[Analysis of the results of the SEIMC External Quality Control Program for HIV-1 and HCV viral loads. Year 2008].
BACKGROUND
Human immunodeficiency virus type 1 (HIV-1) and hepatitis 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 results obtained by microbiology laboratories. This article summarized the results obtained from the 2008 SEIMC External Quality Control Program for HIV-1 and HCV viral loads.


RESULTS
In the HIV-1 program, a total of five standards were sent. One standard consisted in seronegative human plasma, while the remaining four contained plasma from 3 different viremic patients, in the range of 2-5 log(10) copies/mL; two of these standards were identical aiming to determine repeatability. The specificity was complete for all commercial methods, and no false positive results were reported by the participants. A significant proportion of the laboratories (24% on average) obtained values out of the accepted range (mean +/- 0.2 log(10) copies/mL), depending on the standard and on the method used for quantification. Repeatability was very good, with up to 95% of laboratories reporting results within the limits (D < 0.5 log(10) copias/mL). The HCV program consisted of two standards with different viral load contents. Most of the participants (88,7%) obtained results within the accepted range (mean +/- 1.96 SD log(10) UI/mL). Post-analytical errors due to mistranscription of the results were detected for HCV, but not for the HIV-1 program.


CONCLUSIONS
Data from this analysis reinforce the utility of proficiency programmes to ensure the quality of the results obtained by a particular laboratory, as well as the importance of the post-analytical phase on the overall quality. Due to the remarkable interlaboratory variability, it is advisable to use the same method and the same laboratory for patient follow up.
Mira
Nieves Orta
NO
Hospital Francesc de Borja, Gandía, Valencia, España.
Serrano
María del Remedio Guna
Mdel R
Martínez
José Carlos Latorre
JC
Ovies
María Rosario
MR
Pérez
José L
JL
Cardona
Concepción Gimeno
CG
D019411:Clinical Laboratory Techniques / Q000592:standards*; D003951:Diagnostic Errors / Q000517:prevention & control / Q000706:statistics & numerical data; D005188:False Negative Reactions; D015658:HIV Infections / Q000097:blood / Q000821:virology; D015497:HIV-1 / Q000302:isolation & purification*; D016174:Hepacivirus / Q000302:isolation & purification*; D006526:Hepatitis C / Q000097:blood / Q000821:virology; D006801:Humans; D055552:Infectious Disease Medicine / Q000458:organization & administration* / Q000592:standards; D007753:Laboratories / Q000592:standards* / Q000706:statistics & numerical data; D008829:Microbiology / Q000458:organization & administration* / Q000592:standards; D015397:Program Evaluation; D011785:Quality Assurance, Health Care; D011786:Quality Control; D015203:Reproducibility of Results; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012680:Sensitivity and Specificity; D013030:Spain; D019562:Viral Load; D014766:Viremia / Q000821:virology