AIDS and Behavior

, Volume 19, Issue 10, pp 1818–1827 | Cite as

Assessment of Contamination and Misclassification Biases in a Randomized Controlled Trial of a Social Network Peer Education Intervention to Reduce HIV risk Behaviors Among Drug Users and Risk Partners in Philadelphia, PA and Chiang Mai, Thailand

  • Nicole Simmons
  • Deborah Donnell
  • San-san Ou
  • David D. Celentano
  • Apinun Aramrattana
  • Annet Davis-Vogel
  • David Metzger
  • Carl LatkinEmail author
Original Paper


Controlled trials of HIV prevention and care interventions are susceptible to contamination. In a randomized controlled trial of a social network peer education intervention among people who inject drugs and their risk partners in Philadelphia, PA and Chiang Mai, Thailand, we tested a contamination measure based on recall of intervention terms. We assessed the recall of test, negative and positive control terms among intervention and control arm participants and compared the relative odds of recall of test versus negative control terms between study arms. The contamination measures showed good discriminant ability among participants in Chiang Mai. In Philadelphia there was no evidence of contamination and little evidence of diffusion. In Chiang Mai there was strong evidence of diffusion and contamination. Network structure and peer education in Chiang Mai likely led to contamination. Recall of intervention materials can be a useful method to detect contamination in experimental interventions.


Contamination HIV Prevention Injection drug use Social networks Diffusion 


Ensayos controlados de intervenciones de prevención y atención del VIH son susceptibles a la contaminación. En un ensayo controlado aleatorio de una red social intervención de educación inter pares entre personas que se inyectan drogas y sus socios de riesgo en Filadelfia, PA y Chiang Mai, Tailandia, probamos una medida contaminación basada en el recuerdo de los términos de intervención. Se evaluó el recuerdo de la prueba, las condiciones de control negativos y positivos entre los participantes de la intervención y del brazo de control y se compararon las probabilidades relativas (OR) de retirada de prueba vs. términos de control negativo entre los brazos del estudio. Las medidas de contaminación mostraron buena capacidad discriminante entre los participantes en Chiang Mai. En Filadelfia no había pruebas de contaminación y poca evidencia de la difusión. En Chiang Mai hubo una fuerte evidencia de la difusión y la contaminación. Estructura de la red y la educación entre pares en Chiang Mai probablemente llevaron a la contaminación. Llamada a revisión de materiales de intervención puede ser un método útil para detectar la contaminación en las intervenciones experimentales.



This study was supported by the HIV Prevention Trials Network (HPTN) and sponsored by the National Institute of Allergy and Infectious Diseases, National Institute of Child Health and Human Development, National Institute on Drug Abuse, National Institute of Mental Health, and Office of AIDS Research, of the National Institutes of Health, U.S. Department of Health and Human Services, through cooperative agreement U01-AI-46749 with Family Health International, U01-AI-46702 with Fred Hutchinson Cancer Research Center, U01-AI-47984 with Johns Hopkins University, and U01-AI-48014 with the University of Pennsylvania. The authors gratefully acknowledge the contributions of Thira Sirisanthana MD, Tasanai Vongchak RN MPH, Namtip Srirak PhD, Antika Wongthanee, Kanokporn Wiboonnatakul, Lara Siree Johnson, and Chatsuda Auchieng.


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Copyright information

© Springer Science+Business Media New York 2015

Authors and Affiliations

  • Nicole Simmons
    • 1
  • Deborah Donnell
    • 2
  • San-san Ou
    • 2
  • David D. Celentano
    • 3
  • Apinun Aramrattana
    • 4
  • Annet Davis-Vogel
    • 5
  • David Metzger
    • 5
  • Carl Latkin
    • 6
  1. 1.Department of International HealthJohns Hopkins Bloomberg School of Public HealthBaltimoreUSA
  2. 2.Statistical Center for HIV/AIDS Research and Prevention (SCHARP)SeattleUSA
  3. 3.Department of EpidemiologyJohns Hopkins Bloomberg School of Public HealthBaltimoreUSA
  4. 4.Research Institute for Health SciencesChiang Mai UniversityChiang MaiThailand
  5. 5.Department of PsychiatryUniversity of PennsylvaniaPhiladelphiaUSA
  6. 6.Department of HealthBehavior and Society, Johns Hopkins Bloomberg School of Public HealthBaltimoreUSA

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