Table 2 Mean (SD) changes in FEV₁ and FVC % predicted in the azithromycin and placebo groups during the study.

	Azithromycin	Placebo	Azithromycin−placebo difference estimate (95% CI)
FEV1 % predicted (%)
Trend slope over the 12 months
Total population	−4.9 (2.0)	−1.7 (2.0)	−3.2 (−8.9 to 2.3), NS
Patients not infected with PA	−5.0 (2.5)	−1.8 (2.4)	−3.2 (−10.0 to 3.6), NS
Patients infected with PA	−4.1 (3.2)	−1.2 (3.1)	−2.9 (−11.7 to 5.8), NS
Relative change
Total population	−4.3 (17.9)	−1.5 (15.4)	−2.8 (−10.1 to 4.5), NS
Patients not infected with PA	−3.0 (19.3)	−1.1 (13.5)	−1.9 (−10.3 to 6.5), NS
Patients infected with PA	−8.7 (11.5)	−2.7 (21.0)	−6.0 (−22.7 to 10.7), NS
FVC % predicted (%)
Trend slope over the 12 months
Total population	−2.4 (1.7)	−3.6 (1.7)	1.2 (−3.4 to 5.8), NS
Patients not infected with PA	−2.2 (1.9)	−5.1 (1.9)	2.9 (−2.3 to 8.2), NS
Patients infected with PA	−3.2 (3.3)	2.2 (3.2)	−5.4 (−14.5 to 3.7), NS
Relative change
Total population	−1.8 (13.6)	−4.5 (12.1)	2.7 (−3.0 to 8.4), NS
Patients not infected with PA	−1.0 (13.3)	−4.3 (9.2)	3.3 (−2.4 to 9.1), NS
Patients infected with PA	−4.3 (15.4)	−4.9 (19.4)	1.0 (−16.6 to 17.6), NS

CI, confidence interval; FEV₁, forced expiratory volume in 1 second; FVC, forced vital capacity; PA, Pseudomonas aeruginosa; NS, not significant; SD, standard deviation.

Sample sizes in the azithromycin and placebo groups were, respectively, 40 and 42 for the total population, 31 and 32 for patients not infected with PA, and 9 and 10 for patients infected with PA.