Study population
This multicenter, prospective, observational study in NVAF patients treated with rivaroxaban or apixaban was carried out in the National Heart Center Singapore and Khoo Teck Puat Hospital, and approved by the Domain Specific Review Board (Study reference number: 2017/00815). Patients were recruited between 5 October 2017 and 6 February 2020. After providing their signed informed consent, NVAF patients who were at least 21 years of age and on rivaroxaban or apixaban for at least 3 continuous days were included in the study. Pregnant or breastfeeding women or women who had given birth in the past 90 days and patients enrolled in another drug or device study were excluded. A total of 106 rivaroxaban and 40 apixaban patients were recruited. The choice and dose of DOAC prescription was based on their physician’s discretion.
Baseline characteristics including gender, ethnicity, age, height, weight, smoking history, alcohol consumption, serum creatinine, co-morbidities and concomitant medications were recorded. Body mass index (BMI) and CHA2DS2-VASc scores were computed based on the collected records. Creatinine clearance (CrCl) was estimated via the Cockcroft-Gault equation [19]. Patients were followed up by phone at week 2, months 1, 3, 6 and 12. At each check-point, patients were interviewed on compliance and clotting or bleeding events.