Comparison of 5-Item and 11-Item Modified Frailty Index as Predictors of Functional Independence in Patients With Spinal Cord Injury.

STUDY DESIGN: Retrospective Cohort Study.

INTRODUCTION: The 11-item modified Frailty index (mFI-11) by the ACS-NSQIP database was used to predict which patients are high risk for complications and inpatient mortality. ACS-NSQIP now has switched to the 5-item MFI. However, there are no studies on how these frailty indices fare against each other and their prognostic value of functional independence in patients with spinal cord injury (SCI).

OBJECTIVE: To compare the mFI-5 and mFI-11 in order to standardize frailty assessment in the SCI population.

METHODS: Retrospective analysis of 272,174 patients with SCI from 2010 to 2020 from the Pennsylvania Trauma Systems Foundation (PTSF) registry. Multivariable logistic regression was used to determine the predictive value of mFI for functional independence as determined by locomotion and transfer mobility.

RESULTS: A total of 1907 patients were included with a mean age of 46.9 ± 15.1 years. The 3 most common MFI factors were hypertension (32.2%), diabetes mellitus (13.7%) and chronic obstructive pulmonary disease (8.5%). Multivariable logistic regression analyses using MFI-5 and MFI-11 showed that a higher frailty score in MFI-5 (OR 1.375, P < .001) and in MFI-11 (OR 1.366, P < .001) were each predictive of poor functional status at discharge. ROC curves for the MFI-5 (AUC = .818, P < .001) and MFI-11 (AUC = .819, P < .001) demonstrated excellent diagnostic accuracy.

CONCLUSION: The new MFI-5 is equivalent to its predecessor, the MFI-11, and predictive of functional outcomes in patients with SCI. MFI-5 can serve as the preferred frailty index at the point of care and in research contexts.