The quality of warfarin prescribing and monitoring in Veterans Affairs nursing homes

Have We Forgotten About Therapeutic Failure in Older Adults?

BACKGROUND

Three types of adverse drug events have been identified in studies of medication-related harms among older adults: adverse drug reactions, adverse drug withdrawal events, and therapeutic failures (TFs).

METHODS

In this narrative review of medical literature through June 2024, we summarize relevant articles and discuss evidence-based approaches and opportunities for future research to address TFs, as they are lesser recognized adverse drug events.

RESULTS

Despite more than three decades elapsing since TF was first described in 1991, we identified only 16 studies in our review that evaluated TF in older adults. The median rate of TFs among these 16 studies was 7.4%, and most TFs were considered preventable. Common reasons for TF in this population included medication nonadherence and underprescribing of necessary medications. These studies share several limitations, including weak observational study designs and relatively small samples that may not generalize to all populations of older adults. Finally, only five studies utilized an implicit tool (the Therapeutic Failure Questionnaire) that has been shown to have good interrater reliability.

CONCLUSIONS

We acknowledge that clinicians should, and often do, attend first to deprescribing and reducing polypharmacy in managing adverse drug reactions among older adults. We must not forget, however, about TFs as an important and predominantly preventable source of harm among our older adult patients. TFs increase the length of hospital stays, promote disease persistence, reduce quality of life, and increase social costs of disease. We believe TFs remain a prevalent and important problem in older adults. More data are needed from up-to-date robust observational studies to further understand the impact of TFs on economic and humanistic outcomes in older adults.

Time in the therapeutic range, bleeding event, and their determinants in older patients with atrial fibrillation on warfarin in Ethiopia: multicenter cross-sectional study

Background

Atrial fibrillation (AF) poses significant thromboembolism and bleeding risks, especially in older adults. Warfarin continues to be a primary treatment option, and maintaining the Time in Therapeutic Range (TTR) is critical for ensuring its effectiveness. However, suboptimal TTR is associated with increased risks of stroke, bleeding, and mortality. Despite its importance, there is limited data on warfarin management in Ethiopian older adults with AF. Therefore, this study aimed to determine the TTR, bleeding events, and their determinants, in older patients with AF in Ethiopia receiving warfarin therapy.

Method

In this study, older patients with AF who were treated with warfarin and had follow-up visits between May 2021 and May 2024, and met the inclusion criteria, were included. Patients were categorized based on TTR into two groups: poor anticoagulation (TTR < 65%) and good anticoagulation quality (TTR ≥ 65%). Bivariate and Multivariate Logistic regression was performed to predict determinants of a TTR < 65% and bleeding events. Odds ratios with 95% confidence intervals (CIs) were calculated, and statistical significance was set at P < 0.05.

Results

In this study, 384 patients with AF were included. Of this 53.4% were female. Of these 71% of patients had a TTR below 65%, 29% achieved ≥65%, with a median TTR of 45%. Bleeding events were reported by 13.5% of patients. Poor TTR was significantly associated with age (AOR = 1.199, 95% CI: 1.109-1.297), chronic kidney disease (AOR = 27.809, 95% CI: 7.57-101.76), and infrequent INR monitoring at 31-90-day intervals (AOR = 0.15, 95% CI: 0.004-0.051). Regarding determinants of bleeding events, Patients with diabetes mellitus had a 2.6-fold higher bleeding risk (AOR = 2.585, 95% CI: 1.069-6.250), and a CHA2DS2-VASc score ≥3 significantly increased bleeding risk compared to scores ≤2 (AOR = 7.562, 95% CI: 2.770-20.640).

Conclusion

This study highlights suboptimal warfarin therapy among older Ethiopian patients with AF. Poor anticoagulation was associated with advanced age, chronic kidney disease, and infrequent INR monitoring, while diabetes mellitus and high CHA₂DS₂-VASc scores increased bleeding risks. Close monitoring and frequent INR checks are essential to improving outcomes.

Rosendaal linear interpolation method appraising of time in therapeutic range in patients with 12-week follow-up interval after mechanical heart valve replacement

Background

The objective of this study was to evaluate the quality of anticoagulation by the time in therapeutic range (TTR) for patients with 12-week INR follow-up interval.

Materials and methods

From January 2018 to December 2020, a selective group of patients who underwent mechanical valve replacement and followed up at our anticoagulation clinic for adjustment of warfarin dose were enrolled. The incidences of complications of anticoagulation therapy were reported by linearized rates. TTR was calculated by the Rosendaal linear interpolation method.

