It is important to recognize inflammatory
back pain (
IBP) for an early diagnosis of
ankylosing spondylitis (AS). Assessment of Spondyloarthritis International Society (ASAS) has recently published new criteria set for diagnosing
IBP. In the present study, we evaluated the performance of the new ASAS
IBP criteria and to compare the performance of
IBP criteria sets in
axial spondyloarthritis (
axSpA) patients with and without radiographic
sacroiliitis. The study sample included a total of 274 patients with a diagnosis of
axSpA and 50 patients with a diagnosis of chronic (>3 months) mechanical
back pain (MBP). A face-to-face interview by using a standardized questionnaire addressing all the components of
IBP was performed. Data about
HLA-B27 status and
C-reactive protein levels were obtained from the patients' charts. There were significantly more male patients (P < 0.001) in the AS group (68.6 %) than in the non-radiographic
axSpA group (29.6 %) and also than in the MBP group (37.5 %). Among the criteria sets, the
Calin criteria showed the best sensitivity (91.2 %), and the Berlin criteria showed the best specificity (82.4 %) in differentiation of
IBP from MBP. If the morning stiffness item of the
Calin criteria was defined as lasting >30 min (
Calin 30), the specificity improved (72.9 %), but at a price of loss in sensitivity (82.4 %). In this study, new ASAS criteria for
IBP performed almost as good as but not better than the existing criteria sets. Performances of the criteria sets were quite comparable in the differentiation of
IBP from MBP in patients with and without radiographic
sacroiliitis.