Insert Figure 1
There were two main results distribution, i.e., lower and higher than 60mmol/L and 80mmol/L, respectively, with no intermediate values. A strong, statistically significant correlation (rs = 0.83; P < .05) between the two concomitant assays was found; moreover, the difference between the 95% CI lower and upper limits (0.08), denotes high accuracy of our results.
Although SC is used worldwide, to the best of our knowledge there is no previous work that had been attempted to assess its repeatability, regardless the age group. Therefore, the unavailability of previous studies hinders comparisons with our results.
In conclusion, the strong, statistically significant repeatability found in the present study, testify to the clinical usefulness of SC, adds original evidence, and reinforces its role as a reliable screening test for CF.
ACKNOWLEDGMENT
We would like to acknowledge Roberto Vagner Puglia Ladeira, the Laboratory Coordinator, for supporting the study.
CONFLICT OF INTERESTS
The funding organization(s) played no role in the study design; in the collection, analysis, and interpretation of data; in the writing of the report; or in the decision to submit the report for publication.
AUTHOR CONTRIBUTIONS
RMB contributed to manuscript conception, writing, revision and editing. CGA contributed to manuscript conception, writing, editing and to critical revision of the manuscript. OGS contributed to data collection, interpretation and analysis. DN supervised and/or performed SC assays. JVAJ and FHP contributed to data collection, analysis, validation, and interpretation, and writing of the manuscript. PC conceived the study, and the study design; investigation, methodology, funding acquisition, project administration, resources, validation; manuscript conception, writing, editing and to critical revision of the manuscript.
ORCID
Paulo Camargos http://orcid.org/0000-0003-4731-291X
REFERENCES
  1. Rueegg CS, Kuehni CE, Gallati S, Jurca M, Jung A, Casaulta C, Barben J, Swiss Cystic Fibrosis Screening Group. Comparison of two sweat test systems for the diagnosis of cystic fibrosis in newborns.Pediatr Pulmonol . 2019;54(3):264-272.
  2. Lezana JL, Vargas MH, Karam-Bechara J, Aldana RS, Furuya MEY. Sweat conductivity and chloride titration for cystic fibrosis diagnosis in 3834 subjects. J Cyst Fibros. 2003;2(1):1-7.
  3. Greaves R, Jolly L, Massie J, Scott S, Wiley VC, Metz MP, MacKay RJ. Sweat test working party in association with the Royal Australasian College of Pathologists Quality Assurance Programs. Laboratory performance of sweat conductivity for the screening of cystic fibrosis. Clin Chem Lab Med . 2018;56(4):554-559.
  4. Clinical and Laboratory Standards Institute. Sweat testing: sample collection and quantitative chloride analysis. 2009;29(27). Available from: https://clsi.org/media/1362/c34a3_sample.pdf [Accessed July, 19th, 2020].