title: A Comparison of Two Dosing Regimens of ASA Following Total Hip and Knee Arthroplasties.
abstract: The purpose of this study was to compare short-term side effects of aspirin (ASA) 325 mg vs ASA 81 mg orally twice daily (PO BID) when used as thromboembolic prophylaxis following primary total joint arthroplasty.
  
  
  
  A 1-year prospective cohort study was performed on 643 primary unilateral total joint arthroplasty patients operated on by a single surgeon. Two hundred eighty-two patients were administered ASA 325 mg PO BID and 361 patients were administered ASA 81 mg PO BID for 1 month. A questionnaire assessing the side effects of ASA intake was administered 1 month postoperatively.
  
  
  
  The overall rate of gastrointestinal side effects (GI upset and nausea) was 1.9%, but ASA 325 mg had a higher rate 9/282 (3.2%) than ASA 81 mg 3/361 (0.8%), P = .04. Overall GI bleeding was 0.9%, with 2/282 (0.7%) in the ASA 325 mg group, vs 4/361 (1.1%) in the ASA 81 mg group, P = .70. One patient in the ASA 81 mg group (0.3%) developed a deep vein thrombosis. No patient developed pulmonary embolism, periprosthetic joint infection, tinnitus, wheezing and/or shortness of breath, chest pain, or headaches. In the ASA 325 mg group, 9/282 (3.2%) discontinued ASA and in the ASA 81 mg group, 8/361 (2.2%) discontinued ASA, P = .47. Four patients in the ASA 325 group (1.4%) changed to ASA 81 mg.
  
  
  
  ASA 81 mg is associated with significantly less GI distress and nausea compared with ASA 325 mg. GI bleeding was equally prevalent between the 2 dosing regimens, so patients need to be informed of this risk regardless of the ASA dose.
authors.affiliation: Department of Orthopaedic Surgery, Kaiser Permanente, San Francisco, California.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Feldstein
authors.affiliation: Department of Orthopaedic Surgery, Albert Einstein Medical Center, Philadelphia, Pennsylvania.
authors.forename: Sara L
authors.initials: SL
authors.lastname: Low
authors.affiliation: Department of Orthopaedic Surgery, Sidney Kimmel Medical School at Thomas Jefferson University, Rothman Institute, Philadelphia, Pennsylvania.
authors.forename: Antonia F
authors.initials: AF
authors.lastname: Chen
authors.affiliation: Department of Orthopaedic Surgery, Sidney Kimmel Medical School at Thomas Jefferson University, Rothman Institute, Philadelphia, Pennsylvania.
authors.forename: Laura A
authors.initials: LA
authors.lastname: Woodward
authors.affiliation: Department of Orthopaedic Surgery, Sidney Kimmel Medical School at Thomas Jefferson University, Rothman Institute, Philadelphia, Pennsylvania.
authors.forename: William J
authors.initials: WJ
authors.lastname: Hozack
mesh_terms: D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects*; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects*; D001241:Aspirin / Q000008:administration & dosage*; D002985:Clinical Protocols; D005260:Female; D005343:Fibrinolytic Agents / Q000008:administration & dosage*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011655:Pulmonary Embolism / Q000209:etiology; D013923:Thromboembolism / Q000209:etiology / Q000517:prevention & control*; D020246:Venous Thrombosis / Q000209:etiology
chemical_list: D005343:Fibrinolytic Agents; D001241:Aspirin
keywords: aspirin; dose; gastrointestinal upset; thromboprophylaxis; total joint arthroplasty