BACKGROUND: Substitution of generic warfarin for imprint warfarin (Coumadin; DuPont/Bristol-Myers Squibb) has been a controversial issue due to bioavailability and bioequivalence concerns. OBJECTIVE: To assess the risk of thrombotic and hemorrhagic events following substitution of warfarin formulations in patients with atrial fibrillation (AF). METHODS: Historical cohort analysis was performed using a commercial insurance claims database. Adults with a diagnosis of AF between January 2003 and December 2007, with 16 or more months of continuous eligibility, a warfarin prescription within 30 days after index AF diagnosis, and at least 3 warfarin prescription fills during the follow-up period were included. Individuals with AF diagnosis or warfarin prescription during the pre-index period were excluded. Cox proportional hazard regression models controlling for sex and baseline comorbidities (Charlson comorbidity index, CCI) were used to evaluate the risks of thrombotic and hemorrhagic events following warfarin formulation switches. RESULTS: Of 37,756 subjects included in the analysis (mean age 70.96 years, 42.3% females), 12,996 (34.4%) switched warfarin formulations, 20,292 (53.7%) used only 1 generic product, and 4468 (11.8%) used only Coumadin during follow-up. Compared with continued use of Coumadin, switching from that product to the generic formulation was associated with a significantly higher risk of thrombotic events (HR = 1.81; 95% CI 1.42 to 2.31). Similar findings were observed for switching from generic warfarin to Coumadin (HR = 1.76; 95% CI 1.35 to 2.30), and from 1 generic to another generic product (HR = 1.89; 95% CI 1.57 to 2.29). Similarly, switching from Coumadin to generic warfarin (HR = 1.51; 95% CI 1.17 to 1.93), generic warfarin to Coumadin (HR = 1.60; 95% CI 1.23 to 2.1), and from 1 generic to another generic product (HR = 1.74; 95% CI 1.45 to 2.11) were associated with significantly higher risk of hemorrhage than remaining on Coumadin. CONCLUSIONS: Switching warfarin formulations exposed patients with AF to a higher risk of bleeding events compared to remaining on a single product. Maintaining patients on a product with consistent bioavailability may optimize the risk-benefit balance of anticoagulation therapy.
BACKGROUND: Substitution of generic warfarin for imprint warfarin (Coumadin; DuPont/Bristol-Myers Squibb) has been a controversial issue due to bioavailability and bioequivalence concerns. OBJECTIVE: To assess the risk of thrombotic and hemorrhagic events following substitution of warfarin formulations in patients with atrial fibrillation (AF). METHODS: Historical cohort analysis was performed using a commercial insurance claims database. Adults with a diagnosis of AF between January 2003 and December 2007, with 16 or more months of continuous eligibility, a warfarin prescription within 30 days after index AF diagnosis, and at least 3 warfarin prescription fills during the follow-up period were included. Individuals with AF diagnosis or warfarin prescription during the pre-index period were excluded. Cox proportional hazard regression models controlling for sex and baseline comorbidities (Charlson comorbidity index, CCI) were used to evaluate the risks of thrombotic and hemorrhagic events following warfarin formulation switches. RESULTS: Of 37,756 subjects included in the analysis (mean age 70.96 years, 42.3% females), 12,996 (34.4%) switched warfarin formulations, 20,292 (53.7%) used only 1 generic product, and 4468 (11.8%) used only Coumadin during follow-up. Compared with continued use of Coumadin, switching from that product to the generic formulation was associated with a significantly higher risk of thrombotic events (HR = 1.81; 95% CI 1.42 to 2.31). Similar findings were observed for switching from generic warfarin to Coumadin (HR = 1.76; 95% CI 1.35 to 2.30), and from 1 generic to another generic product (HR = 1.89; 95% CI 1.57 to 2.29). Similarly, switching from Coumadin to generic warfarin (HR = 1.51; 95% CI 1.17 to 1.93), generic warfarin to Coumadin (HR = 1.60; 95% CI 1.23 to 2.1), and from 1 generic to another generic product (HR = 1.74; 95% CI 1.45 to 2.11) were associated with significantly higher risk of hemorrhage than remaining on Coumadin. CONCLUSIONS: Switching warfarin formulations exposed patients with AF to a higher risk of bleeding events compared to remaining on a single product. Maintaining patients on a product with consistent bioavailability may optimize the risk-benefit balance of anticoagulation therapy.
Authors: Gregory J Stoddard; Melissa Archer; Laura Shane-McWhorter; Bruce E Bray; Doug F Redd; Joshua Proulx; Qing Zeng-Treitler Journal: AMIA Annu Symp Proc Date: 2015-11-05
Authors: H Gothe; I Schall; K Saverno; M Mitrovic; A Luzak; D Brixner; U Siebert Journal: Appl Health Econ Health Policy Date: 2015-08 Impact factor: 2.561
Authors: Luca Degli Esposti; Diego Sangiorgi; Stefano Buda; Ezio Degli Esposti; Francesco Scaglione Journal: BMJ Open Date: 2016-11-02 Impact factor: 2.692
Authors: Abdulla Shehab; Asim Ahmed Elnour; Akshaya Srikanth Bhagavathula; Pınar Erkekoglu; Farah Hamad; Saif Al Nuaimi; Ali Al Shamsi; Iman Mukhtar; AbdElrazek M Ali AbdElrazek; Aeshal Al Suwaidi; Mahmoud Abu Mandil; Mohamed Baraka; Adel Sadik; Khalid Saraan; Naama M S Al Kalbani; Alaa AbdulAziz Mahmood; Yazan Barqawi; Mohammed Al Hajjar; Omer Abdulla Shehab; Abdulla Al Amoodi; Sahar Asim; Rauda Abdulla; Cristina Sanches Giraud; El Mutasim Ahmed; Zohdi Abu Shaaban; Ahmed Eltayeb Yousif Ahmed Eltayeb Journal: J Saudi Heart Assoc Date: 2015-05-19