Patient selection: primary hip or knee arthroplasty
Key risk factors for a clinically significant thromboembolic event:
(1) obesity (BMI >= 30 kg per square meter, with risk increasing with increasing BMI)
(2) ASA class 3 or 4 (a primary arthroplasty is unlikely in a patient ASA class 5)
(3) failure to provide thromboprophylaxis
where:
• Protection was greater for aspirin or subcutaneous unfractionated heparin as compared to warfarin or low molecular weight heparin (odds ratio 0.2 vs 0.4).
Additional factors:
(1) history of previous thromboemboli (seen in only a subset of patients)
(2) immobility following surgery (not one of the listed potential risk factors)
(3) admission to the ICU after surgery (correlates with higher ASA class)
(4) use of arterial catheter monitoring (correlates with higher ASA class)
