Evaluation of the FI-Lab, a laboratory-based, automated frailty index for acute care: A multicohort study

A recent study has investigated the effectiveness of a laboratory-based frailty index known as the FI-Lab in acute care settings. This multicohort study aimed to determine the optimal configuration of an FI-Lab and evaluate its ability to measure latent health status across the entire adult life span.

The researchers analyzed emergency department encounters in Boston, USA (MIMIC-IV-ED; 2011-2019) and London, UK (King's College Hospital; 2017-2020), as well as a community-based cohort in the UK (UK Biobank; 2006-2010). The primary outcome of interest was 1-year all-cause mortality.

The study found that a FI-Lab constructed from 25 commonly ordered tests, with a minimum threshold of 15 tests, demonstrated hazard ratios for 1-year mortality that were nearly identical to those of chronological age and surpassed the National Early Warning Score 2 (NEWS2). In combined models, each standard deviation increase in the FI-Lab score was associated with a 2.00-fold higher hazard ratio for 1-year mortality (95% CI [1.99, 2.09]; p < 0.001).

The findings suggest that the FI-Lab offers an automated and scalable measure of patient vulnerability that is robust across different healthcare settings and populations. The study concludes that a core set of 20-40 commonly ordered tests is sufficient for capturing meaningful signals. This automated approach provides a pragmatic complement to clinical judgment, eliminating the need for manual data entry or additional tests.