Comparative analysis of four methods for enumeration of platelet counts in thrombocytopenic patients

Abstract

Background: Even with the most reliable automated blood cell analyzers, obtaining an accurate platelet count in patients with thrombocytopenia is still challenging especially when making decisions for platelet transfusions. The Cell-Dyn Sapphire offers three methods for platelet counting including the optical, impedance, and immunological techniques. Aim: A comparative analysis evaluating the performance of these three methods, along with the manual technique, was performed in thrombocytopenic patients. Materials and Methods: A total of 32 blood samples from patients without a history of chemotherapy and a platelet count <50 ×- 109/l were tested in parallel by four different methods. Results: Compared to other techniques, impedance method provided an overestimation of platelet count (P = 0.0008) and failed to show a result in 15% of cases with low platelet counts (<15 ×- 109/l). Good to excellent correlations and reliability values were evidenced among study methods, but a poor reliability was noticed between the impedance and immunological methods with an intraclass correlation coefficient of 0.49 (confidence interval: 0.15–0.73; P = 0.003). In the bias analysis, the impedance method showed the highest levels of disagreement with other techniques. Summary/Conclusion: Collectively, these results provide evidence that the optical or immunological technique appear to be superior to the impedance method in estimating low platelet counts with the automated analyzer Cell-Dyn Sapphire. As such, the healthcare staff and the physicians must be aware of this limitation, especially in the presence of severe thrombocytopenia, when a decision of platelet transfusion has to be made.

Keywords

• Automated analyzer Cell-Dyn Sapphire
• manual method
• platelet counting
• thrombocytopenia