Abstract
Introduction:
Primary total knee arthroplasty (TKA) is associated with perioperative bleeding, and some patients will require allogenic blood transfusion during their inpatient admission. While blood safety has improved in the last several decades, blood transfusion still carries significant complications and costs. Transfusion indications and alternative methods of blood conservation are being explored. However, there is limited nationally representative data on allogenic blood product utilization among TKA patients, and its associated outcomes and financial burden. The purpose of this study was to use a national administrative database to investigate the trends in utilization and outcomes (i.e. in-hospital mortality, length of stay, admission costs, acute complications) of allogenic blood transfusion in primary TKA patients.
Methods:
The Nationwide Inpatient Sample (NIS), the largest all-payer inpatient care database representing a 20% stratified sample of United States hospitals, was utilized. Primary TKA (ICD-9-CM 81.54) cases from 2000 to 2009 were retrospectively queried (n = 4,544,999; weighted national frequency). A total of 67,841 admissions were excluded (Figure 1). The remaining 4,477,158 cases were separated into two study cohorts: (1) patients transfused with allogenic blood products (red blood cells, platelets, serum) (n = 540,270) and (2) patients not transfused (n = 3,936,888). Multivariable regression and generalized estimating equations were used to examine the effect of transfusion on outcomes, adjusting for patient/hospital characteristics and comorbidity.
Results:
During the study period, the overall allogenic blood transfusion rate in primary TKA patients was 12.1%. The rate increased ∼5% from 2000 to 2009, and stayed constant around 13% from 2006 to 2009. Transfusion rates were higher in older patients (80–89 yrs, 21.4%; ≥ 90 yrs, 30.7%), blacks (19.6%), females (14.0%), Medicare patients (14.6%), and Medicaid patients (14.4%). Transfused TKA patients had a greater percent of comorbidities than their non-transfused peers. The largest differences in comorbidity prevalence among transfused and non-transfused patients were: deficiency anemia (27.5% vs. 10.1%), renal failure (4.0% vs. 1.4%), chronic blood loss (3.7% vs. 1.4%), and coagulopathy (3.1% vs. 1.0%) (p < 0.001). Unadjusted trends show that from 2000 to 2009, in-hospital mortality rate decreased (Figure 2A), mean length of stay decreased (Figure 2B), and mean admission cost increased (Figure 2C) for both transfused and non-transfused patients following TKA. Adjusting for patient and hospital characteristics, transfused patients had a 22% (95% CI, 4%–43%) greater likelihood of in-hospital mortality (p = 0.013), 0.68 ± 0.02 days longer length of stay (p < 0.001), and $2,237 ± 76 increased admission costs (p < 0.001). Additionally, patients who received a transfusion had a greater adjusted risk of a postoperative infection (odds ratio, 2.35), pulmonary insufficiency (odds ratio, 1.60), and other complications (p < 0.001) (Figure 3).
Conclusions:
The allogenic blood transfusion rate increased between 2000 and 2009 in the United States. Transfusion has a considerable burden on patients and healthcare institutions, increasing in-hospital mortality, length of stay, admission costs, and acute complications. Preoperative optimization strategies, transfusion criteria, and hemostatic agents for at-risk patients need to be further researched as possible ways to reduce transfusion occurrence and its effects.
