Table 1

Variables used in the marginal structural weight models

VariableVariable type
 Age at symptom onset and at each assessmentDecades
 Months from symptom onset at baseline and at each assessmentTertiles by assessment
 Smoking status at each assessmentNever smoked/Stopped ≥ 10 years before assessment/ Stopped <10 years before assessment/Current smoker
Serological and genetic
 Anti-CCP status at baseline (Axis-Shield DIASTAT kit)<5 U/ml/≥5 U/ml
 CRP category at baseline and assessment (end point immunoturbidimetric agglutination)≤ 10 mg/l/>10 mg/l
 RF status at baseline and by assessment (latex agglutination)<1:40/ ≥1:40
 Number of copies of the SE0/1/2
 Homozygous for SENo/Yes
Disease activity and severity
 DAS28 score at baseline and assessment
 ACR criteria for RA cross-sectional at baseline and cumulative at assessmentNot met/Met
 Number of swollen, tender and (both tender and swollen) joints at baseline and assessmentTertiles by assessment
 Presence of nodules at baseline and assessmentNo/Yes
 HAQ group at baseline and assessment<1/≥1 to <2/≥2
 Presence of erosions by assessmentNo/Yes
 Larsen score by assessmentTertiles by assessment
Physical Component Score (PCS) of SF36
 Mental Component Score (MCS) of SF36
 Diagnosed with any of 14 defined comorbidities by assessmentNo/Yes
Treatment and hospital attendance
 Attended/referred to hospital since last assessmentNo/Yes
 Treated with SSZ, MTX, other DMARDs and steroids at baseline and by assessmentNo/Yes
 Ceased treatment since last assessment or by assessment due to inefficacy or adverse eventNo/Yes
 Remission by baseline and assessmentNo/Yes
  • ACR, American College of Rheumatology; anti-CCP, anti-cyclic citrullinated peptide; CRP, C-reactive protein; DAS28, 28 joint count Disease Activity Score; DMARDs, disease-modifying antirheumatic drugs; HAQ, Health Assessment Questionnaire; MCS, Mental Component Score; MTX, methotrexate; PCS, Physical Component Score; RA, rheumatoid arthritis; RF, rheumatoid factor; SE, shared epitope; SSZ, sulfasalazine.