The IGA of Atopic Dermatitis (AD) was scored on a 5-point scale (0-4), reflecting a global consideration of the erythema, induration and scaling. The overall severity of AD was assessed according to the 5-point scale: 0=Clear, 1=Almost Clear, 2=Mild, 3=Moderate, and 4=Severe. Participants who withdrew from the study were counted as non-responder.

The analysis population included all participants randomly assigned to study intervention and who took at least 1 dose of study intervention. Number of Participants Analyzed refers to the number of participants evaluable for this time point.

The EASI quantifies the severity of AD based on both severity of lesion clinical signs and the percent of body surface area (BSA) affected. The EASI score can vary in increments of 0.1 and range from 0.0 to 72.0, with higher scores representing greater severity of AD. Participants who withdrew from the study were counted as non-responder.

The analysis population included all participants randomly assigned to study intervention and who took at least 1 dose of study intervention. Number of Participants Analyzed refers to the number of participants evaluable for this time point.

PP-NRS assesses the severity of itch (pruritus) due to AD. Participants were asked to assess their worst itching due to AD on an NRS anchored by the terms "no itch" (0) and "worst itch imaginable" (10). Participants who withdrew from the study were counted as non-responder.

The analysis population included all participants randomly assigned to study intervention and who took at least 1 dose of study intervention. Number of Participants Analyzed refers to the number of participants who were evaluable for this outcome measure. Number analyzed refers to the number of participants evaluable for each time point.

The PSAAD is a daily patient reported symptom diary presented as a 15 item questionnaire that includes 11 items developed to measure symptoms of AD, along with 4 additional items for exploratory and psychometric validation purposes (Sleep & Usual Activities Questions and Patient Global Impression of Severity & Patient Global Impression of Change Questions). Participants answer each question about skin condition based on a 24 hour recall. Each question was evaluated on a 11-point scale ranging from 0 to 10, where higher scores indicate more impact on skin condition.The PSAAD total score is calculated as the average of the responses to each of the 11 items and ranges from 0 (none) to 10 (extreme), where higher scores indicate worse severity of AD symptoms.

The analysis population included all participants randomly assigned to study intervention and who took at least 1 dose of study intervention. Number of Participants Analyzed refers to the number of participants evaluable for this time point.

The IGA of AD is scored on a 5-point scale (0-4), reflecting a global consideration of the erythema, induration and scaling. The overall severity of AD was assessed according to the 5-point scale: 0=Clear, 1=Almost Clear, 2=Mild, 3=Moderate, and 4=Severe. Participants who withdrew from the study were counted as non-responder.

The analysis population included all participants randomly assigned to study intervention and who took at least 1 dose of study intervention. Number of Participants Analyzed refers to the number of participants who were evaluable for this outcome measure. Number analyzed refers to the number of participants evaluable for each time point.

The EASI quantifies the severity of AD based on both severity of lesion clinical signs and the percent of BSA affected. The EASI score can vary in increments of 0.1 and range from 0.0 to 72.0, with higher scores representing greater severity of AD. Participants who withdrew from the study were counted as non-responder.

The analysis population included all participants randomly assigned to study intervention and who took at least 1 dose of study intervention. Number of Participants Analyzed refers to the number of participants who were evaluable for this outcome measure. Number analyzed refers to the number of participants evaluable for each time point.

The EASI quantifies the severity of AD based on both severity of lesion clinical signs and the percent of BSA affected. The EASI score can vary in increments of 0.1 and range from 0.0 to 72.0, with higher scores representing greater severity of AD. Participants who withdrew from the study were counted as non-responder.

The analysis population included all participants randomly assigned to study intervention and who took at least 1 dose of study intervention. Number of Participants Analyzed refers to the number of participants who were evaluable for this outcome measure. Number analyzed refers to the number of participants evaluable for each time point.

The EASI quantifies the severity of AD based on both severity of lesion clinical signs and the percent of BSA affected. The EASI score can vary in increments of 0.1 and range from 0.0 to 72.0, with higher scores representing greater severity of AD. Participants who withdrew from the study were counted as non-responder.

