AE=any new untoward medical occurrence or worsening of a pre-existing medical condition which does not necessarily have a causal relationship with treatment.SAE=any untoward medical occurrence that at any dose: results in death, is life-threatening, requires inpatient hospitalization or causes prolongation of existing hospitalization, results in persistent or significant disability/incapacity, is a congenital anomaly/birth defect, results in development of drug dependency or drug abuse, is an important medical event.Related AE/SAE=Certain,Probable,Possible,or Missing relationship to Drug

All treated participants

AE=any new untoward medical occurrence or worsening of a pre-existing medical condition which does not necessarily have a causal relationship with this treatment. AEs of special interest are those AEs that may be associated with the use of immunomodulatory drugs, including all infections, serious infections, and opportunistic infections; autoimmune disorders; neoplasms; acute infusional AEs (pre-specified AEs occurring within 1 hour of start of infusion) and peri-infusional AEs (pre-specified AEs occurring within 24 hours of the start of infusion).

All treated participants

The DAS 28 is a continuous disease measure which is a composite of 4 variables: the 28 tender joint count, the 28 swollen joint count, ESR or CRP, and participant assessment of disease activity measure on a visual analogue scale. The DAS28 has numeric thresholds that define high disease activity (> 5.1), low disease activity (< 3.2) and remission (< 2.6). A clinically significant response= decrease in DAS28 score of >1.2 from baseline.

All treated participants.

Upper Normal Limit (ULN), Lower Normal Limit (LLN), Baseline (BL). Marked abnormality criteria are: Hemoglobin (HGB): >3 g/dL decrease from BL; Hematocrit: <0.75 * BL; Erythrocytes: <0.75 * BL; Platelets (PLT): <0.67 * LLN/>1.5 * ULN, or if BL < LLN then use 0.5 * BL/<100,000 mm^3; Leukocytes: <0.75 * LLN/ >1.25 * ULN, or if BL<LLN then use <0.8 * BL/>ULN, or if BL>ULN then use >1.2 * BL/<LLN; neutrophils+bands: <1.0 * 10^3 c/uL; eosinophils: >0.750 * 10^3 c/uL; basophils: > 400 mm^3; monocytes: >2000 mm^3; lymphocytes: <0.750 * 10^3 c/uL/ >7.50 * 10^3 c/uL.

Participants who received at least 1 infusion of abatacept during the short-term treatment period

Marked abnormality criteria: Alkaline phosphatase (ALP): >2* ULN, or if BL>ULN then use >3* BL; aspartate aminotransferase (AST): >3* ULN, or if BL>ULN then use >4* BL; alanine aminotransferase (ALT): >3* ULN, or if BL>ULN then use >4* BL; G-Glutamyl transferase (GGT): >2* ULN, or if BL>ULN then use >3* BL; Bilirubin: >2* ULN, or if BL>ULN then use >4* BL; blood urea nitrogen (BUN): >2* BL; creatinine: >1.5* BL

All treated participants. n=number of participants with evaluable laboratory results.

Marked abnormality criteria:Sodium (Na): <0.95* LLN/ >1.05* ULN,or if BL<LLN then use 0.95* BL or >ULN,or if BL>ULN then use>1.05* BL or <LLN; potassium (K): <0.9* LLN/>1.1* ULN,or if BL<LLN then use 0.9* BL or >ULN, or if BL>ULN then use>1.1* BL or <LLN; chloride: <0.9* LLN/>1.1* ULN, or if BL<LLN then use 0.9* BL or >ULN, or if BL>ULN then use>1.1* BL or <LLN; calcium (Ca): <0.8* LLN/>1.2* ULN, or if BL<LLN then use 0.75* BL or >ULN, or if BL>ULN then use>1.25* BL or <LLN; phosphorous (P): <0.75* LLN/ >1.25* ULN, or if BL<LLN then use 0.67* BL or >ULN, or if BL>ULN then use>1.33* BL or \

All treated participants. n=number of participants with evaluable laboratory results.

