The Asian project for collaborative derivation of reference intervals: (2) results of non-standardized analytes and transference of reference intervals to the participating laboratories on the basis of cross-comparison of test results

Abstract

Background: The 2009 Asian multicenter study for derivation of reference intervals (RIs) featured: 1) centralized measurements to exclude reagent-dependent variations; 2) inclusion of non-standardized analytes (hormones, tumor makers, etc.) in the target; and 3) cross-check of test results between the central and local laboratories. Transferability of centrally derived RIs for non-standardized analytes based on the cross-check was examined. Methods: Forty non-standardized analytes were centrally measured in sera from 3541 reference individuals recruited by 63 laboratories. Forty-four laboratories collaborated in the cross-check study by locally measuring aliquots of sera from 9 to 73 volunteers (average 22.2). Linear relationships were obtained by the reduced major-axis regression. Error in converting RIs using the regression line was expressed by the coefficient of variation of slope b [CV(b)]. CV(b) < 10% was set as the cut-off value allowing the conversion. The significance of factors for partitioning RIs was determined similarly as in the first report. Results: Significant sex-, age-, and region-related changes in test results were observed in 17, 15, and 11 of the 40 analytes, respectively. In the cross-comparison study, test results were not harmonized in the majority of immunologically measured analytes, but their average CV(b)s were < 10% except for total protein, cystatin C, CA19-9, free thyroxine, and triiodothyronine. After conversion, 74% of centrally derived RIs were transferred to each local laboratory.

Establishment of reference intervals of clinical chemistry analytes for the adult population in Saudi Arabia: a study conducted as a part of the IFCC global study on reference values

“…Therefore, LAVE method was applied in our study to exclude individuals with abnormal results in other related analytes, apparently attributable to those conditions. The performance of the LAVE method have been well characterized in previous reports [14,15] and this study confirmed the need for its use in seven out of nine test items shown in Figure 1. This study also confirmed that RIs by the NP method were easily influenced by latent abnormal results for those test items compared with the RIs derived by the P method.…”

“…The tests results were evaluated by using the same statistical methods described in the previous studies [12][13][14][15] but are described briefly below. …”

Multicenter reference intervals studies: a promising perspective for the future?

“…As in their previous study [ 11 ] they limited the component of inter-laboratory variability by centralizing analyzes of deep-frozen sera of volunteers from 63 participating laboratories (in Japan and South-East Asia) in a single laboratory in Japan. Significant regional differences were identified for 11 analytes.In the second study [ 10 ] volunteers were recruited from 48 laboratories in 14 cities in Japan and 15 laboratories in nine cities in South-East Asia. Analyses of deepfrozen sera of patients were centralized in a single laboratory in Japan, following the same protocol as in the first study.…”

“…In the second study [ 10 ] volunteers were recruited from 48 laboratories in 14 cities in Japan and 15 laboratories in nine cities in South-East Asia. Analyses of deepfrozen sera of patients were centralized in a single laboratory in Japan, following the same protocol as in the first study.…”

“…To compare analytical systems, the investigators propose in the second study [ 10 ] a crosscomparison of test results method. The principle is similar to the method recommended by the IFCC/CLSI (C28 A3) [ 1 ] for the transference of RIs, but the detailed interpretation of the results are original.…”