title: High correlation of human immunodeficiency virus type-1 viral load measured in dried-blood spot samples and in plasma under different storage conditions.
abstract: BACKGROUND
  To measure HIV-1 RNA concentration requires venous extraction of blood, use of RNAase-free materials, and transport in a cold chain, which makes difficult the management of samples in developing countries. We evaluated the utility of the determination of HIV-1 RNA concentration in blood samples dried on filter paper (DBS) and subjected to different conditions, as contrasted with determination in plasma.
  
  
  METHODS
  HIV-1 RNA concentration was determined in HIV-infected patients in DBS and in plasma samples. Samples were subjected to the following: DBS were stored at 4, 22, and 37 degrees C for 1, 3, and 7 days; samples from patients from four regions of Mexico were mailed to a reference laboratory; DBS were sent under environmental conditions; and plasma samples were sent frozen. HIV-1 RNA concentrations were determined by NucliSens in DBS and by Amplicor test in plasma.
  
  
  RESULTS
  HIV-1 RNA concentration determined in DBS subjected to different temperatures and times had a significant correlation (r=0.99) with those obtained in plasma. When compared with values in plasma, Kappa agreement coefficients of values in DBS stored for 7 days at 4, 22, and 37 degrees C were 0.98, 0.83, and 0.94, respectively. Quantification of HIV-1 RNA in 108 DBS mailed from remote areas with different climates demonstrated significant correlation with those obtained in plasma (r=0.95; p <0.001).
  
  
  CONCLUSIONS
  DBS is a simple and reliable method to measure HIV-1 RNA concentration, especially when samples are mailed from remote areas to a reference center. This collection method is an economic and suitable alternative for use in developing countries.
authors.affiliation: Unidad de Investigación Médica en Enfermedades Infecciosas, Instituto Mexicano del Seguro Social (IMSS), Mexico City, Mexico. mtalvarezm@yahoo.com.mx
authors.forename: Ma Tereza
authors.initials: MT
authors.lastname: Alvarez-Muñoz
authors.forename: Silvia
authors.initials: S
authors.lastname: Zaragoza-Rodríguez
authors.forename: Othón
authors.initials: O
authors.lastname: Rojas-Montes
authors.forename: Gerardo
authors.initials: G
authors.lastname: Palacios-Saucedo
authors.forename: Guillermo
authors.initials: G
authors.lastname: Vázquez-Rosales
authors.forename: Alejandro
authors.initials: A
authors.lastname: Gómez-Delgado
authors.forename: Javier
authors.initials: J
authors.lastname: Torres
authors.forename: Onofre
authors.initials: O
authors.lastname: Muñoz
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D005260:Female; D015658:HIV Infections / Q000821:virology; D015497:HIV-1 / Q000378:metabolism*; D006400:Hematocrit; D006801:Humans; D007124:Immunoenzyme Techniques; D008297:Male; D008800:Mexico; D008875:Middle Aged; D012313:RNA / Q000737:chemistry / Q000378:metabolism; D012367:RNA, Viral / Q000737:chemistry; D015203:Reproducibility of Results; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012260:Ribonucleases / Q000378:metabolism; D013048:Specimen Handling; D013696:Temperature; D013997:Time Factors; D019562:Viral Load
chemical_list: D012367:RNA, Viral; D012313:RNA; D012260:Ribonucleases