Determination of the Accuracy of Quantitative Measurement Methods in the Clinical Chemistry Laboratory at Machakos Level V Hospital, Kenya
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Date
2023
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International Journal of Current Aspects
Abstract
Accuracy is the extent to which measurements are closely related to the actual values of the
analyte. Accuracy is one of the key requirements in Laboratory method verification.
Verification is a method of ensuring that tests are carried out per the manufacturer's
specifications when tested by laboratory staff and patients at the facility. Other elements of
verification include precision, linearity verified with reportable range, uncertainty of
measurement, carry-over studies, reference ranges and limit of detection. This study aims to
determine the accuracy of the quantitative measurement methods in the Clinical Chemistry
laboratory in the month of January 2023. It also provides an alternative method for meeting
accreditation requirements on accuracy by medical laboratories seeking accreditation in farstretched laboratories where interlaboratory comparison may not be feasible. A systematic
review and meta-analysis at Machakos County, Kenya. The procedure involved analysing
commercially available internal quality control material five (5) times a day for eight (8) days
bearing the same lot number. Roche Diagnostics, Mannheim, Germany supplied all the
reagents, internal quality control materials and calibrators. Accuracy was determined using
Roche Cobas® Intergra 400 Clinical Chemistry analyser to perform a comparative descriptive
analysis of albumin, alanine aminotransferase (ALT), alkaline phosphatase (Alk Phos),
aspartate aminotransferase (AST), chloride, creatinine, Direct Bilirubin (D. Bil), Gammaglutamyl transferase (GGT), potassium, sodium, total bilirubin, total protein, and urea. The
study followed guidelines issued by the Clinical Laboratory Improvements Amendment 1988
(CLIA) and Clinical Laboratory Standards Institute (2014). Data analysis was carried out
using Excel Windows 10 MS Office 2021. Mean, standard deviation (SD), Z-score, bias %,
coefficient of variation (CV) %, and total error allowable (Tea) were calculated from the results
of measurement of the analytes. All the analytes achieved a mean which fell within the
manufacturer verification interval and hence passed. The bias % score for the analytes was as
follows 5 analytes level (19.2%) scored 0 - ±1, 10 analytes level (38.5%) scored ±1.1 - ±2, 7
analytes level (26.9%) ±2.1 - ±3 and 4 analytes level (15.4%) scored above ±3. All analytes
were found to have an excellent Z-score performance between 0 to ± 1.96. The total error
allowable was found to fall within CLIA and CLSI specifications limits except for chloride
PCC1/ Normal control which failed at 5.82% (CLIA target being ± 5%). Analytes' mean was
expected to fall within the given manufacturer's mean. The bias % for the analytes which was
at zero or near ± zero was considered an excellent score the further away the score was, the
poorer the performance. The Z-score was also calculated to establish how far the observed
mean fell from the target mean. All analytes were found to have an excellent Z-score
performance between 0 to ± 1.96. A Z-score of ± 1.96 to ± 2.57 indicates good performance while a Z-score of over ± 2.58 indicates failed performance. These good results are attributable
to the fact that analysis was carried out within a very short duration by the same person, on
the state-of-the-art instrument, in a well-controlled environment hence no room for analytical
variation. Chloride being an electrolyte failed since it is physiologically controlled in a strict
and narrow range.
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Citation
Mutie, C., Mathenge, S., & Warutere, P., (2023). Determination of the Accuracy of Quantitative Measurement Methods in the Clinical Chemistry Laboratory at Machakos Level V Hospital, Kenya. International Journal of Current Aspects, 7(3), 61-78. https://doi.org/10.35942/05q2nv90