The purpose of this study is to collect valid data from all forms of health care on the incidence, prevalence, the regional distribution, characteristics, management and outcomes of different ILDs under clinical practice conditions.

Interstitial lung diseases (ILD) are a heterogeneous group of more than 200 entities that can be idiopathic or as a result of other diseases and/or treatments. All forms of ILD are considered to be seldom or very seldom (and most of them are so-called "orphan" diseases), in their entirety they seem to represent an epidemiological burden, which should not be underestimated, e.g. as "normal" symptoms of the elderly.

The knowledge about the epidemiology of ILDs is very limited, in general and in Germany in particular. For Germany no current, valid and comprehensive population-based data on ILDs exist because no appropriate ILD classification was available for a long time. The epidemiological data, which were collected before the introduction of the current classification of ILD according to the ATS/ERS consensus and before HRCT was considered the diagnostic gold standard, are not very reliable. Furthermore systemic investigations relating to the development of an ILD of risk groups, such as patients undergoing radio- or chemotherapy or patients with connective tissue disease, are restricted.

Thus, only little is known about costs associated with ILDs. Idiopathic Pulmonary Fibrosis (IPF), as one of the disease entities, was shown to be associated with high healthcare utilization and costs in England and the USA, as in many cases lung transplantation is the only therapeutic option and also new pharmaceutical treatments are costly. But there is a lack of data on healthcare utilization and financial consequences of other ILD than IPF in Germany. Therefore, this registry will provide an important database for health economics and health services research questions.

Against this background, this multi-centre, non interventional prospective observational disease and outcomes registry for ILD aims to collect valid data from all forms of health care on the incidence, prevalence, the regional distribution, characteristics, management and outcomes of different ILDs under clinical practice conditions. In detail, demographic data such as gender, age, country of birth, place of residence; disease related data such as subtype of ILD, treatment center, diagnostic procedures (e.g. HRCT, lung biopsy, pulmonary function tests); risk factors (e.g. smoking status, profession, familial ILD); co-morbidities; ILD management as analysed by the kind and frequency of pharmacological and non-pharmacological therapies; outcome; and consumption of resources will be recorded. Therefore, this registry will allow obtaining a comprehensive and current epidemiologic report for ILDs in Germany and can be particularly helpful in uncovering correlations between risk exposure and disease development.

This study, with up to 100 sites, initially focused on the federal states Baden-Wuerttemberg and Hesse, is planned for a minimum of 5 years and 600 patients should be enrolled as part of the study a screening/baseline visit, on which the Informed Consent Form will be signed, and every 6 months regularly updates/phone contacts will be performed.

Following quality procedures are applicable for this registry:

• Quality assurance plan that addresses data validation and registry procedures, including any plans for site monitoring and auditing.
• Data checks to compare data entered into the registry against predefined rules for range or consistency with other data fields in the registry.
• Source data verification to assess the accuracy, completeness, or representativeness of registry data by comparing the data to external data sources (e.g., medical records, paper or electronic case report forms, or interactive voice response systems).
• Standard Operating Procedures to address registry operations and analysis activities, such as patient recruitment, data collection, data management, data analysis, reporting for adverse events, and change management.
• Sample size assessment to specify the number of participants or participant years necessary to demonstrate an effect.
• Plan for missing data to address situations where variables are reported as missing, unavailable, "non-reported," uninterpretable, or considered missing because of data inconsistency or out-of-range results
• Statistical analysis plan describing the analytical principles and statistical techniques to be employed in order to address the primary and secondary objectives, as specified in the study protocol or plan.

Inclusion Criteria:

• Signed informed consent
• Able to read and understand the scope and nature of data collection
• Aged ≥ 18 at time of informed consent
• Patients diagnosed with interstitial lung disease (ILD). Patients with suspicion on interstitial lung disease cannot be included into the registry, only after consens diagnosis of an ILD. This is also the case for patients with not classifiable ILDs.

Subjects with the following subtypes of ILD will be enrolled:

1. Idiopathic interstitial pneumonia (IIPs)

   • Idiopathic pulmonary fibrosis (IPF)
   • Non-specific interstitial pneumonia (NSIP)
   • Desquamative interstitial pneumonia (DIP)
   • Respiratory bronchiolitis-associated interstitial lung disease (RB-ILD)
   • Cryptogenic organizing pneumonia (COP)
   • Lymphocytic interstitial pneumonia (LIP)
   • Acute interstitial pneumonia (AIP)
   • Rare forms of IIPs (e.g. pleuropulmonary fibroelastosis)
   • Not classifiable IIP

2. Granulomatous lung disease

   • Sarcoidosis
   • Berylliosis
   • Other (e.g. involvement in chronic inflammatory liver and gut diseases, except EAA)

3. Hypersensitivity pneumonitis (exogen allergic alveolitis (EAA))

   • Farmer's lung
   • Bird keepers' lung disease
   • Origin unknown
   • Other

4. Rheumatic and connective tissue diseases with pulmonary involvement like:

   • Connective tissue disease (subtype)
   • Vasculitis
   • Rheumatoid arthritis

5. Pneumoconiosis

   • Asbestosis
   • Silicosis
   • Other

6. Other forms

   • Pulmonary lymphangioleiomyomatosis
   • Pulmonary Langerhans' cell histiocytosis
   • Pulmonary alveolar proteinosis
   • Eosinophilic pneumonia
   • Post-ARDS Fibrosis

7. Drug-related

8. Radiotherapy associated

9. Fibrosis in emphysema patients without signs of other ILDs (i.e. smoking related interstitial fibrosis or "emphysemasclerosis")

10. Others

11. Not classifiable

Furthermore for each subtype it will be queried, if a diagnosis of concomitant emphysema in ILD was made.

Exclusion Criteria:

- Patients without interstitial lung disease

ILD patients from all forms of health care