The Age-Adjusted Modified Frailty Index: An Improved Risk Stratification Tool for Patients Undergoing Primary Total Hip Arthroplasty

Trends in the Adoption of Outpatient Joint Arthroplasties and Patient Risk: A Retrospective Analysis of 2019 to 2021 Medicare Claims Data

INTRODUCTION

Total joint arthroplasties (TJAs) have recently been shifting toward outpatient arthroplasty. This study aims to explore recent trends in outpatient total joint arthroplasty (TJA) procedures and examine whether patients with a higher comorbidity burden are undergoing outpatient arthroplasty.

METHODS

Medicare fee-for-service claims were screened for patients who underwent total hip, knee, or shoulder arthroplasty procedures between January 2019 and December 2022. The procedure was considered to be outpatient if the patient was discharged on the same date of the procedure. The Hierarchical Condition Category Score (HCC) and the Charlson Comorbidity Index (CCI) scores were used to assess patient comorbidity burden. Patient adverse outcomes included all-cause hospital readmission, mortality, and postoperative complications. Logistic regression analyses were used to evaluate if higher HCC/CCI scores were associated with adverse patient outcomes.

RESULTS

A total of 69,520, 116,411, and 41,922 respective total knee, hip, and shoulder arthroplasties were identified, respectively. Despite earlier removal from the inpatient-only list, outpatient knee and hip surgical volume did not markedly increase until the pandemic started. By 2022Q4, 16%, 23%, and 36% of hip, knee, and shoulder arthroplasties were discharged on the same day of surgery, respectively. Both HCC and CCI risk scores in outpatients increased over time (P < 0.001).

DISCUSSION

TJA procedures are shifting toward outpatient surgery over time, largely driven by the COVID-19 pandemic. TJA outpatients' HCC and CCI risk scores increased over this same period, and additional research to determine the effects of this should be pursued.

LEVEL OF EVIDENCE

Level III, therapeutic retrospective cohort study.

Age-Adjusted Modified Frailty Index: Association With Hip Fracture Discharge Functional Dependence

INTRODUCTION

Hip fractures are a common traumatic injury that carry significant morbidity and mortality, and prognostication of functional outcome is becoming increasingly salient. Across multiple surgical specialties, the five-item and 11-item Modified Frailty Index (mFI-5 and mFI-11) have been found to be convenient, quick, and sensitive tools for identifying patients at risk for perioperative complications. A prior study described the superiority of an Age-Adjusted Modified Frailty Index (aamFI) for predicting perioperative complications compared to the mFI-5 in an elective hip surgery. We sought to externally validate the aamFI in a multicenter hip fracture cohort and hypothesize that these risk scores would not only predict functional dependence (FD) at discharge, but that the aamFI would outperform the mFI-5 and mFI-11.

METHODS

The Pennsylvania Trauma Systems Foundation registry was queried from 2010 to 2020 for CPT codes, ICD-9 and ICD-10 codes pertaining to hip fracture patients. Patients with missing locomotion and transfer mobility data were excluded. FD status was determined by discharge locomotion and transfer mobility scores per existing methodology. Univariable and Multivariable analysis as well as receiver operator characteristic curves were used to evaluate and compare the three indices for prediction of functional status at discharge. P value < 0.05 was considered significant.

RESULTS

Twelve thousand seven hundred and forty patients met inclusion criteria (FD: 8183; functional independent 4557). On univariable logistic regression analysis, the mFI-11 (odds ratio [OR] 1.52, 95% confidence interval [CI] 1.47-1.58, P < 0.05), mFI-5 (OR 1.57, 95% CI 1.51-1.63), and aamFI (OR 1.57, 95% CI 1.52-1.62, P < 0.05) were associated with FD. On multivariable logistic regression analysis for predictors of FD, when controlling for age (for the mFI-11 and mFI-5), sex, injury severity score, and admission vitals (systolic blood pressure and respiratory rate), higher mFI-11 and mFI-5 scores independently predicted FD at discharge (OR 1.23, 95% CI 1.18-1.28, P < 0.05 and OR 1.23, 95% CI 1.18-1.29P < 0.05 respectively). Higher aaMFI scores had superior association with functional dependence (OR 1.59, 95% CI 1.54-1.64, P < 0.05). Receiver operator characteristic curves for the mFI-11, mFI-5, and aaMFI showed comparable diagnostic strength (area under curve [AUC] = 0.63 95% CI 0.62-0.64, P < 0.05; AUC = 0.63 95% CI 0.62-0.64, P < 0.05; and AUC = 0.67 95% CI 0.65-0.67, P < 0.05 respectively).