Marked abnormality criteria: serum glucose (Glu):<65 mg/dL/ >220 mg/dL; fasting serum Glu: <0.8* LLN/>1.5* ULN, or if BL<LLN then use 0.8* BL or >ULN, or if BL>ULN then use >2.0* BL or <LLN; total protein: <0.9* LLN/>1.1* ULN; albumin: <0.9* LLN,or if BL<LLN then use <0.75 BL; uric acid: >1.5* ULN, or if BL>ULN then use >2* BL. Urinalysis (Urine protein, urine Glu, urine blood, leukocyte esterase, Red Blood Cells [RBCs], White Blood Cells [WBCs]):Use ≥2 when BL value missing or value ≥4,or when pre-dose=0 or 0.5. Use ≥3 when pre-dose=1. Use ≥4 when pre-dose=2 or 3

All treated participants. n=number of participants with evaluable laboratory results.

Although mean values for systolic and diastolic blood pressure were recorded, mean changes from baseline were not summarized for these data.

Serum samples from all treated adult participants with active rheumatoid arthritis (RA) were screened for the presence of drug-specific antibodies using ELISA. Immunogenicity was defined as the presence of a positive anti-abatacept or anti-CTLA4 antibody.

Treated participants with available serum samples for assay

The DAS 28 is a continuous disease measure which is a composite of 4 variables: the 28 tender joint count, the 28 swollen joint count, ESR or CRP, and participant assessment of disease activity measure on a visual analogue scale. The DAS28 has numeric thresholds that define high disease activity (> 5.1), low disease activity (< 3.2) and remission (< 2.6). Time-matched baseline (Day 0) values and post-baseline values were presented for each post-baseline visit, and represent only that cohort of participants with measurements available at that post-baseline visit.

All treated participants. n=number of evaluable participants.

The DAS28 is a continuous disease measure which is a composite of 4 variables: the 28 tender joint count, the 28 swollen joint count, ESR or CRP, and participant assessment of disease activity measure on a visual analogue scale. The DAS28 has numeric thresholds that define high disease activity (> 5.1), low disease activity (< 3.2) and remission (< 2.6). Time-matched mean change from BL= Post-BL value - time-matched BL value, where the time-matched BL value represents the mean BL (Day 0) value for only that cohort of participants with measurements available at that post-BL visit.

All treated participants. n=number of evaluable participants.

hs-CRP is a acute phase reactant protein that is a clinical marker for Rheumatoid Arthritis (RA). Levels of hs-CRP can be used to determine DAS28.

All treated participants

RF is an autoantibody (antibody directed against an organism's own tissues) most relevant in rheumatoid arthritis. It is an antibody against the Fc portion of Immunoglobulin (Ig)G, which is itself an antibody. RF and IgG join to form immune complexes which contribute to the disease process.

All treated participants

The HAQ-DI includes 20 questions to assess physical functions in 8 domains: dressing, arising, eating, walking, hygiene, reach, grip and common activities. The domain questions are evaluated on a 4-point scale: 0=without any difficulty, 1= with some difficulty, 2= with much difficulty, and 3= unable to do. HAQ-DI= sum of worst scores in each domain divided by the number of domains answered. HAQ-DI ranges from a minimum of 0 (no difficulty) to a maximum overall score of 3(unable to do).

All treated participants

HAQ-DI includes 20 questions to assess physical functions in 8 domains: dressing, arising, eating, walking, hygiene, reach, grip and common activities. The domain questions are evaluated on a 4-point scale: 0=without any difficulty, 1= with some difficulty, 2= with much difficulty, and 3= unable to do. HAQ-DI= sum of worst scores in each domain divided by the number of domains answered. HAQ-DI ranges from a minimum of 0 (no difficulty) to a maximum overall score of 3(unable to do). Clinically meaningful HAQ response=an improvement of at least 0.3 units from baseline in HAQ disability Index.

All treated participants

The SF-36 is a validated instrument measuring health-related quality of life across multiple disease states. It has 36 questions with 8 subscale scores and 2 summary scores (1) physical component summary=physical functioning, role-physical, bodily pain, and general health; (2) mental component summary=vitality, social functioning, role-emotional, and mental health. There is no total overall score; scoring is done for both subscores and summary scores. For subscores and summary scores, 0 =worst score (or quality of life) and 100=best score. Change from Baseline= post-Baseline - Baseline value.

All treated participants. n=number of evaluable participants.

