Abstract
Introduction
Revision total knee arthroplasty (revision TKA) occurs for a wide variety of indications and along with revision total hip arthroplasty is billed for using Diagnosis-Related Groups (DRGs) 466, 467, and 468 in the United States. However, DRGs do not account for revision etiology, a potentially substantial driver of cost. This study investigates revision TKA costs and 30-day complications by indication, employing both local granular as well as national standardized databases.
Methods
Hospitalization costs and complication rates for 1,422 aseptic revision TKAs performed at a high-volume center between 2009 and 2015 were retrospectively reviewed. Additionally, charges for 28,173 revision TKAs in the National Inpatient Sample (NIS) were converted to costs using the Healthcare Cost and Utilization Project cost-to-charge ratios. 30-day complication rates for 3,450 revision TKAs were obtained using the American College of Surgeons National Surgical Quality Improvement Project (ACS-NSQIP). Costs and complications were compared between revision TKAs performed for the indication of fracture, wear/loosening, and instability with use of simultaneous and pairwise comparisons and a multivariable model accounting for American Society of Anesthesiologists (ASA) score, age, and sex.
Results
Local hospitalization costs for fracture (median, $30,643) were significantly higher than those for wear/loosening ($24,734; p < 0.001) or instability ($22,932; p < 0.001), with differences remaining significant even after adjusting for patient comorbidities (p < 0.001). Local fracture patients were admitted for an average of 1.9 days longer (mean length of stay [LOS]: 4.8 days; IQR: 3 – 6) than instability patients (mean LOS: 2.9; IQR: 2 – 3; p < 0.001) and 1.7 days longer than wear/loosening patients (mean LOS: 3.1, IQR: 2 – 3; p < 0.001) but had similar 30-day orthopedic-specific complication rates (10.8%) as compared to instability (11.2%; p > 0.999) and wear/loosening (15.9%; p = 0.333).
Nationally, NIS costs for fracture (median, $31,207) were higher than those for other aseptic indications (wear/loosening: $21,747; instability: $16,456; p< 0.001). Combined medical and surgical complication rates for fracture (56.6% of patients with ≥1 complication) were significantly higher than those for wear/loosening (19.7%) and instability (15.5%) (p < 0.001), with 3.5 – 5.4 fold increased transfusion rates (45.7% fracture, 13.2% wear/loosening, 8.5% instability; p < 0.001) and 1.2 – 3.3 fold increased urinary tract infection rates (2.3% fracture, 0.7% wear/loosening, 1.9% instability; p = 0.004).
Discussion and Conclusion
Hospitalization costs for revision TKA for fracture were 37% to 50% higher than for all other aseptic revision TKAs, both locally and nationally. This increased cost persisted even after multivariable comorbidity adjustment, the current approach for DRG assignment for both revision TKA and THA reimbursement. Indication-specific coding and reimbursement systems are necessary to maintain sustainable access to revision TKA for all patients.
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