Changing patterns of pharmacological thromboprophylaxis use by orthopaedic surgeons in New Zealand

Background: A survey conducted in 1992 found that New Zealand orthopaedic surgeons relied on non-pharmacological methods of deep vein thrombosis prevention in most arthroplasty patients and almost all hip fracture patients. This survey was repeated in 1999 to ascertain whether this pattern of use had changed. Methods: All orthopaedic consultants in New Zealand who performed hip or knee surgery in 1999 were asked to complete a one-page postal questionnaire, asking for information regarding: the frequency with which chemoprophylaxis was employed in patients undergoing surgery for hip fracture, hip arthroplasty, or knee arthroplasty; the drug regimes used; the factors that influenced the choice of chemoprophylaxis; and the factors that limited chemoprophylaxis use in orthopaedic practice. Results: Between 1992 and 1999, the proportion of patients given chemoprophylaxis increased from 3% to 25% for patients with hip fracture, and from 32% to 57% for elective arthroplasty patients. The proportion of surgeons using low molecular weight heparin increased over the 7-year period from 55% to 76%, while aspirin use remained stable at 7% and standard heparin and warfarin decreased to less than 5%. There was a shift away from starting chemoprophylaxis preoperatively towards continuing until discharge, rather than until the patient was mobile. Opinions on indications and contraindications for chemoprophylaxis had not changed substantially during the 7-year period. Conclusions: Orthopaedic surgeons' use of chemoprophylaxis has increased in New Zealand. However, since hospital stays have decreased considerably and most orthopaedic patients are now discharged within a fortnight, prophylaxis may now cover a shorter duration of the at-risk period.