In Reply Mr Colombo and colleagues asked whether all D-dimer assays perform equally when using the age-adjusted D-dimer cutoff to rule out pulmonary embolism or whether different patient characteristics could explain the variability in the proportion of patients with negative D-dimer levels.
We favor the latter hypothesis. There were important differences in patient characteristics across assay subgroups. For example, mean age varied from 58 years in the VIDAS D-Dimer Exclusion group to 67 years in the Tina-quant D-Dimer group.
Righini M, Kamphuisen PW, Le Gal G. Age-Adjusted D-Dimer Cutoff Levels and Pulmonary Embolism—Reply. JAMA. 2014;312(5):557. doi:10.1001/jama.2014.7607