Background: Frailty is a clinical syndrome characterized by vulnerability to stressors resulting from a loss of physiological reserve across multiple systems. Frailty is a common condition in older adults and is associated with disability, morbidity, increased healthcare utilization, and mortality. Frailty assessments derive from two major frameworks: the frailty phenotype and the deficit accumulation model. These models may not detect acute changes in frailty status. The FI-LAB is a feasible and valid assessment based on laboratory values and vital signs. The FI-LAB is based on the deficit accumulation model and represents a more accurate assessment of acute changes in frailty. Previous studies have shown that FI-LAB can help identify poor outcomes for hospitalized older adults but there are no studies in the Veteran hospitalized population. Veterans have a high prevalence of multimorbidity, disability, cognitive impairment and mental illness which are associated with frailty. The purpose of the study is to assess the FI-LAB score as a predictor of hospital length of stay (LOS) and readmission in the first 30 days post discharge (RA-30).

Methods: A retrospective cohort study was conducted in a population of adults ≥60 years old who were admitted to the Miami VAHS ER due to an acute illness. Index admissions were identified between January 2011 and December 2014. Subsequent admissions were collected within a follow-up period of 5 years. Hospitalizations due to procedures, mental illness, social issues, and medical work-ups were excluded. We constructed a 31 item FI-LAB including laboratory values and vital signs upon admission. The groups were categorized as low (<0.25), moderate (0.25 - 0.40), and high (>0.40) based on their FI-LAB scores. LOS was dichotomized into <3 days (short) and ≥3 days (prolonged). We compared the proportion of patients who had a short and prolonged LOS, as well as an RA-30 among the FI-LAB groups using a Chi-square test. We also assessed the independent association between FI-LAB and LOS, as well as RA-30 using a binomial logistic regression model (BLR).

Results: Out of a total of 1731 index admissions during the specified period, 89.3% (n=1545) admissions were included. The Veterans’ mean age was 72.78 (SD=8.97) years. The majority were Caucasian (67.5%) and males (96.2%). According to the FI-LAB, 48.8% (n=754), 39.7% (n=613), and 11.5% (n=178) of the patients were in the low, moderate and high categories, respectively. The high FI-LAB group had significantly higher rates of prolonged hospital stays (72.8%), as compared with the moderate (57%) and low (45.4%) groups, p<.001. Patients in the low FI-LAB group had a significantly lower rate of RA-30 8.5%, p<.001 than the moderate (13.5%) and high FI-LAB (16.2%) groups. Using BLR, when compared with the low FI-LAB group, the moderate and high groups had a higher risk for prolonged LOS, OR:1.64 (95%CI:1.32-2.05) and OR:3.40 (95%CI:2.35-4.92), p<.001, respectively. Regarding readmissions at 30 days, both the moderate and high FI-LAB groups showed a significantly higher risk of RA-30, OR:1.57 (95%CI:1.11-2.22) and OR:1.86 (95%CI:1.13-3.06), p=.015, respectively when compared with the low group.

Conclusions: In this study, higher FI-LAB scores were associated with a higher risk for prolonged LOS and higher rates of RA-30. The FI-LAB may identify older patients at higher risk and assist clinicians in the development of early strategies to reduce poor clinical outcomes of patients with frailty.