Inefficacy of moving average algorithm as principal quality control procedure on Technicon System H6000

Area of Science:

• Clinical Pathology
• Hematology
• Medical Laboratory Science

Background:

• Bull's algorithm is a standard quality control (QC) method for multichannel hematological analyzers.
• Its effectiveness is challenged by simultaneous analytical drift in red blood cell (RBC) and hemoglobin (Hgb) counts, which can mask issues when mean corpuscular volume (MCV) remains stable.

Purpose of the Study:

• To investigate the limitations of Bull's algorithm in detecting analytical drift in hematological parameters.
• To assess the impact of undetected drifts on erythrocytic indices like mean corpuscular hemoglobin (MCH) and mean corpuscular hemoglobin concentration (MCHC).

Main Methods:

• Analysis of data from the Technicon System H6000.
• Utilized commercial controls and fresh blood samples for routine daily QC monitoring.
• Observed and quantified reproducible positive drifts in RBC, Hgb, and calculated hematocrit (Hct) over time.

Main Results:

• A reproducible positive drift in RBC and Hgb, and consequently Hct, was observed, proportional to instrument usage time.
• Bull's QC scheme showed reduced efficacy, failing to detect 'out of control' situations in 38% of MCV, 15% of MCH, and 13% of MCHC monitoring cases.
• The simultaneous drift of RBC and Hgb, with unaffected MCV, led to a null effect on MCH and MCHC, rendering the algorithm less sensitive.

Conclusions:

• Bull's algorithm, in its revisited formulation, has limitations in detecting specific analytical drifts in hematological analyzers.
• The phenomenon of concomitant RBC and Hgb drift poses a risk for inaccurate QC, potentially leading to undetected errors in patient results.
• Alternative or supplementary QC strategies may be necessary to ensure comprehensive quality control in hematology laboratories.