Factors influencing warfarin response in hospitalized patients

Abdel‐Aziz, Mahmoud I.; Ali, Mostafa A. Sayed; Abolghasemi, Hassan; El-Faham, T. H.

doi:10.1016/j.jsps.2015.02.004

Cited by 10 publications

(9 citation statements)

References 40 publications

(54 reference statements)

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“…Fever has previously been reported to influence warfarin sensitivity. 15,16 The increase in responsiveness due to fever could be due to vitamin K-dependent coagulation factor catabolism, or reduced warfarin metabolism via reduction in CYP450 isoenzyme activity. 16 Interestingly, reduced vitamin K status in patients with COVID-19 was recently reported, which, if corroborated by additional studies, could also play a role in warfarin requirements.…”

Section: Introductionmentioning

confidence: 99%

Warfarin Dose Requirements in Adults Hospitalized With COVID-19 Infection: A Retrospective Case Series

Irwin

Adie

Sandison

et al. 2021

Journal of Pharmacy Practice

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Purpose: To describe the impact of hospitalization with COVID-19 infection on warfarin dose requirements in adult inpatients. Summary: A retrospective chart review of 8 adults on warfarin admitted to Michigan Medicine with COVID-19 infection was conducted and reported as a case series. Outcomes of interest were difference in average daily dose of warfarin prior to admission (PTA) and while inpatient (IP), warfarin sensitivity, time in therapeutic range (TTR), confirmed or suspected thromboembolic event, any major or clinically significant bleeding episodes, and in-hospital mortality. IP average daily warfarin doses were lower when compared to PTA average daily doses [1.3 mg (1.3) vs. 6.2 mg (4.1)]. The mean percentage decrease in dose was 68.8% (23) and the mean absolute dose difference was 4.8 mg (4.3). Mean IP percentage tests in range was 30.8% (24.6) and mean IP warfarin sensitivity was 4.2 (3.8), both of which differed from PTA TTR and warfarin sensitivity for those with data available (n = 3, n = 6, respectively). One patient was treated for suspected acute pulmonary embolism while on warfarin and one patient experienced clinically relevant bleeding. In-hospital mortality was zero, mean length of stay (LOS) was 17 days (14.4), and mean intensive care unit (ICU) LOS for the 3 patients requiring ICU level care was 14.3 days (4.5). Conclusion: Decreased warfarin dose requirements were evident in this group of adults hospitalized with COVID-19 infection. These findings suggest lower doses of warfarin may be needed to achieve therapeutic anticoagulation while inpatient.

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Section: Introductionmentioning

confidence: 99%

Warfarin Dose Requirements in Adults Hospitalized With COVID-19 Infection: A Retrospective Case Series

Irwin

Adie

Sandison

et al. 2021

Journal of Pharmacy Practice

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“…Keeping INR values within the target therapeutic range has been a challenge to clinicians. A number of factors have been found to affect warfarin therapeutic response such as liver disease, infection, and vitamin K level . One of the most important causes of variability in warfarin response and fluctuating INR values is warfarin–drug interactions .…”

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confidence: 99%

“…A number of factors have been found to affect warfarin therapeutic response such as liver disease, infection, and vitamin K level. 6,7 One of the most important causes of variability in warfarin response and fluctuating INR values is warfarin-drug interactions. 8,9 Various drugs have been reported to interact with warfarin, which consequently represents a challenge to health care professionals to adjust and maintain the warfarin therapeutic response.…”

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confidence: 99%

Warfarin-drug interactions: An emphasis on influence of polypharmacy and high doses of amoxicillin/clavulanate

