps in monitoring during oral anticoagulation: insights into care transitions, monitoring barriers, and medication nonadherence.
abstract: BACKGROUND
  Among patients receiving oral anticoagulation, a gap of &gt; 56 days between international normalized ratio tests suggests loss to follow-up that could lead to poor anticoagulation control and serious adverse events.
  
  
  METHODS
  We studied long-term oral anticoagulation care for 56,490 patients aged 65 years and older at 100 sites of care in the Veterans Health Administration. We used the rate of gaps in monitoring per patient-year to predict percentage time in therapeutic range (TTR) at the 100 sites.
  
  
  RESULTS
  Many patients (45%) had at least one gap in monitoring during an average of 1.6 years of observation; 5% had two or more gaps per year. The median gap duration was 74 days (interquartile range, 62-107). The average TTR for patients with two or more gaps per year was 10 percentage points lower than for patients without gaps (P &lt; .001). Patient-level predictors of gaps included nonwhite race, area poverty, greater distance from care, dementia, and major depression. Site-level gaps per patient-year varied from 0.19 to 1.78; each one-unit increase was associated with a 9.2 percentage point decrease in site-level TTR (P &lt; .001).
  
  
  CONCLUSIONS
  Site-level gap rates varied widely within an integrated care system. Sites with more gaps per patient-year had worse anticoagulation control. Strategies to address and reduce gaps in monitoring may improve anticoagulation control.
authors.affiliation: Center for Health Quality, Outcomes, and Economic Research, Bedford VA Medical Center, Bedford; Department of Medicine, Section of General Internal Medicine, Boston University School of Medicine, Boston. Electronic address: adamrose@bu.edu.
authors.forename: Adam J
authors.initials: AJ
authors.lastname: Rose
authors.affiliation: Center for Health Quality, Outcomes, and Economic Research, Bedford VA Medical Center, Bedford; Department of Health Policy and Management, Boston University School of Public Health, Boston.
authors.forename: Donald R
authors.initials: DR
authors.lastname: Miller
authors.affiliation: Center for Health Quality, Outcomes, and Economic Research, Bedford VA Medical Center, Bedford; Biostatistics Section, Boston Children's Hospital, Boston.
authors.forename: Al
authors.initials: A
authors.lastname: Ozonoff
authors.affiliation: Center for Health Quality, Outcomes, and Economic Research, Bedford VA Medical Center, Bedford; Department of Medicine, Section of General Internal Medicine, Boston University School of Medicine, Boston; Department of Health Policy and Management, Boston University School of Public Health, Boston.
authors.forename: Dan R
authors.initials: DR
authors.lastname: Berlowitz
authors.affiliation: Center for Health Quality, Outcomes, and Economic Research, Bedford VA Medical Center, Bedford; Department of Medicine, Section of General Internal Medicine, Boston University School of Medicine, Boston; Department of Quantitative Health Sciences (Dr Ash), Division of Biostatistics and Health Services Research, University of Massachusetts School of Medicine, Worcester, MA.
authors.forename: Arlene S
authors.initials: AS
authors.lastname: Ash
authors.affiliation: Center for Health Quality, Outcomes, and Economic Research, Bedford VA Medical Center, Bedford.
authors.forename: Shibei
authors.initials: S
authors.lastname: Zhao
authors.affiliation: Center for Health Quality, Outcomes, and Economic Research, Bedford VA Medical Center, Bedford.
authors.forename: Joel I
authors.initials: JI
authors.lastname: Reisman
authors.affiliation: Center for Health Quality, Outcomes, and Economic Research, Bedford VA Medical Center, Bedford; Department of Medicine, Section of General Internal Medicine, Boston University School of Medicine, Boston.
authors.forename: Elaine M
authors.initials: EM
authors.lastname: Hylek
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D019934:International Normalized Ratio / Q000592:standards*; D008297:Male; D055118:Medication Adherence; D008991:Monitoring, Physiologic / Q000592:standards*; D058996:Quality Improvement; D014859:Warfarin / Q000008:administration & dosage*
chemical_list: D000925:Anticoagulants; D014859:Warfarin