title: Symptomatic pulmonary embolus after joint arthroplasty: stratification of risk factors.
abstract: BACKGROUND
  Prophylaxis for pulmonary embolism (PE) after total joint arthroplasty (TJA) presents the clinical dilemma of balancing the risk of postoperative thrombotic risk and anticoagulation-related complications such as bleeding, hematoma formation, and infection. Risk stratification of patients undergoing TJA is needed to tailor prophylaxis based on thrombotic and bleeding risk.
  
  
  OBJECTIVE
  The purpose of this study was to identify the preoperative comorbidities that were associated with an increased risk of symptomatic PE after joint arthroplasty in a large group of patients who had TJAs and who were treated with either aspirin or warfarin.
  
  
  METHODS
  We conducted a retrospective study of 26,391 primary and revision TJAs performed at our institution between January 2000 and April 2011. A total of 24,567 patients received warfarin prophylaxis for 6 weeks (targeted international normalized ratio of 1.5-2.0) and 1824 patients received 325 mg aspirin twice daily. Symptomatic patients with decreased oxygen saturation were evaluated for PE using either a ventilation/perfusion scan or multidetector CT scan. Symptomatic PEs occurring in patients within 90 days postoperatively identified with CT or ventilation/perfusion scans were considered complications related to surgery, and fatal PEs were those that occurred in patients who died during the hospital admission owing to cardiopulmonary failure after PE. Using a logistic regression analysis, a nomogram was created to predict postoperative symptomatic PE risk.
  
  
  RESULTS
  Risk of postoperative symptomatic PE after primary and revision TJAs was 1.1%. Risk of postoperative fatal PE was 0.02%. Elevated BMI (p < 0.035), procedures on the knee (p < 0.006), higher Charlson Comorbidity Index (p < 0.015), chronic obstructive pulmonary disorder (p = 0.006), atrial fibrillation (p < 0.001), anemia (p < 0.001), presence of deep vein thrombosis (p < 0.001), and depression (p = 0.012) were independent risk factors for symptomatic PE. Based on these risk factors and derived scoring criteria, patients can be classified into low- (0.35%), medium- (1.4%), and high- (9.3%) risk categories.
  
  
  CONCLUSIONS
  Patients who are obese, undergo knee procedures, have an elevated Charlson Comorbidity Index, chronic obstructive pulmonary disease, atrial fibrillation, anemia, depression, or postoperative deep vein thrombosis are at greater risk of having a postoperative PE develop. These risk factors should be considered when deciding on postoperative anticoagulation prophylaxis.
  
  
  METHODS
  Level IV, therapeutic study. See the Instructions for Authors for a complete description of levels of evidence.
authors.affiliation: Department of Orthopaedic Surgery, Rothman Institute, Thomas Jefferson University Hospital, 925 Chestnut Street, 5th Floor, Philadelphia, PA, 19107, USA.
authors.forename: Javad
authors.initials: J
authors.lastname: Parvizi
authors.forename: Ronald
authors.initials: R
authors.lastname: Huang
authors.forename: Ibrahim J
authors.initials: IJ
authors.lastname: Raphael
authors.forename: William V
authors.initials: WV
authors.lastname: Arnold
authors.forename: Richard H
authors.initials: RH
authors.lastname: Rothman
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000627:therapeutic use*; D019643:Arthroplasty, Replacement / Q000009:adverse effects* / Q000401:mortality; D001241:Aspirin / Q000627:therapeutic use*; D016009:Chi-Square Distribution; D002648:Child; D015897:Comorbidity; D003661:Decision Support Techniques; D005260:Female; D005343:Fibrinolytic Agents / Q000627:therapeutic use*; D017052:Hospital Mortality; D006801:Humans; D016014:Linear Models; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D061330:Multidetector Computed Tomography; D049451:Nomograms; D018579:Patient Selection; D055420:Perfusion Imaging; D015143:Philadelphia; D011655:Pulmonary Embolism / Q000175:diagnosis / Q000453:epidemiology / Q000401:mortality / Q000517:prevention & control*; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D016896:Treatment Outcome; D014859:Warfarin / Q000627:therapeutic use*; D055815:Young Adult
chemical_list: D000925:Anticoagulants; D005343:Fibrinolytic Agents; D014859:Warfarin; D001241:Aspirin