Influence of regular physical activity on warfarin dose and risk of hemorrhagic complications.
ABSTRACT: OBJECTIVE:To determine the influence of regular physical activity on stable warfarin dose and risk of major hemorrhage in patients on chronic anticoagulation therapy. DESIGN:Regular physical activity (maintained over > 80% of visits) was ascertained by self-report at initiation of warfarin therapy (target international normalized ratio [INR] = 2-3) in 1272 patients, with changes documented at monthly anticoagulation clinic visits in a population-based prospective cohort. Multi-variable linear regression and survival analysis, respectively, were used to assess influence on warfarin and risk of hemorrhage. SETTING:Outpatient anticoagulation clinic PARTICIPANTS:1272 anticoagulated patients MEASUREMENT AND MAIN RESULTS:There were 683 (53.7%) patients who were regularly physically active (? 30 min ? 3 times/week). Physically active patients required warfarin doses that were 6.9% higher (p=0.006) than in physically inactive patients after controlling for sociodemographic factors, vitamin K intake, clinical factors, and genetic variations.The overall incidence of major hemorrhagic events was 7.6/100 person-years (p-yrs, 95% confidence interval [CI] 6.4-8.9) in our population. The incidence was lower for physically active patients (5.6/100 p-yrs, 95% CI 4.2-7.2) than in inactive patients (10.3/100 p-yrs, 95% CI 8.2-12.9, p=0.0004). Active patients had a 38% lower risk of hemorrhage (hazard ratio 0.62, 95% CI 0.42-0.98, p=0.03) compared with inactive patients. CONCLUSIONS:Regular physical activity is associated with higher warfarin dose requirements and lower risk of hemorrhage. The influence of physical activity on drug response needs to be further explored, and the mechanisms through which it exerts these effects need to be elucidated
Project description:OBJECTIVE:We assessed the influence of age on warfarin dose, percentage time in target range (PTTR), and risk of major hemorrhage. DESIGN:Warfarin users recruited into a large prospective inception cohort study were categorized into three age groups: young (younger than 50 yrs), middle aged (50-70 yrs), and elderly (older than 70 yrs). The influence of age on warfarin dose and PTTR was assessed using regression analysis; risk of major hemorrhage was assessed using proportional hazards analysis. Models were adjusted for demographic, clinical, and genetic factors. SETTING:Two outpatient anticoagulation clinics. PARTICIPANTS:A total of 1498 anticoagulated patients. OUTCOMES:Warfarin dose (mg/day), PTTR, major hemorrhage. RESULTS:Of the 1498 patients, 22.8% were young, 44.1% were middle aged, and 33.1% were elderly. After accounting for clinical and genetic factors, compared with young warfarin users, warfarin dose requirements were 10.6% lower among the middle aged and an additional 10.6% lower for the elderly. Compared with young patients, middle-aged and elderly patients spent more time in target international normalized ratio (INR) range (p<0.0001), despite having fewer INR assessments (p<0.0001). Compared with young warfarin users, absolute risk of hemorrhage was marginally higher among the middle aged (p=0.08) and significantly higher among the elderly (p=0.016). Compared with young warfarin users, after adjustment, the relative risk of hemorrhage increased by 31% for each age category (p=0.026). CONCLUSIONS:In a real-world setting, despite achieving better anticoagulation control, elderly patients had a higher risk of major hemorrhagic events. As the population ages and the candidacy for oral anticoagulation increases, strategies that mitigate the elevated risk of hemorrhage need to be identified.
Project description:STUDY DESIGN:To assess whether warfarin dose requirement, anticoagulation control, and risk of hemorrhage differ in kidney transplant recipients (KTRs) compared with patients without kidney transplants (non-KTRs). DESIGN:Analysis of data from the Warfarin Pharmacogenetics Cohort, a prospective cohort of first-time warfarin users followed at two anticoagulation clinics. SETTING:Two outpatient anticoagulation clinics at two large, academic, tertiary care hospitals. PATIENTS:Adults aged 20 years or older starting warfarin for anticoagulation with a therapeutic international normalized ratio (INR) goal of 2-3 who were KTRs (n=65) or non-KTRs (n=1630). MEASUREMENTS AND MAIN RESULTS:Warfarin dose requirement, anticoagulation control, and risk of hemorrhage were assessed in each group. KTRs required an approximately 20% lower warfarin dose (4.7 vs 5.6 mg/day, p=0.0005) compared with non-KTRs. Genetic variants had similar effects on dose in both groups. Mean percentage of time in therapeutic range (PTTR) was similar among KTRs and non-KTRs. Although the proportion of patients achieving good anticoagulation control (PTTR ? 60%) was low in both groups, it was similar among KTRs and non-KTRs. KTRs had a higher risk of major hemorrhage (hazard ratio 2.1, p=0.0081), but this difference was not statistically significant after controlling for kidney function, clinical, and genetic factors. CONCLUSION:KTRs initiating warfarin require lower doses and closer monitoring to optimize anticoagulation therapy. Additional studies are needed to confirm these findings.
