Predictors of Over-Anticoagulation in Warfarin Users in the UK General Population: A Nested Case-Control Study in a Primary Health Care Database

Mar Martín-Pérez, David Gaist, Francisco J de Abajo, Luis A García Rodríguez

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

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 β2-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.

Original languageEnglish
JournalThrombosis and Haemostasis
Volume119
Issue number1
Pages (from-to)66-76
ISSN0340-6245
DOIs
Publication statusPublished - 1. Jan 2019

Fingerprint

International Normalized Ratio
Warfarin
Case-Control Studies
Primary Health Care
Databases
Population
Logistic Models
Internship and Residency
Glomerular Filtration Rate
Chronic Obstructive Pulmonary Disease
Odds Ratio
Confidence Intervals
Physicians
Health

Keywords

  • database
  • epidemiological studies
  • international normalized ratio
  • risk factors
  • warfarin

Cite this

@article{fb94b93bb77744f1bd1bc423848da697,
title = "Predictors of Over-Anticoagulation in Warfarin Users in the UK General Population: A Nested Case-Control Study in a Primary Health Care Database",
abstract = "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 β2-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.",
keywords = "database, epidemiological studies, international normalized ratio, risk factors, warfarin",
author = "Mar Mart{\'i}n-P{\'e}rez and David Gaist and {de Abajo}, {Francisco J} and {Garc{\'i}a Rodr{\'i}guez}, {Luis A}",
note = "Georg Thieme Verlag KG Stuttgart · New York.",
year = "2019",
month = "1",
day = "1",
doi = "10.1055/s-0038-1676519",
language = "English",
volume = "119",
pages = "66--76",
journal = "Thrombosis and Haemostasis",
issn = "0340-6245",
publisher = "Schattauer",
number = "1",

}

Predictors of Over-Anticoagulation in Warfarin Users in the UK General Population : A Nested Case-Control Study in a Primary Health Care Database. / Martín-Pérez, Mar; Gaist, David; de Abajo, Francisco J; García Rodríguez, Luis A.

In: Thrombosis and Haemostasis, Vol. 119, No. 1, 01.01.2019, p. 66-76.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - Predictors of Over-Anticoagulation in Warfarin Users in the UK General Population

T2 - A Nested Case-Control Study in a Primary Health Care Database

AU - Martín-Pérez, Mar

AU - Gaist, David

AU - de Abajo, Francisco J

AU - García Rodríguez, Luis A

N1 - Georg Thieme Verlag KG Stuttgart · New York.

PY - 2019/1/1

Y1 - 2019/1/1

N2 - 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 β2-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.

AB - 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 β2-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.

KW - database

KW - epidemiological studies

KW - international normalized ratio

KW - risk factors

KW - warfarin

U2 - 10.1055/s-0038-1676519

DO - 10.1055/s-0038-1676519

M3 - Journal article

C2 - 30597501

VL - 119

SP - 66

EP - 76

JO - Thrombosis and Haemostasis

JF - Thrombosis and Haemostasis

SN - 0340-6245

IS - 1

ER -