Respiratory Aspects of Primary Ciliary Dyskinesia.

This review article explores the respiratory aspects of primary ciliary dyskinesia (PCD), a rare, heterogenous, genetic disorder characterized by impaired motile ciliary function. It discusses the clinical diagnosis and management strategies for PCD-related respiratory disease, including chronic sinusitis, otitis media with effusion, recurrent pneumonia, and bronchiectasis. The review emphasizes the need for a multidisciplinary approach to optimize care and clinical trials to improve outcomes in individuals with PCD, highlighting the importance of accurate diagnosis.

Primary Ciliary Dyskinesia in Adult Bronchiectasis: Data from the German Bronchiectasis Registry PROGNOSIS.

BACKGROUND: Primary ciliary dyskinesia (PCD) is a rare genetic disorder caused by the malfunction of motile cilia and a specific etiology of adult bronchiectasis of unknown prevalence. A better understanding of the clinical phenotype of adults with PCD is needed to identify individuals for referral to diagnostic testing. RESEARCH QUESTION: What is the frequency of PCD among adults with bronchiectasis; how do people with PCD differ from those with other etiologies; and which clinical characteristics are independently associated with PCD? STUDY DESIGN AND METHODS: We investigated the proportion of PCD among the participants of the Prospective German Non-CF-Bronchiectasis Registry (PROGNOSIS) study; applied multiple imputation to account for missing data in 64 (FEV1), 58 (breathlessness), 26 (pulmonary exacerbations), and two patients (BMI), respectively; and identified predictive variables from baseline data using multivariate logistic regression analysis. RESULTS: We consecutively recruited 1,000 patients from 38 centers across all levels of the German health care system. Overall, PCD was the fifth most common etiology of bronchiectasis in 87 patients (9%) after idiopathic, postinfective, COPD, and asthma. People with PCD showed a distinct clinical phenotype. In multivariate regression analysis, the chance of PCD being the etiology of bronchiectasis increased with the presence of upper airway disease (chronic rhinosinusitis and/or nasal polyps; adjusted OR [aOR], 6.3; 95% CI, 3.3-11.9; P < .001), age < 53 years (aOR, 5.3; 95% CI, 2.7-10.4; P < .001), radiologic involvement of any middle and lower lobe (aOR, 3.7; 95% CI, 1.3-10.8; P = .016), duration of bronchiectasis > 15 years (aOR, 3.6; 95% CI, 1.9-6.9; P < .001), and a history of Pseudomonas aeruginosa isolation from respiratory specimen (aOR, 2.4; 95% CI, 1.3-4.5; P = .007). INTERPRETATION: Within our nationally representative cohort, PCD was a common etiology of bronchiectasis. We identified few easy-to-assess phenotypic features, which may promote awareness for PCD among adults with bronchiectasis. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov; No.: NCT02574143; URL: www. CLINICALTRIALS: gov.

Endotypes of Exacerbation in Bronchiectasis: An Observational Cohort Study.

Rationale: Bronchiectasis is characterized by acute exacerbations, but the biological mechanisms underlying these events are poorly characterized. Objectives: To investigate the inflammatory and microbial characteristics of exacerbations of bronchiectasis. Methods: A total of 120 patients with bronchiectasis were enrolled and presented with acute exacerbations within 12 months. Spontaneous sputum samples were obtained during a period of clinical stability and again at exacerbation before receipt of antibiotic treatment. A validated rapid PCR assay for bacteria and viruses was used to classify exacerbations as bacterial, viral, or both. Sputum inflammatory assessments included label-free liquid chromatography-tandem mass spectrometry and measurement of sputum cytokines and neutrophil elastase activity. 16 s rRNA sequencing was used to characterize the microbiome. Measurements and Main Results: Bronchiectasis exacerbations showed profound molecular heterogeneity. At least one bacterium was identified in 103 samples (86%), and a high bacterial load (total bacterial load > 107 copies/g) was observed in 81 patients (68%). Respiratory viruses were identified in 55 (46%) patients, with rhinovirus being the most common virus (31%). PCR testing was more sensitive than culture. No consistent change in the microbiome was observed at exacerbation. Exacerbations were associated with increased neutrophil elastase, proteinase-3, IL-1ß, and CXCL8. These markers were particularly associated with bacterial and bacterial plus viral exacerbations. Distinct inflammatory and microbiome profiles were seen between different exacerbation subtypes, including bacterial, viral, and eosinophilic events in both hypothesis-led and hypothesis-free analysis using integrated microbiome and proteomics, demonstrating four subtypes of exacerbation. Conclusions: Bronchiectasis exacerbations are heterogeneous events with contributions from bacteria, viruses, and inflammatory dysregulation.

