Increased PCSK9 associated with cIMT in AS: A useful marker for subclinical atherosclerosis in patients with ankylosing spondylitis

This study aims to investigate the relationship between proprotein convertase subtilisin/ kexin type 9 (PCSK9) levels and subclinical atherosclerosis (SA) in patients with ankylosing spondylitis (AS). Patients and methods: Between January 2022 and March 2022, a total of 56 patients (33 males, 23 females; mean age: 37.8±9.3 years; range, 20 to 60 years) who were under regular follow-up in our clinic and fulfilled the criteria of the Modified New York Diagnostic Criteria for AS and American College of Rheumatology (ACR) for AS were included. Age-and sex-matched 56 healthy volunteers (25 males, 31 females; mean age: 38.4±8.2 years; range, 20 to 60 years) were also recruited as the control group. Demographic, clinical, and laboratory data were recorded. The PCSK9 level and carotid intima-media thickness (cIMT) were evaluated using appropriate methods. Results: The mean serum PCSK9 levels in AS patients (609.3±149.9 vs. 136.3±120.8 ng/mL, p<0.001) and the mean cIMT values (0.51±0.19 vs. 0.43±0.08 mm, p=0.003) were higher than healthy controls. In the multivariate stepwise regression analysis, there was an independent relationship between SA and PCSK9 (?=0.324, p=0.001). Additionally, there was an independent relationship between carotid plaque and PCSK9 (?=0.265, p=0.006). Based on the receiver operating characteristic curve analysis, the optimal PCSK9 cut-off value for plaque was 472.0 ng/mL, sensitivity 90.9%, specificity 65.0% (area under the curve [AUC]=0.759; 95% CI: 0.660-0.857, p=0.005). The optimal PCSK9 cut-off value for SA was 459.5 ng/mL, sensitivity 63.2%, specificity 63.0% (AUC=0.625; 95% CI: 0.512-0.739, p=0.031). Conclusion: Our study showed that serum PCSK9 levels in patients with AS were higher than that in healthy individuals and were associated with SA and arterial plaque formation.