Quality of warfarin control in atrial fibrillation patients in South East Queensland, Australia

The SAMe-TT2R2 score as an indicator of warfarin control for patients with deep vein thrombosis in Queensland, Australia

Oral anticoagulation options for patients with venous thromboembolism (VTE) include vitamin K antagonists like warfarin. Good warfarin control is linked to outcomes of therapy, and the SAMe-TT₂R₂ model has been reported to predict control in atrial fibrillation patients with scores ≥ 2 linked to poor control. There has been limited and conflicting data in VTE populations, therefore this study aimed at determining the predictive ability of this model in Australian patients with deep vein thrombosis. Retrospective data of patients receiving warfarin care at a private pathology clinic in Queensland was collected. The time in therapeutic range (TTR) and SAMe-TT₂R₂ score was calculated for individual patients. Mean TTR and patients with TTR ≥ 65% were used for analysis and comparison across patients categorised as a score of 0-1 and ≥ 2. Of the 533 patients, the majority had a SAMe-TT₂R₂ score of 0-1. No significant difference was found in mean TTR between patients with a score of 0-1 and ≥ 2 but there was a significantly higher percentage of patients with a TTR ≥ 65% between groups (93.8% vs. 69.2%, p < 0.0001, respectively). The SAMe-TT₂R₂ score may assist in identifying patients with VTE likely to achieve good control (TTR ≥ 65%), but further investigation is required to determine the most suitable model for predicting warfarin control in this population.

Physician-Pharmacist Collaborative Clinic Model to Improve Anticoagulation Quality in Atrial Fibrillation Patients Receiving Warfarin: An Analysis of Time in Therapeutic Range and a Nomogram Development

Background: Poor time in therapeutic range (TTR) control is associated with an increased risk of stroke and bleeding in atrial fibrillation (AF) patients receiving warfarin. This study aimed to determine whether the physician-pharmacist collaborative clinic (PPCC) model could improve the anticoagulation quality as well as to create a nomogram for predicting anticoagulation quality in AF patients. Methods: This retrospective observational study enrolled AF patients who either initially received warfarin or returned to warfarin after withdrawal between January 1, 2016 and January 1, 2021, at our institution. The primary outcome was dynamic changes in TTRs (a TTR of ≥60% considered high anticoagulation quality). The secondary outcomes were thromboembolic and bleeding events during follow-up. We compared the dynamic changes in TTRs between the general clinic (GC) and PPCC groups in both the original and propensity score matching (PSM) cohorts. In addition, we explored the potential predictors of high anticoagulation quality and subsequently formulated a nomogram to predict anticoagulation quality. Results: A total of 265 patients with AF were included, comprising 57 patients in the PPCC group and 208 patients in the GC group. During a median follow-up period of 203 days, the PPCC group had a shorter time (76 vs. 199 days, p < 0.001) and more patients achieved a TTR ≥60% (73.7 vs. 47.1%, p = 0.002 by log-rank test) than the GC group. The results from the PSM cohort confirmed this finding. No significant differences in the incidences of thromboembolic events (5.3 vs. 5.3%, p = 1.000) and bleeding events (4.3 vs. 3.5%, p = 1.000) were observed between the two groups. Four variables were explored as predictors related to high anticoagulation quality: treatment within a PPCC, history of bleeding, history of bleeding, and the presence of more than four comorbidities. The nomogram revealed a moderate predictive ability (c-index: 0.718, 95% confidence interval (95%CI): 0.669-0.767) and a moderately fitted calibration curve. Conclusion: The PPCC model contributed to improved anticoagulation quality in AF patients receiving warfarin. The nomogram might be an effective tool to predict anticoagulation quality and could aid physicians and pharmacists in the selection of patients who will likely benefit from sustained and active intervention.

Time to Stable Therapeutic Range on Initiation of Warfarin as an Indicator of Control

OBJECTIVES

Warfarin remains widely used with a time in therapeutic range (TiTR) above 65% recommended for best outcomes. Patients not achieving or maintaining this warfarin control may be better suited to alternate anticoagulants. Despite this, there is limited data defining a suitable trial time in patients initiating warfarin therapy, therefore the aim of this study was to determine the mean time to stable therapeutic range (TtSTR).

