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Table 1 Demographic and clinical characteristics of patients with rheumatoid arthritis by season in NinJa2016

From: Influence of seasonal changes on disease activity and distribution of affected joints in rheumatoid arthritis

  Total Spring Summer Fall Winter p-value#
  n = 12,839 n = 3250 n = 916 n = 1021 n = 7652  
Age (years) 65.2 ± 12.9 65.3 ± 13.1 65.5 ± 13.2 65.4 ± 12.8 65.1 ± 12.9 0.649
Female (%) 10,287 (80.1%) 2600 (80.0%) 746 (81.4%) 825 (80.8%) 6166 (79.9%) 0.680
Disease duration (years) 13.4 ± 11.0 13.4 ± 11.2 13.9 ± 11.4 14.2 ± 10.8 13.2 ± 10.9 0.026
Stage III–IV (%) 5917 (46.1%) 1456 (44.8%) 451 (49.2%) 481 (47.1%) 3529 (46.1%) 0.100
Class 3–4 (%) 2412 (18.8%) 613 (18.9%) 162 (17.7%) 153 (15.0%) 1484 (19.4%) 0.007
TJC 1.9 ± 4.2 2.0 ± 4.1 1.4 ± 3.4 1.6 ± 3.9 2.0 ± 4.3 < 0.001
SJC 1.4 ± 2.7 1.8 ± 3.3 1.4 ± 2.7 1.0 ± 2.3 1.3 ± 2.5 < 0.001
Pain (cm) 2.4 ± 2.3 2.4 ± 2.3 2.5 ± 2.3 2.3 ± 2.2 2.4 ± 2.2 0.463
PGA (cm) 2.5 ± 2.2 2.5 ± 2.2 2.6 ± 2.3 2.4 ± 2.2 2.5 ± 2.2 0.332
PhGA (cm) 1.5 ± 1.4 1.5 ± 1.5 1.4 ± 1.4 1.2 ± 1.3 1.5 ± 1.4 < 0.001
mHAQ 0.39 ± 0.61 0.41 ± 0.63 0.40 ± 0.62 0.38 ± 0.58 0.38 ± 0.61 0.126
CRP (mg/dL) 0.55 ± 1.21 0.56 ± 1.26 0.58 ± 1.14 0.55 ± 1.22 0.55 ± 1.20 0.854
  1. #Chi-square tests were used for categorical variables and analysis of variance tests for continuous variables. TJC tender joint count, SJC swollen joint count, PGA patient global assessment of RA disease activity, PhGA physician global assessment of RA disease activity, VAS visual analog scale, CRP C-reactive protein, mHAQ modified Health Assessment Questionnaire