Spirometry was used to assess pulmonary function by measuring the percentage of predicted function, which was determined on the basis of the height value obtained at the same study visit, for FEV1 (the amount of air that can be exhaled in 1 second). Spirometry was assessed by using current guidelines of the American Thoracic Society (ATS) and European Respiratory Society (ERS). Baseline was the average of percent-predicted FEV1 at screening and randomization.

The ITT Population: all randomized participants with data for FEV1 at Baseline and a minimum of 1 post-Baseline assessment before Week 8. Here, 'Number analyzed' signifies participants evaluable for this outcome measure.

Spirometry was used to assess pulmonary function by measuring the percentage of predicted function, which was determined on the basis of the height value obtained at the same study visit, for FEV1 (the amount of air that can be exhaled in 1 second). Spirometry was assessed by using current guidelines of the American Thoracic Society (ATS) and European Respiratory Society (ERS). The percentage of change in percent-predicted of FEV1 was calculated as follows: ([percent-predicted FEV1-Baseline percent-predicted FEV1]/Baseline percent-predicted FEV1)*100. Baseline was the average of percent-predicted FEV1 at screening and randomization. A negative change from Baseline indicates that percent-predicted of FEV1 decreased.

The ITT Population: all randomized participants with data for FEV1 at Baseline and a minimum of 1 post-Baseline assessment before Week 8. Here, 'Number analyzed' signifies participants evaluable for this outcome measure.

A Respiratory Event Form, which collected data on various signs, symptoms, and effects for each event, was completed by the Investigator when informed by the participant of a respiratory event. Pulmonary exacerbations were assessed by using the modified Fuchs' criteria, which defines an exacerbation as a respiratory event requiring treatment with parenteral antibiotics for any 4 of the following 12 symptoms, with or without intravenous antibiotics: change in sputum; new or increased hemoptysis; increased cough; increased dyspnea; fatigue; temperature >38°C; anorexia; sinus pain; change in sinus discharge; change in physical examination of the chest; decrease in pulmonary function by 10% or more from a previously recorded value; or radiographic changes indicative of pulmonary function. The 48-week exacerbation rate was determined by adding the weekly rates for each arm and dividing the sum by 48.

The ITT Population: all randomized participants with data for FEV1 at Baseline and a minimum of 1 post-Baseline assessment before Week 8. Here, 'Number analyzed' signifies participants evaluable for this outcome measure.

The frequency of awake cough was measured using the LifeShirt, which incorporates motion-sensing transducers, electrodes, a microphone, and a 3-axis accelerometer into a lightweight vest. The rate was determined by dividing the total number of coughs by 24 (the number of hours of the observation period). Baseline was the latest, valid assessment prior to the treatment. A negative change from Baseline indicates that coughing decreased.

The ITT Population: all randomized participants with data for FEV1 at Baseline and a minimum of 1 post-Baseline assessment before Week 8. Here, 'Number analyzed' signifies participants evaluable for this outcome measure.

The CFQ-R consists of 44 items, including generic scales of physical functioning, role functioning, vitality, health perceptions, emotional functioning, and social functioning, and CF-specific scales of respiratory and digestive symptoms, body image, eating disturbances, and treatment burden. Each domain score ranges from 1 to 4. Scores were linearly transformed to a 0 to 100 scale, with higher scores indicating better health. Domain scores were calculated by using the following formula: 100 * (sum of responses - minimum possible sum)/ (maximum possible sum - minimum possible sum). The minimum possible sum = number of questions * 1; the maximum possible = the number of questions * 4. Baseline was the latest, valid assessment prior to the treatment. A negative change from Baseline indicates that health has worsened. Participants may have switched age groups during the study.

The ITT Population: all randomized participants with data for FEV1 at Baseline and a minimum of 1 post-Baseline assessment before Week 8. Here, 'Number analyzed' signifies participants evaluable for this outcome measure.

Spirometry was used to assess pulmonary function by measuring the percentage of predicted function, which was determined on the basis of the height value obtained at the same study visit, for FVC (the amount of air that can be exhaled after taking a deep breath). Spirometry was assessed by using current guidelines of the ATS and ERS. Baseline was the average of percent-predicted FVC at screening and randomization.

The ITT Population: all randomized participants with data for FEV1 at Baseline and a minimum of 1 post-Baseline assessment before Week 8. Here, 'Number analyzed 'signifies participants evaluable for this outcome measure.

