Abstract

Abstract 1103

Background:

Control of anticoagulation during warfarin therapy, as assessed by international normalized ratio (INR), is variable even under optimal conditions. Time in therapeutic range (TTR) has been shown to correlate with the important outcomes of hemorrhage or thrombosis. In this study we assessed the current patterns and quality of anticoagulation management among individuals with atrial fibrillation (AF) compared to venous thromboembolism (VTE) using data extracted from a large, nationally representative database of laboratory results in the United States.

Methods:

The Quest Diagnostics database of laboratory test results, inclusive of all 50 states, was queried for all outpatient INR testing for patients ≥ 18 years of age with AF (ICD-9-CM code 427.31) and compared to those with venous thromboembolic disease (286, 415, 453). To achieve a robust data set for trend analysis, the following inclusion criteria were applied: 1) ≥2 INR results >1.2 during a 12-month period; and 2) ≤60-day interval between consecutive INR measurements. TTR was calculated as % days in range (Rosendaal method) and % INR measurements in range. The data were also analyzed for trends by age, gender, frequency of monitoring, and geographic region (as defined by the US Department of Health and Human Services).

Results:

Overall, 187,573 individuals were included (74% with AF), with a total of 3,493,443 INR measurements. The demographics of the AF and VTE cohorts, frequencies of INR measurements, and TTR findings are summarized in Table 1. The INR distributions for proportions in-range and out-of-range are shown in Table 2. Both the AF and VTE cohorts had significantly lower TTR for patients <45 years old and slightly (∼2-3%) higher TTR for males among most age groups (data not shown). Geographic regions with more frequent INR measurements also tended to have higher TTR; at opposite end of the spectrum, the Northeast (Region 1) showed a mean of 25.2 visits per year and a TTR (in days) of 60.3%, while the Southwest (Region 6) had a mean of 17.5 visits per year and a TTR of 52.8%.

Table 1.

Frequency of INR measurements and time in therapeutic range (TTR) for AF and VTE patients

Study PopulationAnticoagulation Cohort
Atrial FibrillationVenous Thromboembolism
TTR, %TTR, %
Patients, No.Age, YearsVisits per Year, MeanDaysINR VisitsPatients, No.Age, YearsVisits per Year, MeanDaysINR Visits
Overall 138,390 74.1 ± 11.2 22.9 57.7 50.6 49,183 63.1 ± 16.4 27.4 52.0 45.1 
Female 67,863 76.2 ± 10.6 23.5 56.4 49.3 27,425 63.3 ± 17.4 28.0 50.6 43.9 
Male 70,527 72.1 ± 11.3 22.3 58.9 51.8 21,758 62.9 ± 15.0 26.6 53.7 46.6 
Study PopulationAnticoagulation Cohort
Atrial FibrillationVenous Thromboembolism
TTR, %TTR, %
Patients, No.Age, YearsVisits per Year, MeanDaysINR VisitsPatients, No.Age, YearsVisits per Year, MeanDaysINR Visits
Overall 138,390 74.1 ± 11.2 22.9 57.7 50.6 49,183 63.1 ± 16.4 27.4 52.0 45.1 
Female 67,863 76.2 ± 10.6 23.5 56.4 49.3 27,425 63.3 ± 17.4 28.0 50.6 43.9 
Male 70,527 72.1 ± 11.3 22.3 58.9 51.8 21,758 62.9 ± 15.0 26.6 53.7 46.6 
Table 2.

Distribution of anticoagulation measurements in AF and VTE cohorts

Anticoagulation Result CategoryINR RangeAnticoagulation Cohort, Number (%)
AFVTE
NumberPercentNumberPercent
Subtherapeutic <1.5 255,285 9.5 111,862 13.8 
Low intensity therapeutic 1.5–<2.0 618,126 23.0 189,910 23.5 
Therapeutic 2.0–3.0 1,357,843 50.6 364,200 45.1 
Supratherapeutic (1) >3.0–4.0 328,676 12.2 97,366 12.1 
Supratherapeutic (2) >4.0 125,470 4.7 44,705 5.5 
Anticoagulation Result CategoryINR RangeAnticoagulation Cohort, Number (%)
AFVTE
NumberPercentNumberPercent
Subtherapeutic <1.5 255,285 9.5 111,862 13.8 
Low intensity therapeutic 1.5–<2.0 618,126 23.0 189,910 23.5 
Therapeutic 2.0–3.0 1,357,843 50.6 364,200 45.1 
Supratherapeutic (1) >3.0–4.0 328,676 12.2 97,366 12.1 
Supratherapeutic (2) >4.0 125,470 4.7 44,705 5.5 
Conclusions:

This data set represents one of the largest analyses of INR control of warfarin in the United States. The TTR data demonstrate suboptimal anticoagulation in a substantial proportion of INR visits, suggesting that a large proportion of Americans with AF are not receiving the optimum warfarin effect. Corroborating other studies, our data suggest a positive relationship between increased monitoring and INR control, as demonstrated by the regional differences in TTR. Younger patients (<45 y) had significantly lower TTRs than did older patients, and women tended to have lower TTR across most age categories. Taken together, these findings suggest that strategies are needed to improve oral anticoagulation care in the United States.

Disclosures:

Ansell:Bayer, Inc: Consultancy; Bristol Myers Squibb: Consultancy, Data Safety Monitoring Boards; Daiichi Sankyo: Consultancy; Boehringer Ingleheim: Consultancy; Ortho McNeil: Consultancy; Sanofi Aventis: Speakers Bureau.

Author notes

*

Asterisk with author names denotes non-ASH members.