Results

Two hundred and seventy-four patients were eligible for this study. The mean age of these patients was 52.8 ± 12.7 years, and 65.7% (180 cases) of them were females. The mean duration of warfarin therapy was 16.7 ± 28.1 months. A total of 1309 INR values were collected, representing 66789 patient days. In this study, the mean TTR was 63.7% ± 18.6%, weekly doses of warfarin were 20.6 ± 6.0 mg/weekly, and the mean monitoring interval for the patient was 53.6 ± 27.1 days. There were 153 cases in good TTR group (TTR ≥ 60%) and 121 cases in poor TTR group (TTR < 60%). The calculated mean TTR in both groups was 42.6% ± 22.1% and 74.8% ± 10.4%, respectively. Compared with the TTR ≥ 60% group, the TTR < 60% group exhibited a more prevalence of female gender (p = 0.001), atrial fibrillation (p < 0.001), NYHA ≥ III (p < 0.001), and lower preoperative left ventricular ejection fraction (LVEF, p = 0.032). In multivariate analysis, female gender (p = 0.023) and atrial fibrillation (p = 0.011) were associated with TTR < 60%. The incidence of major bleeding and thromboembolic events was 2.7% and 1.1% patient-years, respectively. There was one death which resulted from cerebral hemorrhage. The incidence of death was 0.5% patient-years. The difference in anticoagulation-related complications between the TTR < 60% group and the TTR ≥ 60% group was not statistically significant.

Conclusion

For patients with stable international normalized ratio monitoring results who are follow-up at anticoagulation clinics, a 12-week monitoring interval has an acceptable quality of anticoagulation. The female gender and atrial fibrillation were associated with TTR < 60%.

Magnitudes of Risk Factors of Venous Thromboembolism and Quality of Anticoagulant Therapy in Ethiopia: A Systematic Review

Background

Venous thromboembolism is one of the major public health problems in the world. Though several studies were conducted to estimate common risk factors of venous thromboembolism and quality of anticoagulant therapy in Ethiopia, it is difficult to estimate the overall burdens of risk factors and quality of anticoagulant use because of the lack of a nationwide study.

Objective

To assess magnitudes of risk factors of venous thromboembolism and quality of anticoagulant therapy in Ethiopia.

Materials and Methods

Electronic searching using PubMed, EMBASE, Science Direct, Cochrane Database, Scopus, Hinari, Sci-Hub, African Journals Online Library, and Free-text Web Searches using Google Scholar was conducted from September, 15 to October 27, 2021. Each of the original studies was identified by Mesh terms and Boolean search technique using full title, various keywords and was assessed using the Joanna Briggs Institute Critical Appraisal Checklist. The data were extracted using a format prepared in Microsoft Excel and exported to STATA 14.0 for the outcome analyses.

Results

The database search delivered a total of 2118 studies. After articles were removed by duplications, titles, reading the abstract, and assessed for eligibility criteria, 12 articles were found suitable for the systematic review. Prolonged immobilization (41.30%) was the most commonly observed risk factor of venous thrombosis followed by acute infection (40.25%). The proportion of therapeutic range (INR = 2-3), sub-therapeutic range (INR <2), and supra-therapeutic range (INR >3) were 32.15%, 47.58%, and 17.62%, respectively. One hundred and thirty-eight patients (11.4%) have developed minor or major bleeding complications.

Conclusion

Prolonged immobilization and acute infection were the main risk factors for venous thromboembolism. The quality of anticoagulant therapy in Ethiopia was poor and bleeding complications were high. A strong effort is needed to improve the quality of anticoagulation and close monitoring of patients' international normalized ratio is required to improve treatment outcomes.

Impact of an extended International Normalized Ratio follow-up interval on healthcare use among veteran patients on stable warfarin doses

PURPOSE

To analyze the impact of a 12-week extended International Normalized Ratio (INR) follow-up interval on healthcare use.

METHODS

A prospective cohort study of the use of an extended INR follow-up interval of up to 12 weeks was conducted over 2 years in a pharmacist-managed anticoagulation clinic. A detailed protocol was used to extend the INR follow-up interval to 5-6 weeks and then 7-8 weeks and 11-12 weeks. The number of planned and unplanned anticoagulation encounters, procedures requiring warfarin interruption, telephone triage phone calls, emergency department visits, and hospitalizations were collected. A post hoc subanalysis was also completed on participants who were scheduled for 4 consecutive 12-week intervals.

RESULTS

Compared to baseline, at 12 months there was a mean decrease in planned anticoagulation encounters of 2.24 visits (p < 0.001) among 44 participants. From 12 to 24 months compared to baseline, there was a mean decrease in planned anticoagulation encounters of 3.13 visits (p < 0.001) and an increase of 0.54 unplanned anticoagulation encounters (p = 0.04) among 39 participants. The remainder of healthcare use variables were not statistically significantly different from baseline at any time point. Of the 15 participants scheduled for 4 consecutive 12-week intervals, there was a decrease from baseline of approximately 5 visits over the course of a year (p < 0.001).

