Point-of-care microvolume cytometer measures platelet counts with high accuracy from capillary blood

Dickerson, William M.; Yu, Rebecca; Westergren, Helena U.; Paraskos, Jonathan; Schatz, Philipp; Tigerstrom, Anna; Ekman, Anna; Sánchez, José; Cheng, Jamie; Li, Lillian; Chan, Eugene Y.

BACKGROUND: Point-of-care (PoC) testing of platelet count (PLT) provides real-time data for rapid decision making. The goal of this study is to evaluate the accuracy and precision of platelet counting using a new microvolume (8 μL), absolute counting, 1.5 kg cytometry-based blood analyzer, the rHEALTH ONE (rHEALTH) in comparison with the International Society of Laboratory Hematology (ISLH) platelet method, which uses a cytometer and an impedance analyzer. METHODS: Inclusion eligibility were healthy adults (M/F) ages 18–80 for donation of fingerprick and venous blood samples. Samples were from a random N = 31 volunteers from a single U.S. site. Samples were serially diluted to test thrombocytopenic ranges. Interfering substances and conditions were tested, including RBC fragments, platelet fragments, cholesterol, triglycerides, lipids, anti-platelet antibodies, and temperature. RESULTS: The concordance between the rHEALTH and ISLH methods had a slope = 1.030 and R(2) = 0.9684. The rHEALTH method showed a correlation between capillary and venous blood samples (slope = 0.9514 and R(2) = 0.9684). Certain interferents changed platelet recovery: RBC fragments and anti-platelet antibodies with the ISLH method; platelet fragments and anti-platelet antibodies on the rHEALTH; and RBC fragments, platelets fragments, triglycerides and LDL on the clinical impedance analyzer. The rHEALTH’s precision ranged from 3.1–8.0%, and the ISLH from 1.0–10.5%. CONCLUSIONS: The rHEALTH method provides similar results with the reference method and good correlation between adult capillary and venous blood samples. This demonstrates the ability of the rHEALTH to provide point-of-care assessment of normal and thrombocytopenic platelet counts from fingerprick blood with high precision and limited interferences.