Adherence to Guidelines for Avoiding Drug Interactions Associated with Warfarin - A Nationwide Swedish Register Study

Lindh, Jonatan D.; Andersson, Marine L.; Mannheimer, Buster

doi:10.1371/journal.pone.0097388

Cited by 12 publications

(12 citation statements)

References 42 publications

(52 reference statements)

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“…The mechanism through which tramadol may increase warfarin response is not fully understood, but it is suspected to arise from inhibition of serotonin re‐uptake in platelets, while the liability to an interaction may be related to the CYP2D6 activity . A recent Swedish study illustrated that physicians refrain from prescribing NSAIDs during warfarin therapy while tramadol is rarely avoided . Our study supports these findings by demonstrating a decrease in the frequency of NSAID purchasing after warfarin initiation.…”

Section: Discussionsupporting

confidence: 83%

Co‐Prescribing of Potentially Interacting Drugs during Warfarin Therapy – A Population‐Based Register Study

Rikala

Hauta-Aho

Helin‐Salmivaara

et al. 2015

Basic Clin Pharma Tox

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Abstract:We analysed the occurrence of co-prescribing of potentially interacting drugs during warfarin therapy in the community-dwelling population of Finland. We identified drugs having interaction potential with warfarin using the Swedish Finnish INteraction X-referencing drug-drug interaction database (SFINX) and obtained data on drug purchases from the nationwide Prescription Register. We defined warfarin users as persons purchasing warfarin in 2010 (n = 148,536) and followed them from their first prescription in 2010 until the end of the calendar year. Co-prescribing was defined as at least 1-day overlap between warfarin and interacting drug episodes. In addition, we identified persons who initiated warfarin therapy between 1 January 2007 and 30 September 2010 (n = 110,299) and followed these incident users for a 3-month period since warfarin initiation. Overall, 74.4% of warfarin users were co-prescribed interacting drugs. Co-prescribing covered 46.4% of the total person-years of warfarin exposure. Interacting drugs that should be avoided with warfarin were co-prescribed for 13.4% of warfarin users. The majority of the co-prescriptions were for drugs that are not contraindicated during warfarin therapy but require special consideration. Among incident users, 57.1% purchased potentially interacting drugs during the 3-month period after initiation, while 9.0% purchased interacting drugs that should be avoided with warfarin. To conclude, the occurrence of co-prescribing of potentially interacting drugs was high during warfarin therapy. Our findings highlight the importance of close monitoring of warfarin therapy and the need for further studies on the clinical consequences of co-prescribing of interacting drugs with warfarin.

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Section: Discussionsupporting

confidence: 83%

Co‐Prescribing of Potentially Interacting Drugs during Warfarin Therapy – A Population‐Based Register Study

Rikala

Hauta-Aho

Helin‐Salmivaara

et al. 2015

Basic Clin Pharma Tox

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“…NSAIDs have been among the most common interacting drugs in inpatients and outpatients taking warfarin [3,4,9,27]. This trend seems to have changed and similar results to ours have been recently published in large register-based studies [11,28,29]. These findings may indicate increased awareness of clinicians of the increased bleeding risk associated with concomitant use of NSAIDs with warfarin.…”

Section: Discussionsupporting

confidence: 81%

Frailty and Co-Prescribing of Potentially Interacting Drugs in New Users of Warfarin