Project description:Candidates for chronic warfarin therapy often have co-morbid conditions, such as heart failure, with reduced left ventricular ejection fraction. Previous reports have demonstrated an increased risk of over-anticoagulation due to reduced warfarin dose requirement in patients with decompensated heart failure. However, the influence of left ventricular systolic dysfunction (LVSD), defined as left ventricular ejection fraction <40%, on warfarin response has not been evaluated. Here, we assess the influence of LVSD on warfarin dose, anticoagulation control (percent time in target range), and risk of over-anticoagulation (international normalized ratio >4) and major hemorrhage. Of the 1,354 patients included in this prospective cohort study, 214 patients (16%) had LVSD. Patients with LVSD required 11% lower warfarin dose compared with those without LVSD (p <0.001) using multivariate linear regression analyses. Using multivariate Cox proportional hazards model, patients with LVSD experienced similar levels of anticoagulation control (percent time in target range: 51% vs 53% p = 0.15), risk of over-anticoagulation (international normalized ratio >4; hazard ratio 1.01, 95% confidence interval 0.82 to 1.25; p = 0.91), and risk of major hemorrhage (hazard ratio 1.11; 95% confidence interval 0.70 to 1.74; p = 0.66). Addition of LVSD variable in the model increased the variability explained from 35% to 36% for warfarin dose prediction. In conclusion, our results demonstrate that patients with LVSD require lower doses of warfarin. Whether warfarin dosing algorithms incorporating LVSD in determining initial doses improves outcomes needs to be evaluated.
Project description:BACKGROUND: Patients with mental health conditions (MHCs) experience poor anticoagulation control when using warfarin, but we have limited knowledge of the association between specific mental illness and warfarin treatment outcomes. OBJECTIVE: To examine the relationship between the severity of MHCs and outcomes of anticoagulation therapy. DESIGN: Retrospective cohort analysis. PARTICIPANTS: We studied 103,897 patients on warfarin for 6 or more months cared for by the Veterans Health Administration during fiscal years 2007-2008. We identified 28,216 patients with MHCs using ICD-9 codes: anxiety disorders, bipolar disorder, depression, post-traumatic stress disorder, schizophrenia, and other psychotic disorders. MAIN MEASURES: Outcomes included anticoagulation control, as measured by percent time in the therapeutic range (TTR), as well as major hemorrhage. Predictors included different categories of MHC, Global Assessment of Functioning (GAF) scores, and psychiatric hospitalizations. KEY RESULTS: Patients with bipolar disorder, depression, and other psychotic disorders experienced TTR decreases of 2.63 %, 2.26 %, and 2.92 %, respectively (p?<?0.001), after controlling for covariates. Patients with psychotic disorders other than schizophrenia experienced increased hemorrhage after controlling for covariates [hazard ratio (HR) 1.24, p?=?0.03]. Having any MHC was associated with a slightly increased hazard for hemorrhage (HR 1.19, p?<?0.001) after controlling for covariates. CONCLUSION: Patients with specific MHCs (bipolar disorder, depression, and other psychotic disorders) experienced slightly worse anticoagulation control. Patients with any MHC had a slightly increased hazard for major hemorrhage, but the magnitude of this difference is unlikely to be clinically significant. Overall, our results suggest that appropriately selected patients with MHCs can safely receive therapy with warfarin.
Project description:Little is known about the clinical outcomes associated with posthemorrhage anticoagulation resumption for atrial fibrillation. This study had 2 objectives: first, to evaluate anticoagulation use after a first major bleed on warfarin or dabigatran and, second, to compare effectiveness and safety outcomes between patients discontinuing anticoagulation after a major bleed and patients restarting warfarin or dabigatran.Using 2010 to 2012 Medicare Part D data, we identified atrial fibrillation patients who experienced a major bleeding event while using warfarin (n=1135) or dabigatran (n=404) and categorized them by their posthemorrhage use of anticoagulation. We followed them until an ischemic stroke, recurrent hemorrhage, or death through December 31, 2012. We constructed logistic regression models to evaluate factors affecting anticoagulation resumption and Cox proportional hazard models to compare the combined risk of ischemic stroke and all-cause mortality and the risk of recurrent bleeding between treatment groups.Resumption of anticoagulation with warfarin (hazard ratio [HR] 0.76; 95% confidence interval [CI] 0.59-0.97) or dabigatran (HR 0.66; 95% CI 0.44-0.99) was associated with lower combined risk of ischemic stroke and all-cause mortality than anticoagulation discontinuation. The incidence of recurrent major bleeding was higher for patients prescribed warfarin after the event than for those prescribed dabigatran (HR 2.31; 95% CI 1.19-4.76) or whose anticoagulation ceased (HR 1.56; 95% CI 1.10-2.22), but did not differ between patients restarting dabigatran and those discontinuing anticoagulation (HR 0.65; 95% CI 0.32-1.33).Dabigatran was associated with a superior benefit/risk ratio than warfarin and anticoagulation discontinuation in the treatment of atrial fibrillation patients who have survived a major bleed.