The analysis population included all participants randomly assigned to study intervention and who took at least 1 dose of study intervention. Number of Participants Analyzed refers to the number of participants who were evaluable for this outcome measure. Number analyzed refers to the number of participants evaluable for each time point.

The EASI quantifies the severity of AD based on both severity of lesion clinical signs and the percent of BSA affected. The EASI score can vary in increments of 0.1 and range from 0.0 to 72.0, with higher scores representing greater severity of AD. Participants who withdrew from the study were counted as non-responder.

The analysis population included all participants randomly assigned to study intervention and who took at least 1 dose of study intervention. Number of Participants Analyzed refers to the number of participants who were evaluable for this outcome measure. Number analyzed refers to the number of participants evaluable for each time point.

The EASI quantifies the severity of AD based on both severity of lesion clinical signs and the percent of BSA affected. The EASI score can vary in increments of 0.1 and range from 0.0 to 72.0, with higher scores representing greater severity of AD. Participants who withdrew from the study were counted as non-responder.

The analysis population included all participants randomly assigned to study intervention and who took at least 1 dose of study intervention. Number of Participants Analyzed refers to the number of participants who were evaluable for this outcome measure. Number analyzed refers to the number of participants evaluable for each time point.

PP-NRS assesses the severity of itch (pruritus) due to AD. Participants were asked to assess their worst itching due to AD on an NRS anchored by the terms "no itch" (0) and "worst itch imaginable" (10). Participants who withdrew from the study were counted as non-responder.

The analysis population included all participants randomly assigned to study intervention and who took at least 1 dose of study intervention. Number of Participants Analyzed refers to the number of participants who were evaluable for this outcome measure. Number analyzed refers to the number of participants evaluable for each time point.

PP-NRS assesses the severity of itch (pruritus) due to AD. Participants were asked to assess their worst itching due to AD on an NRS anchored by the terms "no itch" (0) and "worst itch imaginable" (10).

The Full Analysis Set (FAS) included all participants randomly assigned to study intervention and who took at least 1 dose of study intervention. Participants in the FAS with a baseline numeric rating score for severity of pruritus >=4 were included in the analysis.

PP-NRS assesses the severity of itch (pruritus) due to AD. Participants were asked to assess their worst itching due to AD on an NRS anchored by the terms "no itch" (0) and "worst itch imaginable" (10).

The analysis population included all participants randomly assigned to study intervention and who took at least 1 dose of study intervention. Number of Participants Analyzed refers to the number of participants who were evaluable for this outcome measure. Number analyzed refers to the number of participants evaluable for each time point.

BSA efficacy is derived from the sum of the BSA in handprints across 4 body regions assessed as part of the EASI assessment. Handprint refers to that of each individual participant for their own measurement. The BSA efficacy ranges from 0 to 100%, with higher values representing greater severity of AD. The percentage BSA ranges from 0 to 100, with higher scores representing greater severity of AD. Since the scalp, palms, and soles were excluded from the BSA (efficacy) assessment, the maximum possible percentage BSA was less than 100.

The analysis population included all participants randomly assigned to study intervention and who took at least 1 dose of study intervention.

BSA efficacy is derived from the sum of the BSA in handprints across 4 body regions assessed as part of the EASI assessment. Handprint refers to that of each individual participant for their own measurement. The BSA efficacy ranges from 0 to 100%, with higher values representing greater severity of AD. The percentage BSA ranges from 0 to 100, with higher scores representing greater severity of AD. Since the scalp, palms, and soles were excluded from the BSA (efficacy) assessment, the maximum possible percentage BSA was less than 100.

The analysis population included all participants randomly assigned to study intervention and who took at least 1 dose of study intervention.

BSA efficacy is derived from the sum of the BSA in handprints across 4 body regions assessed as part of the EASI assessment. Handprint refers to that of each individual participant for their own measurement. The BSA efficacy ranges from 0 to 100%, with higher values representing greater severity of AD. The percentage BSA ranges from 0 to 100, with higher scores representing greater severity of AD. Since the scalp, palms, and soles were excluded from the BSA (efficacy) assessment, the maximum possible percentage BSA was less than 100.

