Variability of the sweat test in children with Cystic Fibrosis previously CRMS/CFSPID: A retrospective monocenter experience.

Some studies have evaluated the sweat test (ST) intra individual variability in CRMS/CFSPID. Here, we retrospectively evaluated this in a cohort followed at the CF center in Florence, Italy. We enrolled 37 CRMS/CFSPID and 37 CF children, born between 2011 and 2019. A total of 327 ST were retrospectively recovered, of which 17 (5.2%) were quantity not sufficient. After a median follow-up of 33.8 months (range 1.7-88.2), 11 (24.3%) became CF with at least two pathological sweat chloride (SC) values at a median age of 46.9 months (range 1.4-49). The coefficient of variation was 6.2% in CF patients and 32.5% in the CRMS/CFSPID that transitioned to CF (P<.001). Our data highlight a more variability of SC values in CRMS/CFSPID, especially in those that transitioned to a diagnosis of CF. Further studies are needed to understand whether it is correct to define an asymptomatic CRMS/CFSPID with pathological SC as CF.