Table 1

Baseline demographic and clinical characteristics of the study population

Normal gut histology (n=35)Acute inflammation (n=11)Chronic inflammation (n=16)
Age, years*36.4±9.032.8±8.328.9±7.0
Symptom duration, years†7.6±7.52.6±3.74.1±4.5
Male gender19 (54.3)4 (36.4)7 (43.8)
HLA-B27 (+)28 (80.0)10 (90.9)11 (68.8)
ModNY AS11 (31.4)3 (27.3)7 (43.8)
CRP, mg/dL0.4 (0.0–2.4)0.5 (0.0–5.4)0.6 (0–2.2)
BASDAI, numeric rating scale‡3.7 (0.4–7.1)6.0 (2.4–9.6)5.3 (0.4–6.6)
ASDAS2.3 (0.4–3.9)3.0 (1.2–5.4)2.8 (1.0–4.2)
  • In case of numeric variables, results are given as mean with SD or as median and range; dichotomous parameters are presented as frequencies with percentage.

  • *Patients with chronic gut inflammation were significantly younger compared with patients with normal gut histology (one-way ANOVA—independent samples t test).

  • †Patients with acute gut inflammation had a significant shorter symptom duration compared with patients with normal gut histology (Kruskal–Wallis and Mann–Whitney U test). These differences reflect the conclusion of our recently published prediction model for microscopic gut inflammation.2

  • ‡Although patients with normal gut histology had numerically lower values for BASDAI compared with patients with either acute or chronic gut lesions, this difference did not reach statistical significance (p=0.068).

  • ASDAS, Ankylosing Spondylitis Disease Activity Score; BASDAI, Bath Ankylosing Spondylitis Disease Activity Index; CRP, C-reactive protein; HLA, human leucocyte antigen; ModNY AS, ankylosing spondylitis according to modified New York criteria.