MATERIALS AND METHODS

Retrospective data was collected for patients with atrial fibrillation enrolled in a dedicated warfarin program at a private pathology practice within 7 days of warfarin initiation. TiTR at specified timepoints was calculated and median TtSTR determined as defined by TiTR ≥ 65% over three months. Comparisons were made of populations with TtSTR above or below the median.

RESULTS

The 566 patients included in the study had a mean TiTR of 64.9±16.5% at month three and median TtSTR of six months. Patients with TtSTR≤6 months achieved a mean TiTR of 68.9±12.8% at month two and maintained a TiTR over 75% from month 3 to 24. Patients with a TtSTR>6 months obtained a TiTR of 66.4±10.6% at month nine and continued to achieve lower TiTR throughout the 24 months study period.

CONCLUSIONS

A majority of patients can achieve a stable TiTR above 65% within six months so review at six to nine months is likely to be a good indicator of warfarin control and to determine if patients should continue warfarin or switch to alternate anticoagulant therapy.

Anticoagulation Quality of Warfarin and the Role of Physician-Pharmacist Collaborative Clinics in the Treatment of Patients Receiving Warfarin: A Retrospective, Observational, Single-Center Study

Background: The management of patients receiving warfarin is complicated. This study evaluated the anticoagulation quality of warfarin, explored potential predictors associated with poor anticoagulation quality, and elucidated the role of clinical pharmacists in the management of warfarin treatment. Methods: We retrospectively collected data on patients who either initially received warfarin or returned to warfarin after withdrawal between January 1, 2015 and January 1, 2020. The primary outcome was time in therapeutic range (TTR), and a TTR of ≥60% was considered as good anticoagulation quality. The secondary outcomes included thromboembolic and bleeding events during the follow-up. We assessed the TTR of each participant and investigated the potential predictors of poor anticoagulation quality (TTR < 60%) using logistic regression analysis. Additionally, we compared the warfarin anticoagulant quality and the incidence of clinical adverse events between atrial fibrillation patients in physician-pharmacist collaborative clinics (PPCCs) and general clinics. Results: Totally, 378 patients were included. The mean TTR of patients was 42.6 ± 29.8%, with only 32% of patients having achieved good anticoagulation quality. During a mean follow-up period of 192 ± 92 days, we found no significant differences in the incidences of thromboembolic events (5.0% vs. 5.1%, p = 0.967) and bleeding events (1.7% vs. 4.7%, p = 0.241) between patients with good and those with poor anticoagulation quality. The presence of PPCCs (odds ratio [OR]: 0.47, 95% confidence interval [CI]: 0.25-0.90, p = 0.022) was an independent protective factor of poor anticoagulation quality, while the presence of more than four comorbidities (OR: 1.98, 95% CI: 1.22-3.24, p = 0.006) and an average interval of international normalized ratio monitoring of >30 days (OR: 1.74, 95% CI: 1.10-2.76, p = 0.019) were independent risk factors of poor anticoagulation quality. Compared with atrial fibrillation patients in general clinics, patients in PPCCs were found to have a significantly increased mean TTR level (48.4% ± 25.7% vs. 38.0% ± 27.6%, p = 0.014). Conclusion: The anticoagulation quality of warfarin was relatively low at our institution. The presence of more than four comorbidities and an average interval of international normalized ratio monitoring of >30 days independently contributed to poor anticoagulation quality. Meanwhile, the use of PPCC model improved the anticoagulation quality of warfarin.

The SAMe-TT2R2 Score Predicts Warfarin Control in an Australian Population with Atrial Fibrillation

BACKGROUND

Warfarin requires regular monitoring with the time in therapeutic range (TTR), a common indicator of control and TTR > 70% is indicative of efficient anticoagulation. The SAMe-TT2R2 (sex, age, medical history, treatment, tobacco use, race) model has been utilised as a predictor of warfarin control, with a score ≥ 2 indicative of poor control. However, it has been suggested that race may be over-represented in this model. To date, no Australian studies have applied this model, possibly because race is not routinely recorded. Therefore, the aim of this study was to apply the SAMe-TT2R2 model in an Australian population on warfarin managed by both a warfarin care program (WCP) and general practitioner (GP).

