Predictors of Over-Anticoagulation in Warfarin Users in the UK General Population: A Nested Case-Control Study in a Primary Health Care Database.
BACKGROUND: Many patients on warfarin therapy often present with supratherapeutic international normalized ratio (INR) levels, resulting from the influence of several patient-specific factors, which have been associated with adverse outcomes.
OBJECTIVE: This article aims to identify risk factors for over-anticoagulation (INR levels >/=4) in a cohort of patients taking warfarin.
METHODS: A cohort of warfarin users aged 18 to 85 years from January 2005 to April 2013 was identified in The Health Improvement Network U.K. primary care database (N = 12,506). A random date was assigned to all patients within their eligible person-time (index date), and a nested case-control analysis was performed with individuals presenting a first episode of INR level >/=4 after the index date used as cases (N = 699) and patients with non-supratherapeutic INR values (</=3) as controls (N = 9,798). Using unconditional logistic regression models, odds ratios with 95% confidence intervals were calculated adjusted for potential confounders. Two sensitivity analyses were performed with alternative definitions of over-anticoagulation (INR levels >/=5 or > 3).
RESULTS: Among the factors examined, the strongest predictors of over-anticoagulation were warfarin indication (in particular, valvular atrial fibrillation and valve replacement), renal failure (with the risk increasing steeply with decreasing estimated glomerular filtration rate), cancer, anaemia, respiratory infections treated with antibiotics, chronic obstructive pulmonary disease treated with beta2-agonists, polypharmacy (>/=10 medications), low socio-economic status and residency in rural areas. Similar results were obtained when supratherapeutic levels were defined as INR >/=5 or, alternatively, as INR > 3.
CONCLUSION: Predictors of supratherapeutic INR levels found in this study might help physicians identify patients where closer INR monitoring is warranted.
|ジャーナル名||Thrombosis and haemostasis|
|投稿者||Martin-Perez, Mar; Gaist, David; de Abajo, Francisco J; Garcia Rodriguez, Luis A|
|組織名||Spanish Centre for Pharmacoepidemiologic Research (CEIFE), Madrid, Spain.;Department of Neurology, Odense University Hospital, Odense, Denmark.;Department of Clinical Research, Faculty of Health Sciences, University of;Southern Denmark, Odense, Denmark.;Clinical Pharmacology Unit, University Hospital Principe de Asturias, Alcala de;Henares, Madrid, Spain.;Department of Biomedical Sciences, School of Medicine and Health Sciences,;University of Alcala, Alcala de Henares, Madrid, Spain.;Pharmacoepidemiology Group, Ramon y Cajal Health Research Institute (IRYCIS),;Madrid, Spain.|