Correlation between change in body mass and mortality during hospitalization in intensive care unit: a retrospective cohort study

To explore the effect of change in body mass on mortality during hospitalization in intensive care unit（ICU）.

A multicenter and retrospective cohort study was conducted on patients who were firstly hospitalized in ICU and whose length of ICU stay were over 24 h, with data extracted from the eICU Collaborative Research Database. Univariate and multivariate logistic regression models were used to explore the relationship between body mass change and mortality in ICU patients. Interaction analysis was performed between body mass change and related covariates. Based on the results of interaction analysis and clinical practice, the association between body mass change and mortality was analyzed in subgroups stratified by age, Acute Physiology and Chronic Health Evaluation（APACHE）Ⅳ score, length of ICU stay and baseline BMI at ICU admission.

A total of 34 311 ICU patients were included, among which 55.1% were male, the white race accounted for 82.4% and 51.3% were ≥65 years old. Compared with those with decreased body mass, patients with increased body mass had higher rates of renal failure（1 938 cases, 11.1%）, liver failure（106 cases, 0.6%）, sepsis（2 442 cases, 14.0%）, longer ICU stay, longer hospital stay and higher APACHEⅣ scores. The multivariate logistic regression model showed the in-hospital and ICU mortality in patients with body mass gain were 1.25 times（95%CI: 1.16~1.36, P<0.001）and 1.36 times（95%CI: 1.22~1.50, P<0.001）higher than those with body mass decreased respectively. This difference is more significant in patients with higher APACHEⅣ score and the longer ICU stay. The different age subgroup or different baseline BMI levels exerted no effect on the results mentioned.

The change in body mass is the independent risk factor of the in-hospital and ICU motality.