D-dimer strategy v repeated US in suspected DVT with negative results on proximal vein US and no DVT on initial testing*

Outcome at 6 monthsD-dimerRepeated USRRI (95% CI)NNH
*DVT  =  deep venous thrombosis; US  =  ultrasonography. Other abbreviations defined in glossary; RRI, NNH, and CI calculated from data in article.
Symptomatic DVT2.1%1.3%64% (−43 to 372)Not significant