Pulmonary Embolism After Total Knee Arthroplasty

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By ICJR Staff - October 14, 2013

Pulmonary Embolism After Total Knee Arthroplasty

Primary Author: Nicholas B. Schraut

Institution: University of Illinois at Chicago – Department of Orthopaedic Surgery, Chicago, IL, USA

Co-Authors: Vincent Moretti (University of Illinois at Chicago – Department of Orthopaedic Surgery, Chicago, IL, USA), Ritesh Shah (Illinois Bone and Joint Institute, Morton Grove, IL, USA)

INTRODUCTION: Pulmonary embolism (PE) is a rare but potentially devastating complication of total knee arthroplasty (TKA). The purpose of this study was to assess recent national trends in PE occurrence after TKA and evaluate patient outcomes.

METHODS: International Classification of Disease-9th Revision (ICD-9) procedure codes were used to search the National Hospital Discharge Survey (NHDS) for patients admitted to U.S. hospitals after primary TKA for the years 2001-2010. ICD-9 diagnosis codes were used to identify patients who developed an acute PE during the same admission.

Data regarding patient demographics, hospitalization length, discharge disposition, lower-extremity deep vein thrombosis (DVT), mortality, and hospital size/location were gathered. Trends were evaluated by linear regression with Pearson’s correlation coefficient(r), and statistical comparisons were made using Student’s t-test, z-test for proportions, and chisquare analysis with a significance level of 0.05.

RESULTS: 35,220 patients admitted for primary TKA were identified; 159 (0.045%) of these patients developed an acute PE during the same admission. After adjusting for fluctuations in annual TKA performed, the development of PE after TKA demonstrated a weak negative correlation with time (r=0.17, Figure 1), insignificantly decreasing from an average rate of 0.049% between 2001 and 2005 to 0.041% between 2006 and 2010 (p=0.26). The size of the hospital was found to significantly impact the incidence of PE and primary TKA, with the lowest rate seen in hospitals under 100 beds (0.23%) and the highest rate seen in those with over 500 beds (0.65%, p=0.01). No significant differences in PE incidence were noted based on U.S. region (p=0.38).

The mean age of patients with PE was 67.7 years. This group included 54 men and 105 women. The non-PE group had a mean patient age that was insignificantly lower at 66.6 years (p=0.21) and included 12,450 men and 22,611 women. Gender was also not significantly different (p=0.68) between PE groups. The number of medical comorbidities was significantly higher in those with PE (mean 6.42 diagnoses) than those without PE (mean 4.89 diagnoses, p<0.01). Average hospitalization length also varied based on PE status, with significantly longer stays for those with PE (8.2 days versus 3.7 days, p<0.01). The rate of DVT was higher in the PE group (12.7% versus 0.48%, p<0.01). Mortality was also significantly higher for the PE group (3.9% versus 0.09%, p<0.01). Discharge disposition did not significantly vary based on PE status, with 61.5% of PE patients and 64.0% of non-PE patients able to go directly home (p=0.59) after their inpatient stay.

DISCUSSION/CONCLUSION: This study demonstrates that PE can have a significant impact on patient outcomes and healthcare costs, with associated 43-fold increase in mortality and a doubling of the inpatient admission duration. Additionally, although the risk of PE after primary TKA remains rare, efforts to prevent or minimize this complication over the last 10 years have not had a significant impact on its occurrence. This risk of PE appears to be greatest in patients with multiple medical comorbidities and established DVTs. Interestingly, the PE rate also demonstrated variability based on hospital size.