Analysis of the results of HIV-1, HCV and HBV viral loads of the SEIMC External Quality Control Program. Year 2018.

Background: Human immunodeficiency virus type 1 (HIV-1) and hepatitis B (HBV) and C virus (HCV) viral load determinations are among the most relevant markers for the follow-up of patients infected with these viruses. External quality control tools are crucial to ensure the accuracy of the results obtained by microbiology laboratories. This article summarised the results obtained from the 2018 SEIMC External Quality Control Programme for HIV-1, HCV, and HBV viral loads and HCV genotyping.

Methods And Results: In the HIV-1 program, a total of five standards were sent. One standard consisted of seronegative human plasma, while the remaining four contained plasma from three different viremic patients, in the range of 2-5 log copies/mL; two of these standards were identical, with the aim of determining repeatability. A significant proportion of the laboratories (28% on average) obtained values outside the accepted range (mean±0.25 log copies/mL), depending on the standard and on the method used for quantification. Repeatability was good, with most laboratories reporting results within the limits (D<0.5 log copies/mL). The HBV and HCV programme consisted of two standards with different viral load contents. Most of the participants, 87% in the case of HCV and 88% in the HBV, obtained all the results within the accepted range (mean±1.96 SD log UI/mL).

Conclusions: Data from this analysis reinforce the utility of proficiency programmes to ensure the quality of the results obtained by a particular laboratory. Due to the marked interlaboratory variability, it is advisable to use the same method and the same laboratory for patient follow-up.