Association of obesity and metabolic syndrome with disease activity and spinal radiographic damage among patients with ankylosing spondylitis

Ankylosing Spondylitis (AS) is a chronic inflammatory disease characterized by pathological new bone formation and syndesmophyte formation that mainly affects the sacroiliac joints and spine. In this study; It was aimed to investigate the relationship between the presence of total and central obesity and metabolic syndrome and inflammation, disease activity, spinal mobility, functional status and spinal radiographic damage in patients with AS. 100 AS patients over the age of 18 who fulfilled the the 1984 Modified New York criteria and followed by the Physical Medicine and Rehabilitation Rheumatology outpatient clinic of Akdeniz University Medical Faculty Hospital were enrolled. Demographic data of the patients were recorded and clinical histories were taken. Anthropometry was measured to determine total (body mass index [BMI]) and central obesity (waist circumference [WC], waist-to-height ratio [WHtR],waist-to-hip ratio [WHpR)] ). The patients were evaluated according to BMI, WC,WHtR,WHpR and grouped according to the presence of obesity. Metabolic syndrome was defined according to the modified National Cholesterol Education Program Adult Treatment Panel III criteria and patients were grouped according to the presence of metabolic syndrome.Then, disease activity (AS Disease Activity Score [ASDAS], Bath AS Disease Activity Index [BASDAI]), physical function (Bath AS Functional Index [BASFI] ), spinal mobility (Bath AS Metrology Index [ BASMI]), and spinal radiographic damage (Modified Stoke AS Spine Score [m-SASSS]) were analyzed between groups. When the parameters showing the disease activity are evaluated; ASDAS-CRP was higher only in the obese group according to BMI (p=0.035); ASDAS-ESH was higher in the obese group according to BMI and WC (respectively p=0.023; p=0.032).BASMI and BASFI which Show spinal mobility and physical function status, were were significantly higher in the obese AS patients. (p=0,001). m-SASSS, in which the degree of spinal radiographic damage was evaluated,was statistically higher in obese patients by all indeces .Taking the above results together, central obesity had higher correlation values than BMI. BBO; BASMI, BASFI [r (p) values respectively; 0.434 (<0.001); 0.419 (<0.001)] and m-SASSS [r (p); 0.533 (<0.001)] was the central obesity index with the highest correlation. In addition, the presence of metabolic syndrome, which is associated with an increased risk of cardiovascular disease, was found to be associated with high BASFI, BASMI and m-SASSS values in AS patients. In our study, patients with AS with high BMI had higher CRP and disease activity scores (ASDAS). Obesity and metabolic syndrome were associated with poor physical function, decreased spinal mobility, and a high degree of spinal radiographic damage. According to the results, especially the presence of central obesity and metabolic syndrome seems to be a valuable factor in predicting functional status, spinal mobility and spinal radiographic damage in patients with AS. Clinicians and patients should be aware of the negative consequences of being obese and having metabolic syndrome with AS and consider it in their treatment plan.