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.

Low Quality of Warfarin Therapy is Associated With Female Gender but Not With Polypharmacy in Patients With Atrial Fibrillation

Background: We examined the impact of polypharmacy on the quality of the anticoagulation therapy in patients with atrial fibrillation. We also examined the factors that affect the stability of warfarin therapy.

Methods and Results: This retrospective study was conducted using data from 157 consecutive outpatients with atrial fibrillation in a single tertiary referral hospital. Patients who were prescribed warfarin continuously and for whom PT-INR was examined at least three times in a year were included in this study. We examined the quality of warfarin therapy using time in the therapeutic INR range (TTR), percentage of PT-INR determinations in range (PINRR), and the coefficient variation (CV) of PT-INR. We found that the number of prescribed medicines was significantly associated with high BMI and low eGFR, but not with TTR, PINRR, and the coefficient variation of PT-INR in patients with atrial fibrillation. We also found that female gender was independently associated with low PINRR in this study population.

Conclusion: Polypharmacy did not deteriorate the quality of warfarin therapy in patients with atrial fibrillation treated in the tertiary referral hospital. Female gender was an independent predictor of the low quality of warfarin 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.

Discrepancy Among Self-Reported Adherence, Prescription Refills, and Actual Anticoagulant Control

BACKGROUND

Patients must adhere to their prescribed warfarin regimens and regularly monitor the anticoagulation effect to maintain therapeutic levels. The ability to evaluate regimen adherence accurately is crucial to the success of patient coaching. However, prevention of thromboembolic events is challenging when the association between medication adherence and the actual amount of anticoagulant agent taken cannot be determined.

PURPOSE

This study used self-reported medication taken and prescription refills to (a) verify warfarin medication adherence and (b) assist clinicians to determine the discrepancy between medication adherence and anticoagulant control efficacy.

METHODS

This study was conducted at a national-university-affiliated hospital in Yilan County, Taiwan. Structured questionnaires and medical record reviews were adopted. A 100-point visual analog scale was used to measure the reported adherence of participants, whereas medication refill adherence was compared against self-reported adherence. Finally, degree of adherence was evaluated based on time in therapeutic range.

RESULTS

This study included 192 participants. Half (n = 94, 49%) were women, and the mean age was 69.6 years. Mean scores were 92.2% for the visual analog scale and 87.3% for medication refill adherence. Medication adherence correlated significantly with age, as reflected in the visual analog scale scores (p < .05). The participants who were receiving polypharmacy with five types of medicines or less attained higher visual analog scale scores, whereas participants who were on warfarin for 2-12 months exhibited higher medication refill adherence. Time in therapeutic range correlated negatively with age, although stability improved with therapy duration.

CONCLUSIONS/IMPLICATIONS FOR PRACTICE

Despite their high self-reported adherence levels, patients of advanced age require careful monitoring of their time in therapeutic range. The participants in this study who were on warfarin for a relatively longer time exhibited higher stability in the therapeutic range, despite their low medication refill adherence. The results of this study suggest that patient age, duration of warfarin therapy, and polypharmacy are factors associated with medication adherence. The findings may facilitate future assessments of warfarin adherence in patients as well as the implementation of more effective clinical nursing procedures and management practices.

Temporal trends of time in therapeutic range and incidence of cardiovascular events in patients with non-valvular atrial fibrillation

BACKGROUND

Optimal time in therapeutic range (TTR) of vitamin K antagonists (VKAs) is crucial for cardiovascular events (CVEs) prevention in non-valvular atrial fibrillation (NVAF). The relationship between temporal changes of TTR and the incidence of CVEs has been poorly investigated. We investigated 1) temporal trends of TTR in a long-term follow-up of NVAF patients; 2) the incidence of CVEs according to changes of TTR.

METHODS

Prospective observational study including 1341 NVAF outpatients (mean age 73.5 years, 42.5% male) starting VKAs. Patients were divided into 4 groups: Group 0: Optimal TTR, consistently ≥70% (n = 241); Group 1: Temporally worsening TTR, from above to below 70% (n = 263); Group 2: Temporally improving TTR, from below to above 70% (n = 270); Group 3: Suboptimal TTR, consistently <70% (n = 567).

