ACR20 response: greater than or equal to (>=) 20 % improvement in tender joint count (TJC); >= 20% improvement in swollen joint count (SJC); and >= 20% improvement in at least 3 of 5 remaining ACR core measures: participant assessment of pain; participant global assessment of disease activity; physician global assessment of disease activity; self-assessed disability (disability index of the Health Assessment Questionnaire [HAQ]); and C-Reactive Protein (CRP).

Full Analysis Set (FAS) included all randomized participants who received at least 1 dose of study medication and had at least 1 post-baseline measure. The analysis used Baseline Observation Carried Forward (BOCF) imputation for missing values.

ACR20 response: 20% improvement in TJC; >=20% improvement in SJC; and >=20% improvement in at least 3 of 5 remaining ACR core measures: participant assessment of pain; participant global assessment of disease activity; physician global assessment of disease activity; self-assessed disability (disability index of the HAQ); and CRP.

FAS included all randomized participants who received at least 1 dose of study medication and had at least 1 post-baseline measure. Missing values were imputed using BOCF. n=number of participants evaluable at specific time points for each arm group, respectively.

ACR50 response: >= 50% improvement in TJC or SJC and 50% improvement in at least 3 of 5 remaining ACR core measures: participant assessment of pain; participant global assessment of disease activity; physician global assessment of disease activity; self-assessed disability (disability index of the HAQ); and CRP.

FAS included all randomized participants who received at least 1 dose of study medication and had at least 1 post-baseline measure. Missing values were imputed using BOCF. n=number of participants evaluable at specific time points for each arm group, respectively.

ACR70 response: >= 70% improvement in TJC or SJC and 70% improvement in at least 3 of 5 remaining ACR core measures: participant assessment of pain; participant global assessment of disease activity; physician global assessment of disease activity; self-assessed disability (disability index of the HAQ); and CRP.

FAS included all randomized participants who received at least 1 dose of study medication and had at least 1 post-baseline measure. Missing values were imputed using BOCF. n=number of participants evaluable at specific time points for each arm group respectively.

ACR90 response: >= 90% improvement in TJC or SJC and 90% improvement in at least 3 of 5 remaining ACR core measures: participant assessment of pain; participant global assessment of disease activity; physician global assessment of disease activity; self-assessed disability (disability index of the HAQ); and CRP.

FAS included all randomized participants who received at least 1 dose of study medication and had at least 1 post-baseline measure. Missing values were imputed using BOCF. n=number of participants evaluable at specific time points for each arm group respectively.

ACR-n = calculated for each participant by taking the lowest percentage improvement in (1) SJC or (2) TJC or (3) the median of the remaining 5 components of the ACR response (participant's assessment of disease activity; participant's global assessment of pain; physician's assessment of disease activity; participant's assessment of physical function; an acute phase reactant value - CRP). Negative numbers indicate worsening. Area under the curve (AUC) for ACR-n is the measure of the area under the curve of the mean change from baseline in ACR-n. The trapezoidal rule was used to compute the AUC.

FAS included all randomized participants who received at least 1 dose of study medication and had at least 1 post-baseline measure. Here, 'N' (Number of Participants Analyzed) signifies those participants who were evaluable for this measure. Missing values were imputed using Last Observation Carried Forward (LOCF).

Number of tender joints was determined by examining 68 joints and identified the joints that were painful under pressure or to passive motion. The number of tender joints was recorded on the joint assessment form at each visit, no tenderness = 0, tenderness = 1.

FAS included all randomized participants who received at least 1 dose of study medication and had at least 1 post-baseline measure. n=number of participants evaluable at specific time points for each arm group, respectively.

Number of tender joints was determined by examining 68 joints and identified the joints that were painful under pressure or to passive motion. The number of tender joints was recorded on the joint assessment form at each visit, no tenderness = 0, tenderness = 1. A negative value in change from baseline indicated an improvement.

FAS included all randomized participants who received at least 1 dose of study medication and had at least 1 post-baseline measure. Here, 'N' (Number of Participants Analyzed) signifies those participants who were evaluable for this measure. n=number of participants evaluable at specific time points for each arm group, respectively.

Number of swollen joints was determined by examination of 66 joints and identifying when swelling was present. The number of swollen joints was recorded on the joint assessment form at each visit, no swelling = 0, swelling =1.

