mTSS: sum of erosion and joint space narrowing (JSN) scores for 44 joints (16 per hand and 6 per foot). mTSS scores range from 0 (normal) to 448 (worst possible total score).

mTSS: sum of erosion and JSN scores for 44 joints (16 per hand and 6 per foot). mTSS scores range from 0 (normal) to 448 (worst possible total score). An increase in mTSS from baseline represented disease progression and/or joint worsening, no change represented halting of disease progression, and a decrease represents improvement.

ACR70 response: greater than or equal to (≥) 70 percent (%) improvement in tender joints count (TJC) or swollen joints count (SJC) and ≥70% improvement in at least 3 of 5 remaining ACR core measures: 1) physician's global assessment of disease activity, 2) participant's assessment of disease activity, 3) participant's assessment of pain, 4) participant's assessment of functional disability (disability index of the Health Assessment Questionnaire \[HAQ\]), and 5) C-reactive protein (CRP).

BP: pressure exerted by the blood upon the walls of the blood vessels and especially arteries, usually measured on the radial artery using a sphygmomanometer. Systolic BP: the highest arterial blood pressure of a cardiac cycle occurring immediately after systole of the left ventricle of the heart. Diastolic BP: the lowest arterial blood pressure of a cardiac cycle occurring during diastole of the heart.

BP: pressure exerted by the blood upon the walls of the blood vessels and especially arteries, usually measured on the radial artery using a sphygmomanometer. Systolic BP: the highest arterial blood pressure of a cardiac cycle occurring immediately after systole of the left ventricle of the heart. Diastolic BP: the lowest arterial blood pressure of a cardiac cycle occurring during diastole of the heart.

ACR20 response: greater than or equal to (\>=) 20 percent (%) improvement in tender joints count (TJC); \>= 20% improvement in swollen joints 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). For comparison of CP-690,550 with placebo, placebo sequences were combined into single reporting group for Month 3 analysis.

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;common activities over past week. Each item scored on 4-point scale from 0-3:0=no difficulty;1=some difficulty;2=much difficulty;3=unable to do. Overall score was computed as sum of domain scores and divided by number of domains answered. Total possible score range 0-3:0=least difficulty and 3=extreme difficulty. For comparison of CP-690,550 with placebo, placebo sequences were combined into single reporting group for Month 3 analysis.

DAS28-4 (ESR) was calculated from SJC and TJC using 28 joints count, erythrocyte sedimentation rate (ESR)(millimeter/hour \[mm/hour\]) and patient's global assessment (PtGA) of disease activity (participant rated arthritis activity assessment). Total score range:0-9.4, higher score=more disease activity. DAS28-4 (ESR) less than or equal to (\<=)3.2 implied low disease activity, greater than (\>)3.2 to 5.1 implied moderate to high disease activity, less than (\<)2.6=remission. For comparison of CP-690,550 with placebo, placebo sequences were combined into single reporting group for Month 3 analysis.

ACR20 response: greater than or equal to (\>=) 20 percent (%) 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). For comparison of CP-690,550 with placebo, placebo sequences were combined into single reporting group for Month 6 analysis.

DAS28-4 (ESR) was calculated from SJC and TJC using 28 joints count, erythrocyte sedimentation rate (ESR) (millimeters/hour\[mm/hour\]) and patient's global assessment (PtGA) of disease activity(participant rated arthritis activity assessment). Total score range:0-9.4, higher score=more disease activity. DAS28-4 (ESR) less than or equal to (\<=)3.2 implied low disease activity, greater than (\>)3.2 to 5.1 implied moderate to high disease activity, less than (\<)2.6=remission. For comparison of CP-690,550 with placebo, placebo sequences were combined into single reporting group for Month 6 analysis.

mTSS = sum of erosion and Joint Space Narrowing (JSN) scores for 44 joints (16 per hand and 6 per foot). mTSS scores ranged from 0 (normal) to 448 (worst possible total score). Change: scores at observation minus score at baseline. An increase in mTSS from baseline represented disease progression and/or joint worsening, no change represented halting of disease progression, and a decrease represented improvement. For comparison of CP-690,550 with placebo, placebo sequences were combined into single reporting group for Month 6 analysis.

