A COMPARISON OF ANTICOAGULANTS (AC) FOR VENOUS THROMBOEMBOLISM (VTE) PROPHYLAXIS (PROPH) AFTER ORTHOPEDIC SURGERY (OS) USING A CLINICAL COST-EFFECTIVENESS ANALYSIS (CEA) APPROACH

Abstract number: P-M-571

Lazo-Langner¹ A., Coyle² D.A., Barrowman³ N.J., Ramsay² T., Wells¹ P.S., Scarvelis¹ D., Forgie¹ M.A., Rodger¹ M.A.

¹¹Hematology, Ottawa Hospital ²²Epidemiology, U. Ottawa ³³Chalmers Research Group, CHEO, Ottawa, Canada

How-to-cite Lazo-Langner A, Coyle DA, Barrowman NJ, Ramsay T, Wells PS, Scarvelis D, Forgie MA, Rodger MA. A COMPARISON OF ANTICOAGULANTS (AC) FOR VENOUS THROMBOEMBOLISM (VTE) PROPHYLAXIS (PROPH) AFTER ORTHOPEDIC SURGERY (OS) USING A CLINICAL COST-EFFECTIVENESS ANALYSIS (CEA) APPROACH. J Thromb Haemost 2007; 5 Supplement 2: P-M-571

Abstract

Introduction: No study has compared all available AC for VTE proph after OS. This can be done with a clinical CEA where benefits (e.g. averting VTE) and risks (e.g. major bleed-MB) are considered together, which is necessary when evaluating a risky therapy.

Methods: A meta-analysis was done to estimate proportions of risks (MB) and benefits (averted VTE) of AC proph and placebo (PL) in OS. The estimates' means and variances were used to parametrize Monte Carlo simulations for beta distributions using 3,000 replications. Analyses were done for major VTE (mVTE; proximal deep vein thrombosis (DVT) + pulmonary embolism) and total VTE (tVTE; major VTE + distal DVT). Incremental risk and benefit of AC vs PL and risk-benefit ratios were calculated from the replications. AC were compared across a range of benefit-risk tradeoff (BRT) values by calculating the percentage of replications with the highest net clinical benefit (e.g. incremental benefit - incremental risk x BRT) for each AC. The reference BRT was estimated using case-fatality rate ratios of VTE to MB (mVTE/MB=0.39; tVTE/MB=0.10). Sensitivity analyses were done for predefined subgroups.

Results: The table shows the percentage of net risk-beneficial interventions for 5 AC and PL that would be obtained if all were compared in a single trial, divided according to risk acceptance (e.g. the BRT value for mVTE-tVTE to MB).

Table:

	All AC mVTE/MB	All AC tVTE/MB	Xim excluded mVTE/MB	Xim excluded tVTE/MB
Placebo	0	0	0.1	0
Ximelagatran	87.8	64.7	–	–
LMWH	0.2	11.1	16.9	51.4
Heparin	0	5.8	0	17
Warfarin	5.1	2.1	61.5	8.2
Fondaparinux	6.9	16.3	21.5	23.4
Xim, Ximelagatran.

Conclusions: We obtained an estimate of what would result in a trial of all analyzed AC vs PL considering risk and benefit conjointly. The AC of choice varied depending on risk acceptance, outcome, AC initiation timing, MB definition (ISTH-like –if similar to ISTH definition- vs all definitions) and type of OS. These results raise questions regarding generalizability and best outcome definition in OS proph trials.

To cite this abstract use the following format:

Journal of Thrombosis and Haemostasis 2007; Volume 5, Supplement 2: abstract number

Session Details

Date:	01/08/2007
Time:	00:00-00:00
Session name:	XXIst ISTH Congress
Subject:
Location:	Oxford, UK
Presentation type:
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