Summary

The mFI-5 is a better predictor of adverse outcomes in Revision Hip Replacement than ASA

Abstract

Purpose

The modified frailty index (mFI-5) is a 5-factor index used to distinguish patients based on their level of frailty and predict morbidity and mortality. The purpose of this study is to compare the predictive value of mFI-5 to American Society of Anesthesiologists (ASA) Classification for death and surgical infection in revision total hip replacement.

Methods

The 2006-2018 National Surgical Quality Improvement Program (NSQIP) Database was queried for patients undergoing revision total hip replacement based on Current Procedural Terminology (CPT) Codes 27134, 27137, and 27138. mFI-5 was calculated on a 0-5 scale based on the presence of congestive heart failure within 30 days prior to surgery, insulin-dependent or noninsulin-dependent diabetes mellitus, chronic obstructive pulmonary disease or pneumonia, partially dependent or totally dependent functional health status at time of surgery, and hypertension requiring medication. Demographic and comorbidity data were analyzed via univariate chi-square analysis. Categories significant at the p < 0.05 level were included in the bivariate multivariate regression analysis to calculate odds ratios. All odds ratios were calculated to the 95% confidence interval (CI).

Results

7,218 (34.7%) patients had mFI-5 = 0, 9,698 (46.6%) had mFI-5 = 1, and 3,877 (18.6%) had mFI-5 greater than or equal to 2. Patients in the different mFI categories were different in regard to gender, BMI, age, and race. After adjusting for all significant demographics and non-mFI comorbidities, a patient with an mFI-5 score of greater than 2 was 3.555 times more likely to die within thirty days of the operation (CI [2.066-6.116], p < 0.001) and 1.266 times more likely to experience surgical infection (CI [1.009-1.588, p = 0.041). An mFI-5 score of 1, and ASA scores of 2 and greater than or equal to 3 were not significantly associated with death or surgical infection.

Conclusion

mFI-5 is a convenient tool for prediction of short-term complications in patients undergoing revision total hip replacement. mFI-5 was a better predictor of death and surgical infection than ASA. Surgeons can calculate their patients’ mFI-5 scores prior to surgery to estimate risks and outcomes.