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. Participants who were dosed but did not have any attacks in the period were assigned a value of zero. The number of attacks was normalized for the number of days participants participated in a given period and expressed as the monthly frequency.