The sPGA is a physician's determination of the participant's psoriasis lesions overall at a given time point categorized by descriptions for induration, erythema, and scaling. For the analysis of responses, the participant's psoriasis is assessed as clear (0), minimal (1), mild (2), moderate (3), severe (4), or very severe (5). An sPGA (0,1) response was defined as a post-baseline sPGA score of 0 or 1.

All randomized participants. Participants who did not meet clinical response criteria or have missing data at Week 12 will be considered non-responders for the Non-Responder Imputation (NRI) analysis.

The PASI combines assessments of the extent of body-surface involvement in 4 anatomical regions (head, trunk, arms, and legs) and the severity of desquamation (scaling), erythema, and plaque induration/infiltration (thickness) in each region, yielding an overall score of 0 for no psoriasis to 72 for the most severe disease. Participants achieving PASI 75 was defined as having an improvement of at least 75% in the PASI scores compared to baseline.

All randomized participants. Participants who did not meet clinical response criteria or have missing data at Week 12 will be considered non-responders for the Non-Responder Imputation (NRI) analysis.

The sPGA is a physician's determination of the participant's psoriasis lesions overall at a given time point categorized by descriptions for induration, erythema, and scaling. For the analysis of responses, the participant's psoriasis is assessed as clear (0), minimal (1), mild (2), moderate (3), severe (4), or very severe (5). An sPGA (0) response was defined as a post-baseline sPGA score of 0.

All randomized participants. Participants who did not meet clinical response criteria or have missing data at Week 12 will be considered non-responders for the Non-Responder Imputation (NRI) analysis.

The PASI combines assessments of the extent of body-surface involvement in 4 anatomical regions (head, trunk, arms, and legs) and the severity of desquamation (scaling), erythema, and plaque induration/infiltration (thickness) in each region, yielding an overall score of 0 for no psoriasis to 72 for the most severe disease. Participants achieving PASI 90 were defined as having an improvement of at least 90% in the PASI scores compared to baseline.

All randomized participants. Participants who did not meet clinical response criteria or have missing data at Week 12 will be considered non-responders for the Non-Responder Imputation (NRI) analysis.

The PASI combines assessments of the extent of body-surface involvement in 4 anatomical regions (head, trunk, arms, and legs) and the severity of desquamation (scaling), erythema, and plaque induration/infiltration (thickness) in each region, yielding an overall score of 0 for no psoriasis to 72 for the most severe disease. Participants achieving PASI 100 were defined as having an improvement of at least 100% in the PASI scores compared to baseline.

All randomized participants. Participants who did not meet clinical response criteria or have missing data at Week 12 will be considered non-responders for the Non-Responder Imputation (NRI) analysis.

The Itch NRS is a participant-administered single-item 11-point horizontal scale anchored at 0 and 10, with 0 representing "no itch" and 10 representing "worst itch imaginable." Participants indicate their overall severity of itching from Psoriasis by circling the number that best describes the worst level of itching in the past 24 hours.

All randomized participants and had an Itch NRS score >=4 at baseline. Participants who did not meet clinical response criteria or have missing data at Week 12 will be considered non-responders for the NRI analysis.

The DLQI is a simple, participant-administered, 10 question, validated, quality-of-life questionnaire that covers 6 domains: symptoms and feelings, daily activities, leisure, work and school, personal relationships, and treatment. Response categories include "not at all," "a lot," and "very much," with corresponding scores of 1, 2, and 3, respectively, and unanswered ("not relevant") responses scored as "0." Totals range from 0 to 30 (less to more impairment), and a 5 point change from baseline is considered clinically relevant. Least Square (LS) Means in total DLQI score were calculated using Mixed Model Repeated Measures (MMRM) with baseline score as covariate, treatment, pooled center, visit and treatment-by-visit interaction as fixed effects.

All randomized participants and had at least one post-dose measurement of DLQI.

The NAPSI is a numeric, reproducible, objective tool used to evaluate the severity of fingernail bed psoriasis and fingernail matrix psoriasis by area of involvement in the fingernail unit. The fingernail is divided with imaginary horizontal and longitudinal lines into quadrants. Each fingernail is given a score for fingernail bed psoriasis: 0 (none) to 4 (psoriasis in 4 quadrants of the nail) and fingernail matrix psoriasis (0 to 4) depending on the presence (score of 1) or absence (score of 0) of any of the features of fingernail bed and fingernail matrix psoriasis in each quadrant. The NAPSI score of a fingernail is the sum of scores in fingernail bed and fingernail matrix from each quadrant (maximum of 8). Each fingernail is evaluated, and the sum of all the fingernails is the total NAPSI score (range, 0 to 80). LS Means in NAPSI score were calculated using MMRM with baseline score as covariate, treatment, pooled center, visit and treatment-by-visit interaction as fixed effects.

All randomized participants and had fingernail involvement at baseline and had at least one post-dose measurement of NAPSI.

Percentage involvement of psoriasis on each participants body surface area was assessed by the investigator on a continuous scale from 0% (no involvement) to 100% (full involvement), in which 1% corresponds to the size of the participant's hand (including palm, fingers and thumb). LS Means in BSA were calculated using MMRM with baseline BSA as covariate, treatment, pooled center, visit and treatment-by-visit interaction as fixed effects.

All randomized participants and had at least one post-dose measurement of BSA.