RESULTS

In a mean follow-up of 37.7 months (4214.2 patient-years), 108 CVEs occurred (2.6%/year). Survival analysis showed a graded increased risk of CVEs in relation to temporal changes in TTR, with the worst outcomes in Groups 1 and 3 (log-rank test p = 0.013). Multivariable Cox proportional hazards regression analysis showed that Group 1 vs. 0 (HR: 2.096; 95%CI 1.061-4.139, p = 0.033), Group 3 vs. 0 (HR: 2.292; 95%CI 1.205-4.361, p = 0.011), CHA₂DS₂VASc score (HR:1.316; 95%CI 1.153-1.501, p < 0.001) and PPIs (HR:0.453; 95%CI 0.285-0.721, p = 0.001) were independently associated with CVEs.

CONCLUSION

A decrease of TTR <70% over time is observed in almost 20% of NVAF patients. Patients with worsening TTR temporally (ie. from initially above 70% to below 70%) have similar risk of CVEs of patients with consistently suboptimal anticoagulation.

Age is associated with time in therapeutic range for warfarin therapy in patients with atrial fibrillation

Background

Warfarin is the most prescribed oral anticoagulant used for preventing stroke in patients with atrial fibrillation. Time in the therapeutic range (TTR) has been accepted as the best method to evaluate the quality of warfarin therapy. The main aim of the present study was to evaluate the impact of variables on the time in the therapeutic range for warfarin therapy in patients with atrial fibrillation from a referral cardiovascular hospital.

Methods

This retrospective study included 443 patients were included (190 patients with age < 65 years and 253 patients with age ≥65 years) from 2011 to 2014 and TTR was computed according to Rosendaal's method.

Results

Patients with age ≥65 years had higher TTR value (67±22%) compared with patients with < 65 years (60±24%) (p = 0.004). In a linear regression model, only age ≥65 years emerged as a significant predictor of greater TTR values. In multivariate logistic regression model, the variable age ≥65 years was associated with higher OR for having a TTR higher than the median value (OR = 2.17, p < 0.001).

Conclusion

We suggest that the age influenced TTR through greater drug adherence. Strategies for increasing drug adherence might improve quality of warfarin anticoagulation.

The Time in Therapeutic Range and Bleeding Complications of Warfarin in Different Geographic Regions of Turkey: A Subgroup Analysis of WARFARIN-TR Study

Background:

The time in therapeutic range values may vary between different geographical regions of Turkey in patients vitamin K antagonist therapy.

Aims:

To evaluate the time in therapeutic range percentages, efficacy, safety and awareness of warfarin according to the different geographical regions in patients who participated in the WARFARIN-TR study (The Awareness, Efficacy, Safety and Time in Therapeutic Range of Warfarin in the Turkish population) in Turkey.

Study Design:

Cross-sectional study.

Methods:

The WARFARIN-TR study includes 4987 patients using warfarin and involved regular international normalized ratio monitoring between January 1, 2014 and December 31, 2014. Patients attended follow-ups for 12 months. The sample size calculations were analysed according to the density of the regional population and according to Turkish Statistical Institute data. The time in therapeutic range was calculated according to F.R. Roosendaal’s algorithm. Awareness was evaluated based on the patients’ knowledge of the effect of warfarin and food-drug interactions with simple questions developed based on a literature review.

Results:

The Turkey-wide time in therapeutic range was reported as 49.5%±22.9 in the WARFARIN-TR study. There were statistically significant differences between regions in terms of time in therapeutic range (p<0.001). The highest rate was reported in the Marmara region (54.99%±20.91) and the lowest was in the South-eastern Anatolia region (41.95±24.15) (p<0.001). Bleeding events were most frequently seen in Eastern Anatolia (41.6%), with major bleeding in the Aegean region (5.11%) and South-eastern Anatolia (5.36%). There were statistically significant differences between the regions in terms of awareness (p<0.001).

Conclusion:

Statistically significant differences were observed in terms of the efficacy, safety and awareness of warfarin therapy according to different geographical regions in Turkey.