AE=any new untoward medical occurrence or worsening of a pre-existing medical condition which does not necessarily have a causal relationship with treatment.SAE=any untoward medical occurrence that at any dose: results in death, is life-threatening, requires inpatient hospitalization or causes prolongation of existing hospitalization, results in persistent or significant disability/incapacity, is a congenital anomaly/birth defect, results in development of drug dependency or drug abuse, is an important medical event.Related AE/SAE=Certain,Probable,Possible,or Missing relationship to Drug

All treated participants

AE=any new untoward medical occurrence or worsening of a pre-existing medical condition which does not necessarily have a causal relationship with this treatment. AEs of special interest are those AEs that may be associated with the use of immunomodulatory drugs, including all infections, serious infections, and opportunistic infections; autoimmune disorders; neoplasms; acute infusional AEs (pre-specified AEs occurring within 1 hour of start of infusion) and peri-infusional AEs (pre-specified AEs occurring within 24 hours of the start of infusion).

All treated participants

ULN=upper limit of normal; LLN=lower limit of normal; BL=baseline. Marked abnormality criteria=Hemoglobin: >3 g/dL decrease from BL; Hematocrit: <0.75*BL; Erythrocytes:<0.75*BL; Platelets: <0.67*LLN/>1.5 * ULN, or if BL<LLN, use 0.5*BL/<100,000 mm^3; Leukocytes: <0.75*LLN/>1.25*ULN, or if BL<LLN, use <0.8*BL/>ULN, or if BL>ULN,use >1.2*BL/<LLN; neutrophils+bands: <1.0*10^3 c/uL; eosinophils: >0.750*10^3 c/uL; basophils: >400 mm^3; monocytes: >2000 mm^3; lymphocytes: <0.750*10^3 c/uL/>7.50*10^3 c/uL.

Participants who received at least 1 infusion of abatacept during the long-term treatment period. n=number of participants with evaluable laboratory results.

Marked abnormality criteria: Alkaline phosphatase (ALP): >2*ULN, or if BL>ULN, use >3*BL; aspartate aminotransferase (AST): >3*ULN, or if BL>ULN,use >4*BL; alanine aminotransferase (ALT): >3*ULN, or if BL>ULN, use >4*BL; G-Glutamyl transferase (GGT): >2*ULN, or if BL>ULN, use >3*BL; bilirubin: >2*ULN, or if BL>ULN, use >4*BL; blood urea nitrogen (BUN): >2*BL; creatinine: >1.5*BL

All treated participants. n=number of participants with evaluable laboratory results.

Marked abnormality criteria:Sodium (Na): <0.95* LLN/ >1.05* ULN,or if BL<LLN then use 0.95* BL or >ULN,or if BL>ULN then use>1.05* BL or <LLN; potassium (K): <0.9* LLN/>1.1* ULN,or if BL<LLN then use 0.9* BL or >ULN, or if BL>ULN then use>1.1* BL or <LLN; chloride: <0.9* LLN/>1.1* ULN, or if BL<LLN then use 0.9* BL or >ULN, or if BL>ULN then use>1.1* BL or <LLN; calcium (Ca): <0.8* LLN/>1.2* ULN, or if BL<LLN then use 0.75* BL or >ULN, or if BL>ULN then use>1.25* BL or <LLN; phosphorous (P): <0.75* LLN/ >1.25* ULN, or if BL<LLN then use 0.67* BL or >ULN, or if BL>ULN then use>1.33* BL or \

All treated participants. n=number of participants with evaluable laboratory results.

Marked abnormality criteria: serum glucose (Glu):<65 mg/dL/ >220 mg/dL; fasting serum Glu: <0.8* LLN/>1.5* ULN, or if BL<LLN then use 0.8* BL or >ULN, or if BL>ULN then use >2.0* BL or <LLN; total protein: <0.9* LLN/>1.1* ULN; albumin: <0.9* LLN,or if BL<LLN then use <0.75 BL; uric acid: >1.5* ULN, or if BL>ULN then use >2* BL. Urinalysis (Urine protein, urine Glu, urine blood, leukocyte esterase, Red Blood Cells [RBCs], White Blood Cells [WBCs]):Use ≥2 when BL value missing or value ≥4,or when pre-dose=0 or 0.5. Use ≥3 when pre-dose=1. Use ≥4 when pre-dose=2 or 3

All treated participants. n=number of participants with evaluable laboratory results.

