The DLQI is a 10-item skin disease-specific questionnaire used to evaluate the impact of skin disease on health-related quality of life (QOL). The items address symptoms and feelings, daily activities, leisure, work/school, personal relationships, and issues with treatment. Questions are answered on a 4-point scale from 0 (not at all/not applicable) to 3 (very much). Item scores are added to provide a total score from 0 to 30, with higher scores indicating greater impairment of QOL.

All randomized participants; Missing data at week 16 were imputed using multiple imputation.

The DLQI is a 10-item skin disease-specific questionnaire used to evaluate the impact of skin disease on health-related quality of life. The items address symptoms and feelings, daily activities, leisure, work/school, personal relationships, and issues with treatment. Questions are answered on a 4-point scale from 0 (not at all/not applicable) to 3 (very much). Item scores are added to provide a total score from 0 to 30, with higher scores indicating greater impairment of QOL. A negative change from baseline indicates improvement in quality of life.

All randomized participants; Missing data at week 16 were imputed using multiple imputation.

Body surface area is a measurement of involved skin. The overall BSA affected by psoriasis was estimated based on the palm area of the participant's hand (entire palmar surface or "handprint"), which equates to approximately 1% of total BSA.

All randomized participants; Missing data at week 16 were imputed using multiple imputation.

The Itch Numeric Rating Scale (NRS) asked participants to assess the worst severity of itch experienced over the past 24 hours on an 11-point scale anchored from 0, representing 'no itching' to 10, representing 'worst itch imaginable'.

A negative change from baseline indicates improvement in itch severity.

All randomized participants; Missing data at week 16 were imputed using multiple imputation.

Participants were asked to indicate their level of skin discomfort/pain in the past week by placing a vertical stroke on a 100 mm horizontal line on which the left-hand boundary (0) represents no skin discomfort/pain, and the right-hand boundary (100) represents worst possible skin discomfort/pain. The distance from the mark to the left-hand boundary was recorded.

A negative change from baseline indicates improvement in skin discomfort/pain.

All randomized participants; Missing data at week 16 were imputed using multiple imputation.

The PASI score is a measure of psoriatic disease severity taking into account qualitative lesion characteristics (erythema, thickness, and scaling) and degree of skin surface area involvement on defined anatomical regions. 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 total qualitative score (sum of erythema, thickness, and scaling scores) is multiplied by the degree of involvement for each anatomic region and then multiplied by a constant and the values for each anatomic region are summed to yield the PASI score. PASI scores range from 0 to 72, with higher scores reflecting greater disease severity.

All randomized participants; missing data at week 16 were imputed using multiple imputation.

The PBI is a validated patient-reported instrument to assess patient-relevant benefits of psoriasis treatment. Prior to starting study treatment, participants were asked to assess the importance of a series of treatment goals (from not important to very important) by completing the Patient Needs Questionnaire (PNQ). After a period of treatment (16 weeks), participants were then asked to assess the extent to which these goals were achieved (from not at all to very) by completing the Patient Benefit Questionnaire (PBQ). The Patient Benefit Index represents the benefits realized as a function of most important needs. The PBI score ranges from 0 (no benefit) to 4 (maximum benefit).

All randomized participants; Missing data at week 16 were imputed using multiple imputation.

EQ-5D measures the participant's general health state on a vertical VAS and five quality of life domains. The EQ-5D VAS score ranges from 0 to 100, where a score of 0 indicates the worst imaginable health states and a score of 100 indicates the best imaginable health state. A positive change from baseline indicates improvement.

All randomized participants with available data at baseline and week 16.

EQ-5D measures the participants general health state as a vertical VAS and 5 quality of life domains: mobility, self-care, main activity (work, study, housework, family/leisure activities), pain/discomfort, and anxiety/depression. Each dimension is rated on three levels (no problems, some/moderate problems, extreme problems). An EQ-5D summary index is derived by applying a formula that attaches values (weights) to each of the levels in each dimension.

EQ-5D index values were derived using the UK scoring algorithm, where a higher score indicates a better health state. The range of the score is from -0.224 to 1, with 0 corresponding to death, 1 corresponding to full health, and negative numbers indicate health states worse than death. A positive change from baseline indicates improvement.

All randomized participants with available data at baseline and week 16.

The WPAI: PSO is a self-administered questionnaire designed to address impairment to the work productivity and activity of participants due to psoriasis in the past 7 days. Percent of work time missed is derived from the number of hours of work missed due to psoriasis symptoms as a percentage of total hours that should have been worked. A higher percentage indicates more hours missed, and a negative change from baseline indicates improvement.

All randomized participants with available data and who had reported being employed at baseline and at week 16.

The WPAI: PSO is a self-administered questionnaire designed to address impairment to the work productivity and activity of participants due to psoriasis in the past 7 days. Percent impairment while working was derived from the participant's assessment of the degree to which psoriasis affected their productivity while working. A higher percentage indicates greater impairment and less productivity, and a negative change from baseline indicates improvement.

All randomized participants with available data and who had reported being employed at baseline and at week 16.

