Prophylaxis Against Venous Thromboembolism After Hip Surgery-Reply

In Reply. —The literature on prevention of venous thromboembolism following total hip replacement is highly controversial. The overall tone of Dr Megerman's comments reflects the controversy and uncertainty in this area and highlights the need for meta-analysis. We were aware of the different mechanisms of action between intermittent pneumatic compression and static elastic compression. Megerman erroneously assumes, however, that different mechanisms of action translate into different efficacies. We combined these mechanical modalities because of separate crude risks that were no different clinically or statistically. This preliminary analysis consisted of simple tabulation of numerators and denominators for each modality and was determined separately from our more detailed analysis. We carefully considered how to include the few treatment arms that combined pharmacologic and mechanical modalities. As stated in the article, our assignment of these combination groups to the pharmacologic arm was arbitrary but made more clinical sense than assignment to the mechanical