HGB normal range (NR)=11.6 - 16.2 g/dL, marked abnormality (MA) is >3 g/dL decrease from BL. Total protein NR=6.0 - 8.4 g/dL, MA is <0.9* LLN/>1.1* ULN; Albumin NR=3.5 - 5.3 g/dL, MA is <0.9* LLN, or if BL\

All treated participants in the OL. n=number of participants with evaluable laboratory results.

The hematocrit value refers to the percentage of blood volume that is occupied by red blood cells. Hematocrit values for participants were expressed as percentages and were averaged to yield a group mean value (percentage) at a particular time point. The mean change from baseline in hematocrit value (expressed as a percent)= mean post-baseline value (expressed as a percent) - mean baseline value (expressed as a percent).

All treated participants in the OL. n=number of participants with evaluable laboratory results.

Erythrocytes NR= 3.80 - 5.50 *10^6 c/uL, MA is <0.75 * BL

All treated participants in the OL. n=number of participants with evaluable laboratory results.

Erythrocytes NR= 3.80 - 5.50 *10^6 c/uL, MA is <0.75 * BL

All treated participants in the OL. n=number of participants with evaluable laboratory results.

Leukocytes NR=4.1 - 12.3*10^3 c/uL, MA is <0.75 * LLN/ >1.25 * ULN, or if BL<LLN then use <0.8 * BL/>ULN, or if BL>ULN then use >1.2 * BL/<LLN. Neutrophils+bands MA is <1.0 * 10^3 c/uL. Eosinophils MA is >0.750 * 10^3 c/uL. Basophils MA is > 400 mm^3. Monocytes MA is >2000 mm^3. Lymphocytes MA is <0.750 * 10^3 c/uL/ >7.50 * 10^3 c/uL

All treated participants in the OL. n=number of participants with evaluable laboratory results.

HGB normal range (NR)=11.6 - 16.2 g/dL, marked abnormality (MA) is >3 g/dL decrease from BL. Total protein NR=6.0 - 8.4 g/dL, MA is <0.9* LLN/>1.1* ULN; Albumin NR=3.5 - 5.3 g/dL, MA is <0.9* LLN, or if BL\

All treated participants in the OL. n=number of participants with evaluable laboratory results.

Bilirubin NR=0.2-1.2 mg/dL, MA: >2* ULN, or if BL>ULN then use >4* BL. BUN NR=4.0-24.0 mg/dL, MA: >2*BL. Creatinine NR=0.4-1.2 mg/dL, MA: >1.5*BL. Ca NR=8.8-10.2 mg/dL, MA: <0.8*LLN/>1.2*ULN, or if BL<LLN then use 0.75*BL or >ULN, or if BL>ULN then use>1.25*BL or <LLN. P NR=2.8-4.0 mg/dL, MA: <0.75*LLN/ >1.25*ULN, or if BL<LLN then use 0.67*BL or >ULN, or if BL>ULN then use>1.33*BL or <LLN. Glu MA: <65 mg/dL/ >220 mg/dL. Uric acid MA: >1.5*ULN, or if BL>ULN then use >2*BL.

All treated participants in the OL. n=number of participants with evaluable laboratory results.

Na NR=132 - 147 mEq/L, MA is 95* LLN/ >1.05* ULN, or if BL<LLN then use 0.95* BL or >ULN, or if BL>ULN then use>1.05* BL or <LLN. K NR=3.3 - 5.5 mEq/L, MA is <0.9* LLN/>1.1* ULN,or if BL<LLN then use 0.9* BL or >ULN, or if BL>ULN then use>1.1* BL or <LLN. Cl NR=94 - 111 mEq/L, MA is <0.9* LLN/>1.1* ULN, or if BL<LLN then use 0.9* BL or >ULN, or if BL>ULN then use>1.1* BL or \

All treated participants in the OL. n=number of participants with evaluable laboratory results.

Measurements were taken in a seated position before and after abatacept infusion.

All treated participants. n=number of participants with evaluable blood pressure measurements.