The WPAI: PSO is a self-administered questionnaire designed to address impairment to the work productivity and activity of participants due to psoriasis in the past 7 days. Percent overall work impairment takes into account both hours missed due to psoriasis symptoms and the participant's assessment of the degree to which psoriasis affected their productivity while working. A higher percentage indicates greater impairment and less productivity, and a negative change from baseline indicates improvement.

All randomized participants with available data and who had reported being employed at baseline and at week 16.

The WPAI: PSO is a self-administered questionnaire designed to address impairment to the work productivity and activity of participants due to psoriasis in the past 7 days. Percent activity impairment is derived from the patient's assessment of the degree to which psoriasis affected their regular daily unpaid activities, measured on a VAS from 1 (no effect on daily activities) to 10 (psoriasis completely prevented daily activities). A higher percentage indicates greater impairment and less productivity, and a negative change from baseline indicates improvement.

All randomized participants with available data at baseline and at week 16.

An adverse event (AE) is any noxious, unintended, or untoward medical occurrence that may appear or worsen in a participant during a study. It may be a new intercurrent illness, a worsening concomitant illness, an injury, or any concomitant impairment of the participant's health, including laboratory test values, regardless of etiology. Any worsening of a preexisting condition was considered an AE.

A serious adverse event (SAE) is any AE occurring at any dose that:

• Resulted in death;
• Was life-threatening;
• Required inpatient hospitalization or prolongation of existing hospitalization;
• Resulted in persistent or significant disability/incapacity;
• Was a congenital anomaly/birth defect;
• Constituted an important medical event. The Investigator assessed the severity/intensity of each event as mild, moderate, or severe based on level of symptoms.

All randomized participants who received at least one dose of study drug.

Marked laboratory abnormalities are defined for each parameter below.

ULN = upper limit of normal

All randomized participants who received at least one dose of study drug with at least one post-baseline measurement.

Randomized participants who received at least one dose of study drug and with a baseline value and a post-baseline value at each time point.

Randomized participants who received at least one dose of study drug and with a baseline value and a post-baseline value at each time point.

Randomized participants who received at least one dose of study drug and with with a baseline value and a post-baseline value at each time point.

Randomized participants who received at least one dose of study drug and with a baseline value and a post-baseline value at each time point.

The DLQI is a 10-item skin disease-specific questionnaire used to evaluate the impact of skin disease on health-related quality of life (QOL). The items address symptoms and feelings, daily activities, leisure, work/school, personal relationships, and issues with treatment. Questions are answered on a 4-point scale from 0 (not at all/not applicable) to 3 (very much). Item scores are added to provide a total score from 0 to 30, with higher scores indicating greater impairment of QOL.

Randomized participants who entered the apremilast extension phase. Missing data were imputed using non-responder imputation.

The DLQI is a 10-item skin disease-specific questionnaire used to evaluate the impact of skin disease on health-related quality of life. The items address symptoms and feelings, daily activities, leisure, work/school, personal relationships, and issues with treatment. Questions are answered on a 4-point scale from 0 (not at all/not applicable) to 3 (very much). Item scores are added to provide a total score from 0 to 30, with higher scores indicating greater impairment of QOL. A negative change from baseline indicates improvement in quality of life.

Randomized participants who entered the apremilast extension phase with available data at baseline and each time point

The Itch Numeric Rating Scale (NRS) asked participants to assess the worst severity of itch experienced over the past 24 hours on an 11-point scale anchored from 0, representing 'no itching' to 10, representing 'worst itch imaginable'.

A negative change from baseline indicates improvement in itch severity.

Randomized participants who entered the apremilast extension phase with available data at baseline and each time point.

Participants were asked to indicate their level of skin discomfort/pain in the past week by placing a vertical stroke on a 100 mm horizontal line on which the left-hand boundary (0) represents no skin discomfort/pain, and the right-hand boundary (100) represents worst possible skin discomfort/pain. The distance from the mark to the left-hand boundary was recorded.

A negative change from baseline indicates improvement in skin discomfort/pain.

Randomized participants who entered the apremilast extension phase with available data at baseline and each time point

Body surface area is a measurement of involved skin. The overall BSA affected by psoriasis was estimated based on the palm area of the participant's hand (entire palmar surface or "handprint"), which equates to approximately 1% of total BSA.

Randomized participants who entered the apremilast extension phase with available data at baseline and each time point

The PBI is a validated patient-reported instrument to assess patient-relevant benefits of psoriasis treatment. Prior to starting study treatment, participants were asked to assess the importance of a series of treatment goals (from not important to very important) by completing the Patient Needs Questionnaire (PNQ). After a period of treatment (32 weeks and 52 weeks), participants were then asked to assess the extent to which these goals were achieved (from not at all to very) by completing the Patient Benefit Questionnaire (PBQ). The Patient Benefit Index represents the benefits realized as a function of most important needs. The PBI score ranges from 0 (no benefit) to 4 (maximum benefit).

Randomized participants who entered the apremilast extension phase. Missing data were imputed using non-responder imputation.

