Abstract
The relationship between body mass index and pressure ulcers in critically ill patients is controversial. We aimed to investigate the association between body mass index and pressure ulcers by analysing data from the Medical Information Mart for Intensive Care IV (version 2.0) database. Eligible data (21 835 cases) were extracted from the database (2008-2019). The association between body mass index and pressure ulcers in critically ill patients was investigated by adjusting multivariate trend analysis, restricted cubic spline analysis, and segmented linear models. Subgroup analyses and sensitivity analyses were used to ensure the stability of the results. Trend analysis and restricted cubic spline analysis showed an approximate U-shaped correlation between body mass index and the occurrence of pressure ulcers in critically ill patients, with the risk of pressure ulcers decreasing rapidly with increasing body mass index (8.6% decrease per unit) after adjusting for relevant factors; the trend reached its minimum at a body mass index of 27.5 kg/m2, followed by a slow increase in the risk of pressure ulcers with increasing body mass index (1.4% increase per unit). Among the subgroups, the highest overall risk of pressure ulcers and the risk of severe pressure ulcers were significantly higher in the underweight group than in the other subgroups, and the risk associated with the overweight group was the lowest. There is a U-shaped association between body mass index and pressure ulcers in critically ill patients, and being underweight and obese both increase the risk of pressure ulcers. The risk is highest among underweight patients and lowest among overweight patients (but not patients of normal weight), necessitating targeted prevention strategies for critically ill patients with different body mass indexes.