Sukumar S, Gulilat M, Linton B, et al. – In this study involving stable adults aged > 65 years with nonvalvular atrial fibrillation (NVAF) receiving apixaban on a chronic basis, researchers investigated how plasma apixaban levels during the clinical care of these people were affected by lower than recommended doses of direct-acting oral anticoagulants. This study included 110 participants (mean age: 80.4 years; 45% women) with NVAF, 48 of whom received recommended dosing of 5 mg twice/day and 42 of whom received lower than recommended dosing. Patients receiving 2.5 mg twice/day, as suggested, were 20 in total. Apixaban levels higher than expected peak levels were detected in one-third vs clinical trials, and levels above the reported median for peak concentrations were detected in more than two-thirds. Apixaban levels in older adults with NVAF seen clinically were higher than anticipated based on clinical trial data, raising questions about the optimal dosing of apixaban in older adults with NVAF encountered outside of clinical trials. According to the researchers, these findings indicate a role for the monitoring of apixaban levels during care of patients that differ from those in randomized trials or when considering dosing outside of published guidelines.