Objective sputum colour assessment and clinical outcomes in bronchiectasis: data from the European Bronchiectasis Registry (EMBARC).

BACKGROUND: A validated 4-point sputum colour chart can be used to objectively evaluate the levels of airway inflammation in bronchiectasis patients. In the European Bronchiectasis Registry (EMBARC), we tested whether sputum colour would be associated with disease severity and clinical outcomes. METHODS: We used a prospective, observational registry of adults with bronchiectasis conducted in 31 countries. Patients who did not produce spontaneous sputum were excluded from the analysis. The Murray sputum colour chart was used at baseline and at follow-up visits. Key outcomes were frequency of exacerbations, hospitalisations for severe exacerbations and mortality during up to 5-year follow-up. RESULTS: 13 484 patients were included in the analysis. More purulent sputum was associated with lower forced expiratory volume in 1 s (FEV1), worse quality of life, greater bacterial infection and a higher bronchiectasis severity index. Sputum colour was strongly associated with the risk of future exacerbations during follow-up. Compared to patients with mucoid sputum (reference group), patients with mucopurulent sputum experienced significantly more exacerbations (incident rate ratio (IRR) 1.29, 95% CI 1.22-1.38; p<0.0001), while the rates were even higher for patients with purulent (IRR 1.55, 95% CI 1.44-1.67; p<0.0001) and severely purulent sputum (IRR 1.91, 95% CI 1.52-2.39; p<0.0001). Hospitalisations for severe exacerbations were also associated with increasing sputum colour with rate ratios, compared to patients with mucoid sputum, of 1.41 (95% CI 1.29-1.56; p<0.0001), 1.98 (95% CI 1.77-2.21; p<0.0001) and 3.05 (95% CI 2.25-4.14; p<0.0001) for mucopurulent, purulent and severely purulent sputum, respectively. Mortality was significantly increased with increasing sputum purulence, hazard ratio 1.12 (95% CI 1.01-1.24; p=0.027), for each increment in sputum purulence. CONCLUSION: Sputum colour is a simple marker of disease severity and future risk of exacerbations, severe exacerbations and mortality in patients with bronchiectasis.

Structural Lung Disease and Clinical Phenotype in Bronchiectasis Patients: The EMBARC CT Study.

Rationale: Chest computed tomography (CT) scans are essential to diagnose and monitor bronchiectasis (BE). To date, few quantitative data are available about the nature and extent of structural lung abnormalities (SLAs) on CT scans of patients with BE. Objectives: To investigate SLAs on CT scans of patients with BE and the relationship of SLAs to clinical features using the EMBARC (European Multicenter Bronchiectasis Audit and Research Collaboration) registry. Methods: CT scans from patients with BE included in the EMBARC registry were analyzed using the validated Bronchiectasis Scoring Technique for CT (BEST-CT). The subscores of this instrument are expressed as percentages of total lung volume. The items scored are atelectasis/consolidation, BE with and without mucus plugging (MP), airway wall thickening, MP, ground-glass opacities, bullae, airways, and parenchyma. Four composite scores were calculated: total BE (i.e., BE with and without MP), total MP (i.e., BE with MP plus MP alone), total inflammatory changes (i.e., atelectasis/consolidation plus total MP plus ground-glass opacities), and total disease (i.e., all items but airways and parenchyma). Measurements and Main Results: CT scans of 524 patients with BE were analyzed. Mean subscores were 4.6 (range, 2.3-7.7) for total BE, 4.2 (1.2-8.1) for total MP, 8.3 (3.5-16.7) for total inflammatory changes, and 14.9 (9.1-25.9) for total disease. BE associated with primary ciliary dyskinesia was associated with more SLAs, whereas chronic obstructive pulmonary disease was associated with fewer SLAs. Lower FEV1, longer disease duration, Pseudomonas aeruginosa and nontuberculous mycobacterial infections, and severe exacerbations were all independently associated with worse SLAs. Conclusions: The type and extent of SLAs in patients with BE are highly heterogeneous. Strong relationships between radiological disease and clinical features suggest that CT analysis may be a useful tool for clinical phenotyping.

