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This document is the translation of the first consensus-based German-language guidelines on the management of adult bronchiectasis. As such, it does not cover all aspects of the disease, particularly given the limited availability of evidence-based data in many areas. The guidelines committee aimed to provide practical recommendations and statements for clinical practitioners, along with relevant background information. In accordance with Association of Scientific Medical Societies in Germany (AWMF) regulations for consensus-based (S2k) guidelines, the strength of recommendations is indicated by the wording used: “recommend/not recommend” signifies a strong recommendation; “should/should not” indicates a moderate recommendation; and “can be considered/can be waived” represents an open recommendation. For more details on the guidelines’ development process, refer to the guidelines’ report.

Bronchiectasis is a syndrome with a variable clinical course, diagnosed based on both radiological and clinical criteria. Although it presents with characteristic symptoms, these are nonspecific and often overlap with those of other common respiratory conditions, such as asthma or chronic obstructive pulmonary disease (COPD) []. The provision of adequate medical care for patients with bronchiectasis is complicated by several factors. On one hand, bronchiectasis is a heterogeneous disease with a wide range of etiologies – some of which are rare or even extremely rare. On the other hand, it is also associated with numerous complications and comorbidities []. There is also considerable regional variation in the epidemiology of bronchiectasis, along with significant differences across healthcare sectors and levels of care [, ]. In the absence of standardized treatment protocols, care has often been based on available local resources, situational constraints, or the clinical experience of individual physicians and treatment centers []. Evidence remains limited for many aspects of bronchiectasis management, and there are few incentives to seek regulatory approval for the small number of evidence-based generic medications. As a result, pharmacological therapies, medical devices, therapeutic aids, and remedies are frequently used off-label. This imposes a substantial administrative burden on prescribing physicians and often involves considerable liability and reimbursement risks. In many cases, medical interventions are initiated only in response to advanced disease stages – by which point irreversible damage has often already occurred []. Prescribing practices also vary considerably between Germany, Austria, and Switzerland, and even among individual federal states and cantons [].

The prevalence of bronchiectasis – and associated hospitalizations – has steadily increased in recent years [–]. A population-based study found that the prevalence of bronchiectasis among members of the German statutory health insurance (SHI) rose by an average of 10% annually between 2009 and 2017. With an estimated prevalence of approximately 120 cases per 100,000 population, Germany likely had over 100,000 individuals living with bronchiectasis by 2022 []. Prevalence rates across Europe range from 36 to 566 per 100,000 population [, –], while countries in the Asia-Pacific region appear to have the highest global rates [, ]. Notably, in 2013, over 90% of bronchiectasis patients in Germany were treated in outpatient settings – environments where delivering complex, interdisciplinary, and multi-professional care can be particularly challenging []. Data from the European bronchiectasis registry EMBARC indicate a median age of 67 years among patients, with 61% being female. By contrast, patients in the German bronchiectasis registry (PROGNOSIS) were slightly younger, with a median age just under 60, and a similar gender distribution [, ]. Whether the ongoing rise in prevalence reflects a true increase in disease incidence remains uncertain. Factors likely contributing to the trend include demographic changes in industrialized countries, increased life expectancy, greater use of low-threshold computed tomography (CT) imaging, and heightened clinical awareness of the condition among healthcare providers [, ].

Multiple studies highlight the burden bronchiectasis places on healthcare systems, including frequent physician visits, complex multimodal therapies, and hospitalizations due to exacerbations [–]. A population-based case-control study using German SHI data compared the healthcare and productivity-related costs of newly diagnosed bronchiectasis patients to those of matched controls (by age, sex, and comorbidities) []. Over a 3-year follow-up period, total direct costs for bronchiectasis patients were nearly one-third higher than those for the control group. The largest portion of direct healthcare spending was for outpatient medications – especially mucolytics and bronchodilators – which accounted for 41% of the total. Antibiotic expenditures were nearly five times higher among bronchiectasis patients. Hospitalization costs made up 35% of total spending and were, on average, 56% higher than in controls, with average hospital stays lasting nearly 5 days longer. In total, the annual direct and indirect costs attributable to bronchiectasis in 2018 exceeded €38.5 million []. In this context, a study from Spain that analyzed hospitalization costs related to exacerbations found that Pseudomonas aeruginosa infection is associated with significantly increased healthcare costs. It was also identified as an independent risk factor for longer hospital stays and higher post-discharge healthcare expenditures [].

