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

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.