Comparison of the impact of longitudinal body mass index changes on cardiac arrest risk between normal and overweight populations

Abstract Background Being overweight is a key modifiable risk factor for cardiovascular disease. However, the impact of longitudinal changes in body mass index (BMI) on the risk of out‐of‐hospital cardiac arrests (OHCA) remains unclear, especially among overweight populations. Methods This nested case–control study utilized data from the Korean National Health Information Database between 2009 and 2018. A total of 23 453 OHCA patients, who underwent national health check‐ups within 1 and 2–4 years before OHCA occurrence, and 31 686 controls, who underwent similar national health check‐ups, were included. The study population was matched for sex, age and survival status. Conditional logistic regression was employed to analyse the odds ratios (ORs) and 95% confidence intervals (CIs) of each BMI per cent change in assessing the risk of OHCA occurrence within 1 year. Results A reverse J‐shaped association between BMI per cent change and OHCA risk was observed, even among overweight populations. Among the overweight populations, weight loss significantly increased OHCA risk, with ORs (95% CI) of 4.10 (3.23–5.20) for severe weight loss (BMI decrease > 15%), 2.72 (2.33–3.17) for moderate weight loss (BMI decrease 10–15%) and 1.46 (1.35–1.59) for mild weight loss (BMI decrease 5–10%). Conversely, mild weight gain (BMI increase 5–10%) did not significantly increase OHCA risk. The impact of weight changes on the occurrence of OHCA differed by sex, being more prominent in males. Conclusions Significant weight changes within a 4‐year period increase the risk of OHCA with a reverse J‐shaped association, even among overweight and obese individuals. Maintaining a stable weight could be a reliable public health strategy irrespective of the weight status, particularly for males.