Ankylosing spondylitis (AS) is an inflammatory disease of unknown etiology characterized by chronic inflammation of the sacroiliac joints, spine and paraspinal soft tissues. Extra-articular manifestations such as anterior uveitis, inflammatory bowel disease, aortic valve disease and osteoporosis may also occur. Joint fusion and dysfunction may also be seen in progressive disease states. Inflammatory low back pain and morning stiffness are common symptoms of AS. These symptoms lead to limitation of activity and exacerbation of pain in the active phase of the disease. Therefore, evaluation of disease activity in AS is very important in terms of better understanding the pathophysiology of AS, predicting prognosis, and treatment. Currently, two non-specific inflammatory biomarkers, C-reactive protein (CRP) level and erythrocyte sedimentation rate (ESH), are frequently used to monitor disease activity of rheumatic diseases; however, these biomarkers have low sensitivity and specificity . Therefore, it is necessary to identify new indicators that more accurately reflect disease activity.

Recently, complete blood cell count parameters have emerged as useful biomarkers of many inflammatory diseases due to their availability and affordability. Previous studies have shown that platelet (PLT), neutrophil, lymphocyte cell counts, red blood distribution width (RDW), neutrophil-lymphocyte ratio (NLR) and platelet-lymphocyte ratio (PLO) are important indicators of systemic inflammation. In addition, it was found that SII (Systemic Inflammation Index), calculated by the formula "platelet count × neutrophil count/lymphocyte count", increased in active-stage AS patients compared to both the healthy control group and other AS patients in remission, and showed a positive correlation with disease activity .The systemic inflammatory response index (SIRI) is defined as "neutrophil count × monocytes/lymphocyte counts". It has been reported that SIRI can predict survival in various types of cancer, including pancreatic cancer, gallbladder cancer , oral squamous cell carcinoma , and cervical cancer. Again, SIRI can demonstrate disease activity in patients with rheumatoid arthritis (RA), It has been reported that it can predict the development of RA-related interstitial lung disease and tumor development .

Ankylosing spondylitis management strategies should be aimed at controlling disease activity, improving spinal mobility and functional status . Treatment usually includes the use of anti-inflammatory drugs to reduce pain and stiffness, and the use of disease-modifying drugs to try to stop or prevent disease progression. Patients are also advised to exercise to maintain the mobility of the spine and peripheral joints . Studies on this subject reveal that exercise is as important as drug therapy in the treatment of AS . Again, the importance of exercise in AS was emphasized in the clinical guidelines for the treatment of AS by ASAS (The Assesment in Ankylosing Spondylitis : Working Group) and EULAR (European League Against Rheumatism) . In addition to the effects of exercise on muscle strength, joint limitations, physical performance, endurance capacity and quality of life, its anti-inflammatory effects are also known.

In this study, it was aimed to evaluate the effect of exercise therapy on disease activity in AS patients with systemic inflammatory response index (SIRI) and systemic inflammation index (SII). There is not enough evidence in the literature that systemic inflammatory response index (SIRI) and systemic inflammation index (SII) can be used in the evaluation of disease activity in AS.