The analysis population included all participants randomly assigned to study intervention and who took at least 1 dose of study intervention. Number of Participants Analyzed refers to the number of participants evaluable for this time point.

SCORAD is a validated scoring index for AD,which combines extent (0-100),severity (0-18),and subjective symptoms (0-20) based on pruritus and sleep loss,each scored (0-10). Extent,denoted as A,is measured by BSA affected by AD as a percentage of the whole BSA.The score for each body region is added up to determine A (maximum of 100).Severity, denoted as B,consists of the severity of several signs.Each is assessed as none(0),mild(1),moderate(2) or severe(3).The severity scores are added together to give B (maximum of 18).Subjective symptoms,denoted as C,are each scored by the participant using a NRS where "0" is no itch (or no sleeplessness) and "10" is the worst imaginable itch (or sleeplessness).These scores are added to give 'C' (maximum of 20).SCORAD for an individual is calculated by the formula: A/5 + 7B/2 + C (can range from 0 to 103).Higher values of SCORAD represent worse outcome.

The analysis population included all participants randomly assigned to study intervention and who took at least 1 dose of study intervention. Number of Participants Analyzed refers to the number of participants who were evaluable for this outcome measure. Number analyzed refers to the number of participants evaluable for each time point.

SCORAD is a validated scoring index for AD,which combines extent (0-100),severity (0-18),and subjective symptoms (0-20) based on pruritus and sleep loss,each scored (0-10). Extent,denoted as A,is measured by BSA affected by AD as a percentage of the whole BSA.The score for each body region is added up to determine A (maximum of 100).Severity, denoted as B,consists of the severity of several signs.Each is assessed as none(0),mild(1),moderate(2) or severe(3).The severity scores are added together to give B (maximum of 18).Subjective symptoms,denoted as C,are each scored by the participant using a NRS where "0" is no itch (or no sleeplessness) and "10" is the worst imaginable itch (or sleeplessness).These scores are added to give 'C' (maximum of 20).SCORAD for an individual is calculated by the formula: A/5 + 7B/2 + C (can range from 0 to 103).Higher values of SCORAD represent worse outcome.

The analysis population included all participants randomly assigned to study intervention and who took at least 1 dose of study intervention. Number of Participants Analyzed refers to the number of participants who were evaluable for this outcome measure. Number analyzed refers to the number of participants evaluable for each time point.

SCORAD is a validated scoring index for AD,which combines extent (0-100),severity (0-18),and subjective symptoms (0-20) based on pruritus and sleep loss,each scored (0-10). Extent,denoted as A,is measured by BSA affected by AD as a percentage of the whole BSA.The score for each body region is added up to determine A (maximum of 100).Severity, denoted as B,consists of the severity of several signs.Each is assessed as none(0),mild(1),moderate(2) or severe(3).The severity scores are added together to give B (maximum of 18).Subjective symptoms,denoted as C,are each scored by the participant using a NRS where "0" is no itch (or no sleeplessness) and "10" is the worst imaginable itch (or sleeplessness).These scores are added to give 'C' (maximum of 20).SCORAD for an individual is calculated by the formula: A/5 + 7B/2 + C (can range from 0 to 103).Higher values of SCORAD represent worse outcome.

The analysis population included all participants randomly assigned to study intervention and who took at least 1 dose of study intervention. Number of Participants Analyzed refers to the number of participants who were evaluable for this outcome measure. Number analyzed refers to the number of participants evaluable for each time point.

SCORAD is a validated scoring index for AD,which combines extent (0-100),severity (0-18),and subjective symptoms (0-20) based on pruritus and sleep loss,each scored (0-10). Extent,denoted as A,is measured by BSA affected by AD as a percentage of the whole BSA.The score for each body region is added up to determine A (maximum of 100).Severity, denoted as B,consists of the severity of several signs.Each is assessed as none(0),mild(1),moderate(2) or severe(3).The severity scores are added together to give B (maximum of 18).Subjective symptoms,denoted as C,are each scored by the participant using a NRS where "0" is no itch (or no sleeplessness) and "10" is the worst imaginable itch (or sleeplessness).These scores are added to give 'C' (maximum of 20).SCORAD for an individual is calculated by the formula: A/5 + 7B/2 + C (can range from 0 to 103).Higher values of SCORAD represent worse outcome.