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.

Rivaroxaban vs. warfarin on extended deep venous thromboembolism treatment: A cost analysis

Background

Standard treatment for deep venous thromboembolism involves parenteral anticoagulation overlapping with a vitamin K antagonist, an approach that is effective but associated with limitations including the need for frequent coagulation monitoring. The direct oral anticoagulant rivaroxaban is similarly effective to standard therapy as a single-drug treatment for venous thromboembolism and does not require routine coagulation monitoring. The aim of this analysis was to project the long-term costs and outcomes for rivaroxaban compared to standard of care (tinzaparin/warfarin).

Methods

A total of 184 patients who were under anticoagulant therapy with warfarin or rivaroxaban for extended deep venous thromboembolism were retrospectively evaluated; 59 received rivaroxaban and 125 received warfarin therapy. Assessments were made on age, gender, place of residence, the duration of anticoagulation, mean international normalized ratio value, the effective rate of international normalized ratio (time in the therapeutic range), bleeding-related complication rate, duration of hospitalization due to complications, the number of annual outpatient department admission, cost for drug, cost for hospitalization, cost for outpatient department admission and international normalized ratio measurements.

Results

The annual outpatient cost is higher in warfarin group (147.09 ± 78 vs. 62.32 ± 19.79 USD p < 0.001). But annual drug cost is higher in rivaroxaban group (362.6 vs. 71.55 ± 31.01 USD p < 0.001). Overall cost of rivaroxaban group is higher than warfarin group (476.25 ± 36.78 vs. 364.82 ± 174.44 USD). Warfarin is not cost-effective when non-drug costs (342.5 ± 174.44 vs. 113.65 ± 36.77) and hospital costs (173.85 ± 122.73 vs. 64.9 ± 23.55 USD) were analyzed.

Conclusion

This analysis suggests that rivaroxaban has lower costs than warfarin in terms of outpatient department admission and hospital costs due to complications; however, warfarin was more economic when all cost parameters were considered. Time in the therapeutic range was found as 56% for warfarin that should be taken into account while analyzing costs and benefits.

Clinical and economic impact of rivaroxaban on the burden of atrial fibrillation: The case study of Japan

OBJECTIVES

Atrial fibrillation (AF) affects an estimated 1.5 million individuals in Japan, increasing their stroke risk and imposing considerable costs on the Japanese healthcare system. To reduce stroke incidence, guidelines recommend using anticoagulants in moderate-to-high risk non-valvular AF (NVAF) patients; however, many patients receive no treatment, aspirin only, or remain poorly-controlled on vitamin K antagonists (VKAs) due to high VKA discontinuation rates and non-adherence to guidelines. A prevalence-based Markov model was developed to estimate the clinical and budgetary impact of treating these patients with Xarelto(TM) (rivaroxaban, Bayer AG) in Japan.

METHODS

Population, baseline risk of events, and associated management costs were estimated using data from Japanese publications where available. Treatment efficacy and safety were derived from published data and the J-ROCKET AF trial. Drug and physician visit costs were based on data from the Ministry of Health, Labor, and Welfare, the J-ROCKET AF trial, and Japanese clinical guidelines.

RESULTS

This model demonstrates that increased use of rivaroxaban in inadequately-managed NVAF patients could avoid 456 081 non-fatal ischemic strokes (IS) and 76 975 cardiovascular deaths over 10 years in Japan. This clinical benefit offsets the increased incidence of myocardial infarctions and anticoagulant-related bleeding. Decreased event costs could lead to a ¥188.4 billion decrease in net spending over the analysis time horizon.

CONCLUSIONS

Introducing rivaroxaban may decrease the burden of NVAF in Japanese society. From a clinical perspective, the reduction in IS and embolic events outweighs the increased risk of anticoagulant-related bleeding; from an economic perspective, reduced event costs offset drug and physician visit costs, resulting in cost savings.

A cost-utility analysis for catheter ablation of atrial fibrillation in combination with warfarin and dabigatran based on the CHADS2 score in Japan

BACKGROUND

We aimed to clarify the cost-effectiveness of an expensive combination therapy for atrial fibrillation (AF) using both catheter ablation and dabigatran compared with warfarin at each CHADS₂ score for patients in Japan.

