Diagnostics
Performance Assessment of Centrifugation-Based Hematocrit Testing in Primary Care Units: Evidence from Seventy-Two Proficiency Testing Datasets over Eight Years
By Watcharinthon Theansun, Kunchit Kongros, Napaporn Apiratmateekul and 5 others.
Abstract
Background
Centrifugation-based hematocrit (Hct) testing remains widely used in decentralized primary care settings where access to automated hematology analyzers may be limited. Appropriate proficiency testing (PT) performance assessment therefore requires consideration of the analytical variability associated with this measurement method. This study evaluated longitudinal PT data to characterize method-specific variability and compare alternative approaches to RSD estimation for centrifugation-based Hct testing.
Methods
Seventy-two datasets from 32 PT rounds conducted during 2017–2024 were analyzed, with 12 to 310 participants per dataset. PT materials were assessed for homogeneity and stability in accordance with ISO 13528. The relative standard deviation (RSD) was estimated using two approaches: Method A, based on all statistically processed valid results to reflect total interlaboratory variability, and Method B, based on the satisfactory-performance subset (∣z∣ ≤ 2), within which robust statistics were recalculated. Temporal trends were evaluated by linear regression using dataset-specific RSD values. Sensitivity analysis evaluated Method B using alternative z-score inclusion thresholds of ∣z∣ ≤ 1.5, 2.0, 2.5, and 3.0. Performance classifications in 2024 were compared descriptively.