Participant baseline characteristics and demographics by treatment group
| Characteristics | Azithromycin (N=61) | Placebo (N=54) |
| Age, years | 26.1±9.9 | 26.5±9.7 |
| Age, n (%) | ||
| ≥12–<18 years | 14 (23.0) | 12 (22.2) |
| ≥18–<30 years | 28 (45.9) | 25 (46.3) |
| ≥30 years | 19 (31.1) | 17 (31.5) |
| Female, n (%) | 29 (47.5) | 26 (48.1) |
| Race, n (%) | ||
| Caucasian | 55 (90.2) | 49 (90.7) |
| Other* | 6 (9.8) | 5 (9.3) |
| Ethnicity, n (%) | ||
| Hispanic or Latino | 9 (14.8) | 7 (13.0) |
| FEV1, L | 2.59±0.81 | 2.50±0.85 |
| ppFEV1† | 70.7±18.2 | 69.6±21.1 |
| ppFEV1 category, n (%) | ||
| ≥25%–<50% | 11 (18.0) | 11 (20.4%) |
| ≥50%–<75% | 22 (36.1) | 16 (29.6%) |
| ≥75% | 28 (45.9) | 27 (50.0%) |
| Height, cm | 167.9±10.2 | 166.4±9.6 |
| Weight, kg | 63.9±13.8 | 62.7±13.2 |
| Genotype, n (%) | ||
| F508del homozygous | 38 (62.3) | 35 (64.8) |
| F508del heterozygous | 17 (27.9) | 11 (20.4) |
| Other | 6 (9.8) | 7 (13.0) |
| Unavailable | 0 (0) | 1 (1.9) |
| Tobramycin formulation, n (%) | ||
| Solution | 33 (54.1) | 28 (51.9) |
| Powder | 28 (45.9) | 26 (48.1) |
| History of azithromycin use, n (%) | ||
| Current chronic user | 51 (83.6) | 43 (79.6) |
| Non-current chronic user | 10 (16.4) | 11 (20.4) |
| Chronic medication use, n (%) | ||
| Dornase alfa | 53 (86.9) | 48 (88.9) |
| Hypertonic saline | 46 (75.4) | 40 (74.1) |
| High-dose ibuprofen | 2 (3.3) | 2 (3.7) |
| Ivacaftor | 2 (3.3) | 3 (5.6) |
| Ivacaftor/lumacaftor | 14 (23.0) | 18 (33.3) |
| Ivacaftor/tezacaftor | 14 (23.0) | 16 (29.6) |
| Elexacaftor/tezacaftor/ivacaftor | 1 (1.6) | 0 (0) |
| Pseudomonas aeruginosa sputum density | ||
| Participants with sputum culture results, n (%) | 38 (62.3) | 39 (72.2) |
| P. aeruginosa log10 CFU/mL | 4.29±1.80 | 4.22±1.59 |
Plus–minus values are mean±SD.
*Other includes Black/African American, American Indian/Alaska Native, Asian, Native Hawaiian/Pacific Islander, unknown and other.
†Percent predicted calculated using global lung initiative reference equations.
FEV1, forced expiratory volume in one second; ppFEV1, percent of predicted forced expiratory volume in one second.