FAS included all randomized participants who received at least 1 dose of study medication and had at least 1 post-baseline measure. n=number of participants evaluable at specific time points for each arm group, respectively.

Number of swollen joints was determined by examination of 66 joints and identifying when swelling was present. The number of swollen joints was recorded on the joint assessment form at each visit, no swelling = 0, swelling = 1. A negative value in change from baseline indicated an improvement.

FAS included all randomized participants who received at least 1 dose of study medication and had at least 1 post-baseline measure. Here, 'N' (Number of Participants Analyzed) signifies those participants who were evaluable for this measure. n=number of participants evaluable at specific time points for each arm group, respectively.

Participants rated the severity of arthritis pain on a 0 to 100 millimeter (mm) Visual Analog Scale (VAS), where 0 mm = no pain and 100 mm = most severe pain.

FAS included all randomized participants who received at least 1 dose of study medication and had at least 1 post-baseline measure. n=number of participants evaluable at specific time points for each arm group, respectively.

Participants rated the severity of arthritis pain on a 0 to 100 millimeter (mm) Visual Analog Scale (VAS), where 0 mm = no pain and 100 mm = most severe pain.

FAS included all randomized participants who received at least 1 dose of study medication and had at least 1 post-baseline measure. Here, 'N' (Number of Participants Analyzed) signifies those participants who were evaluable for this measure. n=number of participants evaluable at specific time points for each arm group, respectively.

Participants answered: "Considering all the ways your arthritis affects you, how are you feeling today?" Participants responded by using a 0 - 100 mm VAS, where 0 mm = very well and 100 mm = very poorly.

FAS included all randomized participants who received at least 1 dose of study medication and had at least 1 post-baseline measure. n=number of participants evaluable at specific time points for each arm group, respectively.

Participants answered: "Considering all the ways your arthritis affects you, how are you feeling today?" Participants responded by using a 0 - 100 mm VAS, where 0 mm = very well and 100 mm = very poorly.

FAS included all randomized participants who received at least 1 dose of study medication and had at least 1 post-baseline measure. Here, 'N' (Number of Participants Analyzed) signifies those participants who were evaluable for this measure. n=number of participants evaluable at specific time points for each arm group, respectively.

Physician global assessment of arthritis was measured on a 0 to 100 mm VAS, where 0 mm = very good and 100 mm = very bad.

FAS included all randomized participants who received at least 1 dose of study medication and had at least 1 post-baseline measure. Here, 'N' (Number of Participants Analyzed) signifies those participants who were evaluable for this measure. n=number of participants evaluable at specific time points for each arm group, respectively.

Physician global assessment of arthritis was measured on a 0 to 100 mm VAS, where 0 mm = very good and 100 mm = very bad.

FAS included all randomized participants who received at least 1 dose of study medication and had at least 1 post-baseline measure. Here, 'N' (Number of Participants Analyzed) signifies those participants who were evaluable for this measure. n=number of participants evaluable at specific time points for each arm group, respectively.

The test for CRP is a laboratory measurement for evaluation of an acute phase reactant of inflammation through the use of an ultrasensitive assay. Normal range of CRP is 0 milligram per liter (mg/L) to 10 mg/L. A decrease in the level of CRP indicates reduction in inflammation and therefore improvement.

FAS included all randomized participants who received at least 1 dose of study medication and had at least 1 post-baseline measure. Here, 'N' (Number of Participants Analyzed) signifies those participants who were evaluable for this measure. n=number of participants evaluable at specific time points for each arm group, respectively.

The test for CRP is a laboratory measurement for evaluation of an acute phase reactant of inflammation through the use of an ultrasensitive assay. Normal range of CRP is 0 mg/L to 10 mg/L. A decrease in the level of CRP indicates reduction in inflammation and therefore improvement.

FAS included all randomized participants who received at least 1 dose of study medication and had at least 1 post-baseline measure. Here, 'N' (Number of Participants Analyzed) signifies those participants who were evaluable for this measure. n=number of participants evaluable at specific time points for each arm group, respectively.

