Retrospective Analysis of Spinal Radiographs for the Presence of Lumbosacral Transitional Vertebra in Patients with Axial Spondyloarthritis

Background/Aims: Axial spondyloarthritis (axSpA) is characterized by low back pain and sacroiliitis. It is important to exclude other causes of sacroiliitis before diagnosing axSpA. It was hypothesized that as one of the reasons for low back pain and sacroiliitis, the presence of lumbosacral transitional vertebra (LSTV) could lead to diagnostic confusion in axSpA. This study aimed to investigate the prevalence of LSTV in axSpA patients and whether LSTV caused any differences in disease characteristics compared to patients without LSTV. Materials and Methods: This was a retrospective study. Patients with axSpA who had available pelvic and lumbosacral spine radiographs and were over 18 years old were included. They were divided into 2 groups based on the presence of LSTV. These groups were compared in terms of age, sex, r-axSpA prevalence, biologic disease-modifying antirheumatic drugs (DMARDs) usage rates, and C-reactive protein (CRP)/erythrocyte sedimentation rate (ESR) levels. Likewise, patients with available diseasespecific clinical scores (Ankylosing Spondylitis Disease Activity Score with C-reactive protein, Bath Ankylosing Spondylitis Disease Activity Index, Bath Ankylosing Spondylitis Functional Index, Bath Ankylosing Spondylitis Metrology Index [BASMI]) and those using biologic DMARDs were also divided into 2 groups based on the presence of LSTV and were analyzed accordingly. Results: A total of 130 patients (82 males, 48 females) were included. Ninety-five patients were using biologic DMARDs and 41 patients had available disease-specific clinical scores (only 19 had BASMI scores). The rate of presence of LSTV was 25.4% (n = 33). The most common type was Castellvi type 1b (39.4%). No significant differences were observed between axSpA patients with and without LSTV in terms of age, sex, r-axSpA prevalence, biologic DMARD usage, CRP/ESR levels, the number of different biologic DMARDs they had used, disease activity, physical function, and mobility. Conclusion: No diagnostic concerns were identified in axSpA patients with LSTV in this study. However, due to the high rate reported in this study, it is recommended that patients with LSTV undergo a more thorough evaluation prior to an axSpA diagnosis, with a diagnosis approach extending beyond simply meeting a set number of the Assessment in SpondyloArthritis international Society (ASAS) criteria.