Table 1: Comparison in selected characteristics between patients with rheumatoid arthritis and healthy controls.

CharacteristicsCases with RA
Controls

Age (years), mean SD 0.191
Females (%)135 (98.5)96 (94.1)0.076
Serum IL-6 (pg/mL) <0.001

Quantitative variables are expressed as means standard deviations (SD) and qualitative variables as frequencies and percentages (%) as noted. Abbreviations: RA: rheumatoid arthritis, IL-6: interleukin 6.
Comparisons between means were performed with unpaired Student’s t-test. Comparisons between proportions were performed with Chi-squared test.