Evaluating the role of clinical pharmacists in pre-procedural anticoagulation management

OBJECTIVES

While physicians are typically responsible for managing perioperative warfarin, clinic pharmacists may improve pre-procedural decision-making. We assessed the impact of pharmacist-driven care for chronic warfarin-treated patients undergoing outpatient right heart catheterization (RHC).

METHODS

200 warfarin patients who underwent RHC between January 2012 and September 2015 were analyzed. Pharmacist-care (n = 79) was compared to the usual care model (n = 121). The primary outcome was a composite of (1) documentation of anticoagulation plan, (2) holding warfarin at least 5 days prior to procedure, (3) guideline-congruent low molecular weight heparin (LMWH) bridging, and (4) correct LMWH dosing if bridging deemed necessary. Chi-squared test performed to assess the role of pharmacist. A multivariable logistic regression analysis was performed to the composite endpoint, adjusted for the month of procedure.

RESULTS

Compared to the usual care model, pharmacist-driven care (OR 4.69, 95% CI 1.73-12.71, p = 0.002) and date of the procedure (OR 1.06/month, 95% CI 1.01-1.10, p = 0.011) were independently associated with the primary composite outcome. Of the individual outcome components, pharmacist-driven care was only associated with documentation (96.2% vs. 67.8%, OR 9.19, 95% CI 2.19-38.62, p = 0.002). Remaining components including hold warfarin for at least 5 days, appropriate bridging and correct LMWH dosing were not significantly associated with pharmacist-care.

CONCLUSIONS

Pharmacist-care is associated with better guideline-based anticoagulation management, but this was primarily driven by improved documentation. The impact of pharmacist managed peri-procedural anticoagulation on clinical outcomes remains unknown.

Intravenous heparin dosing strategy in hospitalized patients with atrial dysrhythmias

Patients with non-valvular atrial fibrillation (AF) have an elevated stroke risk that is 2-7 times greater than in those without AF. Intravenous unfractionated heparin (UFH) is commonly used for hospitalized patients with atrial fibrillation and atrial flutter (AFL) to prevent stroke. Dosing strategies exist for intravenous anticoagulation in patients with acute coronary syndromes and venous thromboembolic diseases, but there are no data to guide providers on a dosing strategy for intravenous anticoagulation in patients with AF/AFL. 996 hospitalized patients with AF/AFL on UFH were evaluated. Bolus dosing and initial infusion rates of UFH were recorded along with rates of stroke, thromboemobolic events, and bleeding events as defined by the International Society on Thrombosis and Haemostasis criteria. Among 226 patients included in the analysis, 76 bleeding events occurred. Using linear regression analysis, initial rates of heparin infusion ranging from 9.7 to 11.8 units/kilogram/hour (U/kg/h) resulted in activated partial thromboplastin times that were within therapeutic range. The median initial infusion rate in patients with bleeding was 13.3 U/kg/h, while in those without bleeding it was 11.4 U/kg/h; p = 0.012. An initial infusion rate >11.0 U/kg/h yielded an OR 1.95 (1.06-3.59); p = 0.03 for any bleeding event. Using IV heparin boluses neither increased the probability of attaining a therapeutic aPTT (56.1 vs 56.3 %; p = 0.99) nor did it significantly increase bleeding events in the study (35.7 vs 31.3 %; p = 0.48). The results suggest that higher initial rates of heparin are associated with increased bleeding risk. From this dataset, initial heparin infusion rates of 9.7-11.0 U/kg/h without a bolus can result in therapeutic levels of anticoagulation in hospitalized patients with AF/AFL without increasing the risk of bleeding.