Observed Apixaban Anti-Xa Levels in Obese Patients.

BACKGROUND: Recent guidelines suggest that, for venous thromboembolism (VTE), standard doses of apixaban are appropriate in patients with body mass index (BMI) >40 kg/m2 or >120 kg. Atrial fibrillation (AF) is excluded from this recommendation. OBJECTIVE: The goals of our study were to measure and describe anti-Xa levels of patients with a BMI ≥40 kg/m2 and/or a weight ≥120 kg with a clinical indication of AF or VTE who were treated with apixaban, and to determine whether BMI or weight are associated with anti-Xa levels in this population. METHODS: We conducted an observational cohort study at a single health care system in Oregon, USA. Patients meeting enrollment criteria were recruited and had peak and trough apixaban anti-Xa levels drawn. RESULTS: Of 55 patients enrolled, 5 (9%) had peak anti-Xa levels below the reference range and 3 (6%) had trough anti-Xa levels below the reference range. BMI did not significantly correlate with peak or trough anti-Xa levels (r = -0.10, p = 0.45 and r = -0.14, p = 0.31). Weight had a moderate, negative correlation with peak anti-Xa levels (r = -0.42, p = 0.002) and a weak, negative correlation with trough anti-Xa levels (r = -0.32, p = 0.02). CONCLUSIONS AND RELEVANCE: This study provides evidence that anti-Xa levels among obese patients are not substantially different from patients with nomral BMI and weight. This supports recent ISTH guidance for standard dosing of apixaban for VTE patients with BMI >40 kg/m2 or weight >120 kg and provides additional evidence that the standard dosing may also be appropriate in patients with AF.

A retrospective analysis of bleeding risk with rivaroxaban, enoxaparin, and aspirin following total joint arthroplasty or revision.

STUDY OBJECTIVE: Rivaroxaban, enoxaparin, and aspirin are commonly used medications for thromboprophylaxis following lower extremity joint arthroplasty or revision. Previous research has demonstrated efficacy in preventing venous thromboembolism with each medication, however, the comparative risk of bleeding between them remains poorly understood. The aim of this study was to compare the odds of bleeding between rivaroxaban, enoxaparin, and aspirin following lower extremity joint arthroplasty or revision. DESIGN: This is a 3-year retrospective cohort study. SETTING: Data were obtained from 148 facilities across 55 states and territories of the United States. PATIENTS: This study included 85,938 patients who underwent hip or knee arthroplasty or revision. INTERVENTION: Patients received enoxaparin, rivaroxaban, or aspirin as monotherapy for thromboprophylaxis. MEASUREMENTS: The primary outcome was all bleeding, classified as major or minor bleeding, occurring in the 40 days following surgery. The secondary outcome was venous thromboembolism. MAIN RESULTS: Among 85,938 patients, 10,465 received rivaroxaban, 14,047 received enoxaparin, and 61,426 received aspirin. Bleeding occurred in 126 (1.20%) patients with rivaroxaban, 253 (1.80%) with enoxaparin, and 611 (0.99%) with aspirin. There was a significant increase in odds of bleeding in the enoxaparin compared to aspirin group odds ratio (OR) 1.18, 95% confidence interval (CI) 1.01-1.38, p = 0.042), and a trend toward increased odds of bleeding in rivaroxaban compared to aspirin group (OR 1.21, 95% CI 0.99-1.47, p = 0.058) and rivaroxaban compared to enoxaparin (OR 1.03, 95% CI 0.82-1.28, p = 0.827). Odds of venous thromboembolism were not statistically significant between all three study medications. CONCLUSIONS: Among rivaroxaban, enoxaparin, and aspirin used for thromboprophylaxis in knee and hip arthroplasty or revision, aspirin had significantly decreased odds of bleeding complications compared to enoxaparin. Although not statistically significant, aspirin also had a trend toward decreased odds of bleeding complications compared to rivaroxaban. Our study results suggest that aspirin is a safer alternative for use in postoperative thromboprophylaxis following lower extremity joint arthroplasty or revision.

A Retrospective Analysis Comparing Post-Operative Bleeding with Various Doses of Aspirin after Lower Extremity Joint Arthroplasty or Revision.

