Demographic, clinical, and laboratory features of Turkish patients with late onset ankylosing spondylitis.

Ankylosing spondylitis (AS) is a chronic inflammatory disease, which typically begins in early decades of life with primarily axial joints involvement. This disease rarely affects patients older than 50 years of age. The aim of this study was to compare and evaluate the demographic, clinical, and laboratory features of late onset and early onset AS patients who were followed up in a single rheumatology center. A total of 339 patients who have been diagnosed with AS according to modified New York criteria were included in the study. The patients whose initial symptoms were observed after 50 years of age were accepted as late onset AS. Out of 339 patients, 27 (7.9%) were diagnosed as late onset AS and 312 (92.3%) patients were evaluated as early onset AS. Of 27 late onset patients, 10 were male and 17 were female. Delay in the diagnosis was 5.8 years for early onset AS, while it was 3.8 years for late onset AS (p = 0.001). Higher levels of acute phase reactants and more methotrexate (MTX) use were detected in early onset AS patients compared to late onset AS (p = 0.001, p = 0.007, respectively). Statistically, there was no difference between these two groups, with regard to disease clinical activity indexes, anthropometric measurement parameters, uveitis and peripheral joint involvement. In this study, we showed that early and late onset AS patients may present with different clinical, genetic, and laboratory features. Late onset AS patients are characterized with lower human leukocyte antigen-B27 sequence, less inflammatory sign, delayed diagnosis, and less MTX and anti-tumor necrosis factor alpha drug usage.