DKK1 and systemic sclerosis: Dkk1 levels were significantly higher in the RA group (31.8 ± 17.4 pmol/L) compared to healthy controls (25.1 ± 17.2 pmol/L p<0.0001) and SSc (27.2 ± 12.4 pmol/L p<0.01) but not to PsA (27.3 ± 18.8 pmol/L, p 0,051) but were not different in PsA and SSc.