Analytical Performance Evaluation of Three Point-of-Care CBC Analyzers for Management of Clozapine Therapy in Ambulatory Psychiatry Clinics

Abstract

Abstract Background Clozapine is a first-line therapy and the only FDA-approved drug for patients with treatment-resistant schizophrenia (TRS). However, frequent measurement of absolute neutrophil count (ANC) is required to monitor for potential adverse severe neutropenia from clozapine therapy. We evaluated 3 point-of-care (POC) instruments that perform the complete blood count (CBC) with differential to assess their analytical performance and potential to meet the clinical need for clozapine therapy management. Methods A CBC with differential was performed on 104 residual whole blood specimens using 3 CBC analyzers (Sight OLO, PixCell HemoScreen, and Sysmex pocH-100i) to assess analytical precision, linearity, and accuracy vs the ADVIA 2120i and manual differential reference methods. Clinical concordance of ANC between POC devices and manual differential at medical decision points for mild, moderate, or severe neutropenia, and the threshold for clozapine therapy discontinuation (1.0 × 109/L) were determined. Results For CBC parameters, a CV ≤ 6.4% was observed on the OLO, CV ≤ 6.2% for the HemoScreen, and CV ≤ 5.1% with the pocH-100i. Each device accurately identified ANC with the greatest mean bias ±0.42 × 109/L using the pocH-100i vs manual differential. For results near the medical decision points (ANC <1.5 × 109/L), clinical concordance of ANC results was 55.6% for the OLO, 89.5% for the HemoScreen, and 82.4% for the pocH-100i. Conclusions The HemoScreen device demonstrated the best clinical concordance in ANC values at medical decision thresholds for clozapine therapy management.