Measurements were taken in a seated position before and after abatacept infusion.

All treated participants. n=number of participants with evaluable blood pressure readings.

All treated participants. n=number of participants with evaluable heart rate readings.

All treated participants. n=number of participants with evaluable temperature readings.

The SF-36 is a validated instrument measuring health-related quality of life across multiple disease states. It has 36 questions with 8 subscale scores and 2 summary scores (1) physical component summary=physical functioning, role-physical, bodily pain, and general health; (2) mental component summary=vitality, social functioning, role-emotional, and mental health. There is no total overall score; scoring is done for both subscores and summary scores. For subscores and summary scores, 0 =worst score (or quality of life) and 100=best score. Change from Baseline= post-Baseline - Baseline value.

All treated participants. n=number of evaluable participants.

The VAS for Fatigue (VAS-F) consists of a 100 mm line, with 0 (No Fatigue) on 1 end and 100 (Extreme Fatigue) on the other end, which a participant marks to indicate how much fatigue he or she feels. The marked point in mm is converted into a numeric value from 0 to 100, where 0=no fatigue and 100=maximum fatigue. Increasing numbers=increasing fatigue.

All treated participants

The VAS for Fatigue (VAS-F) consists of a 100 mm line, with 0 (No Fatigue) on 1 end and 100 (Extreme Fatigue) on the other end, which a participant marks to indicate how much fatigue he or she feels. The marked point in mm is converted into a numeric value from 0 to 100, where 0=no fatigue and 100=maximum fatigue. Increasing numbers=increasing fatigue.

All treated participants

The DAS28 is a continuous disease measure which is a composite of 4 variables: the 28 tender joint count, the 28 swollen joint count, ESR or CRP, and participant assessment of disease activity measure on a visual analogue scale. The DAS28 has numeric thresholds that define high disease activity (> 5.1), low disease activity (< 3.2) and remission (< 2.6). A clinically significant response= decrease in DAS28 score of >1.2 from baseline.

All treated participants. n=number of evaluable participants.

The DAS28 is a continuous disease measure which is a composite of 4 variables: the 28 tender joint count, the 28 swollen joint count, ESR or CRP, and participant assessment of disease activity measure on a visual analogue scale. The DAS28 has numeric thresholds that define high disease activity (> 5.1), low disease activity (< 3.2) and remission (< 2.6). Time-matched baseline (Day 0)values and post-baseline values were presented for each post-baseline visit, and represent only that cohort of participants with measurements available at that post-baseline visit.

All treated participants analyzed in the LT. N=the total number of participants analyzed, n=the number of participants at that time point with available measurements. Mean time-matched baseline values reflect changing n-values over time

The DAS28 is a continuous disease measure which is a composite of 4 variables: the 28 tender joint count, the 28 swollen joint count, ESR or CRP, and participant assessment of disease activity measure on a visual analogue scale. The DAS28 has numeric thresholds that define high disease activity (> 5.1), low disease activity (< 3.2) and remission (< 2.6). Time-matched mean change from BL= Post-BL value - time-matched BL value, where the time-matched BL value represents the mean BL(Day 0)value for only that cohort of participants with measurements available at that post-BL visit.

All treated participants analyzed in the LT. N=the total number of participants analyzed, n=the number of participants at that time point with available measurements. Mean time-matched baseline values reflect changing n-values over time

The mean number of tender joints was evaluated based on the number of tender joints in a standard 68 joint count. Time-matched baseline (Day 0) values and post-baseline values were presented for each post-baseline visit, and represent only that cohort of participants with measurements available at that post-baseline visit.

All treated participants analyzed in the LT. N=the total number of participants analyzed, n=the number of participants at that time point with available measurements. Mean time-matched baseline values reflect changing n-values over time

The mean number of tender joints was evaluated based on the number of tender joints in a standard 68 joint count. Time-matched mean change from baseline = Post-baseline value - time-matched baseline value, where the time-matched baseline value represents the mean baseline (Day 0) value for only that cohort of participants with measurements available at that post-baseline visit.

