Background Currently 3 sets of criteria are available for inflammatory back pain (IBP) in spondyloarthritis: Calin, Berlin and the ASAS criteria. The performances of these criterias in differentiating IBP in psoriatic arthritis (PsA) with chronic low back pain (CLBP) is currently not known.
Objectives The objective of this study was to assess performance of those 3 different criteria in a large multicentre PsA cohort.
Methods PsART (Psoriatic Arthritis Registry of Turkey) is a prospective, multicentre, nationwide study in Turkey on patients with PsA. Patients are consecutively recruited to this registry, if they are diagnosed as PsA, regardless of any other disease characteristics. In this registry, CLBP was defined as back pain lasting for more than 3 months. All relevant data for IBP according to Calin, Berlin and ASAS criteria for IBP were collected.
Results PsARTcohort included 746 PsA (35.3% male) patients. Overall, 170 of 746 (22.9%) of patients had CLBP. Median PsA duration was 47 (0-538) months. Patients with CLBP were more frequently males (44.4% vs 32.5%, p=0.004), more frequently had pitting (54.5% vs 41.3%, p=0.014) and less frequently had polyarthritis (26.3% vs 51.3%, p<0.001), and DIP joint involvement (7.0% vs 13.0%, p=0.031) than without CLBP. Patients with CLBP also had lower swollen joint counts (mean (SD):1.2 (2.5) vs 1.9 (3.0), p=0.015) and higher BASDAI values (4.6 (5.6) vs 3.5 (2.4), p=0.004). The positivity of each criteria for IBP was comparable for Berlin (n=147; 86.0%) and Calin criteria (n=148; 86.5%) and was lower with the ASAS criteria (n=114; 66.7%). The agreement rate of the Berlin and Calin criteria was 88.8% whereas this was lower between ASAS and Berlin (73.5%) as well as ASAS and Calin criteria (76.5%). When divided according to gender, the agreement of ASAS criteria vs Berlin and Calin criteria was lower only in females (ASAS vs Berlin: 61.7%; ASAS ve Calin: 71.3%, Calin vs Berlin 88.3%), whereas they performed equally in males (ASAS vs Berlin: 88.2%; ASAS ve Calin: 82.9%, Calin vs Berlin 89.5%) (Table 1).
Conclusions Both Calin and Berlin criteria seem to be effective questionaires for evaluating IBP in PsA patients with CLBP. However, ASAS criteria did not perform well particularly in female patients. For this reason, the gender distribution may be an important aspect to consider when recruting patients in clinical trials as well as guiding physicians in clinical practice.
Disclosure of Interest None declared