METHODS

Retrospective data was collected for patients receiving warfarin via a WCP in Queensland and whilst being managed by a GP. Patient data was used to calculate the SAMe-TT2R2 score and the TTR for each patient. Mean TTR was used for analysis and comparison with the categorised SAMe-TT2R2 score.

RESULTS

Of the 3911 patients managed by a WCP, there was a significantly lower mean TTR for patients with a SAMe-TT2R2 score ≥ 2 compared to 0-1 (78.6 ± 10.7% vs. 80.9 ± 9.5%, p < 0.0001). Of these patients, 200 were analysed whilst managed by a GP and the categorised SAMe-TT2R2 score did not result in a statistically different mean TTR (69.3 ± 16.3% with 0-1 vs. 63.6 ± 15.0% with ≥2, p = 0.089), but a score ≥2 differentiated patients with a TTR less than 65%.

CONCLUSIONS

The SAMe-TT2R2 model differentiated Australian patients with reduced warfarin control, despite the exclusion of race. In Australia, the SAMe-TT2R2 score could assist clinicians in identifying Australian patients who may obtain reduced warfarin control and benefit from additional interventions such as a dedicated WCP.

Associations between socioeconomic status, atrial fibrillation, and outcomes: a systematic review

BACKGROUND

Atrial fibrillation (AF) is a growing epidemic and evidence of a relationship to socioeconomic status (SES) is inconsistent. We aimed to summarize the literature about SES and AF and defined two objectives: (1) To examine the association between SES and the risk of AF; (2) To examine the association between SES and AF-related outcomes in an AF-population.

METHODS

We performed a separate search for each objective in Ovid-MEDLINE and Ovid-Embase. For objective 1, the population included was healthy participants and outcome of interest was AF. For objective 2, the population included were patients with AF and outcome of interest was mortality, treatment, ablation for AF, knowledge about AF, and morbidity.

RESULTS

For objective 1, 12 studies were included. No consistent pattern for an association between SES and the risk of AF was discovered. For objective 2, 39 studies comprising 42 outcomes were included. The majority of studies showed an association between low SES and increased mortality and morbidity.

CONCLUSION

Low SES was associated with poorer outcomes when AF was present. These findings may imply that health-care professionals and policy interventions should focus on the promotion of AF-education and management among patients with AF and low SES.

Dedicated warfarin care programme results in superior warfarin control in Queensland, Australia

BACKGROUND

Warfarin is used to prevent stroke in patients with atrial fibrillation (AF). Ongoing monitoring of International normalised ratio (INR) and time in therapeutic range (TTR) commonly used to assess the quality of warfarin management are required. Anticoagulant clinics have demonstrated improved TTRs, particularly in countries with poorer control in primary care settings. Reported TTR in Australia has been relatively high; so, it is unknown if benefit would be seen from dedicated warfarin clinics in Australia. The aim of this study was to compare the level of warfarin control in patients managed by their general practitioner (GP) and a warfarin care programme (WCP) by Sullivan Nicolaides Pathology.

METHOD

Retrospective data were collected for AF patients enrolled in the warfarin care programme at WCP, and included patients with INR tests available while managed by their GP. INR tests were used to calculate TTR and frequency of testing for the time managed by GP and WCP, with mean data used for analysis and comparison.

RESULTS

The eligible 200 warfarin patients had a TTR of 69% with GP management and 82% with WCP management (<.0001). Significant differences were also found between GP and WCP management in the percentage of tests in range, total number of tests and frequency of testing. WCP had a reduced time to repeat test at extremes of INR results.

CONCLUSION

Australian warfarin control was good when managed by either GP or WCP, but WCP management increased TTR by 13%. Dedicated warfarin programmes can improve warfarin control and optimise therapy for patients.

