Derivation and Definitions of Clinical Study Variables for Multiple Long Term Conditions in Patients with Chronic Obstructive Pulmonary Disease: Protocol for a Modified Delphi Methods and Consensus Study on Behalf of the International Cardiovascular and Respiratory Alliance.

Background: Standardized variables and their definitions are essential for robust delivery and reporting of clinical studies and quality improvement in chronic obstructive pulmonary disease (COPD). This protocol describes the rationale and methodology for the derivation and definition of clinical study variables for patients with multimorbidity or at high risk of multimorbidity in COPD. Methods and Analysis: We will follow a four-step process. This will include the formation of an Executive Committee, a Steering Committee and an International Consensus Group. We will conduct a systematic review of the literature from which potential clinical study variables will be extracted and their definitions proposed. Using a modified Delphi process, the Steering Committee will select candidate clinical study variables and as necessary refine their definitions. All three groups will then vote and give feedback on the candidate clinical study variables in a modified Delphi process (with rounds until consensus is achieved) to reach a final suite of internationally agreed hierarchically classified clinical study variables. Ethics and Dissemination: It is anticipated that the results will be published in a peer-reviewed journal and presented in a variety of forums. Ethical approval was not required for this study.