Table 2 Demographic data, spirometric parameters and lung clearance index (LCI) of healthy volunteers and patients with cystic fibrosis (CF)

	Healthy volunteers		CF patients
	Children (age ⩽16 years)	Adults (age ⩾17 years)	CF patients
N	12	48	33
M/F	7/5	19/29	21/12
Mean (range) age (years)	11 (6–16)	33 (19–58)	30 (17–49)
Mean (SD) FEV₁ (% predicted)	95 (11)	102 (12)	66 (23)*
LCI
Mean (SD)	6.3 (0.5)	6.7 (0.4)	13.1 (3.8)*
Range	5.6–7.1	6.0–7.8	6.3–20.4
Mean (SD) CV%	5.4 (3.8)	3.6 (2.1)	4.5 (2.7)

FEV₁, forced expiratory volume in 1 s; CV%, coefficient of variation (%) for intra-visit repeats.
*p<0.001 vs adult healthy volunteers (Mann-Whitney U test).