CONCLUSIONS

The mFI-11, mFI-5, and aamFI are predictive of functional outcome following hip fracture. By including age, the aamFI retains the ease of use of the mFI-5 while improving its prognostic utility for functional outcome.

Age-Adjusted Modified Frailty Index Predicts 30-Day Complications and Mortality in Aseptic Revision Total Hip and Knee Arthroplasty

BACKGROUND

The age-adjusted modified frailty index (aamFI) has been demonstrated to effectively predict postoperative complications and healthcare resource utilization in patients undergoing primary total joint arthroplasty. The purpose of this study was to evaluate the applicability of aamFI in patients undergoing aseptic revision total hip (rTHA) and knee arthroplasty (rTKA).

METHODS

A national database was queried for patients undergoing aseptic rTHA and rTKA from 2015 to 2020. A total of 13,307 rTHA and 18,762 rTKA cases were identified. The aamFI was calculated by adding 1 additional point for age ≥73 years to the previously described 5-item modified frailty index (mFI-5). The area under the curve was calculated and compared to compare predictive accuracy between mFI-5 and aamFI. Logistic regression was used to investigate the relationship between aamFI and 30-day complications.

RESULTS

The incidence of incurring any (≥1) complication increased from 15% for aamFI 0 to 45% for aamFI ≥5 after rTHA and from 5 to 55% after rTKA. Patients who had an aamFI ≥3 (reference aamFI = 0) had increased odds (rTHA: odds ratio (OR) 3.5, 95% confidence interval (CI) 2.9 to 4.1, P < .001; rTKA: OR 4.2, 95% CI 4.4 to 5.1, P < .001) of incurring at least 1 complication. The aamFI, compared to mFI-5, was a more accurate predictor of any complication (rTHA P < .001; rTKA P < .001) and 30-day mortality (rTHA P < .001; rTKA P < .003).

CONCLUSION

The aamFI is an excellent predictor of complications in patients undergoing rTHA and rTKA. The addition of chronological age to the previously described mFI-5 improves the predictive value of this simple metric.

Predictive Ability of Comorbidity Indices for Surgical Morbidity and Mortality: a Systematic Review and Meta-analysis

BACKGROUND

Several contemporary risk stratification tools are now being used since the development of the Charlson Comorbidity Index (CCI) in 1987. The purpose of this systematic review and meta-analysis was to compare the utility of commonly used co-morbidity indices in predicting surgical outcomes.

METHODS

A comprehensive review was performed to identify studies reporting an association between a pre-operative co-morbidity measurement and an outcome (30-day/in-hospital morbidity/mortality, 90-day morbidity/mortality, and severe complications). Meta-analysis was performed on the pooled data.

RESULTS

A total of 111 included studies were included with a total cohort size 25,011,834 patients. The studies reporting the 5-item Modified Frailty Index (mFI-5) demonstrated a statistical association with an increase in the odds of in-hospital/30-day mortality (OR:1.97,95%CI: 1.55-2.49, p < 0.01). The pooled CCI results demonstrated an increase in the odds for in-hospital/30-day mortality (OR:1.44,95%CI: 1.27-1.64, p < 0.01). Pooled results for co-morbidity indices utilizing a scale-based continuous predictor were significantly associated with an increase in the odds of in-hospital/30-day morbidity (OR:1.32, 95% CI: 1.20-1.46, p < 0.01). On pooled analysis, the categorical results showed a higher odd for in-hospital/30-day morbidity (OR:1.74,95% CI: 1.50-2.02, p < 0.01). The mFI-5 was significantly associated with severe complications (Clavien-Dindo ≥ III) (OR:3.31,95% CI:1.13-9.67, p < 0.04). Pooled results for CCI showed a positive trend toward severe complications but were not significant.

