Abstract: Objective To explore the accuracy of traditional sweat chloride test and its diagnostic value for Chinese patients with cystic fibrosis (CF). Methods The sweat chloride level in 118 patients who were suspected to have CF in Peking Union Medical College Hospital from Jan 2012 to Oct 2019 was measured,and the results were compared with the confirmed diagnosis. Results The patients' ages were (25.8±13.6)years old (15 months-67 years old). One hundred and two out of 118 patients obtained valid chloride level from their sweat chloride tests with median concentration of 43.3 mmol/L(IQR:23.8-120.1 mmol/L). Eighty were consistent with their diagnosis. Thirty-nine patients had sweat chloride values higher than 60 mmol/L, while 31(79.49%) of them were finally confirmed CF diagnosis. Sweat chloride levels of fourty cases were lower than 30 mmol/L, of which 32(80%) cases were excluded from CF. Twenty-three patients had sweat chloride level between 30 and 59 mmol/L, while 17(73.91%) of them were excluded from CF diagnosis. 66(64.71%) of our patients had reproducible results of the sweat chloride level. Conclusions The positive predictive value of the sweat chloride test is 79.49% and the negative predictive value is 80% using traditional sweat chloride test measurement. The traditional sweat chloride test has high diagnostic value for Chinese CF patients.

Key words: cystic fibrosis (CF), traditional sweat chloride test, positive predictive value