Spirometry was used to assess pulmonary function by measuring the percentage of predicted function, which was determined on the basis of the height value obtained at the same study visit, for FVC (the amount of air that can be exhaled after taking a deep breath). Spirometry was assessed by using current guidelines of the ATS and ERS. The percentage of change in percent-predicted of FVC was calculated as follows: ((percent-predicted FVC-Baseline percent-predicted FVC)/Baseline percent-predicted FVC)*100. Baseline was the average of percent-predicted FVC at screening and randomization. A negative change from Baseline indicates that percent-predicted of FVC decreased.

The ITT Population: all randomized participants with data for FEV1 at Baseline and a minimum of 1 post-Baseline assessment before Week 8. Here, 'Number analyzed 'signifies participants evaluable for this outcome measure.

A TEAE was any untoward medical occurrence in a participant who received study drug without regard to possibility of causal relationship that occurred or worsened in the period extending from first dose of study drug to 4 weeks after the last dose of study drug. A serious adverse event (SAE) was an AE resulting in any of the following outcomes or deemed significant for any other reason: death; initial or prolonged inpatient hospitalization; life-threatening experience (immediate risk of dying); persistent or significant disability/incapacity; congenital anomaly. AEs included both SAEs and non-serious AEs. AE severity was graded as follows: Grade 1: mild; Grade 2: moderate; Grade 3: severe; Grade 4: life-threatening; Grade 5: fatal. A TEAE was considered related if in the opinion of the Investigator it was possibly or probably caused by the study drug. A summary of other non-serious AEs and all SAEs, regardless of causality is located in the Adverse Events module.

The As-Treated Population: all randomized participants who received at least 1 dose of study drug.

Study drug compliance was assessed by using a Pharmacy Subject Study Drug Accountability Log (completed by the investigational site personnel). The rate of compliance was defined as 100 * (number of sachets taken/number of planned sachets) during the study. All calculations were based on the records of the first dose date to the last dose date. To differentiate dose strengths while maintaining the blind, each kit had a unique kit number and had prominent lettering "A" and "B." Each kit contained 65 packets of 1 of the dose strengths (125, 250, or 1000 mg or matching placebo). Labeling for active drug and placebo was identical.

The As-Treated Population: all randomized participants who received at least 1 dose of study drug.

Patient-reported data were obtained from the participant's electronic daily diary, which was completed by the participant or the caregiver. During study treatment, the electronic daily diary was to be completed by the participant or caregiver each day for each dose. For each participant, compliance is described in terms of the percentage of study drug actually taken. All calculations were based on the records of the first dose date to the last dose date. To differentiate dose strengths while maintaining the blind, each kit had a unique kit number and had prominent lettering "A" and "B." Each kit contained 65 packets of 1 of the dose strengths (125, 250, or 1000 mg or matching placebo). Labeling for active drug and placebo was identical.

The As-Treated Population: all randomized participants who received at least 1 dose of study drug.

Blood samples were drawn immediately before administration of the first daily dose (dose taken with breakfast) of study drug and 2 hours after the first daily dose. Whenever possible, the pre-dose sample was to be obtained within 15 minutes of drug administration. Participants in the Placebo arm did not receive Ataluren and are not included in this Outcome Measure.

The As-Treated Population: all randomized participants who received at least 1 dose of study drug.

During treatment, any intervention including hospitalization or use of oral, inhaled, or intravenous antibiotics was documented if it was due to an exacerbation-like episode. Participants and caregivers recorded interventions in an electronic diary. The rate of interventions was defined as the total days with interventions divided by the total study duration.

The ITT Population: all randomized participants with data for FEV1 at Baseline and a minimum of 1 post-Baseline assessment before Week 8. Here, 'Number analyzed' signifies participants evaluable for specified categories.

During treatment, any disruption in the activities of daily living, such as missed school or work, was documented if it was due to an exacerbation-like episode. Participants and caregivers recorded all disruptions in an electronic diary. The rate of disruptions was defined as the total days with disruptions to daily living divided by the total study duration.

The ITT Population: all randomized participants with data for FEV1 at Baseline and a minimum of 1 post-Baseline assessment before Week 8. Here, 'Number analyzed' signifies participants evaluable for specified categories.

Participants were weighed, and the weight was recorded at Baseline and then every 8 weeks during the treatment period. Baseline was the latest valid assessment prior to the treatment. A positive change from Baseline indicates that weight increased.

