early infant diagnosis of HIV and HIV RNA quantitation under field conditions in Tanzania

Lofgren and colleagues set out to assess technical and operational performance of a dried blood spot-based HIV-1 RNA service for remote healthcare facilities in a low-income country. A method comparison and operational evaluation of dried blood spot RNA against conventional tests for early infant diagnosis of HIV and HIV RNA quantitation under field conditions in Tanzania was conducted. Dried blood spots were prepared and plasma was frozen at -80 degrees C. Dried blood spots were mailed and plasma couriered to a central laboratory for testing using the Abbott m2000 system. Infant diagnosis dried blood spots were also tested for HIV-1 DNA by ROCHE COBAS AmpliPrep/COBAS TaqMan System. Results of dried blood spot RNA were compared with conventional tests; program performance was described. Among 176 infant diagnosis participants, using a threshold of at least 1000 copies/ml, sensitivity and specificity of dried blood spot versus plasma RNA were 1.00 and 0.99, and of dried blood spot RNA versus dried blood spot DNA were 0.97 and 1.00. Among 137 viral load monitoring participants, when plasma and dried blood spot RNA were compared, r value was 0.9709; r value was 0.9675 for at least 5000 copies/ml but was 0.7301 for less than 5000 copies/ml. The highest plasma RNA value at which dried blood spot RNA was not detected was 2084 copies/ml. Median (range) turnaround time from sample collection to result receipt at sites was 23 (4-69) days. The Tanzania mail service successfully transmitted all dried blood spot and results between sites and the central laboratory. Under program conditions in Tanzania, dried blood spot provided HIV-1 RNA results comparable to conventional methods to remote healthcare facilities. The authors propose dried blood spot RNA testing as an alternative to liquid plasma for HIV-1 RNA services in remote areas

In this study, the weekly cost of mailing dried blood spot specimens from healthcare facilities to the central laboratory was 6$ compared to a weekly ground transport of frozen plasma samples on dry ice of 515$. The excellent sensitivity and specificity results for paediatric HIV diagnosis reported for dried blood spot specimens here, combined with a reasonable turnaround time for results in the absence of electronic or fax communications, suggests that cost-effectiveness analyses should be quickly undertaken. The earlier that infants with HIV infection are diagnosed, the sooner they can be placed on treatment .