Table 2. Factors associated with radiographic progression by the Sharp-van der Heijde score (total and by subscales): results of the bivariate analysis.

Variable	Erosion OR (p-value)	Joint space narrowing OR (p-value)	Total score OR (p-value)
Female sex	0.60 (0.286)	0.73 (0.502)	0.77 (0.569)
Age, per year	1.02 (0.165)	1.06 (0.002)	1.05 (0.003)
BMI, per unit	1.01 (0.881)	1.12 (0.026)	1.11 (0.039)
Disease duration, per year	0.99 (0.960)	0.94 (0.656)	0.99 (0.926)
Follow-up time T0-T1, per year	1.61 (0.005)	0.97 (0.832)	1.05 (0.712)
Positive RF	1.29 (0.596)	1.63 (0.279)	1.53 (0.330)
Positive ACPA	1.00 (0.992)	0.53 (0.148)	0.63 (0.289)
Mean DAS28-ESR between T0 and T1, per unit	1.99 (0.008)	1.41 (0.124)	1.88 (0.009)
Mean CRP between T0 and T1, per unit	1.16 (0.001)	1.08 (0.024)	1.20 (0.002)
OPG1, per pmol /L	0.94 (0.660)	1.04 (0.768)	1.02 (0.866)
DKK-1, per pmol /L	1.02 (0.352)	1.00 (0.959)	1.01 (0.548)
Accumulated glucocorticoid dose, per mg	1.00 (0.180)	1.00 (0.442)	1.00 (0.165)
Duration of synthetic DMARD therapy, per month	1.04 (0.007)	1.00 (0.983)	1.00 (0.724)
Anti-TNFα treatment	0.60 (0.209)	0.88 (0.570)	0.84 (0.417)
Antiresorptive or bone forming therapy	0.65 (0.256)	0.96 (0.737)	0.94 (0.636)

Abbreviations: ACPA = anti-citrullinated peptide antibodies; BMI = body mass index; CRP = C-reactive protein; DAS = disease activity score; DKK-1 = Dickkopf-related protein 1; DMARD = disease modifying anti-rheumatic drug; ESR = erythrocyte sedimentation rate; OPG = osteoprotegerin; OR = odds ratio; RF = rheumatoid factor; T0 = baseline visit; T1 = date of the second radiograph.