PMC5974533_01
Bland-Altman Plot of manual titration vs. chloridometer.
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F2
We visually observed a systematic bias between manual methods and Sherwood  chloridometer in the Bland-Altman plot constructed by mean to difference measurements, where the discrepancy increased as the concentations increased (Figure 2).
Bland-Altman Plot of manual titration vs. coulometric endpoint method.
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F3
Although the same bias was observed in the Bland-Altman plot of manual titration vs. the coulometric endpoint method (CF Delta System ), the discrepancy among the healthy population was less prominent (Figure 3).
Bland-Altman Plot of chloridometer vs. coulometric endpoint method.
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F4
The results of the Sherwood  chloridometer and the coulometric endpoint methods (CF Delta System ) were more in agreement and resulted in a well-matched Bland-Altman plot (Figure 4).
ROC curve of the three sweat test methods.
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F5
Likewise, the coulometric endpoint method (CF Delta System ) resulted in 96.7% sensitivity and 100% specificity for a cut-off value of 58.5 mmol/L (AUC: 0.997, 95% CI = 0.975-1.000, p < 0.001) (Figure 5).