Association of neuropathic-like pain characteristics with clinical and radiographic features in patients with ankylosing spondylitis

Ankylosing spondylitis (AS) is a chronic, progressive, and inflammatory disorder and causes chronic back pain. It is not unusual for patients with AS to have symptoms similar to neuropathic pain. We aimed to investigate the neuropathic pain (NeP) component in patients with AS using the painDETECT questionnaire (PD-Q) and to assess the relation between NeP and the disease characteristics of AS. A single-center prospective study was performed, including 105 patients. Patients with AS completed three questionnaires: PD-Q, Beck Depression Inventory (BDI), and Euro Quality of Life (EQ-5D) questionnaires. Patients were classified into three groups according to the PD-Q scores: nociceptive pain (NoP) (score12), mixed pain (MP) (score 13-18), and NeP pain (score19). Fifteen patients (14.2%) were classified into the NeP group, 22 (21.0%) in the MP group, and 68 (64.8%) in the NoP group. The questionnaires and clinical and radiographic findings were analyzed. Patients with NeP and MP scored worse on the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI); BDI; modified Stoke Ankylosing Spondylitis Spine Score; pain-visual analog scale (VAS); and EQ-5L index and showed an increased prevalence of enthesitis and peripheral arthritis. There were no differences in objective inflammatory markers. PD-Q scores were positively correlated with pain-VAS, BASDAI, BDI, and inversely correlated with EQ-5D index. Age, BASDAI, presence of current enthesitis, and BDI score were independently associated with PD-Q scores. The findings showed that NeP component in AS was associated with age, high disease activity, presence of current enthesitis, and depression.