Non-cystic fibrosis bronchiectasis (NCFB) is a chronic airway disease characterized by permanent bronchial dilatation, impaired mucus clearance, recurrent infection, airway inflammation, and repeated exacerbations. Existing bronchiectasis severity tools are clinically useful, but many depend on prior exacerbation history, hospitalization history, subjective symptom assessment, or culture-based microbiological classification. This prospective observational cohort study aims to develop and validate the Bronchiectasis Assessment of Severity and Exacerbations (BASE) framework. BASE is designed to classify current bronchiectasis severity and predict 12-month exacerbation risk using objective baseline functional, radiological, oxygenation, and inflammatory variables. Detailed methodological specifications, including variable definitions, scoring architecture, endpoint hierarchy, development-validation governance, and analytical integrity rules, are archived in a restricted-access Zenodo record: https://doi.org/10.5281/zenodo.20143505 . Participants will receive routine clinical care, and no treatment or intervention will be assigned by the study protocol. Patients will be followed for 12 months to record bronchiectasis exacerbations, hospitalization, lung-function change, inflammatory marker change, and clinical outcomes. The Bronchiectasis Assessment of Severity and Exacerbations (BASE) framework includes two linked baseline models: the BASE Severity model (BASE-S) for current bronchiectasis severity classification and the BASE Prognostic model (BASE-P) for prediction of 12-month exacerbation risk. Both models will be derived in the development cohort and applied unchanged to the validation cohort.
Non-cystic fibrosis bronchiectasis (NCFB) is a chronic airway disease characterized by permanent bronchial dilatation, impaired mucociliary clearance, recurrent infection, persistent airway inflammation, and repeated exacerbations. Disease severity and future exacerbation risk are heterogeneous among patients, and accurate baseline risk stratification remains clinically important for follow-up planning, preventive strategies, and early identification of patients at higher risk of clinical deterioration. Existing bronchiectasis severity tools provide useful clinical stratification, but several established approaches include variables such as previous exacerbation history, previous hospitalization, subjective dyspnea assessment, or culture-based microbiological classification. These variables may be influenced by health-care access, documentation quality, patient perception, physician decision thresholds, sputum sampling quality, timing of culture, and prior antibiotic exposure. Therefore, there is a need to evaluate whether a focused objective disease-signature framework can classify current disease severity and predict future exacerbation risk using baseline functional, radiological, oxygenation, and inflammatory variables. The Bronchiectasis Assessment of Severity and Exacerbations (BASE) framework is designed as a baseline clinical assessment model for adults with non-cystic fibrosis bronchiectasis (NCFB). The framework includes two linked baseline models: the BASE Severity model (BASE-S) for current bronchiectasis severity classification and the BASE Prognostic model (BASE-P) for prediction of 12-month bronchiectasis exacerbation risk. Detailed variable definitions, scoring rules, point-conversion methods, endpoint hierarchy, development-validation governance, and analytic specifications are archived in a restricted-access Zenodo record before final model derivation and validation: https://doi.org/10.5281/zenodo.20143505 . This is a prospective observational cohort study. Participants will not be assigned to any treatment or intervention by the study protocol. All clinical management decisions, including airway clearance, antibiotic treatment, inhaled therapy, microbiological testing, follow-up frequency, and hospitalization decisions, will follow routine clinical care and institutional practice. Eligible participants will undergo baseline clinical assessment, pulmonary function assessment, chest imaging review, resting room-air oxygenation assessment, and inflammatory marker assessment. Follow-up will continue for 12 months. During follow-up, bronchiectasis exacerbations, severe exacerbations requiring hospitalization, lung-function change, inflammatory marker change, treatment escalation, and clinical outcomes will be recorded using structured data collection forms. The study will use a development-validation design. The BASE-S and BASE-P equations, point structures, severity categories, and risk bands will be derived in the development cohort. The final locked models will then be applied unchanged to the validation cohort. No refitting, recalibration, variable substitution, point-score modification, or threshold retuning will be performed in the validation cohort. Model performance will be assessed using discrimination, calibration, risk-band separation, clinical utility where applicable, and comparison with established bronchiectasis severity tools where complete data are available. The intended output is a practical baseline disease-signature framework that can support severity classification and one-year exacerbation-risk prediction in adults with non-cystic fibrosis bronchiectasis (NCFB), while preserving separation from any future interventional treatment studies.
Study Type
OBSERVATIONAL
Enrollment
750
Assiut university-Faculty of Medicine
Asyut, Asyut Egypt, Egypt
RECRUITINGTwelve-Month Bronchiectasis Exacerbation Risk Predicted by the BASE Prognostic Model (BASE-P)
Occurrence of at least one bronchiectasis exacerbation during 12-month follow-up, used as the primary clinical endpoint for development and validation of the BASE Prognostic model (BASE-P). BASE-P is the 12-month risk-prediction component of the Bronchiectasis Assessment of Severity and Exacerbations (BASE) framework for adults with non-cystic fibrosis bronchiectasis (NCFB). Specific point ranges and risk categories have not yet been established and will be derived in the development cohort before locked validation. Higher BASE-P predicted risk values indicate higher expected exacerbation risk. Unit of Measure: Percentage of participants.
Time frame: Baseline to 12 months follow-up.
