Association Between Nonvitamin K Antagonist Oral Anticoagulants or Warfarin and Liver Injury: A Cohort Study.

INTRODUCTION: The risk of liver injury in patients with atrial fibrillation (AF) using nonvitamin K antagonist oral anticoagulants (NOACs) has not been previously examined using liver function tests as the primary outcome in the real-world setting. This study assessed the association between NOACs (dabigatran, rivaroxaban, and apixaban) and warfarin and the risk of liver injury, as defined by laboratory tests. METHODS: Patients newly diagnosed with AF and prescribed NOACs or warfarin between 2010 and 2016, identified using the Hong Kong Clinical Database and Reporting System, were matched on age, sex, health status scores, comorbidities, and medications by propensity score on a 1:1 ratio. Risk of liver injury, defined as laboratory test values >3 times the upper limit of normal of alanine aminotransferase or aspartate aminotransferase and >2 times the upper limit of normal of total bilirubin, was compared between NOAC and warfarin users using Cox proportional hazards regression. RESULTS: After propensity score matching, 13,698 patients were included, of which 141 (2.1%) NOAC users and 232 (3.4%) warfarin users developed liver injury. The hazard ratio (HR) for NOAC vs warfarin users was 0.71 (95% confidence interval: 0.58-0.89). When comparing individual NOACs, only dabigatran (hazard ratio: 0.63; 95% confidence interval: 0.48-0.82) was associated with a lower risk of liver injury. DISCUSSION: Among patients with AF, NOACs as a group, and dabigatran alone were associated with a significantly lower risk of laboratory-based liver injury when compared with warfarin. However, liver injury occurs more frequently in real-world practice than in NOAC randomized controlled trials.

Prevention of Dabigatran-Related Gastrointestinal Bleeding With Gastroprotective Agents: A Population-Based Study.

BACKGROUND & AIMS: Use of dabigatran, an inhibitor of thrombin, increases the risk of gastrointestinal bleeding (GIB). However, it is not clear whether gastroprotective agents (GPAs) prevent GIB in dabigatran users. We investigated the risk of GIB and the role of gastroprotective agents (including proton pump inhibitors and histamine type-2-receptor antagonists) in patients using dabigatran. METHODS: We performed a retrospective cohort study using a population-wide database managed by the Hong Kong Hospital Authority. Patients newly prescribed dabigatran from 2010 through 2013 were included in the analysis. Poisson regression was used to assess the risk of GIB in dabigatran users by incidence rate ratio (IRR), adjusted for patient characteristics, comorbidities, and concurrent medications. RESULTS: Among the 5041 patients newly prescribed dabigatran, 124 (2.5%) developed GIB during follow-up evaluation (4.2/100 patient-years). The risk of GIB in this population increased among patients 75 years and older (IRR, 2.47; 95% confidence interval [CI], 1.66-3.68), patients with a history of peptic ulcers or GIB (IRR, 2.31; 95% CI, 1.54-3.46), and patients who used aspirin (IRR, 1.52; 95% CI, 1.03-2.24). Concomitant use of gastroprotective agents was associated with a reduced risk of GIB (IRR, 0.52; 95% CI, 0.35-0.77). Subcategory analysis showed that use of proton pump inhibitors (IRR, 0.53; 95% CI, 0.31-0.91) or histamine type-2-receptor antagonists (IRR, 0.61; 95% CI, 0.40-0.94) were associated with a lower risk of GIB. Further analysis showed that the risk reduction by gastroprotective agents was significant for only upper GIB (IRR, 0.29; 95% CI, 0.15-0.54), and only for patients with a prior history of peptic ulcers or GIB (IRR, 0.14; 95% CI, 0.06-0.30). CONCLUSIONS: In the Hong Kong population, use of gastroprotective agents was associated with a reduced risk of GIB in patients taking dabigatran. The association was stronger for upper GIB than lower GIB, and in patients with a prior history of peptic ulcers or GIB.

Thromboembolic, bleeding, and mortality risks among patients with nonvalvular atrial fibrillation treated with dual antiplatelet therapy versus oral anticoagulants: A population-based study.