Abdel‐Aziz

Ali

Abolghasemi

et al. 2015

The Journal of Clinical Pharmacology

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The objective of this study was to investigate the effect of polypharmacy and high doses of amoxicillin/clavulanate on warfarin response in hospitalized patients. This was a prospective cross-sectional observational study on 120 patients from July 2013 to January 2014. Potentially interacting drugs were classified according to their tendency of increasing international normalized ratio (INR) or bleeding risk. The 87.5% of patients prescribed high-dose amoxicillin/clavulanate (10-12 g daily) compared with 28.9% of patients prescribed a normal dose (up to 3.6 g daily) had INR values ≥ 4 during the hospital stay (P ≤ .001). Increased number of potentially interacting drugs that are known to increase INR was a significant predictor of having INR values ≥ 4 (OR, 2.5; 95%CI, 1.3-4.7), and increased number of potentially interacting drugs that are known to increase bleeding risk was a significant predictor of experiencing bleeding episodes (OR, 3.1; 95%CI, 1.3-7.3). High doses of amoxicillin/clavulanate were associated with a higher risk of over-anticoagulation when combined with warfarin than were normal doses. Increased risk of having INR ≥ 4 and bleeding events was associated with increased numbers of potentially interacting drugs prescribed, indicating that polypharmacy is a problem of concern. Frequent monitoring of warfarin therapy along with patients' medications is necessary to avoid complications.

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“…Despite patients who received telephone follow-up service having a higher percentage of TTR compared with those in the usual care group, they were only at goal 44% of the time, which does not indicate a good response to warfarin management, i.e., 60% or more [ 12 ]. A number of potential factors have been shown to affect discharge INRs including new initiation of warfarin therapy on hospital admission, shorter hospital stay periods, and concurrent infection [ 13 ]. Current recommendations for the initiation of warfarin therapy are 3–5 mg per day although the initial dose could be lower in some patients such as elderly patients, patient with increased risk of bleeding, or patients with liver disease [ 14 , 15 ].…”

Section: Discussionmentioning

confidence: 99%

Clinical Outcomes of Telemonitoring for Patients on Warfarin after Discharge from Hospital

Ayutthaya

Sakunrak

Dhippayom

2018

International Journal of Telemedicine and Applications

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Objective To evaluate the impact of telephone follow-up service on clinical outcomes in patients on warfarin when discharged from hospital. Methods This randomized controlled trial was conducted at a general hospital in Thailand. Patients aged ≥20 years who were prescribed warfarin when discharged were eligible to participate in this study. They were randomly allocated, using a computer generated random number, to receive either telephone follow-up intervention or usual care. Participants in the intervention group received telephone follow-up by hospital pharmacists for three months. During each telephone call, pharmacists performed medicine use reviews and addressed any problems identified. Key Findings A total of 50 patients participated in this study. The proportion of international normalized ratio (INR) values in the target range for the telephone follow-up group (36/79, 45.6%) was higher than that in the usual care group (19/79, 24.1%), p=0.005. The mean time in the therapeutic range (TTR) in the telephone follow-up group was also higher than that in the usual care group (49.8±34.3 versus 28.0±27.5, p=0.017). All patients in the usual care group experienced one or more out-of-range INR values (25/25, 100%) compared to 21 out of 25 (84%) in the telephone follow-up group, p=0.037. There was no difference between the two groups in the incidence of complications or adverse events associated with warfarin. Conclusions The telephone follow-up service in recently discharged patients helps them achieve and maintain their INR target. This anticoagulant supportive service should be promoted to patients receiving warfarin therapy after discharge. This trial is registered with TCTR20180614006 (Thai Clinical Trials Registry).

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Factors influencing warfarin response in hospitalized patients

Cited by 10 publications

References 40 publications

Warfarin Dose Requirements in Adults Hospitalized With COVID-19 Infection: A Retrospective Case Series

Warfarin Dose Requirements in Adults Hospitalized With COVID-19 Infection: A Retrospective Case Series

Warfarin-drug interactions: An emphasis on influence of polypharmacy and high doses of amoxicillin/clavulanate

Clinical Outcomes of Telemonitoring for Patients on Warfarin after Discharge from Hospital

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