March, 2018 Quick Question: D-dimer Controls

Here are the results of our March, 2018 Quick Question about the appropriate D-dimer controls.

What controls are most valid for managing D-dimer assay precision?

1. VTE decision point control only; 500 ng/mL FEUs 10% (3)
2. Low end of linearity & VTE decision point: 100 and 500 ng/mL FEUs: 32% (10)
3. Low and high ends of linearity & VTE decision point: 100, 500 & 2000 ng/mL FEUs: 19% (6)
4. VTE decision point & high end of linearity: 500 & 2000 ng/mL FEUs 26% (8)
5. Low and high ends of linearity: 100 & 2000 ng/mL FEUs 13% (4)

There is a nearly even distribution among answers 2, 3, and 4, illustrating the variety of approaches and reporting formats that affect D-dimer assays, reflecting perhaps varying emphasis on the importance of accuracy at the low and high ends of D-dimer linearity. Apparently we generally agree that accuracy at the VTE decision point is necessary. See this editorial describing the need to harmonize D-dimer reporting: Longstaff C, Adcock D, Olson JD, Jennings I, Kitchen S, Mutch N, Meijer P, Favaloro EJ, Lippi G, Thachil J. Harmonisation of D-dimer – A call for action. Thromb Res. 2016;137:219–20. See also Olson JD, Cunningham MT, Higgins RA, Eby CS, Brandt JT. D-dimer: simple test, tough problems. Arch Pathol Lab Med. 2013;137:1030–8.