Current Bronchiectasis Severity Classification by the BASE Severity Model (BASE-S)
Baseline bronchiectasis severity classification using the BASE Severity model (BASE-S). BASE-S is the current severity-classification component of the Bronchiectasis Assessment of Severity and Exacerbations (BASE) framework for adults with non-cystic fibrosis bronchiectasis (NCFB). Specific severity point ranges and categories have not yet been established and will be derived in the development cohort before locked validation. Higher BASE-S severity categories indicate greater baseline bronchiectasis disease burden. Unit of Measure: Percentage of participants.
Time frame: Baseline Day 1
Time to First Bronchiectasis Exacerbation
Time from baseline assessment to the first recorded bronchiectasis exacerbation during follow-up. Participants without exacerbation will be censored at the last available follow-up date or at 12 months. Shorter time to first bronchiectasis exacerbation indicates earlier clinical deterioration and worse outcome. Unit of Measure: Days.
Time frame: Baseline to 12 months follow-up.
Number of Bronchiectasis Exacerbations During Follow-Up
Total number of bronchiectasis exacerbations recorded for each participant during the 12-month follow-up period. Higher exacerbation count indicates greater disease instability and worse clinical outcome. Unit of Measure: Number of events.
Time frame: Baseline to 12 months follow-up.
Severe Bronchiectasis Exacerbation Requiring Hospitalization
Occurrence of at least one bronchiectasis exacerbation requiring hospital admission during the 12-month follow-up period. Hospitalization-requiring exacerbation indicates more severe clinical deterioration and worse outcome. Unit of Measure: Percentage of participants.
Time frame: Baseline to 12 months follow-up.
Change in Forced Expiratory Volume in One Second Percent Predicted (FEV1% Predicted)
Change in forced expiratory volume in one second percent predicted (FEV1% predicted) measured by spirometry from baseline to 12 months. Change will be calculated as the 12-month value minus the baseline value. Lower or declining FEV1% predicted indicates worsening airflow limitation and worse functional outcome. Unit of Measure: Percentage points.
Time frame: Baseline to 12 months follow-up.
Change in Resting Room-Air Oxygen Saturation Measured by Pulse Oximetry (SpO₂)
Change in resting room-air oxygen saturation measured by pulse oximetry (SpO₂) from baseline to 12 months, when clinically feasible. Change will be calculated as the 12-month value minus the baseline value. Lower or declining SpO₂ indicates worse oxygenation reserve. Unit of Measure: Percentage points.
Time frame: Baseline to 12 months follow-up.
Change in Neutrophil-to-Lymphocyte Ratio (NLR)
Change in neutrophil-to-lymphocyte ratio (NLR), calculated from complete blood count as absolute neutrophil count divided by absolute lymphocyte count, from baseline to 12 months. Higher or increasing NLR indicates greater systemic neutrophilic inflammatory activity. Unit of Measure: Unitless ratio.
Time frame: Baseline to 12 months follow-up.
Change in C-Reactive Protein (CRP)
Change in C-reactive protein (CRP) from baseline to 12 months using routine laboratory measurement. Change will be calculated as the 12-month value minus the baseline value. Higher or increasing CRP indicates greater systemic inflammatory activity. Unit of Measure: Milligrams per liter (mg/L).
Time frame: Baseline to 12 months follow-up.
Bronchiectasis-Related Hospital Admission
Occurrence of hospital admission related to bronchiectasis deterioration, respiratory infection, bronchiectasis exacerbation, worsening respiratory symptoms, or related respiratory failure during follow-up. Occurrence of bronchiectasis-related hospital admission indicates worse clinical outcome. Unit of Measure: Percentage of participants.
Time frame: Baseline to 12 months follow-up.
Comparison of the Bronchiectasis Assessment of Severity and Exacerbations (BASE) Framework With the Bronchiectasis Severity Index (BSI)
Comparison of the Bronchiectasis Assessment of Severity and Exacerbations (BASE) framework with the Bronchiectasis Severity Index (BSI) for prediction of 12-month bronchiectasis exacerbation outcomes where complete data are available. Higher discrimination and better calibration indicate better predictive performance. Unit of Measure: Area under the receiver operating characteristic curve (0-1 scale).
Time frame: Baseline to 12 months follow-up.
Comparison of the Bronchiectasis Assessment of Severity and Exacerbations (BASE) Framework With the FACED Score
Comparison of the Bronchiectasis Assessment of Severity and Exacerbations (BASE) framework with the FACED score for prediction of 12-month bronchiectasis exacerbation outcomes where complete data are available. Higher discrimination and better calibration indicate better predictive performance. Unit of Measure: Area under the receiver operating characteristic curve (0-1 scale).
Time frame: Baseline to 12 months follow-up.
Comparison of the Bronchiectasis Assessment of Severity and Exacerbations (BASE) Framework With the E-FACED Score
Comparison of the Bronchiectasis Assessment of Severity and Exacerbations (BASE) framework with the E-FACED score for prediction of 12-month bronchiectasis exacerbation outcomes where complete data are available. Higher discrimination and better calibration indicate better predictive performance. Unit of Measure: Area under the receiver operating characteristic curve (0-1 scale).
Time frame: Baseline to 12 months follow-up.
Change in Modified Reiff Score
Change in Modified Reiff score from baseline to 12 months. The Modified Reiff score assesses radiological bronchiectasis extent and bronchial dilatation severity across six lobes, including the lingula, with a total score ranging from 0 to 18. Change will be calculated as the 12-month value minus the baseline value. Higher or increasing Modified Reiff score indicates greater structural radiological bronchiectasis burden or progression. Unit of Measure: Points.
Time frame: Baseline to 12 months follow-up.
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