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Table 1 Characteristics of patients in routine and inception cohorts

From: Acute phase reactants add little to composite disease activity indices for rheumatoid arthritis: validation of a clinical activity score

Characteristic Routine cohort (cross-sectional) Inception cohort (longitudinal)
Patients (n) 767 106
Age (years; mean ± SD) 54.1 ± 14.9 50.5 ± 15.6
Sex (% female) 79.9 75.2
Rheumatoid factor (% positive) 55.3 78.1
Disease duration at baseline (mean ± SD) 8.1 ± 10.6 years 11.5 ± 12.5 weeks
Duration of follow up (years; mean ± SD; range) - 3.2 ± 1.3; 1–7.25
Disease activity characteristics (median [1st;3rd quartile]) At cross-section At baseline
Swollen joint count (0–28) 3 (1;7) 7 (4;13)
Tender joint count (0–28) 2 (0;6) 8 (3;16)
ESR (mm; normal <20) 23 (14;55) 49 (24;70)
CRP (mg/dl; normal <1.0) 1.1 (0.5;2.7) 5.1 (1.9;17.0)
Patient assessment of pain (mm; 0–100) 37 (19;53) 50 (32;66)
Patient global assessment of activity (mm; 0–100) 37 (18;58) 51 (33;66)
Evaluator global assessment of activity (mm; 0–100) 34 (19;49) 44 (31;58)
HAQ (0–3) 0.875 (0.25;1.5) 0.75 (0;1.5)
Larsen score - 1 (0;7)
Completeness of data for analysis   
Cross-sectional correlation between composite indices (n [%]) 767/767 (100)a 105/106 (99.1%)b
Cross-sectional correlation with HAQ scores (n [%]) 720/767 (93.9) 104/106 (98.1)b
Discriminant validity, 1-year follow up (n [%]) - 91/100 (91.0%)
Construct validity, 3-year follow upc (n [%]) - 56/80 (70.0%)
  1. aCompleteness of data was the prerequisite for inclusion. bUsed to validate the results from the cross-sectional analyses in the routine cohort. cIncluding complete radiological data. CRP, C-reactive protein; ESR, erythrocyte sedimentation rate; HAQ, Health Assessment Questionnaire; SD, standard deviation.