Chest radiography has limited sensitivity for detecting bronchiectasis, particularly in mild cases []. Bronchography was replaced by CT as the gold standard for diagnosing bronchiectasis many years ago []. Advances in CT technology – such as thinner slices and higher resolution – have further enhanced diagnostic sensitivity. Modern CT scanners allow for significant reduction in radiation exposure, with doses below 1 mSv now sufficient for evaluating the lung parenchyma and airways []. The natural contrast between air and soft tissue within the lungs eliminates the need for intravenous contrast agents in most routine assessments. However, in more complex clinical scenarios – such as suspected vascular complications (e.g., hemoptysis) or for differential diagnosis (e.g., tumor, pulmonary embolism) – the use of intravenous contrast and higher dose protocols may be warranted. Although specific CT protocols may vary depending on the scanner used and clinical context, the general principles outlined in Box 1 should be followed when assessing the presence or progression of bronchiectasis.

MRI may be considered, particularly for younger patients or when repeated imaging is necessary, as is often the case in children and adolescents with cystic fibrosis (CF). Established MRI protocols are available that provide both morphological and functional information [–]. Recent advances – such as high-resolution morphological sequences and contrast-free functional imaging for visualizing ventilation and perfusion – show promise [, ]. However, these newer techniques are not yet widely available in routine clinical practice and have not been adequately validated for the diagnosis of non-CF bronchiectasis. Box 2 outlines the key diagnostic criteria for bronchiectasis on CT scans. Under normal physiological conditions, the bronchial diameter should not exceed the diameter of the adjacent pulmonary artery. However, several factors must be considered when interpreting the bronchoarterial ratio: Pulmonary artery diameter may vary, e.g., in cases of pulmonary hypertension or hypoxic vasoconstriction Lung volume can affect measurement accuracy Bronchial diameter naturally increases with age.

As such, the bronchoarterial ratio should not be treated as an absolute cutoff but rather interpreted in the context of clinical symptoms and individual variability. According to a recent international consensus statement, a bronchoarterial ratio ≥1.5 (measured as the inner bronchial diameter) offers the highest diagnostic confidence, while a ratio ≥1.0 remains sufficiently sensitive for clinical use []. In routine clinical practice, a visual assessment of bronchial diameter and the bronchoarterial ratio is typically adequate. While software- or AI-based airway analysis does not provide additional diagnostic value, it may be useful for monitoring disease progression or evaluating treatment response, especially in clinical studies utilizing quantitative or semiquantitative scoring systems, such as the Reiff or Bhalla scores [–]. Furthermore, CT imaging is the preferred modality for determining the underlying etiology of bronchiectasis (Box 3). CT imaging can thus offer important insights into the etiology of bronchiectasis. Although no CT pattern is specific to a single underlying cause [], certain imaging features – or their combinations – can help narrow the differential diagnosis and guide further targeted evaluation (see Basic Investigations and Advanced Etiological Diagnosis and Appendix 1 [German] at https://register.awmf.org/de/leitlinien/detail/020-030 ).

The term bronchiectasis refers to both a distinct symptomatic disease and its characteristic radiological findings []. Historically, bronchiectasis not caused by CF is often labeled non-CF bronchiectasis . However, in recent years, the terminology has shifted to define the condition by what it is – bronchiectasis – rather than by what it is not []. This change is supported by the fact that CF accounts for only a small proportion of cases. In Germany, e.g., the estimated number of people living with CF is approximately 8,000, compared to over 100,000 individuals with bronchiectasis [, ]. To distinguish radiologic findings from the actual clinical disease, the term clinically significant bronchiectasis was introduced in recent international consensus recommendations []. This distinction is increasingly important, as advances in high-resolution chest CT – especially in aging populations and in the context of lung cancer screening – have led to more incidental findings of bronchiectasis. These findings, often part of the normal aging process, may not be accompanied by symptoms []. The clinical relevance and long-term prognosis of such incidental cases remain unclear [].

The symptoms of clinically significant bronchiectasis are highly variable, nonspecific, and frequently overlap with those of other chronic respiratory conditions []. In a Delphi consensus process, an international expert panel evaluated 27 symptoms and clinical features to establish a broadly inclusive definition suitable for use in clinical trials. The three symptoms most commonly identified in patients with clinically significant bronchiectasis were: cough on most days of the week, recurrent exacerbations, either current or in the patient’s history [, ]. Other symptoms and varying degrees of severity are also commonly observed, reflecting the disease’s heterogeneity, clinical course, and treatment status (). Recognizing clinically significant bronchiectasis as a distinct clinical entity is essential for several reasons. Clearly defined terminology promotes accurate understanding of the disease, supports the development and implementation of clinical standards, enhances advocacy for affected individuals, and helps attract attention from the media, policymakers, and biomedical research. This, in turn, fosters the advancement of evidence-based therapies. We therefore recommend using the term clinically significant bronchiectasis to clearly distinguish the symptomatic disease from incidental radiological findings alone.