The analysis population included all participants randomly assigned to study intervention and who took at least 1 dose of study intervention. Number of Participants Analyzed refers to the number of participants who were evaluable for this outcome measure. Number analyzed refers to the number of participants evaluable for each time point.

SCORAD is a validated scoring index for AD, which combines extent (A, 0-100), severity (B, 0-18), and subjective symptoms (C, 0-20) based on pruritus and sleep loss, each scored (0-10). The SCORAD for an individual is calculated by the formula: A/5 + 7B/2 + C (can range from 0 to 103). Subjective symptoms (ie, itch and sleep loss) are each scored by the participant using a VAS where "0" is no itch (or no sleep loss) and "10" is the worst imaginable itch (or sleep loss). The value for each should reflect the average on a 10 point scale for the last 3 days/nights. Changes from baseline in SCORAD subjective assessments of itch were not evaluated. Only changes from baseline in SCORAD subjective assessments of sleep loss are presented below.

The analysis population included all participants randomly assigned to study intervention and who took at least 1 dose of study intervention. Number of Participants Analyzed refers to the number of participants who were evaluable for this outcome measure. Number analyzed refers to the number of participants evaluable for each time point.

SCORAD is a validated scoring index for AD, which combines extent (A, 0-100), severity (B, 0-18), and subjective symptoms (C, 0-20) based on pruritus and sleep loss, each scored (0-10). The SCORAD for an individual is calculated by the formula: A/5 + 7B/2 + C (can range from 0 to 103). Subjective symptoms (ie, itch and sleep loss) are each scored by the participant using a VAS where "0" is no itch (or no sleep loss) and "10" is the worst imaginable itch (or sleep loss). The value for each should reflect the average on a 10 point scale for the last 3 days/nights. Changes from baseline in SCORAD subjective assessments of itch were not evaluated. Only changes from baseline in SCORAD subjective assessments of sleep loss are presented below.

The analysis population included all participants randomly assigned to study intervention and who took at least 1 dose of study intervention. Number of Participants Analyzed refers to the number of participants who were evaluable for this outcome measure. Number analyzed refers to the number of participants evaluable for each time point.

The Full Analysis Set (FAS) included all participants randomly assigned to study intervention and who took at least 1 dose of study intervention. The analysis population included all participants in the FAS who had used corticosteroid during treatment period.

The DLQI is a general dermatology questionnaire that consists of 10 items to assess participant-reported health-related quality of life (daily activities, personal relationships, symptoms and feelings, leisure, work and school, and treatment).The DLQI is a psychometrically valid and reliable instrument that has been translated into several languages, and the DLQI total scores have been shown to be responsive to change. The minimally important difference for the DLQI has been estimated as a 3-5 point change from baseline. Each item is scored as "very much (3)", "a lot (2)", "a little (1)" and "not at all (0)". The score can range from 0 to 30. The higher values represent the worse dermatology life quality. Participants who withdrew from the study were counted as non-responder.

The analysis population included all participants randomly assigned to study intervention and who took at least 1 dose of study intervention.

The DLQI is a general dermatology questionnaire that consists of 10 items to assess participant-reported health-related quality of life (daily activities, personal relationships, symptoms and feelings, leisure, work and school, and treatment).The DLQI is a psychometrically valid and reliable instrument that has been translated into several languages, and the DLQI total scores have been shown to be responsive to change. The minimally important difference for the DLQI has been estimated as a 3-5 point change from baseline. Each item is scored as "very much (3)", "a lot (2)", "a little (1)" and "not at all (0)". The score can range from 0 to 30. The higher values represent the worse dermatology life quality. Participants who withdrew from the study were counted as non-responder.