All treated participants analyzed in the LT. N=the total number of participants analyzed, n=the number of participants at that time point with available measurements. Mean time-matched baseline values reflect changing n-values over time

The mean number of swollen joints was evaluated based on the number of swollen joints in a standard 66 joint count. Time-matched baseline (Day 0) values and post-baseline values were presented for each post-baseline visit, and represent only that cohort of participants with measurements available at that post-baseline visit.

All treated participants analyzed in the LT. N=the total number of participants analyzed, n=the number of participants at that time point with available measurements. Mean time-matched baseline values reflect changing n-values over time

The mean number of swollen joints was evaluated based on the number of swollen joints in a standard 66 joint count. Time-matched mean change from baseline = Post-baseline value - time-matched baseline value, where the time-matched baseline value represents the mean baseline (Day 0) value for only that cohort of participants with measurements available at that post-baseline visit.

All treated participants analyzed in the LT. N=the total number of participants analyzed, n=the number of participants at that time point with available measurements. Mean time-matched baseline values reflect changing n-values over time

hs-CRP is a acute phase reactant protein that is a clinical marker for Rheumatoid Arthritis (RA). Levels of hs-CRP can be used to determine DAS28. Time-matched baseline (Day 0) values and post-baseline values were presented for each post-baseline visit, and represent only that cohort of participants with measurements available at that post-baseline visit.

All treated participants analyzed in the LT. N=the total number of participants analyzed, n=the number of participants at that time point with available measurements. Mean time-matched baseline values reflect changing n-values over time

hs-CRP is a acute phase reactant protein that is a clinical marker for Rheumatoid Arthritis (RA). Levels of hs-CRP can be used to determine DAS28. Time-matched mean change from baseline = Post-baseline value - time-matched baseline value, where the time-matched baseline value represents the mean baseline (Day 0) value for only that cohort of participants with measurements available at that post-baseline visit.

All treated participants analyzed in the LT. N=the total number of participants analyzed, n=the number of participants at that time point with available measurements. Mean time-matched baseline values reflect changing n-values over time

The VAS for Fatigue (VAS-F) consists of a 100 mm line, with 0 (No Fatigue) on 1 end and 100 (Extreme Fatigue) on the other end, which a participant marks to indicate how much fatigue he or she feels. The marked point in mm is converted into a numeric value from 0 to 100, where 0=no fatigue and 100=maximum fatigue. Increasing numbers=increasing fatigue. Time-matched baseline (Day 0) values and post-baseline values were presented for each post-baseline visit, and represent only that cohort of participants with measurements available at that post-baseline visit.

All treated participants analyzed in the LT. N=the total number of participants analyzed, n=the number of participants at that time point with available measurements. Mean time-matched baseline values reflect changing n-values over time

The VAS for Fatigue (VAS-F) consists of a 100 mm line, with 0 (No Fatigue) on 1 end and 100 (Extreme Fatigue) on the other end, which a participant marks to indicate how much fatigue he or she feels. The marked point in mm is converted into a numeric value from 0 to 100, where 0=no fatigue and 100=maximum fatigue. Increasing numbers=increasing fatigue. Time-matched mean change from BL = Post-BL value - time-matched BL value, where the time-matched BL value represents the mean BL (Day 0) value for only that cohort of participants with data available at that post-BL visit.

All treated participants analyzed in the LT. N=the total number of participants analyzed, n=the number of participants at that time point with available measurements. Mean time-matched baseline values reflect changing n-values over time

HAQ-DI includes 20 questions to assess physical functions in 8 domains:dressing, arising,eating,walking, hygiene, reach, grip and common activities. Domain questions are evaluated on a 4-point scale: 0=without any difficulty, 1=with some difficulty, 2=with much difficulty, and 3=unable to do. HAQ-DI= sum of worst scores in each domain divided by number of domains answered. HAQ-DI minimum=0 (no difficulty), max overall score=3(unable to do). Time-matched BL(Day 0)values presented for each post-BL visit represent only that cohort of participants with measurements available at that post-BL visit.

