Figure 5.

Correlation of CFTR function as estimated by NPD and LAPD. Each parameter was calculated as the Δchloride-free isoproterenol perfusion compared with the respective value in the normal control population. A, Correlation between NPD and LAPD. No significant correlation was observed between CFTR-dependent chloride transport measured by NPD compared with LAPD in the overall population (r = 0.17, P = .34) or in healthy nonsmokers (r = −0.13, P = .70). B, Number of patients with a discordantly low LAPD compared with NPD vs the number of patients with a concordant or high LAPD. Discordantly low LAPD was defined as an LAPD below the mean (eg, < 100% of normal) when the NPD was equal to or above the mean (eg, ≥ 100% of normal). *P < .05 by Fisher exact test. LAPD = lower airway potential difference; NPD = nasal potential difference. See Figure 2 and 3 legends for expansion of other abbreviations.