Association of Obesity and Cardiovascular Outcomes in Patients With Atrial Fibrillation : a Korean Nationwide Cohort Study

This retrospective nationwide cohort study used administrative claims data from the Korean National Health Insurance Service (NHIS) and the combined health check-up database of the National Health Insurance Corporation between 2013 and 2020.

The investigators included oral anticoagulant (OAC) new users diagnosed with atrial fibrillation (AF) between January 2015 and December 2020. Patients aged <20 years, those who were regarded as valvular AF patients (patients with mitral stenosis or prosthetic heart valve), those with possible alternative indications for OAC (pulmonary embolism, deep vein thrombosis, or recent joint replacement surgery), and those with cancer were excluded from the analysis.

The follow-up period was defined as the time from the index date (date of OAC prescription) to each outcome event, date of death, or end of the study period (December 31, 2020), whichever came first.

Patients' demographic data, comorbidities, concomitant medications, and income level were collected from the Korean NHIS database. The recent health check-up data from the index date was also ascertained, including height, weight, waist circumference, blood pressure, health surveys, and laboratory exam. Health survey included family history, smoking history, alcohol history, and the level of individual physical activity. The investigators defined the proportion of medical use by calculating formula with the recuperation cost and the number of the visit to hospitals.

According to BMI following the World Health Organization recommendation for Asian population, study patients were categorized into 5 groups: underweight, <18.5 kg/m2; normal range, 18.5 to <23 kg/m2; overweight, 23 to <25 kg/m2; obese I, 25 to <30 kg/m2; and obese II, ≥30 kg/m2[4].