Angioedema attack was defined as the participant-reported indication of symptoms or signs such as swelling or pain at any location following a report of no swelling or pain on the previous day. Manifestations of an attack that progress from one site to another, prior to complete resolution, was considered a single attack. Attacks that began to regress and then worsened before complete resolution was also considered one attack. Attacks that began then appeared to resolve and then reappeared without a symptom-free calendar day reported after the appearance of resolution were considered 1 attack. Any events of swelling due to trauma or symmetrical nonpainful swelling of the lower extremities were not considered an angioedema attack. The number of attacks was normalized for the number of days participants participated in a given period and expressed as the monthly frequency.