Project description:Anticoagulation management is difficult in chronic kidney disease, with frequent supratherapeutic international normalized ratios (INRs ? 4) increasing hemorrhagic risk. We evaluated whether the interaction of INR and lower estimated glomerular filtration rate (eGFR) increases hemorrhage risk and whether patients with lower eGFRs experience slower anticoagulation reversal.Prospective cohort study.Warfarin pharmacogenetics cohort (1,273 long-term warfarin users); warfarin reversal cohort (74 warfarin users admitted with INRs ? 4).eGFR, INR as time-dependent covariate, and their interaction in the pharmacogenetics cohort; eGFR in the reversal cohort.In the pharmacogenetics cohort, hemorrhagic (serious, life-threatening, and fatal bleeding) risk was assessed using proportional hazards regression. In the reversal cohort, anticoagulation reversal was assessed from changes in INR, warfarin and metabolite concentrations, clotting factors (II, VII, IX, and X), and PIVKA-II (protein induced by vitamin K absence or antagonist II) levels at presentation and after reversal, using linear regression and path analysis.In the pharmacogenetics cohort, 454 (35.7%) had eGFRs < 60 mL/min/1.73 m(2). There were 137 hemorrhages in 119 patients over 1,802 person-years of follow-up (incidence rate, 7.6 [95% CI, 6.4-8.9]/100 person-years). Patients with lower eGFRs had a higher frequency of INR ? 4 (P<0.001). Risk of hemorrhage was affected significantly by eGFR-INR interaction. At INR<4, there was no difference in hemorrhage risk by eGFR (all P ? 0.4). At INR?4, patients with eGFRs of 30 to 44 and < 30 mL/min/1.73 m(2) had 2.2-fold (95% CI, 0.8-6.1; P=0.1) and 5.8-fold (95% CI, 2.9-11.4; P<0.001) higher hemorrhage risks, respectively, versus those with eGFRs ? 60 mL/min/1.73 m(2). In the reversal cohort, 35 (47%) had eGFRs < 45 mL/min/1.73 m(2). Patients with eGFRs < 45 mL/min/1.73 m(2) experienced slower anticoagulation reversal as assessed by INR (P=0.04) and PIVKA-II level (P=0.008) than those with eGFRs ? 45 mL/min/1.73 m(2).Limited sample size in the reversal cohort, unavailability of antibiotic use and urine albumin data.Patients with lower eGFRs have differentially higher hemorrhage risk at INR ? 4. Moreover, because the INR reversal rate is slower, hemorrhage risk is prolonged.
Project description:Although management of warfarin is challenging for patients with chronic kidney disease (CKD), no prospective studies have compared response to warfarin among patients with minimal, moderate, and severe CKD. This secondary analysis of a prospective cohort of 578 patients evaluated the influence of kidney function on warfarin dosage, anticoagulation control, and risk for hemorrhagic complications. We adjusted all multivariable regression and proportional hazard analyses for clinical and genetic factors. Patients with severe CKD (estimated GFR <30 ml/min per 1.73 kg/m2) required significantly lower warfarin dosages (P = 0.0002), spent less time with their international normalized ratio within the target range (P = 0.049), and were at a higher risk for overanticoagulation (international normalized ratio >4; P = 0.052), compared with patients with no, mild, or moderate CKD. Patients with severe CKD had a risk for major hemorrhage more than double that of patients with lesser degrees of renal dysfunction (hazard ratio 2.4, 95% confidence interval 1.1 to 5.3). In conclusion, patients with reduced kidney function require lower dosages of warfarin, have poorer control of anticoagulation, and are at a higher risk for major hemorrhage. These observations suggest that warfarin may need to be initiated at a lower dosage and monitored more closely in patients with moderate or severe CKD compared with the general population. Diminished renal function may have implications for a larger proportion of warfarin users than previously estimated.
