Abstract
Venous thromboembolism (VTE; deep venous thrombosis and pulmonary embolism) is a known
complication following primary total knee arthroplasty (TKA). The aim of this study
was to investigate the trends of the incidence of VTE after primary TKA and identify
associated risk factors for the occurrence of VTEs in a large cohort of TKA patients.
We performed a retrospective study in which the Nationwide Inpatient Sample (NIS)
database was used to identify all patients who underwent primary TKA over a period
of 13 consecutive years (between 2002 and 2014) in the United States. The occurrence
of a symptomatic VTE was identified with the use of ICD-9-CM (International Classification
of Diseases, Ninth Revision, Clinical Modification) diagnosis codes. A total of 1,460,901
primary TKA procedures were identified in the NIS from 2002 to 2014, and 12,944 of
these patients were recorded as having 13,855 VTEs, consisting of 7,609 deep venous
thromboses (0.52%) and 6,246 pulmonary emboli (0.43%). The overall VTE incidence in
patients undergoing TKA in the United States from 2002 to 2014 was 0.89%. Patient-related
risk factors for VTEs include an older age (odds ratio [OR]: 1.44; 95% confidence
interval [CI]: 1.31–1.59), black race (OR: 1.34; 95% CI: 1.25–1.44), and Medicare
insurance (OR: 1.18; 95% CI: 1.13–1.22). Most of the comorbidities were associated
with an increased risk of VTE following TKA. Particularly, cardiac arrhythmias, coagulopathy,
fluid and electrolyte disorders, pulmonary circulation disorders, and weight loss
increased the risk of VTE by more than twofold. After adjusting for confounders, VTE
was associated with a longer hospital stay (2.81 ± 0.02 day), increased costs (US$14,212.16 ± US$255.64),
and higher mortality rate (OR: 13.04; 95% CI: 11.08–15.35). This nationally representative
study of inpatients in the United States identified several independent risk factors
for VTE perioperatively in TKA patients and provided evidence that VTE patients after
TKA are likely to have worse results than non-VTE patients with regard to the length
of hospital stay, hospital costs, and inhospital mortality. This is a level III, prognostic
study.
Keywords
venous thromboembolic events - total knee arthroplasty - risk factors
