Nonalcoholic fatty liver disease impacts the control of the international normalized ratio in patients with atrial fibrillation

BACKGROUND: It is unclear whether the therapeutic effect of warfarin in patients with atrial fibrillation (AF) and normal liver function differs between those with and without nonalcoholic fatty liver disease (NAFLD). With this in mind, we aimed to evaluate the impact of NAFLD on the international normalized ratio (INR) control in warfarin-treated AF patients with normal liver function. METHODS: We enrolled 600 AF patients aged 28–94 (median 68) with normal liver function who were receiving daily warfarin therapy, 172 with NAFLD and 428 without. The INR and INR/warfarin dosage rate were measured. Four nested multivariable linear regression models adjusted for potential confounders were used to assess whether there were differences in INR and INR/warfarin dose rate between patients with and without NAFLD. RESULTS: The INR, the percentage of patients with INR within the target range of 2.0–3.0, and the INR/warfarin dose rate were lower in patients with NAFLD than those without. In the maximally adjusted multivariable linear regression models, the INR in NAFLD patients (0.22±0.07, P=0.003) was lower than in non-NAFLD patients, and the INR/warfarin dose rate was slightly lower (0.09±0.06, P=0.10) in NAFLD than in non-NAFLD patients. CONCLUSIONS: Our findings suggest that among AF patients, the therapeutic effect of warfarin is impaired in patients who have NAFLD. Therefore, a slightly higher or personally optimized dosage of warfarin might be necessary among AF patients with NAFLD in order to achieve the INR target range.