title: Monitoring of HIV treatment in seven countries in the WHO Region of the Americas.
abstract: OBJECTIVE
  To determine the prevalence of adequate monitoring and the costs of measuring CD4+ T-lymphocytes (CD4+ cell) and human immunodeficiency virus (HIV) viral load in people receiving antiretroviral therapy (ART) in seven countries in the WHO Region of the Americas.
  
  
  METHODS
  We obtained retrospective, longitudinal data for 14 476 adults who started a first ART regimen at seven HIV clinics in Argentina, Brazil, Chile, Haiti, Honduras, Mexico and Peru between 2000 and 2011. We estimated the proportion of 180-day periods with adequate monitoring, which we defined as at least one CD4+ cell count and one viral load measurement. Factors associated with adequate monitoring were analysed using regression methods. The costs of the tests were estimated.
  
  
  RESULTS
  The median follow-up time was 50.4 months; the proportion of 180-day periods with adequate CD4+ cell counts was 69% while the proportion with adequate monitoring was 62%. Adequate monitoring was more likely in participants who were older, who started ART more recently, whose first regimen included a non-nucleoside reverse transcriptase inhibitor or who had a CD4+ cell count less than 200 cells/µl at ART initiation. The cost of one CD4+ cell count ranged from 7.37 United States dollars (US$) in Argentina to US$ 64.09 in Chile; the cost of one viral load measurement ranged from US$ 20.34 in Brazil to US$ 186.28 in Haiti.
  
  
  CONCLUSIONS
  In HIV-infected participants receiving ART in the WHO Region of the Americas, CD4+ cell count and viral load monitoring was often carried out less frequently than regional guidelines recommend. The laboratory costs of monitoring varied greatly.
authors.affiliation: Clínica de Inmuno-Infectología, Departamento de Infectología, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Calle Vasco de Quiroga 15, Colonia Belisario Domínguez Sección XVI, Delegación Tlalpan, México Distrito Federal, CP 14080, Mexico .
authors.forename: Pablo F
authors.initials: PF
authors.lastname: Belaunzarán-Zamudio
authors.affiliation: Clínica de Inmuno-Infectología, Departamento de Infectología, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Calle Vasco de Quiroga 15, Colonia Belisario Domínguez Sección XVI, Delegación Tlalpan, México Distrito Federal, CP 14080, Mexico .
authors.forename: Yanink N
authors.initials: YN
authors.lastname: Caro-Vega
authors.affiliation: Department of Biostatistics, Vanderbilt University, Nashville, United States of America (USA).
authors.forename: Bryan E
authors.initials: BE
authors.lastname: Shepherd
authors.affiliation: Clínica de Inmuno-Infectología, Departamento de Infectología, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Calle Vasco de Quiroga 15, Colonia Belisario Domínguez Sección XVI, Delegación Tlalpan, México Distrito Federal, CP 14080, Mexico .
authors.forename: Brenda E
authors.initials: BE
authors.lastname: Crabtree-Ramírez
authors.affiliation: Instituto de Pesquisa Clínica Evandro Chagas, Fundacão Oswaldo Cruz, Rio de Janeiro, Brazil .
authors.forename: Paula M
authors.initials: PM
authors.lastname: Luz
authors.affiliation: Instituto de Pesquisa Clínica Evandro Chagas, Fundacão Oswaldo Cruz, Rio de Janeiro, Brazil .
authors.forename: Beatriz
authors.initials: B
authors.lastname: Grinsztejn
authors.affiliation: Fundación Huésped, Buenos Aires, Argentina .
authors.forename: Carina
authors.initials: C
authors.lastname: Cesar
authors.affiliation: Fundación Huésped, Buenos Aires, Argentina .
authors.forename: Pedro
authors.initials: P
authors.lastname: Cahn
authors.affiliation: Fundación Arriarán, Universidad de Chile, Santiago, Chile .
authors.forename: Claudia
authors.initials: C
authors.lastname: Cortés
authors.affiliation: Fundación Arriarán, Universidad de Chile, Santiago, Chile .
authors.forename: Marcelo
authors.initials: M
authors.lastname: Wolff
authors.affiliation: Le Groupe Haitien d'Etude du Sarcome de Kaposi et des Infections Opportunistes, Port-au-Prince, Haiti .
authors.forename: Jean W
authors.initials: JW
authors.lastname: Pape
authors.affiliation: Instituto Hondureño de Seguridad Social and Hospital Escuela, Tegucigalpa, Honduras .
authors.forename: Denis
authors.initials: D
authors.lastname: Padgett
authors.affiliation: Instituto de Medicina Tropical Alexander von Humboldt, Lima, Peru .
authors.forename: Eduardo
authors.initials: E
authors.lastname: Gotuzzo
authors.affiliation: Department of Medicine, Vanderbilt University, Nashville, USA .
authors.forename: Catherine
authors.initials: C
authors.lastname: McGowan
authors.affiliation: Clínica de Inmuno-Infectología, Departamento de Infectología, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Calle Vasco de Quiroga 15, Colonia Belisario Domínguez Sección XVI, Delegación Tlalpan, México Distrito Federal, CP 14080, Mexico .
authors.forename: Juan G
authors.initials: JG
authors.lastname: Sierra-Madero
mesh_terms: D000328:Adult; D044966:Anti-Retroviral Agents / Q000191:economics* / Q000627:therapeutic use*; D018791:CD4 Lymphocyte Count / Q000191:economics*; D005260:Female; D019983:Guideline Adherence; D015658:HIV Infections / Q000097:blood / Q000188:drug therapy* / Q000191:economics*; D006205:Haiti; D006721:Honduras; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008800:Mexico; D008875:Middle Aged; D016012:Poisson Distribution; D013020:South America; D019562:Viral Load; D014944:World Health Organization; D055815:Young Adult
chemical_list: D044966:Anti-Retroviral Agents