The analysis population included all participants randomly assigned to study intervention and who took at least 1 dose of study intervention. Number of Participants Analyzed refers to the number of participants who were evaluable for this outcome measure. Number analyzed refers to the number of participants evaluable for each time point.

The HADS is a 14-item patient reported outcome (PRO) measure used to detect states of anxiety and depression over the past week. Seven of the items relate to anxiety and seven relate to depression. Each item is scored from 0 to 3 which means a person can score between 0 to 21 for either anxiety or depression. Higher values represent worse outcome.

The analysis population included all participants randomly assigned to study intervention and who took at least 1 dose of study intervention.

The HADS is a 14-item patient reported outcome (PRO) measure used to detect states of anxiety and depression over the past week. Seven of the items relate to anxiety and seven relate to depression. Each item is scored from 0 to 3 which means a person can score between 0 to 21 for either anxiety or depression. Higher values represent worse outcome.

The analysis population included all participants randomly assigned to study intervention and who took at least 1 dose of study intervention.

The POEM is a 7-item PRO measure used to assess the impact of AD over the past week. Each item is scored as "no days (0)", "1-2 days (1)", "3-4 days (2)", "5-6 days (3)" and "every day (4)". The score ranges from 0 to 28. The higher values represent more severe AD.

The analysis population included all participants randomly assigned to study intervention and who took at least 1 dose of study intervention. Number of Participants Analyzed refers to the number of participants who were evaluable for this outcome measure. Number analyzed refers to the number of participants evaluable for each time point.

The DFI is a validated 10-item measure filled out by the parent/caregiver of the patient used to assess the impact of the patient's eczema on the family. The instrument has a recall period of 7 days. Each item is scored as "very much (3)", "a lot (2)", "a little (1)" or "not at all (0)". The score can range from 0 to 30. The higher values represent the worse impact.

The analysis population included all participants randomly assigned to study intervention and who took at least 1 dose of study intervention. Number of Participants Analyzed refers to the number of participants evaluable for this time point.

The PtGA asked the participant to evaluate the overall cutaneous disease at that point in time on a single-item, 5-point scale. The same category labels used in the IGA were used for the PtGA, ie, "severe (4)", "moderate (3)", "mild (2)","almost clear (1)", and "clear (0)". The PtGA was completed as per schedule of activities.

The analysis population included all participants randomly assigned to study intervention and who took at least 1 dose of study intervention.

The PtGA asked the participant to evaluate the overall cutaneous disease at that point in time on a single-item, 5-point scale. The same category labels used in the IGA were used for the PtGA, ie, "severe (4)", "moderate (3)", "mild (2)","almost clear (1)", and "clear (0)". The PtGA was completed as per schedule of activities.

The analysis population included all participants randomly assigned to study intervention and who took at least 1 dose of study intervention. Number of Participants Analyzed refers to the number of participants evaluable for this outcome measure. Number analyzed refers to the number of participants evaluable for each time point.

The EQ-5D is a validated, standardized, generic instrument that is the most widely used preference based health related quality of life questionnaire in cost effectiveness and health technologies assessment. The EQ-5D-Y is a version of the instrument specifically developed and validated for use by youths aged 12 through 17 years. Components assess level of current health for 5 domains: mobility, self-care, usual activities, pain and discomfort, anxiety and depression. Score scale for each domain ranges from 1 (minimum) to 3 (maximum), with higher scores indicating worse health condition. In addition, respondents use a vertical, graduated Visual Analogue Scale (VAS) to rate their own health between 0 (the worst) and 100 (the best health state he/she can imagine).

The analysis population included all participants randomly assigned to study intervention and who took at least 1 dose of study intervention.

The Functional Assessment of Chronic Illness Therapy Fatigue Scale (FACIT-F) is a 13-item questionnaire. Participants scored each item on a 5-point scale: 0 (none of the time) to 4 (all of the time). Larger the participant's response to the questions (with the exception of 2 negatively stated), greater was the participant's fatigue. For all questions, except for the 2 negatively stated ones, the code was reversed and a new score was calculated as (4 minus the participant's response). The sum of all responses resulted in the FACIT-F score for a total possible score of 0 (worse score) to 52 (better score), with higher scores representing better overall health status (less fatigue). Changes from baseline at Week 12 are presented below. Changes from baseline at other scheduled time points were not evaluated.

