Association between laboratory data-based frailty index and clinical health outcomes in critically ill older patients: A retrospective correlational study

Background: Although frailty assessment is crucial for understanding critically ill patients' prognosis, traditional frailty measures require substantial efforts and time from health care professionals. To address this limitation, the laboratory frailty index (FI-LAB) based on laboratory clinical data was developed. However, knowledge regarding its correlation with health outcomes among critically ill older patients is limited.

Aims: To identify the association between the FI-LAB and acute, mid- and long-term outcomes among critically ill older adults.

Study design: This retrospective correlational study used electronic health records of 2106 older patients who were admitted to the intensive care unit at a tertiary hospital in Seoul, Korea. Acute and mid-term outcomes included occurrence of delirium and in-hospital mortality, and the long-term outcome included 1-year mortality. Logistic regression was used to explore the relationships across FI-LAB, delirium, and in-hospital mortality, while Cox proportional hazard regression was used to analyse the relationship between FI-LAB and 1-year mortality.

Results: Frailty assessed by FI-LAB was significantly associated with increased risk of delirium (odds ratio [OR] = 6.21, 95% confidence interval [CI] = 2.31-25.39, p = .009), in-hospital mortality (OR = 2.38, 95% CI = 1.15-5.79, p = .014), and 1-year mortality (hazard ratio = 2.47, 95% CI = 1.16-5.25, p = .019) after controlling for covariates.

Conclusions: The study highlighted the importance of using FI-LAB for screening frailty in critically ill older adults. Health care providers can improve patients' acute, mid- and long-term outcomes to develop more individualised management plans based on FI-LAB scores.

Relevance to clinical practice: The FI-LAB score calculated from routine laboratory data can be used by nurses as a screening tool to identify frail older adults in critical care. Early detection of frailty would allow for closer monitoring and the implementation of interventions to reduce delirium and mortality.