Percentage of participants with an American College of Rheumatology 20% (ACR20) response. A participant was a responder if the following 3 criteria for improvement from Baseline were met:

• ≥ 20% improvement in 78 tender joint count;

• ≥ 20% improvement in 76 swollen joint count; and

• ≥ 20% improvement in at least 3 of the 5 following parameters:

  • Patient's self-assessment of pain (measured on a 0 to 10 unit numeric rating scale [NRS]);
  • Patient's global self-assessment of disease activity (measured on a 0 to 10 unit NRS);
  • Physician's global assessment of disease activity (measured on a 0 to 10 unit NRS);
  • Patient's self-assessment of physical function (Health Assessment Questionnaire - Disability Index [HAQ-DI]);
  • C-Reactive Protein (CRP) Those who withdrew early or who did not have sufficient data at Week 16 were counted as non-responders.

Full Analysis Set (FAS) population consisting of all participants randomized as specified in the protocol.

HAQ-DI is a patient-reported questionnaire consisting of 20 questions referring to eight domains: dressing/grooming, arising, eating, walking, hygiene, reach, grip, and usual activities. Participants assessed their ability to do each task over the past week using the following response categories: without any difficulty (0); with some difficulty (1); with much difficulty (2); and unable to do (3). Scores on each task are summed and averaged to provide an overall score ranging from 0 to 3, where zero represents no disability and three very severe, high-dependency disability. A higher score indicates worse physical functioning, and a negative change from baseline indicates improvement.

Full analysis set; Participants with a baseline and at least 1 postbaseline value during the placebo-controlled phase were included in the analysis (mixed effects model for repeated measure [MMRM])

Percentage of participants with an American College of Rheumatology 20% (ACR20) response. A participant was a responder if the following 3 criteria for improvement from Baseline were met:

• ≥ 20% improvement in 78 tender joint count;

• ≥ 20% improvement in 76 swollen joint count; and

• ≥ 20% improvement in at least 3 of the 5 following parameters:

  • Patient's self-assessment of pain (measured on a 0 to 10 unit numeric rating scale [NRS]);
  • Patient's global self-assessment of disease activity (measured on a 0 to 10 unit NRS);
  • Physician's global assessment of disease activity (measured on a 0 to 10 unit NRS);
  • Patient's self-assessment of physical function (Health Assessment Questionnaire - Disability Index [HAQ-DI]);
  • C-Reactive Protein (CRP) Those who withdrew early or who did not have sufficient data at Week 16 were counted as non-responders.

FAS population.

The DAS28 measures the severity of disease at a specific time and is derived from the following variables:

• 28 tender joint count
• 28 swollen joint count, which do not include the DIP joints, the hip joint, or the joints below the knee;
• C-reactive protein (CRP)
• Patient's global assessment of disease activity. DAS28 (CRP) scores range from 0 to 9.4. A DAS28 score higher than 5.1 indicates high disease activity, a DAS28 score less than 3.2 indicates low disease activity, and a DAS28 score less than 2.6 indicates clinical remission. A higher value indicates higher disease activity, and a negative change from baseline indicates improvement.

Full analysis set; Participants with a baseline value and at least one post-baseline value (after exclusion of data for early escaped participants) during the placebo-controlled phase are included in the analysis.

The Medical Outcome Study Short Form 36-Item Health Survey, Version 2 (SF-36) is a self-administered instrument that measures the impact of disease on overall quality of life and consists of 36 questions in eight domains (physical function, pain, general and mental health, vitality, social function, physical and emotional health). Norm-based scores were used in analyses, calibrated so that 50 is the average score and the standard deviation equals 10. Higher scores indicate a higher level of functioning. The physical functioning domain assesses limitations in physical activities because of health problems. A positive change from baseline score indicates an improvement.

Full analysis set; Participants with a baseline and at least 1 postbaseline value during the placebo-controlled phase were included in the analysis (mixed effects model for repeated measure [MMRM])

The SF-36 (v 2.0) is a self-administered instrument that measures the impact of disease on overall quality of life and consists of 36 questions in eight domains (physical function, pain, general and mental health, vitality, social function, physical and emotional health). The physical component summary (PCS) score includes the physical functioning, role physical, bodily pain, and general health domains. Minimum clinically important difference (MCID) for the scale scores, as well as the PCS and MCS, is defined as a 2.5-point improvement (increase) from baseline. The summary scores range from 0 to 100, with lower scores reflecting more disability, and higher scores reflecting less disability and better health. The 8 domains are regrouped into the PCS and MCS scores.

Full analysis set. Subjects with a baseline value and at least one post-baseline value (after exclusion of data for early escaped subjects) during the placebo-controlled phase are included in the MMRM model.

Morning stiffness was the participant's assessment of how long their morning stiffness lasted after first waking up in the morning, on average, during the previous week. A higher value indicates longer duration, and a negative change from baseline indicates improvement.

