Inter-Laboratory Comparability of Clinical Chemistry Testing: A New Perspective

Abstract

Background/Aim: Existing external quality assurance proficiency testing may not reflect routine ‘real-world’ daily testing proficiency. The overall aim of the study was to conduct an inter-laboratory comparability testing of some routinely measured clinical chemistry analytes by selected private medical laboratories using the mentor-adept approach. Methodology: Aliquots of freshly separated plasma from a single individual (1ml) each were sent to each of the selected labs and a Teaching hospital for same-day testing. All samples were sent as ‘‘blinded-samples’’ (labelled with anonymous names, ages and attached lab request forms with clinical diagnoses) so that they would be tested as real patient samples. Results: All the labs met the acceptability criteria range for both the z-score and Precision Index. However, many of the labs had their total analytical errors for the tests outside the allowable total error ranges with both European and CLIA recommendations. Conclusion: There are relative similarities in the z-score (inter-laboratory bias) and Precision Index (inter-laboratory precision) among the labs. However, many of the labs did not meet recommended analytical goals for total analytical errors on individual samples run in a day. In the light of the findings, it is highly recommended that though laboratories should be aware of conduction of periodic external quality assurance exercises, such exercises should be done using “blinded-samples” as utilized in this current study without prior notification of the day and time of testing.