PSSI is a composite score ranging from 0 (best) to 72 (worst), derived from the sum scores for erythema, induration, and desquamation multiplied by a score for the extent of scalp area involved. LS Means in PSSI score were calculated using MMRM with baseline score as covariate, treatment, pooled center, visit and treatment-by-visit interaction as fixed effects.

All randomized participants and had scalp psoriasis at baseline and had at least one post-dose measurement of PSSI.

The QIDS-SR16 is a self-administered, 16-item instrument in which a participant is asked to consider each statement as it relates to the way they have felt for the past 7 days. There is a 4-point scale for each item ranging from 0 (best) to 3 (worst). The 16 items are scored to give 9 individual depression domains (sad mood, concentration, self-criticism, suicidal ideation, interest, energy/fatigue, sleep disturbance [initial, middle and late insomnia or hypersomnia], decrease/increase in appetite/weight, and psychomotor agitation/retardation), which are summed to give a single score ranging from 0 to 27, with higher scores denoting greater symptom severity. LS Means in total QIDS-SR16 score were calculated using the analysis of covariance (ANCOVA) model with treatment, pooled center and baseline QIDS total score.

All randomized participants and had at least one post-dose measurement of QIDS-SR16. Participants with missing QIDS-SR16 data were imputed by Last Observation Carried Forward (LOCF) method.

The WPAI-PSO is a 6-item instrument used to assess the impact of psoriasis on productivity impairment within the past 7 days. It has four domains: absenteeism, presenteeism (reduced productivity while at work), an overall work impairment score, and impairment in daily activities performed outside of work. Four scores are derived as percentages: absenteeism, presenteeism, overall work impairment (absenteeism and presenteeism), and impairment in activities performed outside of work. Percentage is calculated as: each score * 100 and ranged from 0 to 100. Higher scores indicate greater impairment in productivity. LS Means in each WPAI-PSO score were calculated using the ANCOVA model with treatment, pooled center and baseline WPAI-PSO score.

All randomized participants, even if the participant did not take the assigned treatment, did not receive the correct treatment, or otherwise did not follow the protocol, and had at least one post-dose measurement of WPAI-PSO. Participants with missing WPAI-PSO data were imputed by Last Observation Carried Forward (LOCF) method.

The SF-36 is a participant-reported outcome measure evaluating participant's health status. It comprises 36 items covering 8 domains: physical functioning, role physical, role emotional, bodily pain, vitality, social functioning, mental health, and general health. Items are answered on Likert scales of varying lengths. The 8 domains are regrouped into the PCS and MCS scores. The summary scores range from 0 to 100, with higher scores indicating better levels of function and/or better health. In this study, the SF-36 acute version was used, which has a 1 week recall period. LS Means in SF-36 score were calculated using the ANCOVA model with treatment, pooled center and baseline SF-36 score.

All randomized participants and had at least one post-dose measurement of SF-36. Participants with missing SF-36 data were imputed by Last Observation Carried Forward (LOCF) method.

The Patient's Global Assessment of Disease Severity is a single-item participant-reported outcome measure on which participants are asked to rate the severity of their psoriasis "today" from 0 (Clear) = no psoriasis, to 5 (Severe) = the worst their psoriasis has ever been. LS Means in Patient's Global Assessment of Disease Severity score were calculated using MMRM with baseline score as covariate, treatment, pooled center, visit and treatment-by-visit interaction as fixed effects.

All randomized participants and had at least one post-dose measurement of Patient's Global Assessment of Disease Severity.

Palmoplantar PASI is a composite score derived from the sum scores for erythema, induration, and desquamation multiplied by a score for the extent of palm and sole area involvement, ranging from 0 to 72. Participants achieving PPASI 50 were defined as having an improvement of at least 50% in the PPASI scores compared to baseline.

All randomized participants and had a diagnosis of palmoplantar psoriasis at baseline. Participants who did not meet clinical response criteria or have missing data at Week 12 will be considered non-responders for the NRI analysis.

Palmoplantar PASI is a composite score derived from the sum scores for erythema, induration, and desquamation multiplied by a score for the extent of palm and sole area involvement, ranging from 0 to 72. Participants achieving PPASI 75 were defined as having an improvement of at least 75% in the PPASI scores compared to baseline.

All randomized participants and had a diagnosis of palmoplantar psoriasis at baseline. Participants who did not meet clinical response criteria or have missing data at Week 12 will be considered non-responders for the NRI analysis.

Palmoplantar PASI is a composite score derived from the sum scores for erythema, induration, and desquamation multiplied by a score for the extent of palm and sole area involvement, ranging from 0 to 72. Participants achieving PPASI 100 were defined as having an improvement of 100% in the PPASI scores compared to baseline.

All randomized participants and had a diagnosis of palmoplantar psoriasis at baseline. Participants who did not meet clinical response criteria or have missing data at Week 12 will be considered non-responders for the NRI analysis.

The percentage of participants with treatment-emergent positive anti-ixekizumab antibodies at any time post-baseline were summarized by treatment group. Percentage of participants with treatment-emergent positive anti-ixekizumab antibodies were calculated as: number of participants with an evaluable baseline sample and ≥1 evaluable post-baseline sample/number of participants in the analysis population * 100.

All randomized participants who received at least one dose of study treatment and had evaluable data.