Frailty Is Associated With Increased 30-day Readmissions and Costs After Total Shoulder Arthroplasty

Frailty has been associated with a greater risk of complications and higher treatment costs for various medical conditions and surgical procedures. The Modified Frailty Index, which analyzes five or six medical comorbidities, helps grade the severity of a patient's frailty. Patients with frailty, as recognized by this index, are more likely to face adverse medical and surgical events after total shoulder arthroplasty (TSA). However, these modified indices often do not consider less common medical conditions that contribute to frailty. As such, we believe that patients may be more readily misdiagnosed as not having frailty. A more comprehensive frailty score that more accurately recognizes frailty in a wider patient population is necessary.

After analyzing for any possible differences due to confounding variables such as age, gender, socioeconomic variables, and insurance provider, we asked: (1) Was frailty, defined as a score of ≥ 5 on the Hospital Frailty Risk Score (HFRS), associated with a higher risk of reoperation or readmission within 30 days of primary TSA? (2) Was frailty associated with an increased risk of major medical or surgical complications after TSA? (3) Was frailty associated with higher hospital costs (assessed by insurance charge-to-cost ratio per admission) and length of stay for patients after TSA?

This study examined the Nationwide Readmissions Database, which includes patients from 28 states, representing 60% of all US residents and 60% of all US hospitalizations. We identified adult patients who were discharged after both anatomic and reverse TSA for primary osteoarthritis between January and November of 2017 to 2019 (patients who underwent TSA in December of each year were excluded). The HFRS was calculated for each patient based on 109 differently weighted ICD-10 Clinical Modification codes as validated in previous studies. Patients with an HFRS of ≥ 5 were considered as having frailty. Of the 107,774 patients who underwent TSA and were recorded in this database, 15% (16,210) were classified as patients with frailty. Patients over age 65 years comprised a larger portion of patients with frailty than patients without frailty (81% [13,130 of 16,210] of patients with frailty versus 74% [67,757 of 91,564] of patients without frailty; p < 0.01). Women comprised a larger portion of patients with frailty than patients without frailty (62% [10,050 of 16,210] women with frailty versus 53% [48,528 of 91,564] women without frailty; p < 0.01). Patients paying with Medicare comprised a larger portion of patients with frailty than patients without frailty (80% [12,968 of 16,210] Medicare payers with frailty versus 72% [65,926 of 91,564] Medicare payers without frailty; p < 0.01). We used the Student t-test to compare demographics and complication risk. After analysis of these confounders and controlling for them, we used multivariate logistic regression to analyze 30-day readmissions and negative binomial regression to analyze length of stay and hospital costs (as estimated by insurance charge-to-cost ratios per patient admission). Length of stay was expressed as an incidence rate ratio (IRR) because it was recorded and analyzed as a continuous variable. The Student t-test was used to compare demographics and risk of major surgical and medical complications of similar severity.

After controlling for confounding variables such as age, gender, socioeconomic status, and insurance provider, we found that frailty was associated with increased odds of reoperation within 30 days (OR 1.61 [95% CI 1.22 to 2.09]; p < 0.001) and increased 30-day readmissions (OR 1.79 [95% CI 1.63 to 1.97]; p < 0.001). We also found that frailty was associated with higher 30-day major surgical complication risk (0.4% [70 of 16,210] versus 0.3% [266 of 91,564]; p < 0.01) and 30-day major medical complication risk (2.6% [421 of 16,210] versus 1.1% [1007 of 91,564]; p < 0.01). We also found that frailty was associated with greater hospitalization costs (IRR 1.09 [95% CI 1.09 to 1.10]; p < 0.001) and longer lengths of hospital stay (IRR 1.46 [95% CI 1.44 to 1.47]; p < 0.001).

Frailty, as measured by the HFRS, is associated with increased postoperative events and estimated hospitalizations costs after TSA. The HFRS is derived from routinely collected administrative data and could help clinicians quickly identify patients at risk of complications without increased cost. Once patients with frailty are identified, clinicians may be able to provide additional counseling regarding patients' increased risk for postoperative complications and costs. An automatically calculated, robust scoring tool such as the HFRS can also aid clinicians in operative decision-making, as patients with severe frailty may be advised against undergoing TSA if the procedure is not absolutely necessary.

Level III, therapeutic study.