Bronchiectasis and asthma: Data from the European Bronchiectasis Registry (EMBARC).

BACKGROUND: Asthma is commonly reported in patients with a diagnosis of bronchiectasis. OBJECTIVE: The aim of this study was to evaluate whether patients with bronchiectasis and asthma (BE+A) had a different clinical phenotype and different outcomes compared with patients with bronchiectasis without concomitant asthma. METHODS: A prospective observational pan-European registry (European Multicentre Bronchiectasis Audit and Research Collaboration) enrolled patients across 28 countries. Adult patients with computed tomography-confirmed bronchiectasis were reviewed at baseline and annual follow-up visits using an electronic case report form. Asthma was diagnosed by the local investigator. Follow-up data were used to explore differences in exacerbation frequency between groups using a negative binomial regression model. Survival analysis used Cox proportional hazards regression. RESULTS: Of 16,963 patients with bronchiectasis included for analysis, 5,267 (31.0%) had investigator-reported asthma. Patients with BE+A were younger, were more likely to be female and never smokers, and had a higher body mass index than patients with bronchiectasis without asthma. BE+A was associated with a higher prevalence of rhinosinusitis and nasal polyps as well as eosinophilia and Aspergillus sensitization. BE+A had similar microbiology but significantly lower severity of disease using the bronchiectasis severity index. Patients with BE+A were at increased risk of exacerbation after adjustment for disease severity and multiple confounders. Inhaled corticosteroid (ICS) use was associated with reduced mortality in patients with BE+A (adjusted hazard ratio 0.78, 95% CI 0.63-0.95) and reduced risk of hospitalization (rate ratio 0.67, 95% CI 0.67-0.86) compared with control subjects without asthma and not receiving ICSs. CONCLUSIONS: BE+A was common and was associated with an increased risk of exacerbations and improved outcomes with ICS use. Unexpectedly we identified significantly lower mortality in patients with BE+A.

Airway "Resistotypes" and Clinical Outcomes in Bronchiectasis.

Rationale: Chronic infection and inflammation shapes the airway microbiome in bronchiectasis. Utilizing whole-genome shotgun metagenomics to analyze the airway resistome provides insight into interplay between microbes, resistance genes, and clinical outcomes. Objectives: To apply whole-genome shotgun metagenomics to the airway microbiome in bronchiectasis to highlight a diverse pool of antimicrobial resistance genes: the "resistome," the clinical significance of which remains unclear. Methods: Individuals with bronchiectasis were prospectively recruited into cross-sectional and longitudinal cohorts (n = 280), including the international multicenter cross-sectional Cohort of Asian and Matched European Bronchiectasis 2 (CAMEB 2) study (n = 251) and two independent cohorts, one describing patients experiencing acute exacerbation and a further cohort of patients undergoing Pseudomonas aeruginosa eradication treatment. Sputum was subjected to metagenomic sequencing, and the bronchiectasis resistome was evaluated in association with clinical outcomes and underlying host microbiomes. Measurements and Main Results: The bronchiectasis resistome features a unique resistance gene profile and increased counts of aminoglycoside, bicyclomycin, phenicol, triclosan, and multidrug resistance genes. Longitudinally, it exhibits within-patient stability over time and during exacerbations despite between-patient heterogeneity. Proportional differences in baseline resistome profiles, including increased macrolide and multidrug resistance genes, associate with shorter intervals to the next exacerbation, whereas distinct resistome archetypes associate with frequent exacerbations, poorer lung function, geographic origin, and the host microbiome. Unsupervised analysis of resistome profiles identified two clinically relevant "resistotypes," RT1 and RT2, the latter characterized by poor clinical outcomes, increased multidrug resistance, and P. aeruginosa. Successful targeted eradication in P. aeruginosa-colonized individuals mediated reversion from RT2 to RT1, a more clinically favorable resistome profile demonstrating reduced resistance gene diversity. Conclusions: The bronchiectasis resistome associates with clinical outcomes, geographic origin, and the underlying host microbiome. Bronchiectasis resistotypes link to clinical disease and are modifiable through targeted antimicrobial therapy.

The Association between Bronchiectasis and Chronic Obstructive Pulmonary Disease: Data from the European Bronchiectasis Registry (EMBARC).

