Mean change in the number of monthly migraine headache days from the last 28 days of Baseline to the last 28 days of treatment (ie, month 3). A migraine headache day is any calendar day (0:00 to 23:59) in which the patient records in the e-diary:

• An attack lasting 4 hours or more and meeting the ICHD-3 criteria for migraine without aura, or
• A migraine with aura, or
• An attack that meets ICHD-3 criteria for probable migraine, (a migraine subtype fulfilling all but one criteria (B-D) for migraine without aura), or
• An attack of any duration that was believed by the patient to be a migraine and was relieved by a triptan, ergot derivative, or other migraine-specific abortive medication.

Data is reported for the mITT population, which includes all randomized patients who received at least one dose of study drug and had at least one post-Baseline evaluable month (that is, at least one of the three 28-day periods has at least 14 non-missing e-diary entries).

Proportion of patients experiencing a ≥ 50% reduction in the number of migraine headache days from the last 28 days of Baseline to the last 28 days of treatment in each treatment group

Data is reported for the mITT population, which includes all randomized patients who received at least one dose of study drug and had at least one post-Baseline evaluable month (that is, at least one of the three 28-day periods has at least 14 non-missing e-diary entries).

Mean change in the number of days using rescue medication (triptan, ergot derivative, or other migraine-specific acute medication) from the last 28 days of Baseline to the last 28 days of treatment.

Data is reported for the mITT population, which includes all randomized patients who received at least one dose of study drug and had at least one post-Baseline evaluable month (that is, at least one of the three 28-day periods has at least 14 non-missing e-diary entries).

Proportion of patients with a Patient Global Impression of Change (PGIC) of 1, "very much improved", or 2, "much improved", at Week 12. Scores range from 1 to 7. Lower scores indicate more improvement.

Data is reported for the mITT population, which includes all randomized patients who received at least one dose of study drug and had at least one post-Baseline evaluable month (that is, at least one of the three 28-day periods has at least 14 non-missing e-diary entries).

Mean change in the number of moderate or severe headache days from the last 28 days of Baseline to the last 28 days of treatment. A moderate or severe headache day is defined as any calendar day wherein a patient records a headache or migraine of moderate or severe peak intensity in the e-diary.

Data is reported for the mITT population, which includes all randomized patients who received at least one dose of study drug and had at least one post-Baseline evaluable month (that is, at least one of the three 28-day periods has at least 14 non-missing e-diary entries).

Mean change in the number of migraine headache days from the last 28 days of Baseline to average number per 28 days over the entire 12-week duration of Treatment Period.

Data is reported for the mITT population, which includes all randomized patients who received at least one dose of study drug and had at least one post-Baseline evaluable month (that is, at least one of the three 28-day periods has at least 14 non-missing e-diary entries).

Mean change from Baseline in the Migraine-Specific Quality of Life Questionnaire (MSQ v2.1) at Week 12. Scores range from 0 to 100. Higher scores indicate better quality of life.

Data is reported for the mITT population, which includes all randomized patients who received at least one dose of study drug and had at least one post-Baseline evaluable month (that is, at least one of the three 28-day periods has at least 14 non-missing e-diary entries).