HAQ-DI: participant-reported assessment of ability to perform tasks in 8 categories of daily living activities: dress/groom; arise; eat; walk; reach; grip; hygiene; and common activities over past week. Each item scored on 4-point scale from 0 to 3: 0=no difficulty; 1=some difficulty; 2=much difficulty; 3=unable to do. Overall score was computed as the sum of domain scores and divided by the number of domains answered. Total possible score range 0-3 where 0 = least difficulty and 3 = extreme difficulty.

FAS included all randomized participants who received at least 1 dose of study medication and had at least 1 post-baseline measure. Here, 'N' (Number of Participants Analyzed) signifies those participants who were evaluable for this measure. n=number of participants evaluable at specific time points for each arm group, respectively.

HAQ-DI: participant-reported assessment of ability to perform tasks in 8 categories of daily living activities: dress/groom; arise; eat; walk; reach; grip; hygiene; and common activities over past week. Each item scored on 4-point scale from 0 to 3: 0=no difficulty; 1=some difficulty; 2=much difficulty; 3=unable to do. Overall score was computed as the sum of domain scores and divided by the number of domains answered. Total possible score range 0-3 where 0 = least difficulty and 3 = extreme difficulty.

FAS included all randomized participants who received at least 1 dose of study medication and had at least 1 post-baseline measure. Here, 'N' (Number of Participants Analyzed) signifies those participants who were evaluable for this measure. n=number of participants evaluable at specific time points for each arm group, respectively.

DAS28-3 (CRP) was calculated from the SJC and TJC using the 28 joints count and CRP (mg/L). Total score range: 0 to 9.4, higher score indicated more disease activity. DAS28-3 (CRP) less than or equal to (<=) 3.2 implied low disease activity and greater than (>) 3.2 to 5.1 implied moderate to high disease activity, and less than (<) 2.6 = remission.

FAS included all randomized participants who received at least 1 dose of study medication and had at least 1 post-baseline measure. Here, 'N' (Number of Participants Analyzed) signifies those participants who were evaluable for this measure. n=number of participants evaluable at specific time points for each arm group, respectively.

DAS28-3 (CRP) was calculated from the SJC and TJC using the 28 joints count and CRP (mg/L). Total score range: 0 to 9.4, higher score indicated more disease activity. DAS28-3 (CRP) <= 3.2 implied low disease activity and > 3.2 to 5.1 implied moderate to high disease activity, and < 2.6 = remission.

FAS included all randomized participants who received at least 1 dose of study medication and had at least 1 post-baseline measure. Here, 'N' (Number of Participants Analyzed) signifies those participants who were evaluable for this measure. n=number of participants evaluable at specific time points for each arm group, respectively.

DAS28-4 (ESR) calculated from SJC and TJC using 28 joint count, erythrocyte sedimentation rate (ESR) (millimeters per hour [mm/hour]) and PtGA of disease activity (transformed score ranging 0 to 10; higher score indicated greater affectation due to disease activity). Total score range: 0 to 9.4, higher score indicated more disease activity. DAS28-4 (ESR) <= 3.2 implies low disease activity and > 3.2 to 5.1 implies moderate to high disease activity, and < 2.6 = remission.

FAS included all randomized participants who received at least 1 dose of study medication and had at least 1 post-baseline measure. Here, 'N' (Number of Participants Analyzed) signifies those participants who were evaluable for this measure. n=number of participants evaluable at specific time points for each arm group, respectively.

DAS28-4 (ESR) calculated from SJC and TJC using 28 joint count, ESR [mm/hour] and PtGA of disease activity (transformed score ranging 0 to 10; higher score indicated greater affectation due to disease activity). Total score range: 0 to 9.4, higher score indicated more disease activity. DAS28-4 (ESR) <= 3.2 implies low disease activity and > 3.2 to 5.1 implies moderate to high disease activity, and < 2.6 = remission.

FAS included all randomized participants who received at least 1 dose of study medication and had at least 1 post-baseline measure. Here, 'N' (Number of Participants Analyzed) signifies those participants who were evaluable for this measure. n=number of participants evaluable at specific time points for each arm group, respectively.

Disease improvement was classified as good, moderate, and none based on improvement in DAS28-4 (ESR) from baseline and present DAS28-4 (ESR) score. Good: an improvement from baseline of >1.2 and a present score of <=3.2; none: an improvement of <=0.6 or >0.6 to <=1.2 with a present score of >5.1; remaining participants were classified as having moderate (Mod) improvement. Scores of good and moderate were considered to have therapeutic response.

