HIV screening in blood donation: Diagnostic accuracy of chemiluminescence and rapid test compared to nucleic acid test in a large-scale Eastern India cohort.

Ensuring the safety of blood transfusion remains a global priority, with Human Immunodeficiency Virus (HIV) posing a significant risk. This study evaluates the prevalence of HIV and diagnostic performance of chemiluminescent immunoassay (CLIA), nucleic acid testing (NAT), and rapid diagnostic tests (RDTs) among blood donors in Eastern India. This cross-sectional study analyzed 65,586 blood donors screened over 6 years. All samples underwent initial HIV screening by CLIA, followed by NAT. CLIA-reactive samples (n = 163) were re-tested using both NAT and RDT for diagnostic concordance, with NAT serving as the reference standard. A random subset of CLIA non-reactive donors was also tested with NAT. Sensitivity, specificity, predictive values, accuracy, and Cohen's kappa were calculated. The prevalence of HIV was found to be 0.248 % using the chemiluminescent immunoassay (CLIA), 0.078 % with nucleic acid testing (NAT), and 0.076 % using rapid diagnostic tests (RDT). Key statistical findings are as follows Sensitivity: Specificity: Positive predictive value (PPV) NAT confirmed 51 HIV infections, including two window period cases missed by CLIA and RDT. High CLIA S/CO values (≥50) showed complete concordance across all platforms. HIV-reactive donors were predominantly male (95.1 %), aged 30-49 years, and unmarried. While CLIA is effective for high-throughput screening, its specificity declines in low S/CO ranges, necessitating confirmatory testing. RDTs provide excellent specificity and are valuable for confirmation. NAT remains indispensable for identifying early infections, especially in high-risk populations. Incorporating S/CO-based algorithms and NAT can enhance transfusion safety in resource-limited settings.