The ITT Population: all randomized participants with data for FEV1 at Baseline and a minimum of 1 post-Baseline assessment before Week 8. Here, 'Number analyzed' signifies participants evaluable for this outcome measure.

Expression of IL-8 was measured in serum and in sputum. Sputum was spontaneously produced and tested by using standardized procedures developed by the Cystic Fibrosis Foundation Therapeutics, Inc. Therapeutics Development Network (CFFT-TDN). Baseline was the latest valid assessment prior to the treatment. A negative change from Baseline indicates that the concentration of IL-8 decreased.

The ITT Population: all randomized participants with data for FEV1 at Baseline and a minimum of 1 post-Baseline assessment before Week 8. Here, 'Number analyzed' signifies participants evaluable for this outcome measure.

Expression of neutrophil elastase was measured in sputum. Sputum was spontaneously produced and tested by using standardized procedures developed by the CFFT-TDN. Baseline was the latest valid assessment prior to the treatment. A positive change from Baseline indicates that the concentration of neutrophil elastase increased.

The ITT Population: all randomized participants with data for FEV1 at Baseline and a minimum of 1 post-Baseline assessment before Week 8. Here, 'Number analyzed' signifies participants evaluable for this outcome measure. Twenty-two participants each in the ataluren and placebo groups were not evaluable.

Expression of CRP was measured in serum. Baseline was the latest valid assessment prior to the treatment. A positive change from Baseline indicates that CRP concentration increased.

The ITT Population: all randomized participants with data for FEV1 at Baseline and a minimum of 1 post-Baseline assessment before Week 8. Here, 'Number analyzed' signifies participants evaluable for this outcome measure.

Lungs were imaged by using non-contrast, spiral CT. The total lung score for each CT scan was established by the sum of 5 characteristics from the Brody scoring system, with scores ranging from 0 to 40.5, with lower scores indicating better lung function. The characteristics scored were bronchiectasis (score range 0 - 12), mucus plugging (score range 0- 6), peribronchial thickening (score range 0 - 9), parenchyma (score range 0 - 9), and hyperinflation (score range 0 - 4.5). Baseline was the latest valid assessment prior to the treatment. A positive change from Baseline indicates that lung function worsened.

The ITT Population: all randomized participants with data for FEV1 at Baseline and a minimum of 1 post-Baseline assessment before Week 8. Here, 'Number analyzed' signifies participants evaluable for this outcome measure. Eleven and 10 participants in the ataluren and placebo groups, respectively, were not evaluable.

TEPD was assessed in each nostril using standardized equipment, techniques, and solutions. Assessments were made on the nasal epithelium cells lining the inferior turbinate. Warmed solutions of Ringer's solution, amiloride, chloride-free gluconate, isoproterenol, and adenosine triphosphate (ATP) were perfused for ≥3-minute sequentially through a nasal catheter while a voltage tracing was recorded. Total chloride transport was computed for each nostril. The total chloride transport values were calculated by subtracting the voltages at the end of a perfusion from the voltage at the end of an earlier perfusion (isoproterenol - amiloride). The average of the values for each nostril was computed. If the assessment was available in only 1 nostril, this value was used as if it were the average of both nostrils. Baseline was the latest, valid assessment prior to the treatment. A positive change from Baseline indicates that nasal chloride transport increased.

The ITT Population: all randomized participants with data for FEV1 at Baseline and a minimum of 1 post-Baseline assessment before Week 8. Here, 'Number analyzed' signifies participants evaluable for this outcome measure.

Sweat was collected, from each arm, by using pilocarpine iontophoresis. The chloride concentration in the sweat was quantified for each arm by using standard laboratory methods. Tests were also considered valid if the sweat collection time was ≤35 minutes; tests with longer collection times were also considered valid if extra time was needed to obtain sufficient volume (≥15uL) for analysis. For analysis purposes, the average of the values from each arm were computed. If the assessment was valid and/or available in only 1 arm, this value was used as if it were the average of both arms. The method used was consistent with the CFFT-TDN guidelines. Baseline was the latest, valid assessment prior to the treatment. A negative change from Baseline indicates that sweat chloride concentration decreased.

The ITT Population: all randomized participants with data for FEV1 at Baseline and a minimum of 1 post-Baseline assessment before Week 8. Here, 'Number analyzed' signifies participants evaluable for this outcome measure. Two and 5 participants in the ataluren and placebo groups, respectively, were not evaluable.