Clinical Value of IgG Antibody Test in Screening for Clonorchis sinensis Infection in High-Risk Population.

Background: In areas where C. sinensis is endemic, early screening and diagnosis of C. sinensis infection is crucial to prevent complications and interrupt the chain of transmission. Testing for C. sinensis IgG antibodies is frequently employed as a screening method for detecting the disease. However, its effectiveness in populations with a high risk remains to be determined. This study aimed to evaluate the clinical value of IgG antibody testing for screening C. sinensis infection in high-risk populations.

Methods: Between October 2020 and September 2023, 1,080 participants from Liuzhou Municipal Liutie Central Hospital patients were recruited. All participants underwent enzyme-linked immunosorbent assay (ELISA) to detect IgG antibodies and fecal examination for C. sinensis eggs using the Kato-Katz technique. The study examined the diagnostic concordance between two methods by using inter-rater agreement evaluation (Kappa). The diagnostic effectiveness of IgG antibodies was assessed comprehensively and across different gender and age categories, with the outcomes of the parasite egg test serving as the benchmark for diagnosis.

Results: Out of the 1,080 participants, 48.0% (518/1,080) tested positive for C. sinensis eggs, and 46.9% (506/1,080) tested positive for IgG antibodies. The Kappa value of the two methods' diagnostic concordance was 0.599. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of IgG antibody detection were 78.0%, 81.9%, 79.8%, 80.1%, and 80.0%, respectively, using C. sinensis eggs as the diagnostic criterion. Gender and age subgroup analyses revealed that diagnostic specificity, negative predictive value (NPV), and accuracy were higher in females than males (p = 0.003, 0.001, and 0.049, respectively). Sensitivity tended to decrease, while specificity tended to increase with age (p = 0.007 and 0.010, respectively).

Conclusions: The technique for detecting Clonorchiasis IgG antibodies has a certain degree of accuracy in diagnosing C. sinensis, but its sensitivity is low, particularly in mild infections and in the elderly population. Diagnosis requires a combination of other assays or further optimization of the technique's performance.