Background Inflammatory back pain (IBP) is the first and most common symptom of ankylosing spondylitis (AS). In daily rheumatology practice, we noticed that a considerable number of male patients with AS did not experience IBP.

Objectives The aim of this study was to investigate the frequency of IBP in male AS patients and compare it with that in female AS patients.

Methods The study included patients with AS. A face-to-face interview was performed with all the participants by using a standardized questionnaire addressing all the components of IBP. IBP was defined based on the Berlin criteria which have been previously reported as having the highest specificity among all the current IBP criteria sets. To evaluate the specificity of the Berlin criteria in each of the male and female AS patient groups, 63 patients with chronic (>3 months) mechanical back pain (MBP) were also enrolled in the study.

Results There were 181 patients with AS (124 male, mean age: 41.2 yrs; 57 female, mean age: 44.6 yrs) who fulfilled the modified New York criteria and 63 patients with chronic MBP (28 male, mean age: 47.2 yrs; 35 female, mean age: 43.5 yrs). There were no significant differences in mean ages and mean education durations between males and females in both AS and MBP groups.

The prevalence of IBP was found to be 87.7% in female patients with AS and 66.1% in male patients with AS based on the Berlin criteria (p=0.002). The specificity of the criteria was determined to be high both in females (85.7%) and males (89.2%).

Female patients with AS had higher BASDAI levels than males (p=0.048) but no difference was determined in BASFI and serum CRP levels between females and males.

Conclusions The results of this study suggested that a considerable proportion of male patients with AS did not experience IBP although they had similar CRP levels compared with females.

Disclosure of Interest None declared