METHODS

A Markov model was constructed to analyze costs and quality-adjusted life years associated with AF therapeutic options with a time horizon of 10 years. The target population was 60-year-old patients with paroxysmal AF. The indication for anticoagulation was determined according to the Japanese guideline. Anticoagulation-related data were derived from the RE-LY study and the AF recurrence rate was set at 2.7% per month during the first 12 months and at 0.40% per month afterwards. Stroke risk was determined according to AF recurrence, anticoagulation, and CHADS₂ score. The risks for stroke recurrence and stroke death were also considered. Costs were calculated from the healthcare payer's perspective, and only direct medical costs were included.

RESULTS

Warfarin was the most preferred option for patients with a CHADS₂ score of 0 from a health economics aspect. Ablation under warfarin was preferred for a CHADS₂ score of 1-3, while ablation under dabigatran was preferred for a CHADS₂ score ≥4. The quality of life score for AF had the largest impact on the incremental cost-effectiveness ratios in the analysis between the anticoagulation arm and the anticoagulation+ablation arm for a CHADS₂ score of 2. Within the range of the Japanese willingness-to-pay threshold (¥5,000,000), the ablation+warfarin arm became the best option with its probability of 81.7% for a CHADS₂ score of 2; the dabigatran+ablation arm was the most preferred option with its probability of 56.1% for a CHADS₂ score of 4.

CONCLUSIONS

Ablation under dabigatran therapy is an expensive therapeutic option, but it might benefit patients with a low quality of life and a high CHADS₂ score.

Efficacy and safety of non-vitamin K antagonist oral anticoagulants vs. warfarin in Japanese patients with atrial fibrillation – meta-analysis

BACKGROUND

Non-vitamin K antagonist oral anticoagulants (NOAC) have been developed as alternatives to warfarin. Until recently, the latter was the standard oral anticoagulant for patients with non-valvular atrial fibrillation (NVAF). The efficacy and safety of NOAC in Japanese patients with NVAF has been investigated in small trials or subgroups from global randomized control trials (RCT).

METHODS AND RESULTS

We conducted a systematic review and meta-analysis of RCT, to compare the efficacy and safety of NOAC to those of warfarin in Japanese patients with NVAF. Published research was systematically searched for RCT that compared NOAC to warfarin in Japanese patients with NVAF. Random-effects models were used to pool efficacy and safety data across RCT. Three studies, involving 1,940 patients, were identified. Patients randomized to NOAC had a decreased risk for stroke and systemic thromboembolism (relative risk [RR], 0.45; 95% CI: 0.24-0.85), with a non-significant trend for lower major bleeding (RR, 0.66; 95% CI: 0.29-1.47), intracranial bleeding (RR, 0.46; 95% CI: 0.18-1.16) and gastrointestinal bleeding (RR, 0.52; 95% CI: 0.25-1.08).

CONCLUSIONS

NOAC are more efficacious than warfarin for the prevention of stroke and systemic embolism in Japanese patients with NVAF. The present findings offer clinicians a more comprehensive picture of NOAC as a therapeutic option to reduce the risk of stroke in Japanese NVAF patients.

Association between smoking habits and the first-time appearance of atrial fibrillation in Japanese patients: Evidence from the Shinken Database

BACKGROUND

We previously reported a cross-sectional analysis regarding the relationship between smoking and atrial fibrillation (AF) in a single hospital-based cohort with Japanese patients, but the effect of cessation of smoking and/or total tobacco consumption were unclear.

METHODS AND RESULTS

We used data from the Shinken Database 2004-2011 (men/women, n=10,714/6803, respectively), which included all new patients attending the Cardiovascular Institute between June 2004 and March 2012. After excluding those previously diagnosed with AF (n=2296), 15,221 patients (men/women, n=9016/6205) were analyzed. During the follow-up period of 2.0±2.1 years (range 0.0-8.1), the incidence rates of new AF in smokers and non-smokers were 9.0 and 5.0 per 1000 patient-years, respectively. In adjusted models with Cox regression analysis, smokers were independently associated with new AF [hazard ratio (HR) 1.47, 95% confidence interval (CI) 1.09-2.00]. Also, current smokers (HR 1.81, 95% CI 1.17-2.79) and smokers with Brinkman index ≥800 (HR 1.69, 95% CI 1.05-2.70) were independently associated with new AF. However, in current smokers, the HRs were not different by Brinkman index (Brinkman index <800/≥800; HR 1.81/1.82, 95% CI 1.07-3.05/0.94-3.51, respectively).

