Table 1 Characteristics of the Swedish Biologics Register (ARTIS) cohort of RA patients treated with anti-TNF therapy from 1998 to 2006, overall and in subsets thereof
N (%) or mean (standard deviation)
All patients starting anti-TNFPatients starting 1998–2001Patients starting 2002–6Patients developing lymphoma
Overall6604 (100%)2492 (100%)4112 (100%)26 (100%)
Sex
    Men1630 (25%)627 (25%)1003 (24%)9 (35%)
    Women4974 (75%)1865 (75%)3109 (76%)17 (65%)
Mean age at entry, years55 (13)55 (13)55 (13)63 (11)
Year of first anti-TNF start,
    1998–200124922492 (100%)0 (0%)19 (71%)
    2002–318230 (0%)1823 (45%)5 (19%)
    2004–622890 (0%)2289 (55%)2 (7%)
RA duration at start, years10.6 (9.8)10.7 (9.5)10.5 (10)12 (10)
Swollen joints (28) at start9.5 (6.1)11 (6.2)8.7 (5.9)11 (7)
Tender joints (28) at start8.7 (6.7)9.7 (7.1)8.2 (6.5)10 (7.3)
DAS28 at start5.5 (1.3)5.8 (1.2)5.3 (1.4)5.7 (1.2)
HAQ at start1.4 (0.6)1.5 (0.6)1.3 (0.6)1.5 (1.2)
ESR at start37 (25)42 (26)34 (25)38 (25)
DMARD at start
    No1057 (16%)481 (19%)576 (14%)4 (15%)
    Methotrexate4563 (69%)1612 (65%)2951 (72%)15 (58%)
    Other than methotrexate697 (11%)266 (11%)431 (11%)5 (19%)
    No information287 (4%)133 (5.3%)154 (3.7%)2 (7%)
Oral steroids
    Yes3383 (51%)1223 (49%)2160 (52%)10 (38%)
    No2216 (33%)608 (24%)1608 (39%)8 (31%)
    No information1005 (15%)661 (27%)344 (8.4%)8 (30%)
Co-morbidity at treatment start
    Any infection746 (11%)244 (9.8%)502 (12%)4 (15%)
    Diabetes268 (4.1%)116 (4.7%)152 (3.7%)2 (8%)
    Any cardiovascular disease478 (7.2%)173 (6.9%)305 (7.4%)1 (4%)
    Any chronic obstructive pulmonary disease228 (3.5%)83 (3.3%)145 (3.5%)1 (4%)
    Joint replacement surgery1852 (28%)855 (34%)997 (25%)10 (38%)
Use of inpatient care up until treatment start
    No of all hospital discharges Q1/Q2/Q3/Q4 (%)*25/25/25/2522/23/25/2830/27/21/2012/23/34/30
    No of hospital RA discharges Q1/Q2/Q3/Q4 (%), mean25/25/25/25, 3.428/14/24/32, 4.649/16/17/17, 2.76/6/12/42, 5.1
    Mean no of days in hospital58 (93)72 (101)51 (87)99 (121)
  • *Q denotes quartiles as defined by the distribution among all 6404 patients. DAS28, disease activity score based on 28 joints; DMARD, disease-modifying antirheumatic drug; ESR, erythrocyte sedimentation rate; HAQ, health assessment questionnaire; RA, rheumatoid arthritis; TNF, tumour necrosis factor.