Comments on Point of Care D-Dimer Testing in the Emergency Department: A Bioequivalence Study

Abstract

Dear Editor We read with interest the article “Point of Care D-Dimer Testing in the Emergency Department: A Bioequivalence Study” by Per- veen et al. published in Ann Lab Med 2013;33:34-38 [1]. In this article, the authors compared the performance of the D-di- mer assays on the AQT90 FLEX analyzer (Radiometer Medical Aps, Åkandevej, Denmark) and the VIDAS analyzer (bioMérieux SA, RCS Lyon, France). The study had 2 objectives: 1. To determine any significant difference between the 2 assays in the time from sample draw until result. 2. To quantify the agreement between the results obtained by the 2 assays when performed on samples from the same sample draw. A pilot study determined that a minimum sample size of 100 patients was required for the first objective. The main study in- cluded 104 patients and revealed a significant difference be- tween the 2 assays in the time from sample draw until result. For the second objective, determining the agreement between the results obtained by the 2 assays, the pilot study did not de- termine a minimum sample size; however, the data from the 104 patients were used in this regard. Additionally, imaging re- sults were available for 40 patients in the study sample. Among these, 7 patients had positive imaging and 33 patients had negative imaging results. Only these 40 imaging results were used to calculate the sensitivity and the specificity for the 2 as-says. Therefore, we agree with the authors when they state that the sample size was not large enough to compare the clinical performance of both assays with respect to venous thrombo- embolism.