CONCLUSIONS

Smoking was independently associated with the first-appearance of AF in patients in sinus rhythm, especially when the patients continued their smoking habit. However, in patients who continued smoking, difference by total tobacco consumption was not observed, suggesting the significance of cessation of smoking for preventing AF. Our data are limited because of a single hospital-based nature and a relatively short observation period.

Quality of vitamin K antagonist control and outcomes in atrial fibrillation patients: a meta-analysis and meta-regression

BACKGROUND

Atrial fibrillation (AF) patients frequently require anticoagulation with vitamin K antagonists (VKAs) to prevent thromboembolic events, but their use increases the risk of hemorrhage. We evaluated time spent in therapeutic range (TTR), proportion of international normalized ratio (INR) measurements in range (PINRR), adverse events in relation to INR, and predictors of INR control in AF patients using VKAs.

METHODS

We searched MEDLINE, CENTRAL and EMBASE (1990-June 2013) for studies of AF patients receiving adjusted-dose VKAs that reported INR control measures (TTR and PINRR) and/or reported an INR measurement coinciding with thromboembolic or hemorrhagic events. Random-effects meta-analyses and meta-regression were performed.

RESULTS

Ninety-five articles were included. Sixty-eight VKA-treated study groups reported measures of INR control, while 43 studies reported an INR around the time of the adverse event. Patients spent 61% (95% CI, 59-62%), 25% (95% CI, 23-27%) and 14% (95% CI, 13-15%) of their time within, below or above the therapeutic range. PINRR assessments were within, below, and above range 56% (95% CI, 53-59%), 26% (95% CI, 23-29%) and 13% (95% CI, 11-17%) of the time. Patients receiving VKA management in the community spent less TTR than those managed by anticoagulation clinics or in randomized trials. Patients newly receiving VKAs spent less TTR than those with prior VKA use. Patients in Europe/United Kingdom spent more TTR than patients in North America. Fifty-seven percent (95% CI, 50-64%) of thromboembolic events and 42% (95% CI, 35 - 51%) of hemorrhagic events occurred at an INR <2.0 and >3.0, respectively; while 56% (95% CI, 48-64%) of ischemic strokes and 45% of intracranial hemorrhages (95% CI, 29-63%) occurred at INRs <2.0 and >3.0, respectively.

CONCLUSIONS

Patients on VKAs for AF frequently have INRs outside the therapeutic range. While, thromboembolic and hemorrhagic events do occur patients with a therapeutic INR; patients with an INR <2.0 make up many of the cases of thromboembolism, while those >3.0 make up many of the cases of hemorrhage. Managing anticoagulation outside of a clinical trial or anticoagulation clinic is associated with poorer INR control, as is, the initiation of therapy in the VKA-naïve. Patients in Europe/UK have better INR control than those in North America.

Measures of vitamin K antagonist control reported in atrial fibrillation and venous thromboembolism studies: a systematic review

OBJECTIVE

To aid trialists, systematic reviewers and others, we evaluated the degree of standardisation of control measure reporting that has occurred in atrial fibrillation (AF) and venous thromboembolism (VTE) studies since 2000; and attempted to determine whether the prior recommendation of reporting ≥2 measures per study has been employed.

DESIGN

Systematic review.

SEARCH STRATEGY

We searched bibliographic databases (2000 to June 2013) to identify AF and VTE studies evaluating dose-adjusted vitamin K antagonists (VKAs) and reporting ≥1 control measure. The types of measures reported, proportion of studies reporting ≥2 measures and mean (±SD) number of measures per study were determined for all studies and compared between subgroups.

