Clinical application value of different SCC-Ag reference intervals

This study aimed to establish a reference interval for squamous cell carcinoma antigen (SCC-Ag) that is tailored to a local population and to evaluate its clinical utility in comparison with the existing reference interval (≤1.5 μg/L) as recommended by the National Guide to Clinical Laboratory Procedures (4th Edition) and manufacturers. The study retrospectively analyzed data from 5251 healthy individuals to develop a locally applicable SCC-Ag reference interval, following guidelines from the CLSI-C28-A3c document and the WS/T 402-2012 Clinical Laboratory Test Project Reference Range. Subsequently, a cohort of 6191 healthy subjects was selected to evaluate the screening efficacy of the different SCC-Ag reference intervals. Additionally, 948 patients were included to assess the diagnostic performance of the 2 SCC-Ag reference intervals. The study proposes a reference interval for SCC-Ag of ≤2.2 μg/L. Utilizing this threshold, the positive rate among healthy subjects was 1.696%, significantly lower than the 7.931% rate based on the manufacturer-provided reference interval, indicating statistically significant differences. Furthermore, the sensitivity and negative predictive value of the newly proposed SCC-Ag reference interval were notably lower compared to the manufacturer's reference interval. However, the specificity, positive predictive value, Youden index, and overall accuracy of the proposed interval exceeded those of the existing manufacturer-provided interval. Thus, in the context of screening healthy individuals and diagnosing patients, the SCC-Ag reference interval established in this study demonstrates superiority over the current manufacturer-provided interval. Consequently, this proposed reference interval may offer more effective information for clinical decision-making.