The PASI score is a measure of psoriatic disease severity taking into account qualitative lesion characteristics (erythema, thickness, and scaling) and degree of skin surface area involvement on defined anatomical regions. 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 total qualitative score (sum of erythema, thickness, and scaling scores) is multiplied by the degree of involvement for each anatomic region and then multiplied by a constant and the values for each anatomic region are summed to yield the PASI score. PASI scores range from 0 to 72, with higher scores reflecting greater disease severity.

Randomized participants who entered the apremilast extension phase. Missing data were imputed using non-responder imputation.

EQ-5D measures the participant's general health state on a vertical VAS and five quality of life domains. The EQ-5D VAS score ranges from 0 to 100, where a score of 0 indicates the worst imaginable health states and a score of 100 indicates the best imaginable health state. A positive change from baseline indicates improvement.

Randomized participants who entered the apremilast extension phase with available data at baseline and week 52

EQ-5D measures the participants general health state as a vertical VAS and 5 quality of life domains: mobility, self-care, main activity (work, study, housework, family/leisure activities), pain/discomfort, and anxiety/depression. Each dimension is rated on three levels (no problems, some/moderate problems, extreme problems). An EQ-5D summary index is derived by applying a formula that attaches values (weights) to each of the levels in each dimension.

EQ-5D index values were derived using the UK scoring algorithm, where a higher score indicates a better health state. The range of the score is from -0.224 to 1, with 0 corresponding to death, 1 corresponding to full health, and negative numbers indicate health states worse than death. A positive change from baseline indicates improvement.

Randomized participants who entered the apremilast extension phase with available data at baseline and week 52

The WPAI: PSO is a self-administered questionnaire designed to address impairment to the work productivity and activity of participants due to psoriasis in the past 7 days. Percent of work time missed is derived from the number of hours of work missed due to psoriasis symptoms as a percentage of total hours that should have been worked. A higher percentage indicates more hours missed, and a negative change from baseline indicates improvement.

Randomized participants who entered the apremilast extension phase with available data and who had reported being employed at baseline and at week 52.

The WPAI: PSO is a self-administered questionnaire designed to address impairment to the work productivity and activity of participants due to psoriasis in the past 7 days. Percent impairment while working was derived from the participant's assessment of the degree to which psoriasis affected their productivity while working. A higher percentage indicates greater impairment and less productivity, and a negative change from baseline indicates improvement.

Randomized participants who entered the apremilast extension phase with available data and who had reported being employed at baseline and at week 52.

The WPAI: PSO is a self-administered questionnaire designed to address impairment to the work productivity and activity of participants due to psoriasis in the past 7 days. Percent overall work impairment takes into account both hours missed due to psoriasis symptoms and the participant's assessment of the degree to which psoriasis affected their productivity while working. A higher percentage indicates greater impairment and less productivity, and a negative change from baseline indicates improvement.

Randomized participants who entered the apremilast extension phase with available data and who had reported being employed at baseline and at week 52.

The WPAI: PSO is a self-administered questionnaire designed to address impairment to the work productivity and activity of participants due to psoriasis in the past 7 days. Percent activity impairment is derived from the patient's assessment of the degree to which psoriasis affected their regular daily unpaid activities, measured on a VAS from 1 (no effect on daily activities) to 10 (psoriasis completely prevented daily activities). A higher percentage indicates greater impairment and less productivity, and a negative change from baseline indicates improvement.

Randomized participants who entered the apremilast extension phase with available data at baseline and week 52

An AE is any noxious, unintended, or untoward medical occurrence that may appear or worsen in a participant during a study. It may be a new intercurrent illness, a worsening concomitant illness, an injury, or any concomitant impairment of the participant's health, including laboratory test values, regardless of etiology. Any worsening of a preexisting condition was considered an AE.

A serious adverse event (SAE) is any AE occurring at any dose that:

• Resulted in death;
• Was life-threatening;
• Required inpatient hospitalization or prolongation of existing hospitalization;
• Resulted in persistent or significant disability/incapacity;
• Was a congenital anomaly/birth defect;
• Constituted an important medical event. The Investigator assessed the severity/intensity of each event as mild, moderate, or severe based on level of symptoms.

All randomized participants who received at least one dose of apremilast, ie, participants originally randomized to apremilast and participants originally randomized to placebo who entered the apremilast extension phase and received at least one dose of apremilast.

Randomized participants who received at least 1 dose of apremilast, ie, participants originally randomized to apremilast and participants originally randomized to placebo who entered the apremilast extension phase with at least 1 treatment of apremilast, and with at least 1 post-baseline measurement.

Randomized participants who received at least 1 dose of apremilast, ie, participants originally randomized to apremilast and participants originally randomized to placebo who entered the apremilast extension phase, with a baseline value and at least 1 post-baseline value.

Randomized participants who received at least 1 dose of apremilast, ie, participants originally randomized to apremilast and participants originally randomized to placebo who entered the apremilast extension phase with at least 1 treatment of apremilast, with a baseline value and at least 1 post-baseline value.

Randomized participants who received at least 1 dose of apremilast, ie, participants originally randomized to apremilast and participants originally randomized to placebo who entered the apremilast extension phase with at least 1 treatment of apremilast, with a baseline value and at least 1 post-baseline value.

Baseline and end of apremilast extension period; week 52, or earlier for participants who discontinued prior to week 52