The Italian External Quality Assessment Program for CF Sweat Chloride Test: Results of the 2015 Round

Abstract

Background: Sweat chloride test is the gold standard test for cystic fibrosis (CF) diagnosis. In 2014 the Istituto Superiore di Sanità (ISS) established the first Italian pilot external quality assessment (EQA) program for CF sweat chloride test. In 2015 this activity was recognized as a third party service carried out by the ISS. The present paper describes the results of the first official 2015 sweat chloride test EQA program and results are compared with the 2014 round ones. Methods: the scheme is prospective; participation is open to Italian laboratories performing sweat test analysis for CF diagnosis. Enrollment is voluntary and since 2015 the payment of a fee is required. Participants are registered identified by an identification number known only to the ISS. Assessment covers analysis, interpretation and reporting. Results: thirteen laboratories, belonging to the Italian public Referral Centers for CF, participated in the 2015 round; nine already participated in 2014. Variability in scores of chloride titration and heterogeneity in interpretation / reporting results were identified in 2014 and 2015. Conclusions: results show variability in performance of laboratories indicating that the quality of laboratory performance is unpredictable unless EQA participation is mandatory as a component of compulsory laboratory accreditation..

Intra‐individual biological variation in sweat chloride concentrations in CF, CFTR dysfunction, and healthy pediatric subjects

“…Despite several international and national guidelines and consensus about diagnostic criteria for CF and sweat testing procedures, there are still differences in sweat stimulation, collection time, and processing worldwide . Furthermore, analyses derived from different national CF registries in Europe have shown a significant percentage of misdiagnosis of CF based on inadequate performance and false interpretation of the sweat test .…”

“…Determining the intra-and inter-individual biological variability of sweat chloride is, therefore, crucial not only for diagnostic therapeutic purposes, 4 but also to evaluate the effectiveness of new CFTR protein modulators, since the concentration of chloride in sweat can be considered a surrogate biomarker of the CFTR protein function 10. Despite several international and national guidelines and consensus about diagnostic criteria for CF5,15 and sweat testing procedures, 1-3 there are still differences in sweat stimulation, collection time, and processing worldwide [16][17][18][19][20][21]. Furthermore, analyses derived from different national CF registries in Europe have shown a significant percentage of misdiagnosis of CF based on inadequate performance and false interpretation of the sweat test 22,23.…”

The Italian external quality assessment program for Cystic Fibrosis sweat chloride test: CFTR modulators and the impact of a new sweat test report form

“…The I-EQA-SCT was established in 2014 at the Italian National Center for Rare Diseases of the Istituto Superiore di Sanità (ISS, Rome) and is fully described elsewhere [ 13 , 14 ].…”

“…The aim of the present paper is to discuss the impact of this new ST report format in mock cases, simulating CF patients undergoing CFTR modulators therapy by laboratories participating to the 2022-23 round of the Italian External Quality Assessment program for sweat chloride test (I-EQA-SCT) [ 13 ]. Results related to the analysis and reporting on these cases will be fully described highlighting major issues.…”