Table 1: Demographic and clinical characteristics of the studied patients.

ParameterAll patients ( )Knee synovitis responders ( )Knee synovitis nonresponders ( )

Age (years)43.3 ± 2.943.1 ± 3.244.7 ± 1.3
Age at disease onset (years)36.0 ± 2.636.7 ± 2.830.7 ± 1.3
Time interval between initiation of DMARDs and anti-TNF agent (months)11.4 ± 1.111.3 ± 1.311.9 ± 0.5
Male gender19 (70.4)16 (66.6)3 (100.0)
Disease subtype
 AS2 (7.4)2 (8.3)0 (0.0)
 PsA17 (63.0)14 (58.3)3 (100.0)
 unSpA8 (29.6)8 (33.3)0 (0.0)
HLA-B27*
 Positive4 (66.6)4 (66.6)
 Negative2 (33.4)2 (33.4)
Pattern of DMARD therapy before addition of anti-TNF agent
 Monotherapy21 (77.8)18 (75.0)3 (100.0)
 Combination6 (22.2)6 (25.0)0 (0.0)
Pattern of arthritis on anti-TNF initiation
 Monoarthritis8 (29.6)6 (25.0)2 (66.6)
 Oligoarthritis (inflamed joints <4)19 (70.4)18 (75.0)1 (33.4)
Current therapy
 Anti-TNF monotherapy14 (51.9)12 (50.0)2 (66.6)
 Anti-TNF + DMARD13 (48.1)12 (50.0)1 (33.4)

DMARDs: disease-modifying antirheumatic drugs; TNF: tumour necrosis factor; AS: ankylosing spondylitis; PsA: psoriatic arthritis; unSpA: undifferentiated spondyloarthritis.
*Included only the patients with known HLA-B27 status ( ).
Values given as mean ± standard error of the mean (SEM) or (%).