Inclusion criteria and search methods
The Cochrane Airways Register of Trials is a unique database containing definite, probable and possible randomised controlled trials (RCTs) and quasi-randomised trials (CCTs) relevant to the Group's scope and topics. The Register includes trial reports on asthma, chronic obstructive pulmonary disease (COPD), sleep apnoea, bronchiectasis, interstitial lung diseases, and pulmonary hypertension.

The Register is developed, maintained and administered by the Information Specialist at the Cochrane Airways editorial base. References to trial reports are identified through systematic searches of bibliographic databases, and handsearching of respiratory conference abstracts. Full details about the sources searched, and the database search strategies used to identify trial reports for the Register are described in this document.

How we maintain the Register
The process for maintaining the Register is shown in this flow diagram. Records identified through database searches are downloaded and imported into the Cochrane Register of Studies (CRS). We use the RCT Classifier, a machine learning tool built in to the CRS, to help identify reports of RCTs and quasi-RCTs. Records with a very low likelihood of being a report of a RCT are discarded. Records that have already been rejected by Cochrane Crowd are also discarded. The remaining records are checked by the Information Specialist and the record is then coded as an RCT or CCT according to Cochrane's definition. If the study design is unclear from the information available, the record is retained in the Register until the full-text of the paper can be checked and the study design verified. Eligible records are published in the CENTRAL database on the Cochrane Library.

What we use it for

• To support the production of Cochrane reviews. The Information Specialist searches the Register for all Cochrane Airways standard intervention reviews of RCTs.
• To inform prioritisation of review topics. Scoping searches of the Register help us to identify evidence gaps and active areas of research. The routine literature surveillance process we use to populate the Register can help to identify new and emerging treatments.

Access to the Trials Register
Review authors working with Cochrane Airways have access to the Trials Register via the Group’s Information Specialist. The Trials Register is made available to a wider audience through the CENTRAL database on the Cochrane Library. You can identify this subset of CENTRAL by searching all fields using the code SR-AIRWAYS.

For more details about the search methods support available to Cochrane Airways review author teams, please see Search methods support and Reference management.