DATA EXTRACTION

Through the use of a standardised data extraction tool, we independently extracted all data, with disagreements resolved by a separate investigator.

RESULTS

148 studies were included, 57% of which reported ≥2 control measures (mean/study=2.13±1.36). The proportion of time spent in the target international normalised ratio range (TTR) was most commonly reported (79%), and was frequently accompanied by time above/below range (52%). AF studies more frequently reported ≥2 control measures compared with VTE studies (63% vs 37%; p=0.004), and reported a greater number of measures per study (mean=2.36 vs 1.53; p<0.001). Observational studies were more likely to provide ≥2 measures compared with randomised trials (76% vs 33%; p<0.001) and report a greater number of measures (mean=2.58 vs 1.63; p<0.001). More recent studies (2004-2013) reported ≥2 measures more often than older (2000-2003) studies (59% vs 35%; p=0.05) and reported more measures per study (mean=2.23 vs 1.48; p=0.02).

CONCLUSIONS

While TTR was often utilised, studies reported ≥2 measures of VKA control only about half of the time and lacked consistency in the types of measures reported. A trend towards studies reporting greater numbers of VKA control measures over time was observed over our review time horizon, particularly, with AF and observational studies.

Introduction of point-of-care testing in Japanese outpatient clinics is associated with improvement in time in therapeutic range in anticoagulant-treated patients

BACKGROUND

Warfarin reduces the risk of stroke in patients with atrial fibrillation, but requires a moderate-to-high time in therapeutic range (TTR). We hypothesized that point-of-care (POC) testing for prothrombin time-internationalized normalized ratio (PT-INR) could improve the TTR in patients receiving warfarin.

METHODS AND RESULTS

Eight outpatient clinics that introduced POC testing for PT-INR participated in this study. We identified 148 consecutive patients who received warfarin for at least 12 months before and after the introduction of POC testing. We compared the TTR before and after the introduction of POC testing for each patient. TTR after the introduction of POC testing was significantly higher than that beforehand (51.9%±33.0% vs. 69.3%±26.3%; P<0.0001). The improvement in TTR was statistically significant in patients who had low TTR (<70%) before the introduction of POC testing. After the introduction of POC, the time spent above the target INR showed no significant change (3.7%±10.6% vs. 3.3%±6.3%, P=0.7322), while that spent below the target INR improved significantly (44.4%±34.4% vs. 27.4%±27.6%, P<0.0001).

CONCLUSIONS

The introduction of POC testing was associated with an improvement in TTR, mainly through a reduction in the time spent below the target INR.

An explanation of recommendation differences: illustrations from recent atrial fibrillation guidelines

The development of guidelines and their use in all areas of medicine has greatly expanded in recent years. However, despite a shared evidence base, recommendations provided by different professional societies and healthcare authorities often vary considerably. The rapid advances in atrial fibrillation (AF) and the multiplicity of guidelines devoted to AF have made it particularly susceptible to this problem. Many nonmedical aspects are important in the development of guidelines, and without understanding them correct interpretation of guidelines is difficult. Conflicts of interest, the regulatory environment, and local data all influence guidelines. Nuanced wording, resource availability, and strategic purpose add complexity to guideline recommendations. This article reviews major AF guidelines from around the world and discusses aspects which have nothing to do with the scientific evidence base in order to help the practicing physician understand and make better use of differing guideline recommendations.

Effects of smoking habit on the prevalence of atrial fibrillation in Japanese patients with special reference to sex differences

BACKGROUND

Tobacco smoking is a well-known risk factor for cardiovascular disease, but controversial results have been reported regarding its relationship with atrial fibrillation (AF). Moreover, no study on the relationship between smoking and AF has yet been undertaken in a Japanese context.

METHODS AND RESULTS

We used data from the Shinken Database 2004-2011 (men/women, n=10,714/6,803, respectively), which included all new patients attending the Cardiovascular Institute between June 2004 and March 2012. AF was diagnosed in 1,698 and 598 men and women, respectively. In men, smokers were more prevalent in the AF than in the non-AF group (54.5% vs. 44.7%), whereas in women the prevalence of smokers was similar between AF and non-AF groups (14.4% vs. 15.4%). This discrepancy between the sexes seems to derive from a characteristic distribution pattern of smoking habit in women. After adjustment for various cofactors, smoking was independently associated with AF (odds ratio 1.54; 95% confidence interval 1.35-1.75; P<0.001) without a significant interaction between sex categories (P=0.195).

