Invited editorial Randomised controlled trials in children's services
| Published date | 13 March 2008 |
| Pages | 2-8 |
| DOI | https://doi.org/10.1108/17466660200800001 |
| Date | 13 March 2008 |
| Author | David Torgerson,Carole Torgerson |
2
1Director of the
York Trials Unit,
University of York
2Reader in Evidence-
based Education,
University of York
Journal of Children’s Services
Volume 3 Issue 1 September 2008
©Pavilion Journals (Brighton) Ltd
Background
In this two-part special edition of the Journal of
Children’s Services (Volume 3, issues 1 and 2) the use
of the randomised controlled trial (RCT) takes centre
stage. The RCT is the best method to assess a causal
relationship between intervention and outcome
(Torgerson & Torgerson, 2008). The only other
method that can, in theory, provide an unbiased
estimate of causality is the regression discontinuity
(RD) design (Shadish et al,2002). However,it is much
less efficient than an RCT and typically requires at
least 2.75 times as many participants to achieve
similar statistical power. Furthermore, the method is
morecomplex to understand and has been rarely
used since Donald Campbell developed it in the
1960s (Cook & Wong, 2008).
The RCT is, in principle, a very easy design to
undertake. In this special edition (Part 1), Mark
Dynarski and Patricia Del Grosso outline the basic
design of the method. As they note, random
assignment acts like a lottery and results in an equal
distribution between the groups – programme and
control – of the variables that might affect outcomes.
Any chance differences between the groups in
observable variables can be corrected using
regression analytical techniques. Other methods, as
the authors are careful to point out, such as pre- and
post-test or statistical matching may result in biased
answers due to problems of temporal change or
confounding.
The superiority of the RCT over most other methods
of impact evaluation lies in the fact that unknown or
unmeasured variables will be equally distributed
between groups. In other approaches, such as case-
control or cohort studies, we can never be certain that
this is the case. Consequently,there will always be
doubt as to whether bias, introduced by such unknown
variables, has led to an over- or under-estimate of
effectiveness or, worse, suggested a possibility of
benefit when there is actually a possibility of harm.
Anon-random history of RCTs
Although the first known randomised trials were
undertaken in the 1930s in the field of education
(Walters, 1931; 1932) – among undergraduate
students at Purdue University in the US – the first
trial involving children was undertaken in 1936. This
study,again in the US, evaluated an intervention
delivered to teenage boys at risk of falling into a life
of crime (McCord, 1978). Several hundred boys were
randomised to receive either social care support or no
specific intervention. However,it is in the field of
health carewhere RCTs have mainly become
established, with the early patulin trial in the UK for
the common cold (Medical Research Council, 1944)
and the more widely known streptomycin trial for
tuberculosis treatment (Medical Research Council,
1948). The latter is more widely known, possibly
because it showed a statistically significant difference
in contrast with the patulin study.
The widespread use of trials in healthcare research
is probably due to at least two reasons. First, there
have been many pharmaceutical disasters in this field.
Numerous widely-used products have later been
shown to have the potential for devastating effects on
human health. For instance, routine oxygen
supplementation of premature infants was found to
cause blindness (Silverman, 1977), and the provision
of DES (Diethylstilbestrol) to pregnant women in order
to prevent pregnancy loss was shown to be ineffective
and result in an increase in female cancers among
both the pregnant women and any of their female
children (Oakley, 2000). Similarly, the widespread use
of anti-arrhythmic drugs to suppress unusual rhythms
David J Torgerson1and Carole J Torgerson2
Invited editorial
Randomised controlled trials in
children’s services
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