What question did this study set out to answer?

To assess the relationship between advancing patient age and international normalized ratio (INR) values at the onset of warfarin-associated major bleeding events.

May 1, 2004Pharmacotherapy The Journal of Human Pharmacology and Drug Therapy

Effect of Age on International Normalized Ratio at the Time of Major Bleeding in Patients Treated with Warfarin

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Why the study?

Does advanced age lower the INR threshold at which major bleeding occurs in patients treated with warfarin?

Population

66 patients receiving warfarin therapy who experienced major bleeding during a 20-month index period at two…

Comparison

Age 65 years or older vs Age younger than 65 years

Design

Cohort

Authors

AWAnn K. WittkowskyUniversity of Washington KWKelly S. WhitelyUniversity of Washington EDEmily Beth DevineUniversity of Washington

Discussion

Member takes

Implication

Patients ≥65 years may experience major bleeding at lower INRs; hypothesis-generating and requires prospective validation before guiding targets.

Key Points

To assess the relationship between advancing patient age and international normalized ratio (INR) values at the onset of warfarin-associated major bleeding events.
Retrospective medical record review conducted across two university-affiliated anticoagulation clinics.
Included 66 patients (mean age 61.2 years, range 21–90 years) receiving warfarin who suffered major bleeding requiring hospitalization over a 20-month index period.
Patients aged 65 years or older exhibited a significantly lower mean INR at the time of major bleeding compared with patients younger than 65 years (mean INR 3.1 vs. 4.2; p = 0.01; mean difference -1.1 units, 95% CI -1.9 to -0.27).
Mean INR at the time of a major bleeding event decreased by 0.03 for every 1-year increase in age (p = 0.02).

Structured PICO

Does advanced age lower the INR threshold at which major bleeding occurs in patients treated with warfarin?

Population

66 patients (mean age 61.2 yrs, range 21-90 yrs) receiving warfarin therapy who experienced major bleeding (defined as bleeding requiring hospitalization) during a 20-month index period at two university-affiliated anticoagulation clinics.

Intervention

Age 65 years or older

Comparator

Age younger than 65 years

Outcome

Mean international normalized ratio (INR) at the time of a major bleeding eventsurrogate

Older patients experience warfarin-related major bleeding at significantly lower INR levels than younger patients, suggesting a need for more careful management of anticoagulation in this population.

Cite This Study

Wittkowsky et al. (2004) studied this question.

synapsesocial.com/papers/6a82b790040bdabcf346fe5b https://doi.org/10.1592/phco.24.6.600.34735

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Implication

Patients ≥65 years may experience major bleeding at lower INRs; hypothesis-generating and requires prospective validation before guiding targets.

Effect of Age on International Normalized Ratio at the Time of Major Bleeding in Patients Treated with Warfarin

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

Effect of Age on International Normalized Ratio at the Time of Major Bleeding in Patients Treated with Warfarin

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

Also Consider

Also Consider