Serum visfatin level and subfoveal choroidal thickness as independent associates of radiographic ankylosing spondylitis: a case-control study.

Adipocytokines have been implicated in the pathogenesis of ankylosing spondylitis (AS), although their exact role remains unclear. Optical coherence tomography (OCT) provides quantitative ocular measurements and may detect subclinical ocular changes in AS. This study evaluated serum adipocytokine levels and OCT findings in patients with radiographic AS and investigated possible correlations between these parameters. This cross-sectional study included 47 patients with radiographic AS diagnosed according to the modified New York criteria and 23 age- and sex-similar healthy controls. Serum visfatin, resistin, adiponectin, and fetuin-A levels were measured using enzyme-linked immunosorbent assay. OCT parameters, including retinal nerve fiber layer (RNFL), ganglion cell complex (GCC), macular thickness, and subfoveal choroidal thickness, were recorded using spectral-domain OCT. Multivariable logistic regression was performed to identify biomarkers independently associated with AS. Visfatin levels were higher (6.7 [3.9-14.0] vs. 4.5 [3.9-8.1] ng/mL, p<0.001), whereas fetuin-A levels were lower (3253 [1652-5565] vs 3724 [2204-5651] ng/mL, p=0.017) in patients with AS compared with controls. Adiponectin and resistin levels did not differ (both p>0.05). Subfoveal choroidal thickness was greater in AS patients (262 [124-387] vs. 197 [101-300] µm, p<0.001), whereas RNFL, GCC, and macular thickness were similar between the groups (all p>0.05). On multivariable analyses adjusted for age, sex, BMI, and CRP, visfatin (OR=3.894, 95% CI 1.378-11.004) and choroidal thickness (OR=1.047, 95% CI 1.007-1.088) remained independently associated with AS (both p<0.05). Conclusion: Elevated visfatin and increased choroidal thickness were independently associated with AS, suggesting subclinical ocular involvement even in the absence of uveitis. Prospective, larger studies are needed to confirm the clinical utility of these parameters.