Rationale: COPD and bronchiectasis are commonly reported together. Studies report varying impacts of co-diagnosis on outcomes, which may be related to different definitions of disease used across studies. Objectives: To investigate the prevalence of chronic obstructive pulmonary disease (COPD) associated with bronchiectasis and its relationship with clinical outcomes. We further investigated the impact of implementing the standardized ROSE criteria (radiological bronchiectasis [R], obstruction [FEV1/FVC ratio <0.7; O], symptoms [S], and exposure [⩾10 pack-years of smoking; E]), an objective definition of the association of bronchiectasis with COPD. Methods: Analysis of the EMBARC (European Bronchiectasis Registry), a prospective observational study of patients with computed tomography-confirmed bronchiectasis from 28 countries. The ROSE criteria were used to objectively define the association of bronchiectasis with COPD. Key outcomes during a maximum of 5 years of follow-up were exacerbations, hospitalization, and mortality. Measurements and Main Results: A total of 16,730 patients with bronchiectasis were included; 4,336 had a clinician-assigned codiagnosis of COPD, and these patients had more exacerbations, worse quality of life, and higher severity scores. We observed marked overdiagnosis of COPD: 22.2% of patients with a diagnosis of COPD did not have airflow obstruction and 31.9% did not have a history of ⩾10 pack-years of smoking. Therefore, 2,157 patients (55.4%) met the ROSE criteria for COPD. Compared with patients without COPD, patients who met the ROSE criteria had increased risks of exacerbations and exacerbations resulting in hospitalization during follow-up (incidence rate ratio, 1.25; 95% confidence interval, 1.15-1.35; vs. incidence rate ratio, 1.69; 95% confidence interval, 1.51-1.90, respectively). Conclusions: The label of COPD is often applied to patients with bronchiectasis who do not have objective evidence of airflow obstruction or a smoking history. Patients with a clinical label of COPD have worse clinical outcomes.

Inflammatory Molecular Endotypes in Bronchiectasis: A European Multicenter Cohort Study.

Rationale: Although inflammation and infection are key disease drivers in bronchiectasis, few studies have integrated host inflammatory and microbiome data to guide precision medicine. Objectives: To identify clusters among patients with bronchiectasis on the basis of inflammatory markers and to assess the association between inflammatory endotypes, microbiome characteristics, and exacerbation risk. Methods: Patients with stable bronchiectasis were enrolled at three European centers, and cluster analysis was used to stratify the patients according to the levels of 33 sputum and serum inflammatory markers. Clusters were compared in terms of microbiome composition (16S ribosomal RNA sequencing) and exacerbation risk over a 12-month follow-up. Measurements and Main Results: A total of 199 patients were enrolled (109 [54.8%] female; median age, 69 yr). Four clusters of patients were defined according to their inflammatory profiles: cluster 1, milder neutrophilic inflammation; cluster 2, mixed-neutrophilic and type 2; cluster 3, most severe neutrophilic; and cluster 4, mixed-epithelial and type 2. Lower microbiome diversity was associated with more severe inflammatory clusters (P < 0.001), and ß-diversity analysis demonstrated distinct microbiome profiles associated with each inflammatory cluster (P = 0.001). Proteobacteria and Pseudomonas at phylum and genus levels, respectively, were more enriched in clusters 2 and 3 than in clusters 1 and 4. Furthermore, patients in cluster 2 (rate ratio [RR], 1.49; 95% confidence interval [CI], 1.16-1.92) and cluster 3 (RR, 1.61; 95% CI, 1.12-2.32) were at higher risk of exacerbation over a 12-month follow-up compared with cluster 1, even after adjustment for prior exacerbation history. Conclusions: Bronchiectasis inflammatory endotypes are associated with distinct microbiome profiles and future exacerbation risk.

Clinical outcomes of bronchiectasis in India: data from the EMBARC/Respiratory Research Network of India registry.

