ISAR is the first global severe asthma registry; a joint initiative where national registries (both newly created and pre-existing) retain ownership of their own data but open their borders and share data with ISAR for ethically approved research purposes. The ISAR initiative is conducted by Optimum Patient Care Global Limited (OPC), with scientific oversight from the ISAR Core Steering Committee (ISC), academic support from the Respiratory Effectiveness Group (REG), ethical governance from the Anonymized Data Ethics & Protocol Committee (ADEPT), co-funding from OPC and AstraZeneca since May 2017. Prospective patient recruitment by 2022 is 13,150 patients with severe asthma.