[Harmonization of practices: application to the measurement of enzymatic activities used in prevention, screening, diagnosis and therapeutic monitoring].
The large metrological variation (CV, about 25%) observed between laboratories, at the national French level, for the measurement of enzymatic activities results in a loss of efficiency in using laboratory results. Current data show that the standardisation of methods is insufficient to solve this problem and needs to be completed by an harmonisation of the practices including the use of a common reference (calibrator). The present work, carried out by the joint working group between laboratories of the Centres for Periodic Health Examination and the French Society of Clinical Biology (SFBC), deals mainly with the feasibility and evaluation of the improvement of the consistency of the results. Twenty laboratories participated in this study. Five independent surveys were conducted during an height month period. Two enzymes were selected because of their clinical importance and their interest in prevention, screening, diagnosis or epidemiology: ALT (alanine aminotransferase) and GGT (gamma-glutamyltransferase). In each survey three kinds of samples i.e. control sera, candidate calibrators and human serum pools, each of them at two levels of activity (one physiological and the other pathological) were measured in duplicate. The low intra-laboratory imprecision and the high degree of the standardisation of used methods, due to an important effort previously done in this field, permitted to consider a common calibration. The stability and mainly the commutability, i.e. the ability for the candidate calibrator to show a behaviour similar to that of human samples towards the used methods, allowed to reduce the inter-laboratory variation by a half to two third-fold, reaching a coefficient of variation < 5% similar to those observed for cholesterolemia or glycemia. This level of consistency should permit to use common reference limits and common decision limits, after validation of this approach in real practice. The consequences of the harmonisation of practices, extended to the all laboratories, exceed largely the scope of this study. The reduction of the uncertainty and a better approach of the accuracy for the measurement of enzymatic activities should led to a real benefit for the patients in terms of prevention, screening, diagnosis or therapeutic monitoring and consequently for the public health.
Schiele
F
F
Laboratoire de biologie clinique, Centre de médecine préventive, 2, avenue du Doyen-Jacques-Parisot, 54500 VandOEuvre-lès-Nancy.
Férard
G
G
Lessinger
J M
JM
Henny
J
J
D000410:Alanine Transaminase / Q000097:blood; D002138:Calibration; D004796:Clinical Enzyme Tests / Q000592:standards*; D004812:Epidemiologic Methods; D005602:France; D006801:Humans; D007753:Laboratories / Q000592:standards*; D011785:Quality Assurance, Health Care; D011786:Quality Control; D012016:Reference Values; D015203:Reproducibility of Results; D012958:Societies, Scientific; D005723:gamma-Glutamyltransferase / Q000097:blood
D005723:gamma-Glutamyltransferase; D000410:Alanine Transaminase