Comparison of a Qualitative CMV PCR Kit Developed in a Laboratory Setting for Different Clinical Sample Types with the Reference Method

Background: The aim of this study was to evaluate the clinical performance of an in-house qualitative CMV real-time PCR assay for the detection of cytomegalovirus (CMV) DNA in various non-plasma clinical sample types, in comparison with a commercial ref-erence method. Methods: In this prospective comparative study, 186 clinical sam-ples—including bronchoalveolar lavage fluid (BALF), stool, urine, colonoscopic biopsy, amniotic fluid, and intraocular fluid—were analyzed. A total of 166 samples with valid results from both test systems were included in the inter-method comparison. CMV DNA was detected using an in-house qualitative PCR assay in parallel with the reference method (artus® CMV QS-RGQ kit). Clinical performance was assessed using positive percent agreement (PPA), negative percent agreement (NPA), overall percent agreement (OPA), Cohen’s kappa coefficient (κ), and predictive values, in accordance with the CLSI EP12-A2 guideline for qualitative diagnostic tests. Results: When all clinical samples were evaluated collectively, good overall agreement was observed between the developed test and the reference method (κ = 0.66). High PPA, NPA, and kappa values were obtained for stool, urine, and invasive samples. In BALF samples, inter-method agreement was mod-erate, and the high NPV supported clinical exclusion of CMV infection. Predictive values varied according to the CMV DNA positivity rate of the analyzed sample groups. Conclusions: The laboratory-developed qualitative CMV PCR assay showed good inter-method agreement with a commercial reference method and appears suitable for qualitative CMV detection in non-plasma clinical specimens under routine laboratory conditions. The findings reflect comparative performance rather than gold-standard-based diagnostic accuracy or viral load quantification.