et al. 2020

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Background Warfarin is underutilised in frail older people because of the fear of bleeding complications. Drug interactions are an independent bleeding risk factor. However, the extent to which potential drug interactions are taken into account at warfarin therapy initiation in frail patients is not known. Objective The objective of this study was to investigate the use of potentially interacting drugs increasing the bleeding risk before and after warfarin initiation in frail and non-frail patients. Methods We conducted an observational study including inpatients aged ≥ 60 years initiated on warfarin in a tertiary hospital in Adelaide, South Australia. Frailty status was assessed with the Reported Edmonton Frail Scale. Medication charts were reviewed before and after warfarin initiation. Results In total, 151 patients (102 non-frail and 49 frail) were included. Before warfarin initiation, the use of clopidogrel and acetaminophen was more common in frail patients compared with non-frail patients (25.5% vs 10.2%, p = 0.0135, 63.8% vs 35.7% p = 0.0014, respectively). The use of non-steroidal anti-inflammatory drugs, 9.2% in non-frail patients and 6.4% in frail patients before warfarin initiation, was completely stopped after warfarin initiation in both groups. The use of antiplatelet drugs decreased from 56.1% in non-frail patients and 66.0 % in frail patients to 12.2% and 14.9%, respectively. Instead, the use of drugs affecting the metabolism of warfarin or vitamin K increased in both groups. No statistically significant difference was seen in the exposure to interacting drugs between study groups after warfarin initiation. Acetaminophen, senna glycosides and cytochrome P450 2C9 inhibiting drugs were the most common interacting drugs at discharge used in 49.0%, 18.4% and 20.4% of non-frail patients and 53.2%, 29.8% and 19.1% of frail patients, respectively. Conclusions The overall frequency of potential drug interactions was moderate and frail patients were not exposed to warfarin drug interactions more often than non-frail patients. Further studies in larger study populations are required to verify these results.

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“…We thought that we must increase the TTR values of patients on warfarin therapy in Turkey at least by educating patients and physicians. Lindh et al (20) showed that Swedish doctors in the vast majority of cases refrain from prescribing NSAIDs to patients already on warfarin. There was no study showing the approach of Turkish physicians with respect to the patients on warfarin.…”

Section: Discussionmentioning

confidence: 99%

The awareness, efficacy, safety, and time in therapeutic range of warfarin in the Turkish population: warfarin -tr

Çelik¹,

İzcı²,

Kobat³

et al. 2015

Anatol J Cardiol

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Objective:The awareness, time in therapeutic range (TTR), and safety of warfarin therapy were investigated in the adult Turkish population.Methods:This multicenter prospective study includes 4987 patients using warfarin and involved regular international normalized ratio (INR) monitoring between January 1, 2014 and December 31, 2014. TTR was calculated according to F.R. Roosendaal’s algorithm. Awareness was evaluated based on the patients’ knowledge of warfarin’s affect and food–drug interactions.Results:The mean TTR of patients was 49.52±22.93%. The patients with hypertension (55.3%), coronary artery disease (23.2%), congestive heart failure (24.5%), or smoking habit (20.8%) had significantly lower TTR levels than the others. Of the total number of patients, 42.6% had a mechanical valve, 38.4% had non-valvular atrial fibrillation (AF), and 19% had other indications for warfarin. Patients with other indications had lower TTR levels than those with mechanical valve and non-valvular AF (p=0.018). Warfarin awareness decreased in higher age groups. The knowledge of warfarin’s food–drug interactions was 55%. People with higher warfarin awareness had higher TTR levels. Patients with ≤8 INR monitoring/year had lower TTR levels (46.4±25.3 vs. 51.1±21.3, respectively, p<0.001) and lower awareness (44.6% vs. 60.6%, p<0.001) than patients with ≥8 INR monitoring/year. In this study, 20.1% of the patients had a bleeding event (major bleeding 15.8%, minor bleeding 84.2%) within a year.Conclusion:Both the mean TTR ratios and awareness of the Turkish population on warfarin therapy were found to be low. It was thought that low TTR levels of the Turkish population may be caused by the low awareness of warfarin, warfarin’s food–drug interactions, and high rates of concomitant diseases. (Anatol J Cardiol 2016; 16: 595-600)

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Adherence to Guidelines for Avoiding Drug Interactions Associated with Warfarin - A Nationwide Swedish Register Study

Cited by 12 publications

References 42 publications

Co‐Prescribing of Potentially Interacting Drugs during Warfarin Therapy – A Population‐Based Register Study

Co‐Prescribing of Potentially Interacting Drugs during Warfarin Therapy – A Population‐Based Register Study

Frailty and Co-Prescribing of Potentially Interacting Drugs in New Users of Warfarin

The awareness, efficacy, safety, and time in therapeutic range of warfarin in the Turkish population: warfarin -tr

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