BACKGROUND: Identifying risk factors for poor outcomes can help with risk stratification and targeting of treatment. Risk factors for mortality and exacerbations have been identified in bronchiectasis but have been almost exclusively studied in European and North American populations. This study investigated the risk factors for poor outcome in a large population of bronchiectasis patients enrolled in India. METHODS: The European Multicentre Bronchiectasis Audit and Research Collaboration (EMBARC) and Respiratory Research Network of India (EMBARC-India) registry is a prospective observational study of adults with computed tomography-confirmed bronchiectasis enrolled at 31 sites across India. Baseline characteristics of patients were used to investigate associations with key clinical outcomes: mortality, severe exacerbations requiring hospital admission, overall exacerbation frequency and decline in forced expiratory volume in 1 s. RESULTS: 1018 patients with at least 12-month follow-up data were enrolled in the follow-up study. Frequent exacerbations (≥3 per year) at baseline were associated with an increased risk of mortality (hazard ratio (HR) 3.23, 95% CI 1.39-7.50), severe exacerbations (HR 2.71, 95% CI 1.92-3.83), future exacerbations (incidence rate ratio (IRR) 3.08, 95% CI 2.36-4.01) and lung function decline. Coexisting COPD, dyspnoea and current cigarette smoking were similarly associated with a worse outcome across all end-points studied. Additional predictors of mortality and severe exacerbations were increasing age and cardiovascular comorbidity. Infection with Gram-negative pathogens (predominantly Klebsiella pneumoniae) was independently associated with increased mortality (HR 3.13, 95% CI 1.62-6.06), while Pseudomonas aeruginosa infection was associated with severe exacerbations (HR 1.41, 95% CI 1.01-1.97) and overall exacerbation rate (IRR 1.47, 95% CI 1.13-1.91). CONCLUSIONS: This study identifies risk factors for morbidity and mortality among bronchiectasis patients in India. Identification of these risk factors may support treatment approaches optimised to an Asian setting.

Genome sequencing reveals underdiagnosis of primary ciliary dyskinesia in bronchiectasis.

BACKGROUND: Bronchiectasis can result from infectious, genetic, immunological and allergic causes. 60-80% of cases are idiopathic, but a well-recognised genetic cause is the motile ciliopathy, primary ciliary dyskinesia (PCD). Diagnosis of PCD has management implications including addressing comorbidities, implementing genetic and fertility counselling and future access to PCD-specific treatments. Diagnostic testing can be complex; however, PCD genetic testing is moving rapidly from research into clinical diagnostics and would confirm the cause of bronchiectasis. METHODS: This observational study used genetic data from severe bronchiectasis patients recruited to the UK 100,000 Genomes Project and patients referred for gene panel testing within a tertiary respiratory hospital. Patients referred for genetic testing due to clinical suspicion of PCD were excluded from both analyses. Data were accessed from the British Thoracic Society audit, to investigate whether motile ciliopathies are underdiagnosed in people with bronchiectasis in the UK. RESULTS: Pathogenic or likely pathogenic variants were identified in motile ciliopathy genes in 17 (12%) out of 142 individuals by whole-genome sequencing. Similarly, in a single centre with access to pathological diagnostic facilities, 5-10% of patients received a PCD diagnosis by gene panel, often linked to normal/inconclusive nasal nitric oxide and cilia functional test results. In 4898 audited patients with bronchiectasis, <2% were tested for PCD and <1% received genetic testing. CONCLUSIONS: PCD is underdiagnosed as a cause of bronchiectasis. Increased uptake of genetic testing may help to identify bronchiectasis due to motile ciliopathies and ensure appropriate management.

Endotyping Chronic Obstructive Pulmonary Disease, Bronchiectasis, and the "Chronic Obstructive Pulmonary Disease-Bronchiectasis Association".

Rationale: Bronchiectasis and chronic obstructive pulmonary disease (COPD) are two disease entities with overlapped clinical features, and codiagnosis frequently occurs (termed the "COPD-bronchiectasis association"). Objectives: To investigate the sputum microbiome and proteome in patients with bronchiectasis, COPD, and the COPD-bronchiectasis association with the aim of identifying endotypes that may inform treatment. Methods: Sputum microbiome and protein profiling were carried out using 16S rRNA amplicon sequencing and a label-free proteomics workflow, respectively, in a cohort comprising patients with COPD (n = 43), bronchiectasis (n = 30), and the COPD-bronchiectasis association (n = 48). Results were validated in an independent cohort of 91 patients (n = 28-31 each group) using targeted measurements of inflammatory markers, mucins, and bacterial culture. Measurements and Main Results: Principal component analysis of sputum microbiome and protein profiles showed a partial separation between the COPD and the "COPD-bronchiectasis association" group. Further analyses revealed that patients with the "COPD-bronchiectasis association" had a higher abundance of proteobacteria, higher expression of mucin-5AC and proteins from the "neutrophil degranulation" pathway compared to those with COPD. In contrast, patients with COPD had an elevated expression of mucin-5B and several peptidase inhibitors, higher abundance of common commensal taxa, and a greater microbiome diversity. The profiles of "COPD-bronchiectasis association" and bronchiectasis groups were largely overlapping. Five endotypes were proposed with differential inflammatory, mucin, and microbiological features. The key features related to the "COPD-bronchiectasis association" were validated in an independent cohort. Conclusions: Neutrophilic inflammation, differential mucin expression, and Gram-negative infection are dominant traits in patients with the "COPD-bronchiectasis association."