All treated participants analyzed in the LT. N=the total number of participants analyzed, n=the number of participants at that time point with available measurements. Mean time-matched baseline values reflect changing n-values over time

HAQ-DI includes 20 questions to assess physical functions in 8 domains:dressing, arising, eating, walking, hygiene, reach, grip and common activities. Domain questions are evaluated on a 4-point scale: 0=without any difficulty, 1=with some difficulty, 2=with much difficulty, and 3=unable to do. HAQ-DI= sum of worst scores in each domain divided by number of domains answered. HAQ-DI minimum=0(no difficulty), max overall score=3(unable to do). Post-BL values presented for each visit represent only that cohort of participants with measurements available at that post-BL visit.

All treated participants analyzed in the LT. N=the total number of participants analyzed, n=the number of participants at that time point with available measurements. Mean post-baseline values reflect changing n-values over time

HAQ-DI includes 20 questions assessing physical functions in 8 domains:dressing,arising,eating,walking,hygiene,reach,grip and common activities.Domain questions evaluated on 4-point scale: 0=without any difficulty,1=with some difficulty,2=with much difficulty,and 3=unable to do. HAQ-DI=sum of worst scores in each domain ÷ number of domains answered. HAQ-DI minimum=0 (no difficulty), max overall score=3(unable to do). Time-matched mean change from BL= Post-BL value - time-matched BL value. Time-matched BL value=mean BL (Day 0)value for only that cohort with data available at that post-BL visit.

All treated participants analyzed in the LT. N=the total number of participants analyzed, n=the number of participants at that time point with available measurements. Mean time-matched baseline values reflect changing n-values over time

HAQ-DI includes 20 questions to assess physical functions in 8 domains: dressing, arising, eating, walking, hygiene, reach, grip and common activities. The domain questions are evaluated on a 4-point scale: 0=without any difficulty, 1= with some difficulty, 2= with much difficulty, and 3= unable to do. HAQ-DI= sum of worst scores in each domain divided by the number of domains answered. HAQ-DI ranges from a minimum of 0 (no difficulty) to a maximum overall score of 3(unable to do). Clinically meaningful HAQ response=an improvement of at least 0.3 units from baseline in HAQ disability Index.

All treated participants. N=the total number of participants analyzed, n=the number of participants at that time point with available measurements.

SF-36 has 36 questions with 8 subscale scores and 2 summary scores (1) physical component summary=physical functioning, role-physical, bodily pain, and general health;(2) mental component summary=vitality,social functioning,role-emotional, and mental health. There is no total overall score; scoring is done for both subscores and summary scores. For subscores and summary scores, 0 =worst score and 100=best score. Time-matched BL (Day 0) values presented for each post-BL visit represent only that cohort of participants with measurements available at that post-BL visit

All treated participants analyzed in the LT. N=the total number of participants analyzed, n=the number of participants at that time point with available measurements. Mean time-matched baseline values reflect changing n-values over time

SF-36 measures health-related quality of life and has 36 questions with 8 subscale scores and 2 summary scores (1)physical component summary=physical functioning,role-physical,bodily pain,and general health; (2)mental component summary=vitality,social functioning,role-emotional,and mental health. There is no total overall score; scoring is done for both subscores and summary scores. For subscores and summary scores, 0=worst score and 100=best score. Post-BL values presented for each post-BL visit represent only that cohort of participants with measurements available at that post-BL visit.

All treated participants analyzed in the LT. N=the total number of participants analyzed, n=the number of participants at that time point with available measurements. Mean post-baseline values reflect changing n-values over time

SF-36 has 36 questions with 8 subscale scores and 2 summary scores (1)physical component summary=physical functioning,role-physical,bodily pain,and general health; (2)mental component summary=vitality,social functioning,role-emotional,and mental health. There is no total overall score; scoring is done for both subscores and summary scores. For subscores and summary scores, 0=worst score and 100=best score. Time-matched mean change from BL= Post-BL value - time-matched BL value. Time-matched BL value=mean BL (Day 0)value for only that cohort with data available at that post-baseline visit.

All treated participants analyzed in the LT. N=the total number of participants analyzed, n=the number of participants at that time point with available measurements. Mean time-matched baseline values reflect changing n-values over time

Serum samples from all treated adult participants with active rheumatoid arthritis (RA) were screened for the presence of drug-specific antibodies using ELISA. Immunogenicity was defined as the presence of a positive anti-abatacept or anti-CTLA4 antibody.

Treated participants with available serum samples for assay