Canadian Journal of Public Health

, Volume 97, Issue 1, pp 72–75 | Cite as

CRTs — Cluster Randomized Trials or “Courting Real Troubles”

Challenges of Running a CRT in Rural Gujarat, India
  • M. Kent RansonEmail author
  • Tara Sinha
  • Saul S. Morris
  • Anne J. Mills


This paper addresses the logistical challenges of implementing public health interventions in the setting of cluster randomized trials (CRTs), drawing on the experience of carrying out a CRT within a community-based health insurance (CBHI) scheme in rural India. Our CRT is seeking to improve the equity impact — i.e., reduce the differential in claims submission for hospitalization between poor and less poor — of this CBHI in rural areas. Five main challenges are identified and discussed: 1) assigning control clusters, 2) blinding, 3) implementing interventions simultaneously, 4) minimizing leakage, and 5) piggy-backing on a changing scheme. These challenges are not likely to be unique to low-income settings, although the fifth challenge is particularly likely when working with relatively small and resource-constrained programs. While compromises to methodological best-practice may reduce internal validity, they make the intervention more ‘real’, and potentially more applicable, to other programs and settings. Further, careful documentation of compromises allows them to be considered in the final analysis.

MeSH terms

Health insurance India nongovernmental organizations randomized controlled trials 


Cet article traite des difficultés logistiques rencontrées dans la mise en oeuvre d’interventions de santé publique dans le cadre d’essais contrôlés randomisés par grappes. Il tire les enseignements d’une expérience menée au sein d’un système d’assurance-santé communautaire dans une région rurale de l’Inde. Il s’agit d’une intervention randomisée par grappes qui a pour but d’améliorer l’équité du système, à savoir réduire l’écart entre les demandes de remboursement des frais d’hospitalisation soumises par les populations pauvres et moins pauvres. Cinq grandes difficultés sont présentées et discutées dans l’article: 1) la mise en place des groupes de contrôle, 2) la création des conditions d’un test en aveugle, 3) la simultanéité des interventions, 4) le risque de contamination entre les groupes et 5) l’implantation sur un dispositif connaissant des modifications. Ces problèmes ne sont pas propres au contexte des pays en développement, bien que le dernier soit plus courant dans le cas de petits programmes aux ressources limitées. Les concessions faites par rapport aux canons méthodologiques sont susceptibles de réduire la validité interne de l’étude, mais elles rendent l’intervention plus réaliste et potentiellement plus applicable à d’autres contextes. En outre, une documentation précise de ces compromis nous permet de les prendre en compte à la fin de l’analyse.


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Copyright information

© The Canadian Public Health Association 2006

Authors and Affiliations

  • M. Kent Ranson
    • 1
    Email author
  • Tara Sinha
    • 2
  • Saul S. Morris
    • 3
  • Anne J. Mills
    • 4
  1. 1.Health Policy Unit, London School of Hygiene and Tropical Medicine (LSHTM)LondonUK
  2. 2.Vimo SEWA, Self-Employed Women’s AssociationUK
  3. 3.London School of Hygiene and Tropical MedicineUK
  4. 4.Health Economics and Financing ProgrammeLondon School of Hygiene and Tropical MedicineUK

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