A Study Comparing Upadacitinib (ABT-494) to Placebo in Adults With Rheumatoid Arthritis on a Stable Dose of Conventional Synthetic Disease-Modifying Antirheumatic Drugs (csDMARDs) Who Have an Inadequate Response to csDMARDs Alone

Change From Baseline in in Disease Activity Score 28 (CRP) at Week 12

The DAS28 is a composite index used to assess rheumatoid arthritis disease activity, calculated based on the tender joint count (out of 28 evaluated joints), swollen joint count (out of 28 evaluated joints), Patient's Global Assessment of Disease Activity (0-100), and hsCRP (in mg/L). Scores on the DAS28 range from 0 to approximately 10, where higher scores indicate more disease activity. A negative change from Baseline in DAS28 (CRP) indicates improvement in disease activity.

Time frame: Baseline and Week 12

Change From Baseline in Health Assessment Questionnaire Disability Index (HAQ-DI) at Week 12

The Health Assessment Questionnaire - Disability Index is a patient-reported questionnaire that measures the degree of difficulty a person has in accomplishing tasks in 8 functional areas (dressing, arising, eating, walking, hygiene, reaching, gripping, and errands and chores) over the past week. Participants assessed their ability to do each task on a scale from 0 (without any difficulty) to 3 (unable to do). Scores were averaged to provide an overall score ranging from 0 to 3, where 0 represents no disability and 3 represents very severe, high-dependency disability. A negative change from Baseline in the overall score indicates improvement.

Time frame: Baseline and Week 12

Change From Baseline in Short-Form 36 (SF-36) Physical Component Summary (PCS) Score at Week 12

The Short Form 36-Item Health Survey (SF-36) Version 2 is a self-administered questionnaire that measures the impact of disease on overall quality of life during the past 4 weeks. The SF-36 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 score is a weighted combination of the 8 subscales with positive weighting for physical functioning, role-physical, bodily pain, and general health. The PCS was calculated using norm-based scoring so that 50 is the average score and the standard deviation equals 10. Higher scores are associated with better functioning/quality of life; a positive change from Baseline score indicates an improvement.

Time frame: Baseline and Week 12

Percentage of Participants Achieving Clinical Remission Based on DAS28 (CRP) at Week 12

Clinical remission (CR) based on DAS28 (CRP) is defined as achieving a DAS28 (CRP) of less than 2.6. DAS28 (CRP) is a composite index used to assess rheumatoid arthritis disease activity, calculated based on the tender joint count (out of 28 evaluated joints), swollen joint count (out of 28 evaluated joints), Patient's Global Assessment of Disease Activity (0-100), and hsCRP (in mg/L). Scores on the DAS28 range from 0 to approximately 10, where higher scores indicate more disease activity.

Time frame: Week 12

Percentage of Participants Achieving Low Disease Activity Based on CDAI at Week 12

Low disease activity based on the clinical disease activity index (CDAI) is defined as a CDAI score ≤ 10. CDAI is a composite index for assessing disease activity based on the summation of the total tender joint count (out of 28 evaluated joints), swollen joint count (out of 28 evaluated joints), patient global assessment of disease activity measured on a VAS from 0 to 10 cm, and physician global assessment of disease activity measured on a VAS from 0 to 10 cm. The total CDAI score ranges from 0 to 78 with higher scores indicating higher disease activity.

Time frame: Week 12

Change From Baseline in Duration of Morning Stiffness at Week 12

Participants were asked to indicate the time it took for them to get as limber as possible after awakening with morning stiffness over the past 7 days.

Time frame: Baseline and Week 12

Change From Baseline in in Functional Assessment of Chronic Illness Therapy - Fatigue (FACIT-Fatigue) at Week 12

The FACIT-Fatigue scale is a 13-item tool that measures an individual's level of fatigue during their usual daily activities over the past 7 days. Each of the fatigue and impact of fatigue items are measured on a five point Likert scale from 0 (not at all) to 4 (very much). The FACIT-Fatigue scale is the sum of the individual 13 scores and ranges from 0 to 52 where higher scores indicate better the quality of life. A positive change from Baseline indicates improvement.

Time frame: Baseline and week 12

Percentage of Participants With an American College of Rheumatology 50% (ACR50) Response at Week 12

Participants who met the following 3 conditions for improvement from Baseline were classified as meeting the ACR50 response criteria: 1. ≥ 50% improvement in 68-tender joint count; 2. ≥ 50% improvement in 66-swollen joint count; and 3. ≥ 50% improvement in at least 3 of the 5 following parameters: * Physician global assessment of disease activity; * Patient global assessment of disease activity; * Patient assessment of pain; * Health Assessment Questionnaire - Disability Index (HAQ-DI); * High-sensitivity C-reactive protein (hsCRP).

Time frame: Baseline and Week 12

Percentage of Participants With an American College of Rheumatology 70% (ACR70) Response at Week 12

Participants who met the following 3 conditions for improvement from Baseline were classified as meeting the ACR70 response criteria: 1. ≥ 70% improvement in 68-tender joint count; 2. ≥ 70% improvement in 66-swollen joint count; and 3. ≥ 70% improvement in at least 3 of the 5 following parameters: * Physician global assessment of disease activity; * Patient global assessment of disease activity; * Patient assessment of pain; * Health Assessment Questionnaire - Disability Index (HAQ-DI); * High-sensitivity C-reactive protein (hsCRP).

Time frame: Baseline and Week 12

Percentage of Participants With an American College of Rheumatology 20% (ACR20) Response at Week 1

Participants who met the following 3 conditions for improvement from Baseline were classified as meeting the ACR20 response criteria: 1. ≥ 20% improvement in 68-tender joint count; 2. ≥ 20% improvement in 66-swollen joint count; and 3. ≥ 20% improvement in at least 3 of the 5 following parameters: * Physician global assessment of disease activity; * Patient global assessment of disease activity; * Patient assessment of pain; * Health Assessment Questionnaire - Disability Index (HAQ-DI); * High-sensitivity C-reactive protein (hsCRP).

Time frame: Baseline and Week 1