CONCLUSION

The contemporary frailty-based index, mFI-5, outperformed the CCI in predicting short-term mortality and severe complications post-surgically. Risk stratification instruments that include a measure of frailty may be more predictive of surgical outcomes compared to traditional indices like the CCI.

The Impact of Frailty on Outcomes Following Primary Total Hip Arthroplasty in Patients of Different Sex and Race: Is Frailty Equitably Detrimental?

BACKGROUND

Whether frailty impacts total hip arthroplasty (THA) patients of different races or sex equally is unknown. This study aimed to assess the influence of frailty on outcomes following primary THA in patients of differing race and sex.

METHODS

This is a retrospective cohort study utilizing a national database (2015-2019) to identify frail (≥2 points on the modified frailty index-5) patients undergoing primary THA. One-to-one matching for each frail cohort of interest (race: Black, Hispanic, Asian, versus White (non-Hispanic), respectively; and sex: men versus women) was performed to diminish confounding. The 30-day complications and resource utilizations were then compared between cohorts.

RESULTS

There was no difference in the occurrence of at least 1 complication (P > .05) among frail patients of differing race. However, frail Black patients had increased odds of postoperative transfusion (odds ratio [OR]: 1.34, 95% confidence interval [CI]: 1.02-1.77), deep vein thrombosis (OR: 2.61, 95% CI: 1.08-6.27), as well as >2-day hospitalization and nonhome discharge (P < .001). Frail women had higher odds of having at least 1 complication (OR: 1.67, 95% CI: 1.47-1.89), nonhome discharge, readmission, and reoperation (P < .05). Contrarily, frail men had higher 30-day cardiac arrest (0.2% versus 0.0%, P = .020) and mortality (0.3 versus 0.1%, P = .002).

CONCLUSION

Frailty appears to have an overall equitable influence on the occurrence of at least 1 complication in THA patients of different races, although different rates of some individual, specific complications were identified. For instance, frail Black patients experienced increased deep vein thrombosis and transfusion rates relative to their non-Hispanic White counterparts. Contrarily, frail women, relative to frail men, have lower 30-day mortality despite increased complication rates.

The Impact of Frailty Is Age Dependent in Patients Undergoing Primary Total Knee Arthroplasty: The Age-Adjusted Modified Frailty Index

BACKGROUND

Frailty is a well-established risk factor in patients undergoing total knee arthroplasty (TKA). How age modifies the impact of frailty on outcomes in these patients, however, remains unknown. In this study, we aimed to describe and evaluate the applicability of a novel risk stratification tool-the age-adjusted modified Frailty Index (aamFI)-in patients undergoing TKA.

METHODS

A national database was queried for all patients undergoing primary TKA from 2015 to 2019. There were 271,271 patients who met inclusion criteria for this study. First, outcomes were compared between chronologically young and old frail patients. In accordance with previous studies, the 75th percentile of age of all included patients (73 years) was used as a binary cutoff. Then, frailty was classified using the novel aamFI, which constitutes the 5-item mFI with the addition of 1 point for patients ≥73 years. Multivariable logistic regressions were then used to investigate the relationship between aamFI and postoperative outcomes.

RESULTS

Frail patients ≥73 years had a higher incidence of complications compared to frail patients <73 years. There was a strong association between aamFI and complications. An aamFI of ≥3 (reference aamFI of 0) was associated with an increased odds of 30-day mortality (odds ratio [OR] 8.6, 95% CI 5.0-14.8), any complication (OR 3.1, 95% CI 2.9-3.3), deep vein thrombosis (OR 1.5, 95% CI 1.2-1.8), and nonhome discharge (OR 6.1, 95% CI 5.8-6.4; all P < .001).

CONCLUSION

Although frailty negatively influences outcomes following TKA in patients of all ages, chronologically old, frail patients are particularly vulnerable. The aamFI accounts for this and represents a simple, but powerful tool for stratifying risk in patients undergoing primary TKA.