The pathophysiology underlying bronchiectasis exacerbations remains incompletely understood []. Traditionally, bacterial infections have been considered the primary and most common trigger []. However, respiratory viruses are also frequently detected – using molecular techniques – in up to 50% of respiratory specimens during exacerbations [–], though they are often present during clinically stable periods as well []. The role of respiratory viruses in triggering exacerbations is indirectly supported by data from the COVID-19 pandemic: social distancing and enhanced hygiene measures were associated with a 48% reduction in exacerbation rates []. In addition to infections, environmental factors such as particulate matter and nitrogen dioxide pollution, along with complex microbial interactions – including bacterial metabolism and interkingdom dynamics among bacteria, fungi, and viruses – appear to contribute to exacerbation development [, , ].

An exacerbation is a key event in the life of a person living with bronchiectasis []. These episodes are associated with intense, predominantly neutrophil-driven inflammation and have a significant negative impact on prognosis and quality of life [, , ]. Moreover, recent studies suggest that patients with prominent type-2 inflammation face a substantially higher risk of experiencing frequent and/or severe exacerbations [–]. Data from the German bronchiectasis registry PROGNOSIS indicate a median exacerbation frequency of one per year, with 30% of patients experiencing none or three or more exacerbations annually, and 40% having 1–2 exacerbations per year []. An international expert panel has proposed a consensus definition of bronchiectasis exacerbation, based solely on clinical criteria [] (Box 4). Although originally developed for use in clinical trials, the current consensus definition of bronchiectasis exacerbation is now widely applied in routine clinical practice due to its pragmatic, patient-centered, and specific nature. However, not all patients present with the required minimum of three out of six key symptoms, so the diagnosis may also be supported by additional clinical signs and findings (). Supporting indicators that may aid in diagnosing an exacerbation include. Fever or a body temperature ≥38°C []. Increased respiratory rate (≥30 breaths/min)

New or worsening auscultatory findings (e.g., wheezing, rhonchi, rales) Elevated markers of systemic inflammation Worsening pulmonary function (e.g., decline in FEV1 or peak flow) New or increased opacities in chest X-ray, often due to retained bronchial secretions ()

Correct interpretation of laboratory and diagnostic findings often depends on knowledge of a patient’s baseline status. The utility of biomarkers such as C-reactive protein (CRP) and procalcitonin in diagnosing bronchiectasis exacerbations remains limited and is not explicitly included in current international guidelines [–]. This limitation is largely due to the presence of chronic local and systemic inflammation in bronchiectasis, which can lead to elevated CRP levels even during clinically stable periods [–]. In contrast, procalcitonin appears to have low sensitivity for detecting exacerbation []. Consequently, there is an urgent need for further clinical research to validate these and other biomarkers in this context. Pulmonary function testing is also not reliably diagnostic, as lung function may fluctuate from day to day [, ]. Without an adequate number of baseline measurements over time, distinguishing between normal variability and a clinically relevant decline associated with exacerbation is often challenging. Nevertheless, measuring biomarkers and obtaining instrument-based assessments can support treatment decisions, such as assessing exacerbation severity and determining the need for hospitalization or parenteral antibiotic therapy. Exacerbation severity is generally classified based on clinical evaluation and treatment implications [, , ]: Severe exacerbation: requires hospitalization, typically with intravenous antibiotics

Moderate exacerbation: managed in the outpatient setting with oral antibiotics Mild exacerbation: does not require hospitalization or antibiotics and can be managed through adjustment of maintenance therapy.

In their consensus paper, the abovementioned international expert panel also recommended replacing the term chronic bacterial colonization with chronic bacterial infection . In patients with clinically significant bronchiectasis, referring to the presence of a prognostically relevant pathogen such as P. aeruginosa as mere “colonization” may dangerously understate its clinical significance. The panel emphasized that the presence of inflammation and tissue damage fulfills the criteria for infection [, , ]. The proposed definition of chronic infection is admittedly pragmatic (Box 5), acknowledging that it may also apply to culture-negative patients undergoing suppressive antibiotic therapy. Importantly, the standard of care in bronchiectasis differs significantly from that in CF. The expectation of six sputum, induced sputum, deep throat swab, or bronchoalveolar lavage (BAL) cultures per year – standard in CF care – is often unrealistic in the bronchiectasis setting []. Unlike in CF, the clinical relevance of intermittent pathogen detection in bronchiectasis remains uncertain and likely depends heavily on the specific microbiological methods used.

