Ethical issues in the design and conduct of cluster randomised controlled trials

Dear Editor

The article by Edwards and colleagues on ethics in cluster randomised
trials was a helpful and considered discussion of an important matter for
all involved in conducting such trials. The issue of autonomy however, is
not easily disposed of. In individually randomised trials there are many
safeguards for participants welfare. These include the right to decline to
be studied, but the principle of autonomy has a more fundamental
importance which is about being able to make decisions on matters which
affect oneself. The idea of a "guardian" to protect the welfare of the
cluster may be part of the answer to this dilemma. The responsibilities of
such a guardian are heavy and require a complete independence from the
research team - not easy in the current atmosphere of primary care
networks and increasing contact between academics and front line health
care workers if the clusters are based on units such as general practices
or hospital departments. Secondly, the guardians need to be familiar with
the methodological constraints and ethical imperatives of health service
research - not easy for head teachers, social work team managers or other
community representatives if the clusters are based on these groupings.

Ultimately cluster randomised trials without individual consent (and
some with consent!) preclude the principle of autonomy. Edwards'
distinction between cluster-cluster and individual-cluster trials leaves a
big grey area which is not resolved by debates over maximising benefits,
protecting individuals welfare, and the need to prevent contamination of
the intervention. We are all part of the general public and we do not like
to lose our autonomy in the context of clinical trials, even of apparently
benign interventions. The idea of a guardian may even be more ominous than
blind ignorance. Cluster randomised trials are both important and
necessary so we do need to seek to resolve this matter. I do not have an
answer but ultimately it will have to come from the lay public rather than
the research community.

Richard Reading
Honorary Senior Lecturer
School of Health Policy and Practice
University of East Anglia
Norwich NR4 7TJ

Competing interest. I am involved in conducting a cluster randomised
trial of the effects of providing Citizen's Advice Bureau services in
primary care on maternal and child health.

Reference

1 Edwards SJL, Braunholtz DA, Lilford RJ, Stevens AJ. Ethical issues
in the design and conduct of cluster randomised controlled trials. BMJ
1999;318:1407-9