title: Low-Dose Aspirin Is Effective Chemoprophylaxis Against Clinically Important Venous Thromboembolism Following Total Joint Arthroplasty: A Preliminary Analysis.
abstract: BACKGROUND
  Aspirin is a safe and effective prophylaxis for the prevention of venous thromboembolism following total joint arthroplasty. The optimal dose of aspirin prophylaxis is unknown. Our hypothesis was that lower-dose aspirin is as effective as higher-dose aspirin for the prevention of venous thromboembolism and is associated with fewer gastrointestinal side effects.
  
  
  METHODS
  In a prospective, crossover study, we analyzed 4,651 primary total joint arthroplasty cases performed from July 2013 to June 2015. For 4 weeks, 3,192 patients received enteric-coated 325-mg aspirin twice daily (the 325-mg aspirin group) and 1,459 patients received 81-mg aspirin twice daily (the 81-mg aspirin group). There were no significant differences (p > 0.05) in sex, body mass index, or Charlson Comorbidity Index between the two patient populations. Recorded complications occurring within 90 days postoperatively included symptomatic venous thromboembolism (deep venous thrombosis and pulmonary embolism), gastrointestinal complications, acute periprosthetic joint infection, and death.
  
  
  RESULTS
  The incidence of venous thromboembolism of 0.1% (95% confidence interval [CI], 0% to 0.3%) in the 81-mg aspirin group (1 with deep venous thrombosis and 1 with pulmonary embolism) was not significantly different (p = 0.345) from 0.3% (95% CI, 0.1% to 0.6%) in the 325-mg aspirin group (7 with deep venous thrombosis and 5 with pulmonary embolism). The incidence of gastrointestinal bleeding or ulceration of 0.3% (95% CI, 0% to 0.5%) in the 81-mg aspirin group was slightly, but not significantly (p = 0.66), lower than the 0.4% (95% CI, 0.2% to 0.6%) in the 325-mg aspirin group. The incidence of acute periprosthetic joint infection was 0.2% (95% CI, 0% to 0.4%) in the 81-mg aspirin group compared with 0.5% (95% CI, 0.2% to 0.7%) in the 325-mg aspirin group (p = 0.28). The 90-day mortality rate was similar in both groups at 0.1% (95% CI, 0% to 0.2%) in the 81-mg aspirin group and 0.1% (95% CI, 0% to 0.2%) in the 325-mg aspirin group (p = 0.78).
  
  
  CONCLUSIONS
  Our study demonstrates that low-dose aspirin is not inferior to high-dose aspirin for venous thromboembolism prophylaxis following total joint arthroplasty. This is not unexpected, as the available literature demonstrates that low-dose aspirin is as effective as higher-dose aspirin in the prevention of acute coronary syndrome and cerebrovascular events.
  
  
  METHODS
  Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.
authors.affiliation: 1Rothman Institute at Thomas Jefferson University Hospital, Philadelphia, Pennsylvania.
authors.forename: Javad
authors.initials: J
authors.lastname: Parvizi
authors.forename: Ronald
authors.initials: R
authors.lastname: Huang
authors.forename: Camilo
authors.initials: C
authors.lastname: Restrepo
authors.forename: Antonia F
authors.initials: AF
authors.lastname: Chen
authors.forename: Matthew S
authors.initials: MS
authors.lastname: Austin
authors.forename: William J
authors.initials: WJ
authors.lastname: Hozack
authors.forename: Jess H
authors.initials: JH
authors.lastname: Lonner
mesh_terms: D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects*; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects*; D001241:Aspirin / Q000008:administration & dosage*; D018890:Chemoprevention; D018592:Cross-Over Studies; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D005260:Female; D005343:Fibrinolytic Agents / Q000008:administration & dosage*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000209:etiology / Q000517:prevention & control; D011446:Prospective Studies; D054556:Venous Thromboembolism / Q000209:etiology / Q000517:prevention & control*
chemical_list: D005343:Fibrinolytic Agents; D001241:Aspirin