Association between daily sitting time and heart attack and cardiovascular mortality: the mediation effects of serum...

This study aimed to explore the relationship between daily sitting time and the risk of heart attack and cardiovascular mortality, as well as the mediating effect of serum osmolality.

Data were collected from the 2007-2020 National Health and Nutrition Examination Survey, including sitting time and heart attack history from questionnaires, serum osmolality from lab tests, and death causes from follow-ups. Logistic regression and subgroup analyses were used to examine the relationships, while restricted cubic spline (RCS) was employed to analyze the mediating effect.

Among 10,597 participants, heart attack and cardiovascular mortality increased with daily sitting time. The highest hazard ratio for cardiovascular mortality was observed in the group with the longest sitting time (G4). RCS analysis revealed that serum osmolality significantly mediated the risk of heart attack due to prolonged sitting. After a median follow-up of 6-7 years, the risk of heart attack death increased with sitting time, especially when serum osmolality was ≥277 mmol/kg. Subgroup analyses indicated that sitting time was significantly associated with heart attack risk, influenced by race, sex, education, poverty income ratio, smoking, drinking, and BMI.

Daily sitting time was significantly associated with the risk of heart attack and cardiovascular mortality; participants sitting ≥8 hours had a higher incidence than those sitting <4 hours. Serum osmolality plays a key mediating role in the impact of sitting time on heart attack development.