• An SAE is defined as any untoward medical occurrence that, at any dose, meets one or more of the criteria listed: results in death, is life-threatening, requires inpatient hospitalization or prolongation of existing hospitalization, results in persistent disability/incapacity, is a congenital anomaly/birth defect.
• TEAE is defined as an event that first occurred or worsened in severity after baseline and on or prior to the date of the last visit within the treatment period.

All participants who received at least 1 dose of study treatment. As per prespecified analysis in the statistical analysis plan, adverse events were collected and analyzed by ixekizumab dosing regimen [that is, Q2W/Q4W and Q4W].

Participants achieving a PASI-75 without the use of other background antipsoriasis therapy were considered responders. The PASI quantifies the severity of a psoriasis based on lesion severity and the percent of body surface area (BSA) affected. Erythema, thickness, and scaling are scored on a scale of 0 (none) to 4 (very severe) on 4 anatomic regions of the body: head, trunk, upper limbs, and lower limbs. Degree of involvement on each of the 4 anatomic regions is scored on a scale of 0 (no involvement) to 6 (90% to 100% involvement). The sum of severity scores for erythema, thickness, and scaling is multiplied by the degree of involvement for each anatomic region and then multiplied by a constant corresponding to the region's percent BSA (0.1, 0.3, 0.2, and 0.4 for the above 4 regions, respectively). The resultant score for each anatomic region is then summed to yield the final PASI score. It ranges from 0 to 72, with higher scores reflecting greater disease severity.

All participants with a psoriasis indication, who do not qualify for active psoriatic arthritis (PsA) and had received at least 1 dose of study treatment. As per planned analysis, the outcome measure was planned to be analyzed for participants with plaque psoriasis (PsO) and with no active psoriatic arthritis (PsA).

The sPGA is an assessment by the physician to determine participant's overall psoriatic lesions, at a given time point. For the analysis of responses, the participant's psoriasis indication is assessed on a 5-point scale as: 0 (clear), 1 (minimal), 2 (mild), 3 (moderate), 4 (severe) incorporating an assessment of the severity of the three primary signs of the disease: induration, erythema, and degree of scaling.

The investigator examines all of the lesions on the participant and assigns a score ranging from 0 to 5 for induration, erythema and degree of scaling. Scores for induration, erythema and scaling are then summed, and the mean of these 3 scores produces the overall sPGA score.

Participants with an sPGA score of 0 (clear) or 1 (minimal) were considered responders and are reported here.

All participants with a psoriasis indication, who do not qualify for active psoriatic arthritis (PsA) and had received at least 1 dose of study treatment. As per planned analysis, the outcome measure was planned to be analyzed for participants with plaque psoriasis (PsO) and with no active psoriatic arthritis (PsA).

The ACR 20 is defined as:

• 20% improvement from baseline in both tender joint count (68 counts) and swollen joint count (66 counts)
• 20% improvements improvement in at least three of the following five items: Patient's global assessment of arthritis pain (measured on a 100-mm visual analog scale [VAS]); Patient's global assessment of disease activity (measured on a 100-mm VAS); Physician's global assessment of disease activity (measured on a 100-mm VAS); Patient's assessment of physical function as measured by the Health Assessment Questionnaire - Disability Index (HAQ-DI); Acute-phase reactant as measured by high-sensitivity C-reactive protein (hs-CRP) assay.

All participants with an active psoriatic arthritis indication who received at least 1 dose of study treatment. As per planned analysis, the outcome measure was planned to be analyzed for participants with active psoriatic Arthritis.