The aforementioned international expert panel also recommends avoiding the use of the term eradication in the future. This recommendation is based on the fact that – although culture-based methods remain the diagnostic standard in routine care – they may lack the sensitivity to detect certain pathogens. In contrast, molecular diagnostic techniques – such as microbiome analysis – can identify pathogens that may not be captured through conventional culture methods [].

The original definition of bronchiectasis was based on post-mortem examinations, where the condition was characterized as irreversible airway damage resulting from structural remodeling and scarring of the large bronchi []. Over recent decades, however, understanding of the disease has shifted toward the recognition that bronchiectasis is typically the result of a prolonged pathological process []. This process often begins with an identifiable underlying condition or predisposing disease, such as CF, COPD, primary ciliary dyskinesia (PCD), Kartagener’s syndrome, primary immunodeficiency disorder (PID), or persistent bacterial bronchitis (PBB) (see Follow-Up and Microbiological Surveillance). These conditions are commonly associated with impaired mucociliary clearance and increased vulnerability of the bronchial epithelium [, ]. Mucus retention alone can initiate chronic airway inflammation, which is further amplified by viral or bacterial infections and exacerbations. This creates a vicious cycle of infection, inflammation, and progressive structural damage. If not identified and managed early, this cycle leads to airway remodeling, bronchial dysfunction, and ultimately, irreversible bronchiectasis []. A hallmark of bronchiectasis is the occurrence of recurrent exacerbations, which may evolve into chronic bacterial infection, most commonly involving Staphylococcus aureus , Haemophilus influenzae , and – especially in advanced stages or certain etiologies – P. aeruginosa [].

Based on Peter Cole’s vicious cycle model , bronchiectasis has traditionally been viewed as a neutrophil-dominated inflammatory disease of the airways, accompanied by mucus hypersecretion from goblet cells (). Key inflammatory mediators include interleukin (IL)-1β, IL-8, TNF-α, and leukotrienes, as well as neutrophil serine proteases such as neutrophil elastase, proteinase 3, and cathepsin G. These proteases, in turn, activate matrix metalloproteinases and are themselves activated by the cysteine protease cathepsin C (CatC; also known as dipeptidyl peptidase 1, DPP-1) [, , ]. However, both clinical experience and emerging evidence suggest that not all patients exhibit a neutrophilic profile. Some patients show a type 2-driven or eosinophilic inflammatory pattern, or evidence of autoimmune comorbidity, and respond well to anti-allergic, anti-eosinophilic, or immunomodulatory therapies, especially in terms of exacerbation prevention [–]. These inflammatory endotypes may not always align with the primary etiology of bronchiectasis but may represent clinically relevant, treatable traits, or comorbidities [, , , ]. The term eosinophilic phenotype of bronchiectasis generally refers to cases with underlying eosinophilic disorders or relevant comorbidities such as asthma, allergic bronchopulmonary aspergillosis (ABPA), or eosinophilic granulomatosis with polyangiitis (EGPA). In such cases, optimal management focuses on treating the underlying disease, ranging from guideline-based asthma therapy with high-dose inhaled corticosteroids (ICSs) to the use of biologic agents approved for eosinophilic diseases, as well as targeted treatments for ABPA and EGPA based on severity [, ]. An independent eosinophilic endotype of bronchiectasis is also being explored. As with other chronic airway diseases, peripheral eosinophil levels appear to correlate with the risk of exacerbations [, , ].

Importantly, a thorough medical history – including early symptom onset and prior findings, even before bronchiectasis is radiologically apparent – is essential for identifying potentially missed or mismanaged underlying conditions. Data from the PROGNOSIS cohort indicate that over 40% of participants had known bronchiectasis for more than 10 years []. It is not uncommon for adult patients to present with a complex history and evolving clinical phenotypes. For example, a patient initially presenting with asthma and eosinophilic mucus retention may, over time, develop a dominant neutrophilic component due to recurrent exacerbations or prolonged oral corticosteroid (OCS) use, potentially leading to chronic bacterial infection. A deeper understanding of the pathophysiology and individual disease progression of bronchiectasis enables earlier, more targeted therapeutic interventions. In this context, it is important to highlight that PBB – a leading cause of chronic productive cough in children and adolescents – is an independent condition, though often underrecognized by pulmonologists. PBB responds well to targeted antibiotic therapy and, when appropriately managed, may prevent the progression to bronchiectasis [, ].