STUDY OBJECTIVE: Previous studies have shown that aspirin is noninferior to other anticoagulation therapies in preventing postoperative venous thromboembolism following lower extremity arthroplasty or revision; however, its optimal dosing for this indication is less clear. This study aims to compare the odds of bleeding between different aspirin dosages following lower extremity joint arthroplasty or revision. DESIGN: This is a 3-year retrospective multi-center cohort study across the United States and its territories. SETTING: This study included patients admitted for total hip or knee arthroplasty or revision and were treated with prophylactic aspirin. PATIENTS, INTERVENTION, MEASUREMENTS: Patients were assigned to groups based on a total daily aspirin dose of 81, 162, 325, or 650 mg. Data were analyzed for postsurgical bleeding and thromboembolism events occurring during the initial admission and up to 40 days following surgery. Other exploratory variables included type of surgery, hip or knee arthroplasty, length of stay, and patient demographic data. MAIN RESULTS: Among 53,848 patients receiving aspirin, 3922 received a total daily dose of 81 mg, 19,341 received a total daily dose of 162 mg, 5256 received a total daily dose of 325 mg, and 25,329 received a total daily dose of 650 mg. Bleeding occurred in 466 (0.87%) patients and venous thromboembolism (VTE) in 209 patients (0.39%). The odds of bleeding were compared using logistic regression, with the 650-mg dose as the reference group. None were statistically significant for bleeding between all studied aspirin doses: 81 mg (OR 1.12, 95% CI 0.83-1.51, p = 0.451), 162 mg (OR 0.83, 95% CI 0.67-1.03, p = 0.097), and 325 mg (OR 0.83, 95% CI 0.59-1.13, p = 0.245). The odds of VTE were also not statistically significant: 81 mg (OR 0.71, 95% CI 0.40-1.17, p = 0.181), 162 mg (OR 0.75 95% CI 0.54-1.03, p = 0.072), and 325 mg (OR 1.00, 95% CI 0.64-1.53, p = 0.989). CONCLUSIONS: There were no significant differences in the odds of bleeding or venous thromboembolism among all studied aspirin dosages in patients receiving aspirin for thromboprophylaxis following lower extremity joint arthroplasty or revision.

Correcting Hypokalemia in Hospitalized Patients Does Not Decrease Risk of Cardiac Arrhythmias.

BACKGROUND: It is currently standard practice to correct hypokalemia for the purpose of preventing cardiac arrhythmias in all hospitalized patients. However, the efficacy of this intervention has never been previously studied. OBJECTIVE: The objective of our study was to evaluate whether patients without acute coronary syndrome or history of arrhythmias were at increased risk of clinically significant cardiac arrhythmias if their potassium level was not corrected to ≥3.5 mEq/L. DESIGN: A retrospective case control study. SETTING: A community hospital. PARTICIPANTS: We enrolled selected patients who had episodes of hypokalemia during their hospital stay and were monitored on telemetry. Patients were split into groups based on success of replacing serum potassium to ≥3.5 mEq/L after 24 hours. MEASUREMENTS: The primary outcome was the development of an arrhythmia. Arrhythmias included supraventricular tachycardia, atrial fibrillation, atrial flutter, Mobitz type II second-degree or third-degree AV block, ventricular tachycardia, or ventricular fibrillation. A one-tailed Fisher's exact test and logistic regression were used for analysis. RESULTS: A total of 1338 hypokalemic patient days were recorded. Out of these days, 22 arrhythmia events (1.6% of patient days) were observed, 8 in the uncorrected group (1% patient days) and 14 in the corrected group (2.6% patient days). We found no statistically significant relationship between successfully correcting potassium to ≥3.5 mEq/L and number of arrhythmic events (p=0.037, OR = 2.38 (95% CI: 0.99, 6.03)). Logistic regression revealed that correction of potassium does not seem to be significantly related to arrhythmias (ß = 0.869, p=0.0517). CONCLUSIONS: In the acute care setting, we found that patients with hypokalemia whose potassium level did not correct to ≥3.5 mEq/L were not at increased odds of having an arrhythmia. This study suggests that the common practice of checking and replacing potassium is likely inconsequential.