BACKGROUND: Dual antiplatelet therapy (DAPT) with aspirin plus clopidogrel is used for stroke prevention in patients with atrial fibrillation (AF) who refuse to take use oral anticoagulants (OACs). However, clinical data comparing these treatments are limited. OBJECTIVE: The purpose of this study was to compare the clinical outcomes between DAPT and OAC in patients with AF. METHODS: A cohort study using a population-wide database of the Hong Kong Hospital Authority was performed. New patients with AF from 2010-2014 who were prescribed DAPT or OAC (warfarin or dabigatran) were followed until July 31, 2016. Outcomes were thromboembolism, bleeding, and death. Propensity score (PS) matching at a ratio of 1:2 was used to select DAPT users with characteristics similar to those of OAC users, analyzed using Poisson regression. RESULTS: Among 51,946 new patients with AF, 8520 users of OAC and DAPT were identified. The likelihood of receiving DAPT over OAC increased with older age and previous intracranial hemorrhage. Among DAPT users, the incidences of thromboembolism, death, and bleeding per 100 patient-years were 15.8, 17.6, and 5.1, respectively. Compared to DAPT users, PS-matched analysis indicated a lower incidence of thromboembolism and/or death among OAC users (dabigatran: incidence rate ratio [IRR] 0.32; 95% confidence interval [CI] 0.19-0.55; warfarin: IRR 0.58; 95% CI 0.36-0.95), with no significant differences in bleeding events. CONCLUSION: DAPT users were at markedly increased risk for thromboembolism and death compared to OAC users. These findings indicate the need for improved stroke risk reduction strategies among patients taking DAPT and the opportunities for using OAC in high-risk groups to prevent additional events.

Trends in statin prescription prevalence, initiation, and dosing: Hong Kong, 2004-2015.

BACKGROUND AND AIMS: Clinical practice guidelines recommend specific statin doses for the primary and secondary prevention of cardiovascular disease. Little is known about how statin utilization and dosing have evolved over time in Hong Kong. The aim of this study was to describe trends in statin prevalence, initiation, and dosing from 2004 to 2015. METHODS: Patients receiving public health services, who were prescribed a statin, were included if they received a lipid test at a single center (n = 58,672). Using the territory-wide electronic health record, prescribed daily statin dose, nondaily dose frequency, and statin dose intensity were determined for statin prescriptions from 2004 to 2015. Statin prescription prevalence and initiation rates were estimated using the appropriate at-risk population in the hospital catchment area as the denominator. Prescribed daily doses were stratified by primary or secondary cardiovascular prevention status to assess changes in statin dosing over time. RESULTS: The prescription prevalence of statins was higher in 2015 (8.68%; 95% CI, 8.60%-8.75%) as compared with 2004 (1.82%; 95% confidence interval [CI], 1.78%-1.86%). Initiation rates for new statin users increased from 2004 to 2013. High-intensity statins were infrequently prescribed. New users generally had higher statin initiation rates for primary prevention. There were small increases in the prescribed daily doses of statins. Nondaily statin dosing was infrequent (0.42% of all prescriptions). CONCLUSIONS: The prevalence and initiation of statin prescriptions increased in Hong Kong, and was in part driven by low-intensity statins for the primary prevention of cardiovascular disease.

Sex-Based Differences in Outcomes of Oral Anticoagulation in Patients With Atrial Fibrillation.

BACKGROUND: Women with atrial fibrillation are at a higher risk of stroke, despite treatment with warfarin. It is unclear if women treated with direct oral anticoagulants (DOACs) have better clinical outcomes, especially when considering the quality of anticoagulation control of warfarin. OBJECTIVES: This study compared the effectiveness and safety outcomes of DOACs versus warfarin in men and women with stratifications for anticoagulation control. METHODS: Patients newly diagnosed with atrial fibrillation and prescribed oral anticoagulants during 2010 to 2015 were identified using the Hong Kong clinical database. Propensity score matching was performed in men and women separately. Further analysis was conducted to stratify warfarin users according to their anticoagulation control. Cox regression was used to compare the risk of ischemic stroke or systemic embolism, intracranial hemorrhage (ICH), gastrointestinal bleeding, and all-cause mortality in the specific sex. RESULTS: There were 4,972 men and 4,834 women successfully matched in our cohort. Compared with warfarin, DOAC use was associated with a lower risk of ICH (hazard ratio [HR]: 0.16; 95% confidence interval [CI]: 0.06 to 0.40) and all-cause mortality (HR: 0.55; 95% CI: 0.39 to 0.77) in women but not in men. The treatment by sex interaction was significant for ICH only, and a significantly lower risk of ICH remained in the DOAC group when compared with warfarin users with good anticoagulation control (HR: 0.13; 95% CI: 0.02 to 1.00) among women only. The risks of ischemic stroke or systemic embolism and gastrointestinal bleeding with DOACs versus warfarin were comparable in both sexes. CONCLUSIONS: DOACs were associated with a lower risk of ICH and all-cause mortality in women only, where the association of lower ICH risk remained when compared with warfarin users with good anticoagulation control.