Evaluation of a simplified filtration technique for the routine measurement of erythrocyte deformability

The purpose of this study was to assess the value of a widely-used simplified filtration technique (mini-test) by comparing it, in parallel experiments, with a constant-flow rate method currently used in our laboratory for the measurement of erythrocyte deformability. Both methods employed 3 micrometer pore-diameter Nucleopore membranes and were performed under different flow conditions, using washed erythrocyte suspensions. In a total of 49 evaluable test pairs obtained from blood samples of 55 patients with either diabetes mellitus [36], post-splenectomy status [13] or haemolytic anaemia [6], we observed a sensitivity of 40% and a specificity of 75.5% for the mini-test versus our reference method. A near 20-fold lower cell/pore ratio appears as the single most important technical difference explaining the apparent lack of sensitivity of the mini-test. Suggestions are given as to how to modify the mini-test in order to obtain maximum sensitivity in the future.