CONCLUSIONS

Smoking was independently associated with AF without a significant interaction between sex categories among Japanese patients visiting a cardiovascular hospital. Further studies using a prospective cohort design are required to confirm a causal link between smoking and AF in Japanese patients.

Does warfarin use impact hospital length of stay? A retrospective study looking at patients treated for atrial fibrillation

The authors received anecdotal practice information from clinicians indicating that when warfarin was initiated in the hospital setting, it may be associated with an increased length of stay (LOS): specifically to achieve a desired minimum international normalized ratio (INR) of 2.0 before discharge in a subset of patients where clinicians perceived follow-up after discharge was not deemed optimal. Given that oral thromboprophylactic anticoagulation with warfarin is the mainstay treatment for the prevention of stroke in atrial fibrillation (AF), the authors decided to look at hospitalized patients from this population to determine if a subset of these patients experienced an increased LOS. The study design entailed a retrospective chart review of consecutive patients admitted to a large, tertiary care, academic center. Patients were included if they were admitted with a primary, secondary, or most responsible diagnosis of paroxysmal or chronic AF. Medical records were audited over an 18-month period (February 1, 2009, to July 31, 2010) to determine the average LOS and to identify patients with a documented prolonged LOS secondary due to subtherapeutic INR at the time of potential discharge. Our final study cohort of 189 patients had an average LOS of 5.2 days (SD = 5.2). However, for eight (4.2%) of these patients discharge was delayed an additional 2.25 days (SD = 1.3) for reasons solely attributed to achieving a therapeutic INR.

[How to properly use warfarin and new anticoagulants]

Warfarin has unmet medical needs such as blood coagulation monitoring, limitation of vitamin K intake, and interaction with other drugs, while novel oral anticoagulants (NOACs) do not have such kind of unmet medical needs. Therefore, NOACs are recommended to busy patients or patients far from hospitals, or who do not want to limit vitamin K or use many other drugs concomitantly. NOACs are also recommended to patients with low time in therapeutic range (TTR). NOACs are also recommended to warfarin-naïve patients. Warfarin is recommended to patients with economical difficulty because it is much cheaper than NOACs. If needed, warfarin should be selected in patients with renal insufficiency or under hemodialysis because NOACs are contraindicated. New guidelines by the European Society of Cardiology recommend NOACs to low risk patients with CHA2DS2-VASc score 1, and also as the first line to those with CHA2DS2-VASc 2 or more. Finally, drug should be determined by patients' preference. Doctors should give adequate information helpful for patients' selection.

Gender-specific relationship between serum uric acid level and atrial fibrillation prevalence

BACKGROUND

Although various kinds of cardiovascular risk factors have been reported to be associated with atrial fibrillation (AF), the relationship between serum uric acid level and AF has not been fully examined.

METHODS AND RESULTS

Data were collected from a single hospital-based cohort in the Shinken Database 2004-2008 (n=11,123), and consisted of serum uric acid level for 7,155 patients. The association between serum uric acid level and AF prevalence was evaluated on logistic regression. Uric acid significantly increased the crude AF prevalence in both men and women (both, P<0.001). The odds ratio (OR) and 95% confidence interval (95%CI) in the highest tertile compared with the lowest one were 3.368 (2.478-4.578) and 1.408 (1.169-1.695) in women and men, respectively. Uric acid was also significantly associated with other various cardiovascular risk factors for AF. Even after the multivariate model was adjusted using these variables, the effect of uric acid on AF was independent in women (OR, 1.888; 95%CI: 1.278-2.790), but not in men.

CONCLUSIONS

Reflecting the composite of various cardiovascular risk factors, serum uric acid level was apparently associated with AF prevalence. The independent association in women might imply some sex-specific mechanisms. The results should be confirmed in prospective studies.