Oxidative stress and related factors in patients with ankylosing spondylitis

Ankylosing spondylitis (AS) is a chronic inflammatory disease of the spine and sacroiliac joints of unknown etiology. Recent studies have reported increased oxidative stress, which is implicated in the pathogenesis of a number of diseases, in AS. The purpose of this study was to investigate oxidative stress and related factors in AS.

Eighty-five patients with AS [36 (16-64) years; 65 male/20 female] and 56 healthy subjects [36 (21-63) years; 39 male/17 female] with no known cardiovascular risk factors were enrolled. Serum total oxidant status (TOS) and total anti-oxidant status (TAS) were studied. The Bath ankylosing spondylitis functional index (BASFI), Bath ankylosing spondylitis disease activity index (BASDAI), and Bath ankylosing spondylitis metrology index (BASMI) were calculated. A logistic regression model was used to identify the independent risk factors for TOS.

No differences were observed in terms of demographic characteristics, laboratory findings, or TAS concentrations between the patient and control groups. However, the serum TOS levels were significantly higher in the AS group than in the controls (p=0.003). The comparison of cases of active (BASDAI ≥4) and inactive AS revealed significantly higher TOS levels in the active disease group. The TOS and TAS concentrations did not differ between patients treated with biological agents and those treated with conventional agents. Correlation analysis yielded significant correlations between TOS and TAS, BASMI, BASFI, BASDAI, erythrocyte sedimentation rate (ESR), and high-sensitive C-reactive protein (hs-CRP) (p<0.05; r values ranged from 0.291 to 0.452) and a positive correlation between TAS and BASMI (p<0.05; r=0.344). Based on regression analysis, BASDAI, BASMI, and hs-CRP independently predicted the TOS levels [p<0.05, R²: 0.262, and standard error of the estimate (SEE): 10.96].

Oxidative stress levels were higher in patients with AS than in healthy subjects. Patients with active disease status had significantly higher oxidative stress than patients with inactive disease status and healthy controls. Treatment status has no effect on TOS, and BASMI, BASDAI, and hs-CRP are independent variables associated with TOS. The TAS levels were found to be associated with only BASMI.