Association between a frailty index derived from laboratory tests and clinical outcomes in critical care patients with asthma: a retrospective study based on the MIMIC-IV database

Background In this study, we aimed to explore the association between elevated Frailty Index laboratory-derived (FI-Lab) levels and the prognosis in critically ill patients with asthma to advance clinical management strategies and optimize patient outcomes. Methods A retrospective analysis was performed on intensive care unit (ICU) patients diagnosed with asthma identified from the Medical Information Mart for Intensive Care (MIMIC-IV, version 3.0) database. Demographic characteristics, clinical parameters, and FI-Lab values were collected for analysis. The prognostic factors were evaluated using multivariate Cox regression models. Results Our findings revealed a strong association between elevated FI-Lab levels and adverse clinical outcomes in ICU patients with asthma. Among the 2,339 patients, those presenting with higher FI-Lab scores at admission exhibited a significantly increased risk of complications, including prolonged ICU stays and higher mortality rates. Specifically, a 0.1-unit increase in the FI-Lab score was associated with a 1.32-fold increased risk of 28-day mortality [hazard ratio (HR) = 1.32, 95% confidence interval (CI): 1.17–1.50, p < 0.001], 1.25-fold increased risk of ICU mortality (HR = 1.25, 95% CI: 1.05–1.47, p = 0.011), and 1.33-fold increased risk of 90-day mortality (HR = 1.33, 95% CI: 1.20–1.48, p < 0.001). Additionally, when the FI-Lab scores were analyzed as categorical variables, significant associations with the 28-day, ICU, and 90-day mortality rates remained consistent across all models. Conclusions Elevated FI-Lab levels are a strong prognostic factor in ICU patients with asthma. Incorporating the FI-Lab into clinical evaluations may provide a new scientific basis for assessing the prognosis of severe asthma and potentially improving patient outcomes. Randomized controlled trials are required to validate our findings.