DAS28-4 (ESR) calculated from swollen joint count (SJC) and tender/painful joint count (TJC) using 28 joint count, erythrocyte sedimentation rate (ESR) (millimeters per hour \[mm/hour\]) and patient's global assessment (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) less than or equal to (=\<) 3.2 implied low disease activity, greater than (\>) 3.2 to 5.1 implied moderate to high disease activity and less than (\<) 2.6=remission. For comparison of CP-690,550 with placebo, placebo sequences were combined into single reporting group for Month 6 analysis.

DAS28-4 (ESR) calculated from swollen joint count (SJC) and tender/painful joint count (TJC) using 28 joint count, erythrocyte sedimentation rate (ESR) (millimeters per hour \[mm/hour\]) and patient's global assessment (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) less than or equal to (=\<) 3.2 implied low disease activity, greater than (\>) 3.2 to 5.1 implied moderate to high disease activity and less than (\<) 2.6=remission.

Treatment-emergent non serious AEs by System Organ Class (SOC) (all causalities) and Laboratory Test Abnormalities (without regard to baseline) The stated number of participants analyzed was the total number of participants in each group (AEs). The actual number of participants analyzed for each laboratory parameter varied, and is provided for each. Abs=absolute; ALT=alanine aminotransferase; AST=aspartate aminotransferase; ESR=erythrocyte sedimentation rate; GGT=gamma glutamyl transferase; hgb=hemoglobin; HDL=high density lipids; LDL=low density lipids; LLN=lower limit of normal; qual=qualitative; Tot=total; ULN=upper limit of normal; WBC=white blood cell

An AE was any untoward medical occurrence in a participant who received study drug without regard to possibility of causal relationship. SAE was an AE resulting in any of the following outcomes or deemed significant for any other reason: death; initial or prolonged inpatient hospitalization; life-threatening experience (immediate risk of dying); persistent or significant disability/incapacity; congenital anomaly. A treatment emergent AE was defined as an event that emerged during the treatment period that was absent before treatment, or worsened during the treatment period relative to the pretreatment state. AEs included both serious and non-serious adverse events.

Criteria for laboratory abnormalities: hemoglobin (Hg), hematocrit, red blood cell (RBC), high density lipoprotein (HDL) cholesterol:\<0.8\*lower limit of normal (LLN), platelet\<0.5\*LLN/\>1.75\*upper limit of normal (ULN), white blood cell (WBC)\<0.6\*LLN/\>1.5\*ULN, lymphocyte, neutrophil, protein, albumin \<0.8\*LLN/\>1.2\*ULN, basophil, eosinophil, monocyte, low density lipoprotein (LDL) cholesterol: \>1.2\*ULN; bilirubin\>1.5\*ULN, aspartate amino transferase(AT), alanine AT, gammaglutamyl transferase, alkaline phosphatase:\>3.0\*ULN; blood urea nitrogen, creatinine, cholesterol, triglyceride:\>1.3\*ULN; sodium \<0.95\*LLN/\>1.05\*ULN, potassium, chloride, calcium, bicarbonate: \<0.9\*LLN/\>1.1\*ULN; glucose\<0.6\*LLN/\>1.5\*ULN; Urine (specific gravity\<1.003/\>1.030, pH\<4.5/\>8, glucose, ketone, protein, blood/Hg(\>=1; RBC, WBC\>=20; creatinine kinase\>2\*ULN).

Treatment-emergent AEs by SOC (all causalities) - all participants, by time. Data presented for Post Month 96 includes data up to and including Month 114.

Long term safety and tolerability of Tofacitinib was measured as following: percentage (%) of participants with AEs, percentage of participants who discontinued due to AEs. An AE is any untoward medical occurrence in participant who received study drug without regard to possibility of causal relationship.

ACR20 response: greater than or equal to (\>=) 20 percent (%) improvement in painful and tender joint count; \>= 20% improvement in swollen joint count; 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).

ACR20 response: greater than or equal to (\>=) 20 percent (%) 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).