Dried blood spots for measurement of HIV-1 viral load (VL) in Argentina
Presented by María Lorena Vázquez (Argentina).
M.L. Vázquez, I. Zapiola, A. Gun, S. Gómez, A. Krolewiecki, O. Sued, S. Kaufman, P. Cahn
Fundación Huésped, Buenos Aires, Argentina
Background: Measurement of plasma HIV-RNA levels is standard of care for HIV+ patients in Argentina. Despite the existing laboratory network performing standard VL tests access to care is limited in remote areas. In order to simplify storage and shipment of samples, dried blood spots (DBS) specimens could be a good alternative. We evaluated the correlation between VL in paired samples of plasma and DBS in clinical samples from a reference center in Argentina.
Methods: From August 2009 through January 2010, parallel plasma and DBS specimens were collected from HIV-1 infected patients. DBS samples were stored at room temperature (19ºC to 38ºC) for seven days before testing. RNA extraction was done with the bioMérieux NucliSENS® miniMAGTM, and VL detection was done with bioMérieux NucliSENS® HIV-1 EasyQ assay. Statistical analysis: Student`s T-test or Mann-Whitney were used to determine differences and Spearman for correlations.
Results: Eighty two patients were enrolled. Paired plasma and DBS samples were tested. Plasma VL ranged from < 50 to >500000 copies/ml. Thirty one (37.8%) had undetectable VL in both types of samples. A strong correlation between methods was observed for the whole study population (R2=0.946, p< 0.001) and also for the samples with VL >50c/mL (n=51) (R2=0.848, p< 0.001). Among the undetectable samples(n=31) all were undetectable by DBS. We detected HIV-1 RNA in 33% (1 of 3), 67% (4 of 6) and 100% (42 of 42) of DBS specimens with corresponding plasma VL of 50-400, 401-3000, and ≥3000 copies/mL, respectively.
Conclusions: This study demonstrates that DBS provided HIV-1 VL results comparable to plasma. Since no false positive and only 4 false negative DBS results were found (all with VL < 3000 copies/mL), we conclude that DBS is a simple and cheap technique that may be considered as alternative to standard VL quantification in resource-limited settings.
Support: Fogarty AITRP Grant#5D43TW001037
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