Serum clusterin in primary knee osteoarthritis patients and its relation with disease activity, severity, and ultrasonographic findings

Osteoarthritis (OA) represents the most prevalent form of arthritis worldwide and constitutes a significant cause of pain and disability in the geriatric population. OA is characterized by its complex, degenerative, and inflammatory nature, thereby contributing to escalating costs within global healthcare and social welfare systems. Clusterin (CLU), a secreted glycoprotein that was purified in 1983, is widely expressed in various organs and induced during cellular stress, inflammation, and apoptosis. The aim of the work was to determine serum level of CLU in patients with primary knee OA and study their correlations with disease activity, radiographic severity and ultrasound assessment. This cross-sectional study included 60 individuals. Participants were allocated to two distinct groups: 30 patients with primary KOA, diagnosed according to the 2016 revised ACR criteria, and 30 age- and sex-matched healthy controls. All participants underwent comprehensive history-taking, clinical examination, assessment of serum CLU concentrations, and imaging studies, including plain radiography and ultrasonography of the most affected knee joint. Our study showed a statistically significant difference in median CLU concentrations between cases and the control group (31.07 vs. 3.92, respectively; P < 0.001). Statistically significant positive correlation between CLU concentrations and disease duration (r = 0.384), BMI (r = 0.582), presence of deformity (r = 0.592), US grading (r = 0.931), US assessing osteophytes (r = 0.493), and X-ray grading (r = 0.771). Receiver operating characteristic curve analysis revealed an area under the curve of 0.957 (95% CI: 0.90–1.00), showing high diagnostic accuracy. The optimal cut-off point of ≥ 15.19 µg/mL provided 96.7% sensitivity, 90.0% specificity, and 93.3% total accuracy. Elevated Serum CLU concentrations in patients with primary KOA compared to healthy controls might reflect disease activity, radiographic severity, and ultrasonographic changes. The high sensitivity and specificity highlight its ability to distinguish OA patients from healthy individuals.