Inflammatory back pain and associated disease conditions among patients with chronic low back pain in Bangladesh.

Aim: Inflammatory back pain (IBP) is the earliest symptom of axial and other forms of spondyloarthritis (SpA). However, there are no published data on prevalence of IBP among patients suffering from chronic low back pain (CLBP) in Bangladesh. In this study, we estimated the prevalence of IBP and the subtypes of SpA in a tertiary hospital in Bangladesh.

Methods: This 1 year cross-sectional study was conducted among 240 CLBP patients in a rheumatology outpatient clinic. Assessment of Spondyloarthritis International Society classification criteria of IBP and predefined recognized classification criteria were followed to define different subtypes of SpA. Means and standard deviations were reported for continuous variables. Descriptive and bi-variate analyses were accordingly performed.

Results: Of 240 CLBP patients, 60 (25%) had IBP and 180 (75%) had mechanical back pain (MBP). Among the 60 IBP patients, 52 (86.6%) had predominantly axial SpA (axSpA) and eight (13.4%) had predominantly peripheral spondyloarthritis. In the axSpA group, 49 (94.2%) had radiographic axSpA (rd-axSpA) also known as AS and three (5.8%) had non-radiographic axSpA (nr-axspA). AxSpA patients could be divided into eight (15.35%) with psoriasis, two (3.8%) with reactive arthritis and one patient (1.9%) had arthritis associated with inflammatory bowel disease. Fifty (83.3%) IBP and 73 (40.6%) MBP patients had age at onset of back pain < 40 years. Forty-two (70%) of the IBP and 100 (55.6%) of the MBP patients had normal body mass index. All these differences were statistically significant (P ≤ 0.0001).

Conclusions: Inflammatory back pain is common among patients presenting with CLBP. The commonest cause of IBP is AS, followed by PsA and nr-axSpA.