FAS included all randomized participants who received at least 1 dose of study medication and had at least 1 post-baseline measure. Here, 'N' (Number of Participants Analyzed) signifies those participants who were evaluable for this measure. n=number of participants evaluable at specific time points for each arm group, respectively.

CRP value less than or equal to upper limit of normal (ULN) implied disease remission (ULN=4.9 mg/L).

FAS included all randomized participants who received at least 1 dose of study medication and had at least 1 post-baseline measure. Here, 'N' (Number of Participants Analyzed) signifies those participants who were evaluable for this measure. n=number of participants evaluable at specific time points for each arm group, respectively.

DAS28-3 (CRP) defined remission was classified as a score of <2.6.

FAS included all randomized participants who received at least 1 dose of study medication and had at least 1 post-baseline measure. Here, 'N' (Number of Participants Analyzed) signifies those participants who were evaluable for this measure. n=number of participants evaluable at specific time points for each arm group, respectively.

SF-36 is a standardized survey evaluating 8 domains (of 2 components [C]; physical [Ph] and mental [Mn]) of functional health and well being: physical and social (So) functioning (Fn), physical and emotional role (role-physical [R-P], role-emotional [R-E]) limitations, bodily pain (BP), general health (GH), vitality (Vit), mental health (MnH). The score for a section is an average of the individual question scores, which are scaled 0-100 (100=highest level of functioning).

FAS included all randomized participants who received at least 1 dose of study medication and had at least 1 post-baseline measure. Here, 'N' (Number of Participants Analyzed) signifies those participants who were evaluable for this measure. n=number of participants evaluable at specific time points for each arm group, respectively.

SF-36 is a standardized survey evaluating 8 domains (of 2 components [C]; physical [Ph] and mental [Mn]) of functional health and well being: physical and social (So) functioning (Fn), physical and emotional role (role-physical [R-P], role-emotional [R-E]) limitations, bodily pain (BP), general health (GH), vitality (Vit), mental health (MnH). The score for a section is an average of the individual question scores, which are scaled 0-100 (100=highest level of functioning).

FAS included all randomized participants who received at least 1 dose of study medication and had at least 1 post-baseline measure. Here, 'N' (Number of Participants Analyzed) signifies those participants who were evaluable for this measure.n=number of participants evaluable at specific time points for each arm group, respectively.

EQ-5D: participant rated questionnaire to assess health-related quality of life in terms of a single utility score. Health State Profile component assesses level of current health for 5 domains: mobility, self care, usual activities, pain and discomfort, and anxiety and depression; 1 indicates better health state (no problems); 3 indicates worst health state (confined to bed). Scoring formula developed by EuroQoL Group assigns a utility value for each domain in the profile. Score is transformed and results in a total score range -0.594 to 1.000; higher score indicates a better health state.

FAS included all randomized participants who received at least 1 dose of study medication and had at least 1 post-baseline measure. Here, 'N' (Number of Participants Analyzed) signifies those participants who were evaluable for this measure. n=number of participants evaluable at specific time points for each arm group, respectively.

EQ-5D: participant rated questionnaire to assess health-related quality of life in terms of a single utility score. Health State Profile component assesses level of current health for 5 domains: mobility, self-care, usual activities, pain and discomfort, and anxiety and depression; 1 indicates better health state (no problems); 3 indicates worst health state ("confined to bed"). Scoring formula developed by EuroQol Group assigns a utility value for each domain in the profile. Score is transformed and results in a total score range -0.594 to 1.000; higher score indicates a better health state.

FAS included all randomized participants who received at least 1 dose of study medication and had at least 1 post-baseline measure. Here, 'N' (Number of Participants Analyzed) signifies those participants who were evaluable for this measure. n=number of participants evaluable at specific time points for each arm group, respectively.

Blood samples for immunoglobulin assessments were obtained to determine IgG, IgM, and IgA levels in serum.

FAS included all randomized participants who received at least 1 dose of study medication and had at least 1 post-baseline measure. Here, 'N' (Number of Participants Analyzed) signifies those participants who were evaluable for this measure. n=number of participants evaluable at specific time points for each arm group, respectively.

Blood samples for immunoglobulin assessments were obtained to determine change from baseline in serum IgG, IgM, and IgA levels.

