Results of an unannounced proficiency test for the quantification of hepatitis C virus (HCV) RNA in Shanghai, China

Sensitive and accurate hepatitis C virus (HCV) RNA quantification is essential for the management of chronic hepatitis C therapy. Currently, in Shanghai, China, many laboratories offer to quantify the HCV RNA level using various reverse transcription-polymerase chain reaction (rRT-PCR) assays, but the degree of proficiency may vary between them. The objective of this study was to realistically evaluate the performance of clinical laboratories for HCV RNA quantification by a new way of proficiency test program (unannounced inspection). Inactivated chimeric influenza viral particles (CIVP) encapsulating specific RNA sequences of HCV were prepared as positive samples. The sample panel, which consisted of two negative and eight positive samples with different concentrations of CIVP (25 IU/ml to 2.5×106 IU/ml), was distributed to 40 clinical laboratories for HCV RNA quantification. The results reported by the participating laboratories were compared and scored. It was found that 75 % (30/40) of the laboratories obtained an acceptable or better performance score, while the other 10 laboratories had room for improvement. Reported results for individual samples ranged from 125 IU/ml (minimum) to 6.0×104 IU/ml (maximum). The greatest variation was observed for samples with a relatively low concentration. Interlaboratory variability among replicate samples was significantly greater than intralaboratory variability (p < 0.05). Our results demonstrate that there is room for some laboratories to improve their performance in the quantification of HCV RNA in Shanghai. Additionally, this study underlines the importance of unannounced inspection for realistically monitoring the quality of diagnostic laboratories.