Project description:OBJECTIVE:We evaluated whether percent time in target range (PTTR), risk of over-anticoagulation [international normalized ratio (INR)>4], and risk of hemorrhage differ by race. As PTTR is a strong predictor of hemorrhage risk, we also determined the influence of PTTR on the risk of hemorrhage by race. PARTICIPANTS AND METHODS:Among 1326 warfarin users, PTTR was calculated as the percentage of interpolated INR values within the target range of 2.0-3.0. PTTR was also categorized as poor (PTTR<60%), good (60?PTTR<70%), or excellent (PTTR?70%) anticoagulation control. Over-anticoagulation was defined as INR more than 4 and major hemorrhages included serious, life-threatening, and fatal bleeding episodes. Logistic regression and survival analyses were carried out to evaluate the association of race with PTTR (?60 vs. <60) and major hemorrhages, respectively. RESULTS:Compared with African Americans, European Americans had higher PTTR (57.6 vs. 49.1%; P<0.0001) and were more likely to attain 60?PTTR<70% (22.9 vs. 13.1%; P<0.001) or PTTR of at least 70% (26.9 vs. 18.2%; P=0.001). Older (>65 years) patients without venous thromboembolism indication and chronic kidney disease were more likely to attain PTTR of at least 60%. After accounting for clinical and genetic factors, and PTTR, African Americans had a higher risk of hemorrhage [hazard ratio (HR)=1.58; 95% confidence interval (CI): 1.04-2.41; P=0.034]. Patients with 60?PTTR<70% (HR=0.62; 95% CI: 0.38-1.02; P=0.058) and PTTR of at least 70% (HR=0.27; 95% CI: 0.15-0.49; P<0.001) had a lower risk of hemorrhage compared with those with PTTR less than 60%. CONCLUSION:Despite the provision of warfarin management through anticoagulation clinics, African Americans achieve a lower overall PTTR and have a significantly higher risk of hemorrhage. Personalized medicine interventions tailored to African American warfarin users need to be developed.
Project description:Oral anticoagulation therapy prevents stroke and improves survival in patients with atrial fibrillation, but the therapy is underutilized. We sought to identify the prevalence of contraindications for oral anticoagulation and the proportion of patients potentially eligible for different agents.We identified patients with nonacute atrial fibrillation in a nationally representative 5% sample of 2009 Medicare data. We divided the population into patients ineligible for any oral anticoagulant, patients eligible for warfarin only, and patients eligible for any anticoagulant. We compared patient characteristics and the use of anticoagulation among the subgroups.Among 86,671 patients with atrial fibrillation, 1872 (2.2%) were ineligible for anticoagulation because of an absolute contraindication, most frequently a history of intracranial hemorrhage (60%). Patients ineligible for any anticoagulant were the same age as the overall group (mean age, 80.5 vs. 80.4 years). However, they had higher rates of dementia (19% vs. 8.6%) and heart failure (59% vs. 43%) and higher mean CHADS2 scores (3.8 vs. 2.8). Of the remaining 84,799 patients eligible for anticoagulation, 7146 (8.4%) were eligible for warfarin only (most commonly because of mechanical heart valves [66%] and end-stage renal disease [12%]). Sixty-five percent of patients eligible for anticoagulation received warfarin, and the proportion was similar for patients with a relatively high risk of bleeding.Older adults with atrial fibrillation rarely have absolute contraindications to oral anticoagulation therapy. Among patients without contraindications, most appeared to be eligible for any anticoagulant, and relatively high-risk features appeared not to influence warfarin use.
Project description:Bridging anticoagulation is commonly prescribed to patients with atrial fibrillation who are initiating warfarin or require interruption of anticoagulation. Current guidelines recommend bridging for patients at high risk of stroke. Among patients with atrial fibrillation and one or more risk factors for ischemic stroke, the recently published BRIDGE trial found forgoing bridging during interruption to be, on average, noninferior to bridging with respect to ischemic complications, with significantly fewer hemorrhagic complications.We sought to examine the benefits and harms of bridging anticoagulation across the spectrum of ischemic and hemorrhagic stroke risk and thereby enable more nuanced, risk-stratified decision-making when bridging is considered during initiation or interruption of vitamin K antagonists.A Monte Carlo simulation, using a combination of literature-derived estimates, registry data, and trial data.Net clinical benefit, weighting for ischemic strokes, intracranial hemorrhages, and extracranial major hemorrhages.The benefits and harms of bridging anticoagulation vary according to underlying patient risk profiles for both thromboembolic stroke and major intracranial bleeding. Patients at high risk of ischemic stroke and low risk of hemorrhage derive benefit from bridging during initiation or interruption of warfarin therapy. Patients at similarly high or low risk of both outcomes may receive benefit from bridging during initiation and bridging during interruption, but this was sensitive to underlying assumptions. The need for stratification along both axes of risk was robust to a wide range of parameters.Bridging anticoagulation may provide benefit to patients at high risk of ischemic stroke and low risk of intracranial hemorrhage who are initiating or interrupting warfarin therapy, while patients at high or low risk of both complications may be harmed. The use of bridging anticoagulation in patients with non-valvular atrial fibrillation should be considered only after stratification by risk of ischemic and hemorrhagic complications.