Standard-of-care versus pharmacist-supported interventions to improve anticoagulation control in Namibia

A prior assessment of warfarin management for outpatients at Windhoek Central Hospital (WCH) reported median Time in Therapeutic Range (TTR) to be under 25% in 2018. This falls well below the target of 65%, requiring intervention to enhance the quality of care. To enhance anticoagulation control at the WCH anticoagulation clinic by introducing pharmacist-involved interventions and comparing outcomes with the historical control group. All patients presenting at the warfarin outpatient clinic were invited to participate for the intervention. The intervention included a pharmacist, an improved data collection tool, and a dosage adjustment tool. Patients were followed for seven months. The main outcome measure was TTR computed using the Rosendaal method. A between-group (historical control group vs. intervention group) comparison of the quality of anticoagulation control was based on paired and unpaired patient cases. Binary logistic regression was used to identify predictors of good-quality of anticoagulation control. The intervention recruited 115 patients between Jan-July 2021; 21 (18%) were able to be matched to the historic control. TTR for those in the intervention was 42% (IQR: 18–64%). For unpaired cases, median iTTR in the intervention group was 42%, equating to an increase of 18% from the historical baseline. For paired cases, TTR increased from 29 to 40%. INR at their first clinic visit (OR 0.34 95%CI: 0.13–0.86) and warfarin dosage concordance (OR 0.17 95%CI: 0.04–0.84) were identified as predictors of good anticoagulation control in the intervention group. Pharmacist-directed interventions enhanced anticoagulation control in this setting, with baseline INR and warfarin dosage concordance playing crucial roles.