Regulatory polymorphisms in extracellular matrix protease genes and susceptibility to rheumatoid arthritis: a case-control study

Table 1 Clinical characteristics of the rheumatoid arthritis patients included in the study

Characteristic	Value
Females (%)	421 (76.5)
Age of disease onset (median, IQR)	49 (37–57)
Follow-up (median, IQR)	13 (7–21)
Rheumatoid factor (%)^a	280 (62.5)
Bone erosions (%)^a	284 (64.8)
Extra-articular manifestations (%)^a	48 (11.2)
DMARDS use (%)^a	465 (94.9)
Tobacco use (%)^a	84 (18.4)

^aThis information was not available for a variable number of patients (from 10.9 for disease-modifying anti-rheumatic drugs (DMARDS) use to 21.8% for extra-articular manifestations). IQR, interquartile range.

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