The analysis population included all participants randomly assigned to study intervention and who took at least 1 dose of study intervention.

An adverse event (AE) was any untoward medical occurrence in a clinical investigation participant administered a product; the event did not need to have a causal relationship with the treatment. TEAEs were AEs that occurred following the start of treatment or AEs increasing in severity during treatment. Treatment-related TEAEs were determined by the investigator.

The analysis population included all participants randomly assigned to study intervention and who took at least 1 dose of study intervention.

A serious adverse event (SAE) was any untoward medical occurrence 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; resulted in congenital anomaly/birth defect. Treatment-related SAEs were determined by the investigator.

The analysis population included all participants randomly assigned to study intervention and who took at least 1 dose of study intervention.

An AE was any untoward medical occurrence in a clinical investigation participant administered a product; the event did not need to have a causal relationship with the treatment. TEAEs were AEs that occurred following the start of treatment or AEs increasing in severity during treatment. Treatment-related TEAEs were determined by the investigator.

The analysis population included all participants randomly assigned to study intervention and who took at least 1 dose of study intervention.

Laboratory tests included hematology (including coagulation panel), clinical chemistry, lipid profile panel, and routine urinalysis. LLN is lower limit of normal. ULN is upper limit of normal.

The analysis population included all participants randomly assigned to study intervention and who took at least 1 dose of study intervention. Number of Participants Analyzed refers to the number of participants who were evaluable for this outcome measure. Number analyzed refers to the number of participants with at least one observation of the given laboratory test.

A 12-lead ECG was obtained using an ECG machine that automatically calculates the heart rate and measures PR, QRS, QT, and corrected QT intervals. All scheduled ECGs were performed after the participant had rested quietly for at least 10 minutes in a supine position. Reading of ECGs were performed by a central reader who has expertise reading and interpreting ECGs in adolescents. The QTcF interval is the only prespecified ECG criteria (Marked prolongation of the QTcF interval to >500 ms or >60 ms change from screening ECG); data are presented below.

The analysis population included all participants randomly assigned to study intervention and who took at least 1 dose of study intervention. Number of Participants Analyzed refers to the number of participants who were evaluable for this outcome measure.

Vital signs (pulse rate, systolic and diastolic blood pressure) were obtained with participant in the seated position, after having sat calmly for at least 5 minutes.

The analysis population included all participants randomly assigned to study intervention and who took at least 1 dose of study intervention. Number of Participants Analyzed refers to the number of participants who were evaluable for this outcome measure.

The immunogenicity analysis was to evaluate the effect of abrocitinib on immunogenicity to a tetanus, diphtheria and pertussis combination vaccine (Tdap) vaccine in adolescent participants 12 to <18 years of age with moderate to severe AD. Participants who completed 8 weeks of treatment with study intervention received Tdap at Week 8, and had blood samples collected for the evaluation of immunogenicity to the vaccine at Weeks 8 and 12. The fold increase was defined as the ratio (post-vaccination: pre-vaccination) of concentration values. The geometric mean fold rise (GMFR) is presented below, and was calculated by first arithmetically averaging the logarithmically transformed ratio (post-vaccination: pre-vaccination) values, and then back transformation. A 95% CI for GMFR was constructed by back transformation of the CI for the logarithmically transformed GMFRs computed using the Student's t distribution.

The immunogenicity sub-study analysis set included all participants who had completed 8 weeks of treatment and received Tdap vaccination. Number of Participants Analyzed refers to the number of participants evaluable in the analysis set at the specified visit.

The PK analysis included all participants randomly assigned to study intervention and who took at least 1 dose of study intervention. Samples from site 1173 were excluded from the analysis.

The PK analysis included all participants randomly assigned to study intervention and who took at least 1 dose of study intervention. Samples from site 1173 were excluded from the analysis.