CONCLUSION

An extended INR follow-up interval appears to decrease anticoagulation healthcare use without an increase in acute healthcare use. While this intervention could be cost-effective, institutions need to consider safety, efficacy, and feasibility prior to implementation.

Assessment of Oral Anticoagulant Use in Residents of Long-Term Care Homes: Evidence for Contemporary Suboptimal Use

Objective: To describe the quality of warfarin use in residents of long-term care facilities and investigate potential predictors oral anticoagulant use. Design: Retrospective chart review (August 2013 to September 2014). Setting: Thirteen long-term care (LTC) and assisted living facilities (ALF). Participants: Residents from LTC or ALF settings who ( a) received warfarin or direct-acting oral anticoagulants (DOACs) and ( b) residents with a valid indication for oral anticoagulants such as atrial fibrillation, venous thromboembolism, but were not receiving these drugs. Primary Outcome: Time in therapeutic international normalized ratio (INR) range (TTR). Results: A total of 563 residents (70% female) with an average age of 85 years were identified. Participants had an average of 7.5 comorbidities and 9 medications. A total of 391 (69%) residents with indications for OACs were receiving such medications. Indications were atrial fibrillation (63%), venous or pulmonary embolism (16%), cardiac valves (0.4%); 26% did not have documented indications. Warfarin and DOACs were prescribed for 213 (38%) and 178 (32%) respectively, and 172 (31%) received no OACs The TTR ranged from 56%-75% (mean 63%). The frequency of INR determinations ranged from every 7 to 20 days, (mean 13 days) with no apparent relationship between frequency of testing and TTR. Conclusion: The TTR was higher (63.8%) than literature average (50%), but remains suboptimal given expected benefits of TTRs >75% versus TTRs circa 60%. Documentation of indications for OACs needs improvement, and it is possible that OACs are underused. Further work is necessary to understand how OAC use may be optimized in these facilities.

Quality of anticoagulation management with warfarin among outpatients in a tertiary hospital in Addis Ababa, Ethiopia: a retrospective cross-sectional study

Background

Warfarin is the most widely used anticoagulant in the world. The difficulty of managing warfarin contributes to great potential for patient harm, both from excessive anticoagulation and insufficient anticoagulation. This study assessed the International Normalized Ratio (INR) control outcome measures and warfarin dose adjustment practices at cardiology and hematology outpatient clinics at a teaching hospital in Addis Ababa, Ethiopia.

Methods

The study was based on a cross - sectional study design involving 360 retrospective patients’ chart review among outpatients who received warfarin for its various indications.

Results

The mean frequency of INR monitoring per patient was 62.9 days (17.2–143.7 days).

Patients spent 52.2%, 29.0% and 18.8% of the time in sub-therapeutic, therapeutic and supra-therapeutic ranges, respectively. The daily warfarin dose was increased 50.9% and 36.9% and decreased in 52.8% and 60.9% of the time for occurrences of sub-therapeutic and supra-therapeutic INRs to achieve target ranges of 2.0–3.0 and 2.5–3.5, respectively.

Conclusion

The quality of anticoagulation management with warfarin among outpatients in Tikur Anbessa Specialized Hospital was sub-optimal. This was reflected by low Time in Therapeutic Range (TTR), longer than recommended INR monitoring frequency, and minimal actions taken to adjust warfarin dose after occurrences of non-therapeutic INRs.

Interaction of vitamin K antagonists and trimethoprim-sulfamethoxazole: ignore at your patient's risk

The aim of the study was to summarize available literature regarding the interaction between vitamin K antagonists (VKAs) and trimethoprim-sulfamethoxazole (co-trimoxazole, TMP-SMX), and to provide recommendations for managing patient risk from this interaction. Data sources were English-language publications in the medical literature and Internet databases. Relevant publications that directly or indirectly addressed the VKA-TMP-SMX interaction were selected and reviewed. The mechanism of the VKA-TMP-SMX interaction, frequency of concurrent use, effect on international normalized ratio (INR), increased risk of bleeding, and strategies for risk reduction are summarized. The concurrent use of VKA and TMP/SMX rapidly and consistently raises INR and is associated with a two- to five-fold increase in bleeding. Concurrent use of VKA and TMP-SMX should be avoided when possible. When VKA and TMP-SMX are co-prescribed, VKA dose reduction is usually required. Patient education as well as early and frequent INR monitoring is recommended to reduce risk from this interaction.

Postdischarge international normalized ratio testing and long-term clinical outcomes of patients with heart failure receiving warfarin: findings from the ADHERE registry linked to Medicare claims

BACKGROUND

Effective warfarin thromboprophylaxis requires maintaining anticoagulation within the recommended international normalized ratio (INR) range. INR testing rates and associations between testing and outcomes are not well understood.

HYPOTHESIS

INR testing rates after hospitalization for acute decompensated heart failure are suboptimal, and testing is associated with lower risks of mortality and adverse clinical events.

