Inter-laboratory variability of haemoglobin measurements obtained from selected clinical laboratories in Kenya

Abstract

Background: Accurate and precise tests results generated by clinical laboratories would assist correct decision making in the diagnosis and management of patients. Quality assurance, which comprises of internal quality control (IQC) and external quality assessment (EQA), is intended to ensure the reliability of the laboratory results.

Objectives: To evaluate the inter-laboratory variation of haemoglobin (Hb) measurements.

Design: A descriptive cross-sectional study.

Subjects: EQA samples with low (A), normal (B) and high (C) Hb concentrations

Setting: A total of 292 clinical laboratories selected from 21 out of 47 Kenyan Counties. Main outcome measures: Mean deviation from the expected mean of the references and coefficient of variation (CV).

Results: A total of 68%, 64% and 51% of laboratories gave accurate results for the sample A, B and C respectively. Based on the Clinical Laboratory Improvement Amendments of 1988 (CLIA’88) criteria, 61% of laboratories had acceptable performance. Interlaboratory variation of 33.3%, 25.1% and 29.4% for samples A, B and C was recorded irrespective of the analyser a laboratory used. When grouped according to the type of analyser, CV reduced to 5.1% (Haemocontrol) to 41% (Urit) for sample A, 2.2% (Celltac) to 35% (Diaspect) for sample B and 3.4% (Medonic) to 42.6% (Diaspect) for sample C. These differences were statistically significant (p <0.001) across all Hb concentrations.

Conclusions: The inter-laboratory variation in Hb measurements resulted from variation in methodologies and types of analysers. Regular participation in External Quality Assessment Schemes (EQAS) is essential in order to achieve inter-laboratory comparability of Hb results.