Characterization of Eosinophilic Bronchiectasis: A European Multicohort Study.

Rationale: Bronchiectasis is classically considered a neutrophilic disorder, but eosinophilic subtypes have recently been described. Objectives: To use multiple datasets available through the European Multicentre Bronchiectasis Audit and Research Collaboration to characterize eosinophilic bronchiectasis as a clinical entity focusing on the impact of eosinophils on bronchiectasis exacerbations. Methods: Patients were included from five countries to examine the relationships between blood eosinophil counts and clinical phenotypes after excluding coexisting asthma. 16S rRNA sequencing was used to examine relationships between eosinophil counts and the sputum microbiome. A post hoc analysis of the PROMIS (Inhaled Promixin in the Treatment of Non-Cystic Fibrosis Bronchiectasis) phase 2 trial was used to examine the impact of blood eosinophil counts on exacerbations in patients with Pseudomonas aeruginosa infection. Measurements and Main Results: A relationship between sputum and blood eosinophil counts was demonstrated in two cohorts. In analysis of 1,007 patients from five countries, 22.6% of patients had blood eosinophil counts of ⩾300 cells/µl. Counts of <100 cells/µl were associated with higher bronchiectasis severity and increased mortality. There was no clear relationship with exacerbations. Blood eosinophil counts of ⩾300 cells/µl were associated with both Streptococcus- and Pseudomonas-dominated microbiome profiles. To investigate the relationship of eosinophil counts with exacerbations after controlling for the confounding effects of infection, 144 patients were studied in a clinical trial after treatment with antipseudomonal antibiotics. Compared with patients with blood eosinophil counts of <100 cells/µl (reference), elevated eosinophil counts of 100-299 cells/µl (hazard ratio, 2.38; 95% confidence interval, 1.33-4.25; P = 0.003) and ⩾300 cells/µl (hazard ratio, 3.99; 95% confidence interval, 2.20-7.85; P < 0.0001) were associated with shorter time to exacerbation. Conclusions: Eosinophilic bronchiectasis affects approximately 20% of patients. After accounting for infection status, raised blood eosinophil counts are associated with shortened time to exacerbation.

Heterogeneity of treatment response in bronchiectasis clinical trials.

BACKGROUND: Recent randomised clinical trials in bronchiectasis have failed to reach their primary end-points, suggesting a need to reassess how we measure treatment response. Exacerbations, quality of life (QoL) and lung function are the most common end-points evaluated in bronchiectasis clinical trials. We aimed to determine the relationship between responses in terms of reduced exacerbations, improved symptoms and lung function in bronchiectasis. METHODS: We evaluated treatment response in three randomised clinical trials that evaluated mucoactive therapy (inhaled mannitol), an oral anti-inflammatory/antibiotic (azithromycin) and an inhaled antibiotic (aztreonam). Treatment response was defined by an absence of exacerbations during follow-up, an improvement of QoL above the minimum clinically important difference and an improvement in forced expiratory volume in 1 s (FEV1) of ≥100 mL from baseline. RESULTS: Cumulatively the three trials included 984 patients. Changes in FEV1, QoL and exacerbations were heterogeneous in all trials analysed. Improvements in QoL were not correlated to changes in FEV1 in the azithromycin and aztreonam trials (r= -0.17, p=0.1 and r=0.04, p=0.4, respectively) and weakly correlated in the mannitol trial (r=0.22, p<0.0001). An important placebo effect was observed in all trials, especially regarding improvements in QoL. Clinical meaningful lung function improvements were rare across all trials evaluated, suggesting that FEV1 is not a responsive measure in bronchiectasis. CONCLUSIONS: Improvements in lung function, symptoms and exacerbation frequency are dissociated in bronchiectasis. FEV1 is poorly responsive and poorly correlated with other key outcome measures. Clinical parameters are poorly predictive of treatment response, suggesting the need to develop biomarkers to identify responders.