FAS included all randomized participants who received at least 1 dose of study medication and had at least 1 post-baseline measure. Here, 'N' (Number of Participants Analyzed) signifies those participants who were evaluable for this measure.

The following biomarkers were assessed: Cluster of Differentiation 3 (CD3), CD4, CD8, CD19 and CD56. FACS analysis for lymphocyte subset markers were used to assess the effects of repeated doses of CP-690,550.

FAS included all randomized participants who received at least 1 dose of study medication and had at least 1 post-baseline measure. Here, 'N' (Number of Participants Analyzed) signifies those participants who were evaluable for this measure. n=number of participants evaluable at specific time points for each arm group, respectively.

The following biomarkers were assessed: CD3, CD4, CD8, CD19 and CD56. FACS analysis for lymphocyte subset markers were used to assess the effects of repeated doses of CP-690,550.

FAS included all randomized participants who received at least 1 dose of study medication and had at least 1 post-baseline measure. Here, 'N' (Number of Participants Analyzed) signifies those participants who were evaluable for this measure.

Participant-rated questionnaire to assess key constructs of sleep over the past week. Consists of a 12-item based on 7 sub scales: sleep disturbance (SD), snoring (Sno), awakened short of breath (ASOB) or with headache, sleep adequacy (Ade), and somnolence (Som) (range:0-100); sleep quantity (Qua)(range:0-24), and optimal (Opt) sleep (yes: 1, no: 0)and nine item index measures of sleep disturbance were constructed to provide composite scores: sleep problem summary (SPS) and overall sleep problems (OSP). Except sleep adequacy, optimal sleep and quantity, higher scores=greater impairment. Scores are transformed (actual raw score minus lowest possible score divided by possible raw score range* 100); total score range: 0 to 100; higher score = greater intensity of attribute.

FAS included all randomized participants who received at least 1 dose of study medication and had at least 1 post-baseline measure. Here, 'N' (Number of Participants Analyzed) signifies those participants who were evaluable for this measure. n=number of participants evaluable at specific time points for each arm group, respectively.

Participant-rated questionnaire to assess key constructs of sleep over the past week. Consists of a 12-item based on 7 subscales: sleep disturbance (SD), snoring (Sno), awakened short of breath (A SOB) or with headache, sleep adequacy (Ade), and somnolence (Som) (range: 0-100); sleep quantity (Qua) (range: 0-24), and optimal (Opt) sleep (yes: 1, no: 0) and 9 item index measures of sleep disturbance were constructed to provide 2 composite scores: sleep problem summary (SPS) and overall sleep problems (OSP). Except sleep adequacy, optimal sleep and quantity, higher scores=greater impairment. Scores are transformed (actual raw score minus lowest possible score divided by possible raw score range*100); total score range: 0 to 100; higher score = greater intensity of attribute.

FAS included all randomized participants who received at least 1 dose of study medication and had at least 1 post-baseline measure. Here, 'N' (Number of Participants Analyzed) signifies those participants who were evaluable for this measure. n=number of participants evaluable at specific time points for each arm group, respectively.

FACIT-Fatigue is a 13-item questionnaire. Participant scored each item on a 5-point scale: 0 (Not at all) to 4 (Very much). The larger the participant's response to the questions (with the exception of 2 negatively stated), the greater the 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-Fatigue score for a total possible score of 0 (worse score) to 52 (better score). A higher score reflected an improvement in the participant's health status.

FAS included all randomized participants who received at least 1 dose of study medication and had at least 1 post-baseline measure. Here, 'N' (Number of Participants Analyzed) signifies those participants who were evaluable for this measure. n=number of participants evaluable at specific time points for each arm group, respectively.

FACIT-Fatigue is a 13-item questionnaire. Participant scored each item on a 5-point scale: 0 (Not at all) to 4 (Very much). The larger the participant's response to the questions (with the exception of 2 negatively stated), the greater the 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-Fatigue score for a total possible score of 0 (worse score) to 52 (better score). A higher score reflected an improvement in the participant's health status.

FAS included all randomized participants who received at least 1 dose of study medication and had at least 1 post-baseline measure. Here, 'N' (Number of Participants Analyzed) signifies those participants who were evaluable for this measure. n=number of participants evaluable at specific time points for each arm group, respectively.