Full Analysis Set; Analysis includes participants with a baseline and at least one post-baseline value; last observation carried forward (LOCF) imputation was used

Morning stiffness severity was the participant's assessment of how severe their morning stiffness was after first waking up in the morning, on average, during the previous week. The severity was recorded as none, mild, moderate, moderately severe, or very severe. The response of no improvement includes subjects who had no change or worsened. Improvement is defined as the change from baseline of a more severe assessment to less severe assessment.

Full Analysis Set; Participants who withdrew early or who did not have sufficient data at Week 24 were counted as non-responders

HAQ-DI is a patient-reported questionnaire consisting of 20 questions referring to eight domains: dressing/grooming, arising, eating, walking, hygiene, reach, grip, and usual activities. Participants assessed their ability to do each task over the past week using the following response categories: without any difficulty (0); with some difficulty (1); with much difficulty (2); and unable to do (3). Scores on each task are summed and averaged to provide an overall score ranging from 0 to 3, where zero represents no disability and three very severe, high-dependency disability. A higher score indicates worse physical functioning, and a negative change from baseline indicates improvement.

Full analysis set; participants with a baseline value and at least 1 postbaseline value during the placebo-controlled phase were included in the mixed effects model for repeated measures (MRMM).

The DAS28 measures the severity of disease at a specific time and is derived from the following variables:

• 28 tender joint count
• 28 swollen joint count, which do not include the DIP joints, the hip joint, or the joints below the knee;
• C-reactive protein (CRP)
• Patient's global assessment of disease activity. DAS28 (CRP) scores range from 0 to 9.4. A DAS28 score higher than 5.1 indicates high disease activity, a DAS28 score less than 3.2 indicates low disease activity, and a DAS28 score less than 2.6 indicates clinical remission. A negative change from baseline indicates improvement.

Full analysis set; participants with a baseline value and at least 1 postbaseline value during the placebo-controlled phase were included in the mixed effects model for repeated measures (MRMM).

The SF-36 (v 2.0) is a self-administered instrument that measures the impact of disease on overall quality of life and consists of 36 questions in eight domains (physical function, pain, general and mental health, vitality, social function, physical and emotional health). Norm-based scores were used in analyses, calibrated so that 50 is the average score and the standard deviation equals 10. Higher scores indicate a higher level of functioning. The physical functioning domain assesses limitations in physical activities because of health problems. A positive change from Baseline score indicates an improvement.

Full analysis set; participants with a baseline value and at least 1 postbaseline value during the placebo-controlled phase were included in the mixed effects model for repeated measures (MRMM).

Morning stiffness was the participant's assessment of how long their morning stiffness lasted after first waking up in the morning, on average, during the previous week. A higher value indicates longer duration, and a negative change from baseline indicates improvement.

Full analysis set; Analysis includes participants with a baseline and at least one post-baseline value; last observation carried forward (LOCF) imputation was used

Morning stiffness severity was the participant's assessment of how severe their morning stiffness was after first waking up in the morning, on average, during the previous week. The severity was recorded as none, mild, moderate, moderately severe, or very severe. Improvement is defined as the change from baseline of a more severe assessment to less severe assessment. Full Analysis Set; Participants who discontinued early prior to Week 16 and those who did not have sufficient data for a definitive determination of response status at Week 16 were counted as non-responders.

Full Analysis Set; Participants who discontinued early prior to Week 16 and those who did not have sufficient data for a definitive determination of response status at Week 16 were counted as non-responders

Percentage of participants with an American College of Rheumatology 20% (ACR20) response. A participant was a responder if the following 3 criteria for improvement from Baseline were met:

• ≥ 20% improvement in 78 tender joint count;

• ≥ 20% improvement in 76 swollen joint count; and

• ≥ 20% improvement in at least 3 of the 5 following parameters:

  • Patient's self-assessment of pain (measured on a 0 to 10 unit numeric rating scale [NRS]);
  • Patient's global self-assessment of disease activity (measured on a 0 to 10 unit NRS);
  • Physician's global assessment of disease activity (measured on a 0 to 10 unit NRS);
  • Patient's self-assessment of physical function (Health Assessment Questionnaire - Disability Index [HAQ-DI]);
  • C-Reactive Protein (CRP)

Full analysis set; participants discontinued early prior to the visit and participants who did not have sufficient data for a definitive determination of response status for the visit were counted as nonresponders.

Percentage of participants with an American College of Rheumatology 20% (ACR20) response. A participant was a responder if the following 3 criteria for improvement from Baseline were met:

• ≥ 20% improvement in 78 tender joint count;

• ≥ 20% improvement in 76 swollen joint count; and

• ≥ 20% improvement in at least 3 of the 5 following parameters:

  • Patient's self-assessment of pain (measured on a 0 to 10 unit numeric rating scale [NRS]);
  • Patient's global self-assessment of disease activity (measured on a 0 to 10 unit NRS);
  • Physician's global assessment of disease activity (measured on a 0 to 10 unit NRS);
  • Patient's self-assessment of physical function (Health Assessment Questionnaire - Disability Index [HAQ-DI]);
  • C-Reactive Protein (CRP)

Apremilast Participants as Randomized or Transitioned, which includes all participants who randomized or escaped/transitioned (at Week 16 or Week 24) to apremilast, and with available data at each time point.