Bronchiectasis is a disease with highly heterogeneous etiology, and as of March 2024, no pharmacological therapies are explicitly approved for its treatment []. As a result, identifying and treating the underlying cause is of critical importance since all other available therapies are primarily symptom-based [, ]. Only through targeted, etiology-specific treatment can a causal approach be achieved – typically offering the most effective means to improve a patient’s quality of life. The most common causes of bronchiectasis vary significantly across Europe [, ]. In Germany, the bronchiectasis registry PROGNOSIS has been systematically collecting standardized data on disease etiology since 2015 to support diagnostic clarification []. Based on these data, five key etiologies account for 92% of all documented cases () []. Although a previously undiagnosed case of CF as the underlying cause of bronchiectasis is relatively rare, the prognostic and therapeutic implications of such a diagnosis are significant – not only for the patient but also for potentially affected family members, siblings, and offspring. This consideration is particularly important given the availability of highly effective CFTR modulator therapies, which in many patients can achieve (partial) correction of the underlying CFTR dysfunction [–].

Despite increasingly standardized and thorough diagnostic approaches, the proportion of idiopathic bronchiectasis in Europe remains high, at approximately 30–40% [, ]. Conversely, this also implies that identifying a specific etiology may offer a targeted treatment opportunity for up to two-thirds of individuals with the condition. It is important to acknowledge, however, that distinguishing an etiology from a comorbidity can be challenging in clinical practice (see Comorbidity).

Acute and chronic infections are common in patients with bronchiectasis and play a central role in both the pathogenesis and progression of the disease [, ]. The microbiological analysis of respiratory tract samples therefore is of great importance for clarifying the cause, making treatment decisions and monitoring progress. Some recommendations have already been established as national standards for the treatment of CF, although these recommendations only apply in part to bronchiectasis, which is characterized by a heterogeneous etiology [, ]. Laboratories follow the applicable guidelines and quality standards for microbiological and infectious disease diagnostics of the AWMF, the German Medical Association and the DGHM [, , ]. Proper microbiological testing requires specialized expertise in handling respiratory specimens from this patient group. Such expertise is critical for ensuring valid diagnostic results – beginning with the pre-analytical phase, continuing through sample processing, and including the appropriate selection of culture methods and other diagnostics.

In patients capable of spontaneous expectoration, sputum is the preferred specimen for microbiological testing, as it can typically be collected without additional burden to the patient. If spontaneous sputum production is not possible, expectoration can be induced via inhalation of hypertonic saline or with the assistance of a physiotherapist. In cases of clinical deterioration of unknown origin or when localized findings are present, samples from deeper respiratory tract regions – such as tracheal or bronchial secretions or BAL – should be used for microbiological analysis. When requesting microbiology testing, clinicians should note that standard diagnostic protocols may not sufficiently detect certain pathogens, such as P. aeruginosa , other non-fermenting bacteria, small colony variants, fungi, Nocardia spp. , and particularly mycobacteria [, , , ]. In such cases, laboratories should be informed explicitly, and the diagnostic scope expanded as needed. There are currently no uniform recommendations for the frequency of microbiological testing in bronchiectasis. However, comprehensive microbiological testing is recommended at the initial diagnosis and during episodes of clinical deterioration [, ]. In routine follow-up, screening for newly acquired pathogens – particularly P. aeruginosa and NTM – is typically performed every 6–12 months. This facilitates timely adjustments to anti-infective therapy based on the identified pathogens and their resistance profiles [].

The clinical relevance of individual pathogens often depends on patient-specific factors. While the pathogenic role of P. aeruginosa is well established, it is increasingly assumed that other pathogens may also contribute significantly to disease progression – particularly considering their recognized importance in the pulmonary manifestations of CF [, –].

Data from Germany indicate that approximately one-third of patients with bronchiectasis are infected with P. aeruginosa [, ]. A 2015 meta-analysis found that chronic P. aeruginosa infection is associated with a nearly threefold increase in mortality risk [], a risk that is further influenced by the frequency of exacerbations []. Patients with chronic P. aeruginosa infection experience more frequent exacerbations, including a sixfold increased risk of severe exacerbations requiring hospitalization. They also present with more severe respiratory symptoms, reduced quality of life, lower lung function (FEV 1 ), and more pronounced radiologic changes [, , ]. These clinical findings are supported by analyses of the sputum microbiome in bronchiectasis patients, which show that Pseudomonas dominance correlates with reduced microbial diversity, higher mortality, and increased rates of exacerbation and hospitalization []. Chronic P. aeruginosa infection is thus a key indicator of disease severity and is incorporated into the most widely used bronchiectasis severity scoring systems (see Risk Stratification) [, , ]. Beyond its clinical impact, P. aeruginosa infection also leads to significantly higher healthcare costs, primarily due to increased hospitalizations and greater use of healthcare resources [, ].