Frailty assessment index based on lab tests may help predict outcomes in hospitalized older adults

The index uses data from 27 laboratory values routinely assessed within 72 hours of hospital admission.

A frailty assessment tool based on laboratory tests at hospital admission may help predict adverse outcomes in older adults when combined with chronic frailty assessment, according to a new study.

Researchers in the United Kingdom created a frailty index using data from 27 laboratory values routinely assessed within 72 hours of hospital admission. This frailty index (FI-Laboratory) was developed in a prospective cohort of older adults consecutively admitted to the acute geriatric medicine service at a large tertiary care hospital between April 2015 and January 2017. Hospital admissions shorter than 24 hours were excluded.

Acute health status was assessed with FI-Laboratory, while chronic health status was assessed with the Clinical Frailty Scale (CFS). To obtain a score on FI-Laboratory, the proportion of abnormal test results was calculated from the total number of tests ordered. The CFS is scored from 1 to 9, with 1 indicating very fit and 9 indicating terminally ill. The study's main outcomes were total hospital days, need for a higher level of care, readmission during the enrollment period, and mortality from the date of hospital admission to Dec. 11, 2018. Results were published by CMAJ on Jan. 6.

Overall, 2,552 admissions for 1,750 patients were included in the analysis, and laboratory values for the index were available for 2,254 admissions (88.3%, 1,580 patients). Patients' average age was 84.8 years, and 55.3% were women. The FI-Laboratory correlated weakly with the Clinical Frailty Scale (CFS). An increase in CFS score and three additional abnormal values on FI-Laboratory were each associated with more hospital days (rate ratios, 1.43 [95% CI, 1.35 to 1.52] and 1.47 [95% CI, 1.41 to 1.54], respectively), more frequent discharge to a higher level of care (odds ratios, 1.39 [95% CI, 1.27 to 1.52] and 1.30 [95% CI, 1.16 to 1.47]), higher readmission rates (hazard ratios, 1.26 [95% CI, 1.17 to 1.37] and 1.18 [95% CI, 1.11 to 1.26]), and higher mortality rates (hazard ratios, 1.39 [95% CI, 1.28 to 1.51] and 1.45 [95% CI, 1.37 to 1.54]).

The researchers noted that their study was done at only one center and that the FI-Laboratory score was missing in 11.6% of cases, among other limitations. However, they concluded that this frailty index based on commonly obtained laboratory values can help in early identification of acutely ill adults who are admitted to the hospital and are at risk for adverse outcomes. Future research should focus on whether the FI-Laboratory can improve clinical outcomes and whether changes in the index during hospital admission provide prognostic information, the authors wrote.