prevents blood clots just as well as a commonly used and more expensive blood-thinning drug does

prevents blood clots just as well as does a commonly used and a more expensive blood-thinning drug

prevents blood clots just as well as will a commonly used and more expensive blood-thinning drug

works just as well as a commonly used and more expensive blood-thinning drug at the prevention of blood clots

works just as well as does a commonly used blood-thinning drug, which is also more expensive, at preventing blood clots