METHODS

We conducted a retrospective cohort study of patients who were long-term warfarin users and were hospitalized for heart failure, had a medical history of atrial fibrillation or valvular heart disease, and were enrolled in fee-for-service Medicare. INR testing was defined as ≥1 outpatient INR test within 45 days after discharge. Using Cox proportional hazards models, we examined associations between testing and all-cause mortality, all-cause readmission, and adverse clinical events at 1 year.

RESULTS

Among 8558 patients, 7722 (90.2%) were tested. After 1 year, tested patients had lower all-cause mortality (23.5% vs 32.6%; P < 0.001) and fewer myocardial infarctions (2.0% vs 3.3%; P = 0.02). These differences remained significant after multivariable adjustment with hazard ratios of 0.72 (95% confidence interval [CI]: 0.63-0.84; P < 0.001) and 0.58 (95% CI: 0.41-0.83; P = 0.003), respectively. Differences in all-cause readmission, thromboembolic events, ischemic stroke, and bleeding events were not statistically significant.

CONCLUSIONS

Postdischarge outpatient INR testing in patients with heart failure complicated by atrial fibrillation or valvular heart disease was high. INR testing was associated with improved survival and fewer myocardial infarctions at 1 year but was not independently associated with other adverse clinical events.

A study of elderly adults taking warfarin admitted with prolonged international normalized ratio: a community hospital's experience

OBJECTIVES

To assess bleeding complications and outcome of individuals receiving oral anticoagulants who were admitted to the hospital with an international normalized ratio (INR) greater than 4 by comparing them according to age (≤ 80, >80).

DESIGN

Retrospective cohort study.

SETTING

Community hospital.

PARTICIPANTS

All individuals (N = 253) admitted to the Department of Internal Medicine over a period of 4 years with an INR greater than 4: Group I, aged 80 and younger (n = 127); Group II, older than 80 (n = 126). Data included bleeding complications, survival, and quality of INR control before admission and up to 48 months after admission.

RESULTS

Atrial fibrillation was the most common indication for warfarin therapy. Its incidence was higher in the older group (88% vs 73%, P = .004). More elderly participants lived in nursing homes (23% vs 9.4%. P = .004) or received in-home assistance (38.9% vs 20.5%, P = .002). There was no difference in INR upon admission, duration of warfarin treatment, or frequency of INR tests before admission. The incidence of bleeding events was 18.1% in Group I and 12.7% in Group II (P = .30). Major bleeding events occurred in 1.6% of Group I and none of Group II (P = .50). During follow-up after the first admission, the incidence of INR greater than 4 was higher in Group II (87.3% vs 70%, P = .02), without a difference in the number of additional admissions or bleeding events.

CONCLUSION

Primary care physicians can safely maintain warfarin treatment in elderly adults, even in those with a history of hospitalization for high INR, using frequent INR measurements.

Use of warfarin in long-term care: a systematic review

BACKGROUND

The use of warfarin in older patients requires special consideration because of concerns with comorbidities, interacting medications, and the risk of bleeding. Several studies have suggested that warfarin may be underused or inconsistently prescribed in long-term care (LTC); no published systematic review has evaluated warfarin use for stroke prevention in this setting. This review was conducted to summarize the body of published original research regarding the use of warfarin in the LTC population.

METHODS

A systematic literature search of the PubMed, Cumulative Index to Nursing and Allied Health Literature, and Cochrane Library was conducted from January 1985 to August 2010 to identify studies that reported warfarin use in LTC. Studies were grouped by (1) rates of warfarin use and prescribing patterns, (2) association of resident and institutional characteristics with warfarin prescribing, (3) prescriber attitudes and concerns about warfarin use, (4) warfarin management and monitoring, and (5) warfarin-related adverse events. Summaries of study findings and quality assessments of each study were developed.

RESULTS

Twenty-two studies met the inclusion criteria for this review. Atrial fibrillation (AF) was the most common indication for warfarin use in LTC and use of warfarin for stroke survivors was common. Rates of warfarin use in AF were low in 5 studies, ranging from 17% to 57%. These usage rates were low even among residents with high stroke risk and low bleeding risk. Scored bleeding risk had no apparent association with warfarin use in AF. In physician surveys, factors associated with not prescribing warfarin included risk of falls, dementia, short life expectancy, and history of bleeding. International normalized ratio was in the target range approximately half of the time. The combined overall rate of warfarin-related adverse events and potential events was 25.5 per 100 resident months on warfarin therapy.

CONCLUSIONS

Among residents with AF, use of warfarin and maintenance of INR levels to prevent stroke appear to be suboptimal. Among prescribers, perceived challenges associated with warfarin therapy often outweigh its benefits. Further research is needed to explicitly consider the appropriate balancing of risks and benefits in this frail patient population.