Low molecular weight heparin
Sir, - In light of the recent article 'Prevention of deep leg vein thrombosis' (Aust Prescr 1998;21:37-9), and in accordance with accepted orthopaedic practice, is it not irrational that low molecular weight heparin is still not on PBS authority prescription for total knee replacement? This anomaly has been apparent to orthopaedic surgeons for several years and needs to be corrected.

J.S. Quain
Orthopaedic Surgeon
Darlinghurst, N.S.W.

PBAC response:
Listing of low molecular weight heparins for the prevention of deep venous thrombosis following knee replacement surgery would require that the sponsors of these drugs submit detailed data demonstrating that the legislative requirements of listing in this indication are met. To date, the PBAC has considered the listing of only one low molecular weight heparin in this condition. Applications concerning this item were rejected because these were not based on head-to-head comparisons with non-fractionated heparin, and insufficient data were provided on the background incidence of proximal deep vein thromboses following knee surgery. Thus, the data provided were inadequate to establish the incremental benefit and cost-effectiveness of this product for this indication.

To date, none of the manufacturers of other low molecular weight heparins have tendered data supporting the listing of these products as prophylaxis against deep vein thrombosis in patients undergoing knee replacement surgery. Under these circumstances, the PBAC is not in a position to recommend listing as suggested by Dr Quain.