Table 2

Sociodemographic and laboratory characteristics of the PsSpA (n=118), AS (n=157) and pPsA (n=127) cases (numerical variables)

 PsSpAASpPsAAS versus PsSpApPsA versus PsSpA
Median (IQR)Median (IQR)Median (IQR)Mean diffMean diff
Mean (SD)Mean (SD)Mean (SD)(95% CI)p Value(95% CI)p Value
Age at (years)
 Clinical assessment58.09 (11.42)53.44 (13.61)58.13 (11.71)−4.63 (−7.68 to −1.58)0.003*−0.03 (−2.95 to 2.88)0.98*
 Arthritis onset31.27 (21.06, 46.24)20.00 (16.00, 26.00)37.98 (28.37, 46.32)0.01†
 Arthritis diagnosis35.99 (27.27, 52.00)29.00 (23.00, 38.00)39.99 (29.70, 48.73)0.33†
 Psoriasis onset31.50 (17.50, 41.50)27.00 (16.00, 14.00)0.68†
 Psoriasis diagnosis33.00 (19.00, 43.00)30.00 (19.00, 46.00)0.20†
Disease duration at (years)
 Recent axial radiograph15.50 (7.00, 26.00)19.00 (10.00, 29.00)13.00 (6.00, 23.00)0.13†0.41†
 Clinical assessment18.00 (9.00, 27.00)22.00 (10.00, 31.00)15.00 (7.00, 26.00)0.13†0.34†
 C reactive protein3 (2, 7)4 (1, 10)2 (0, 5)1.06 (0.99 to 1.12)0.07‡0.79 (0.74 to 0.84)<0.0001‡
 Body mass index (BMI)29.52 (5.16)29.92 (4.96)29.69 (5.36)−1.60 (−2.21 to −0.84)0.01*−0.18 (−0.62 to 0.51)0.81*
  • *Two-tailed Student's t-test.

  • †Mann-Whitney U test.

  • ‡Poisson regression (adjusted for: sex, age, disease duration, anti-TNF use ever, synthetic DMARD use ever, and BMI).

  • Anti-TNF, antitumour necrosis factor; AS, ankylosing spondylitis; DMARD, disease modifying antirheumatic drug; Mean diff, mean difference; pPsA, peripheral psoriatic arthritis; PsSpA, psoriatic spondyloarthropathy.