HAQ-DI is a patient-reported questionnaire consisting of 20 questions referring to eight domains: dressing/grooming, arising, eating, walking, hygiene, reach, grip, and usual activities. Participants assessed their ability to do each task over the past week using the following response categories: without any difficulty (0); with some difficulty (1); with much difficulty (2); and unable to do (3). Scores on each task are summed and averaged to provide an overall score ranging from 0 to 3, where zero represents no disability and three very severe, high-dependency disability. A higher score indicates worse physical functioning, and a negative change from baseline indicates improvement.

Apremilast participants as randomized or transitioned; The Placebo/Apremilast 30 mg BID group includes participants initially randomized to placebo and switched to apremilast 30 mg BID at Week 16 or 24 and with available data at each time point.

The DAS28 measures the severity of disease at a specific time and is derived from the following variables:

• 28 tender joint count
• 28 swollen joint count, which do not include the DIP joints, the hip joint, or the joints below the knee;
• C-reactive protein (CRP)
• Patient's global assessment of disease activity. DAS28 (CRP) scores range from 0 to 9.4. A DAS28 score higher than 5.1 indicates high disease activity, a DAS28 score less than 3.2 indicates low disease activity, and a DAS28 score less than 2.6 indicates clinical remission. A negative change from baseline indicates improvement.

Apremilast participants as randomized or transitioned. The Placebo/Apremilast30 mg BID group includes participants initially randomized to placebo and switched to apremilast 30 mg BID at Week 16 or 24 and with available data at each time point.

The SF-36 (v 2.0) is a self-administered instrument that measures the impact of disease on overall quality of life and consists of 36 questions in eight domains (physical function, pain, general and mental health, vitality, social function, physical and emotional health). Norm-based scores were used in analyses, calibrated so that 50 is the average score and the standard deviation equals 10. Higher scores indicate a higher level of functioning. The physical functioning domain assesses limitations in physical activities because of health problems. A positive change from Baseline score indicates an improvement.

Apremilast Subjects as Randomized or Transitioned; The Placebo/30 mg BID group includes participants initially randomized to placebo and switched to apremilast 30 mg BID at Week 16 or 24and with available data at each time point.

Morning stiffness was the participant's assessment of how long their morning stiffness lasted after first waking up in the morning, on average, during the previous week. A higher value indicates longer duration, and a negative change from baseline indicates improvement.

Apremilast participants as randomized or transitioned; The Placebo/ Apremilast 30 mg BID group includes participants initially randomized to placebo and switched to apremilast 30 mg BID at Week 16 or 24 And with available data at each time point.

Morning stiffness severity was the participant's assessment of how severe their morning stiffness was after first waking up in the morning, on average, during the previous week. The severity was recorded as none, mild, moderate, moderately severe, or very severe. Improvement is defined as the change from baseline of a more severe assessment to less severe assessment.

Apremilast participants as randomized or transitioned. The Placebo/30 mg BID group includes subjects initially randomized to placebo and switched to apremilast 30 mg BID at Week 16 or 24 and with available data at each time point

A TEAE is an AE with a start date on or after the date of the first dose of Investigational Product (IP). An AE is any noxious, unintended, or untoward medical occurrence, that may appear or worsen in a participant during the course of 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 (ie, any clinically significant adverse change in the frequency or intensity of a preexisting condition) was considered an AE. A serious AE (SAE) is any untoward adverse event that is fatal, life-threatening, results in persistent or significant disability or incapacity, requires or prolongs existing in-patient hospitalization, is a congenital anomaly or birth defect, or a condition that may jeopardize the patient or may require intervention to prevent one of the outcomes listed above.

Safety population includes all participants who were randomized and received at least one dose of IP.

A TEAE is an AE with a start date on or after the date of the first dose of Investigational Product (IP). An AE is any noxious, unintended, or untoward medical occurrence, that may appear or worsen in a participant during the course of 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 (ie, any clinically significant adverse change in the frequency or intensity of a preexisting condition) was considered an AE. A serious AE (SAE) is any untoward adverse event that is fatal, life-threatening, results in persistent or significant disability or incapacity, requires or prolongs existing in-patient hospitalization, is a congenital anomaly or birth defect, or a condition that may jeopardize the patient or may require intervention to prevent one of the outcomes listed above.

APR participants as treated (AAT) population; AAT = participants who received at least 1 dose of APR at any time during the study, (those initially randomized to the APR 30 BID at Week 0, those initially randomized to placebo who entered EE and transitioned to APR at Week 16, and those initially randomized to PBO who transitioned to APR at Week 24)