Description

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 patients who underwent implantable cardioverter-defibrillator (ICD) insertion between January 2015 and December 2020. Patients aged <20 years, those who were already taken ICD insertion before 2015, and those with cancer were excluded from the analysis. The follow-up period was defined as the time from the index date (date of device procedure) 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.

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]. The investigators defined the proportion of medical use by calculating formula with the recuperation cost and the number of the visit to hospitals.

During the follow-up period, the investigators assessed 3 clinical outcomes, including all-cause death, cardiovascular hospitalization and the recurrence rate. Clinical outcomes were mainly defined by the the International Classification of Diseases, 10th revision (ICD-10). Patients were censored at the clinical outcomes or the end of the study period (December 31, 2020), whichever came first.

All categorical variables are presented as frequencies and percentages. Normally distributed data were presented as mean ± standard deviation, whereas nonparametric data are presented as median and interquartile range by BMI.

Cox proportional hazard regression analyses were performed to identify the association of BMI with the primary and secondary outcomes, calculating hazard ratio (HR) and 95% confidence interval (CI) and adjusting for the following potential confounders: sex, age, systolic blood pressure, fasting glucose level, total cholesterol level, alcohol consumption, smoking status, physical activity, household income, use of antihypertensive agents, use of statins, use of antiplatelet agents, previous history of MI, previous history of stroke, and index year. All analyses were conducted using R-statistics.