Factors influencing warfarin control in Australia and Singapore

INTRODUCTION

Warfarin is widely used for patients with non-valvular atrial fibrillation (NVAF). Variations in warfarin control, as measured by time in therapeutic range (TTR), have been reported across different regions and ethnicities, particularly between Western and Asian countries. However, there is limited data on comparative factors influencing warfarin control in Caucasian and Asian patients. Therefore, the aim of this study was to determine warfarin control and potential factors influencing this in patients with NVAF in Australia and Singapore.

METHODS

Retrospective data was collected for patients receiving warfarin for January to June 2014 in Australia and Singapore. TTR was calculated for individuals with mean patient TTR used for analysis. Possible influential factors on TTR were analysed including age, gender, concurrent co-morbidities, and concurrent medication.

RESULTS

The mean TTR was significantly higher in Australia (82%) than Singapore (58%). At both sites, chronic kidney disease significantly lowered this TTR. Further factors influencing control were anaemia and age<60years in Australia, and vascular disease, CHA₂DS₂-VASc score of 6, and concurrent platelet inhibitor therapy in Singapore.

DISCUSSION

Warfarin control was significantly higher in Australia compared to Singapore, however chronic kidney disease reduced control at both sites. The different levels of control in these two countries, together with patient factors further reducing control may impact on anticoagulant choice in these countries with better outcomes from warfarin in Australia compared to Singapore.

A High HASBLED Score Identifies Poor Warfarin Control in Patients Treated for Non-Valvular Atrial Fibrillation in Australia and Singapore

Warfarin reduces stroke risk in atrial fibrillation (AF) patients. The quality of warfarin control, measured by time in therapeutic range (TTR), impacts outcome and adverse events. One tool evaluating risk of adverse events and potential warfarin control would simplify risk-benefit assessment of warfarin. Recently, HASBLED was demonstrated effective for this purpose, but this was in well-controlled patients with deep vein thrombosis. HASBLED as a predictor of warfarin control has not been validated in other populations including differing indications, warfarin control levels and ethnicities. The aim of this study was to determine whether HASBLED can predict warfarin control in patients with AF in Australia and Singapore. Retrospective data were collected for patients receiving warfarin between January and June 2014 in Australia and Singapore. Patient data were used to calculate HASBLED at the start and end of the study period. TTR was calculated for each patient, and mean TTR used for analysis to stratified HASBLED scores. Of the 4370 patients, there were 3199 in Australia and 1171 in Singapore with mean TTRs of 82% and 58%, respectively. At the start of the study, a HASBLED score ≥3 predicted significantly lower TTR in Singapore, whilst at the end of the study, this score identified patients with poor control in both Australia and Singapore. A HASBLED score ≥3 in patients treated with warfarin can differentiate significantly lower TTRs in Australian and Singapore patients with AF. HASBLED may assess bleed risk and warfarin control, identifying patients at high risk of poor warfarin outcome requiring additional INR monitoring or alternative anticoagulation.

The Use of Fish Oil with Warfarin Does Not Significantly Affect either the International Normalised Ratio or Incidence of Adverse Events in Patients with Atrial Fibrillation and Deep Vein Thrombosis: A Retrospective Study

Background: Warfarin is a leading anticoagulant in the management of atrial fibrillation (AF) and deep vein thrombosis (DVT). Drug interactions influence the safety of warfarin use and while extensive literature exists regarding the effect on warfarin control and bleeding incidence with many medicines, there is little evidence on the influence of complementary medicines. The aim of this study was to assess the influence of fish and krill oil supplementation on warfarin control and bleeding incidence in AF and DVT patients. Methods: A retrospective analysis was conducted utilising patient information from a large private pathology clinic. AF and DVT patients receiving long-term warfarin therapy (>30 days) at the clinic and taking fish and krill oil supplements were eligible for study inclusion. Results: Of the 2081 patients assessed, a total of 573 warfarin users met the inclusion criteria with 145 patients in the fish and krill oil group (supplement group) and 428 patients in the control group. Overall, it was found that fish and krill oils did not significantly alter warfarin time in therapeutic range (TTR) or bleeding incidence, even when compared by gender. Conclusion: Omega-3 supplementation with fish and krill oil does not significantly affect long-term warfarin control and bleeding and thromboembolic events when consumed concurrently in patients managed at an anticoagulation clinic.