Abstract
Introduction:
Over the last several decades, life expectancy following solid organ transplant (i.e. kidney, liver, heart, lung, and pancreas) has increased significantly, largely due to improvements in surgical technique, immunosuppressive regimens, patient selection, and postoperative care. As this population ages, many of these transplant patients become candidates for total knee arthroplasty (TKA). However, these patients may be at greater risk of complications following TKA due to immunosuppression and metabolic derangements secondary to organ dysfunction. The purpose of this study was to use a large, nationally representative database to compare morbidity, mortality, length of stay (LOS), and charges for TKA patients with and without a history of solid organ transplant.
Methods:
This retrospective study was a review of the Nationwide Inpatient Sample (NIS; the largest all-payer inpatient care United States database representing a 20% stratified sample) from 1998 to 2010. Patients who had a primary TKA (ICD-9-CM 81.54) were included (n = 5,706,675, weighted national frequency). A total of 763,924 cases were excluded for the following: age <18 years, pathologic fracture of lower extremity, malignant neoplasm and/or metastatic cancer, previous and/or bilateral arthroplasty, admission type other than “elective”. The remaining 4,942,751 patients were categorized as transplant (n = 5,245; included only liver, kidney, heart, lung and/or pancreas transplant) or non-transplant group (n = 4,931,017; no history of any transplant including solid organ or tissue). A multivariable regression model was used to identify any association(s) between a history of solid organ transplant and morbidity, mortality, LOS and hospital charges, while adjusting for patient and hospital characteristics.
Results:
Between 1998 and 2010, the volume of TKA increased among transplant patients at a rate of 382%, which was significantly higher than that of the non-transplant group (197%; p < 0.01). Patients with a history of transplant had a significantly higher prevalence of renal failure (+69.3%), liver disease (+22.9%), uncomplicated diabetes (+9.0%), hypertension (+8.9%), deficiency anemia (+8.9%) (p < 0.001). Transplant patients suffered 1 or more complication at a rate of 7.3%, which was significantly higher than that of the non-transplant group (5.7%; p < 0.001). A 0.1% mortality rate was observed in the non-transplant group, while no deaths were reported in the transplant group. Unadjusted trends for mean LOS (Figure 1) show that transplant patients have a longer LOS (4.2 days) than non-transplant patients (3.7 days; p < 0.001), although LOS decreased for both groups. Overall mean charges per admission (USD) were significantly higher for the transplant cohort ($ 40,999) than the non-transplant group ($ 35,686; p < 0.001), and both increased over time (Figure 2). After adjusting for patient demographics, hospital characteristics, and comorbidity, transplant patients stayed 0.46 days longer in the hospital (p < 0.01) and had $ 3,480 increased charges (p < 0.01). There was no statistically significant increase in hospital complications (adjusted odds ratio = 1.20; p = 0.13).
Conclusions:
While the annual number of TKAs performed in the United States on patients with a history of solid organ transplant is relatively low, the rate is increasing at nearly twice that of non-transplant patients undergoing TKA. Transplant patients have a significantly higher number of comorbidities, longer LOS, and greater charges than patients with no transplant history
