A scale developed to measure the potential harm caused by invasive
placebos in local anaesthesia research has been successfully tested by a
group of 43 independent clinicians, according to research published in
the April issue of Anaesthesia.
The consultant anaesthetists were asked to assess the risk of harm posed
by control group interventions described in ten published clinical
anaesthesia studies using the Serious Harm and Morbidity (SHAM) scale.
There was substantial agreement between the 22 consultants who were
given clinical examples to illustrate the scale and moderate agreement
between the 21 consultants who were not provided with clinical examples
to inform their decisions.
Agreement was also particularly high among consultants holding academic
posts and the authors suggest this may reflect their greater familiarity
with assessing medical research.
The anaesthetists also agreed with the scores allocated to the studies
by the scale’s developers in 68% of cases.
The details of the SHAM scale, which was created by doctors in Adelaide,
Australia, were first published in Anaesthesia in February 2011.
This paper showed that a large number of clinical studies employed
highly invasive placebos.
“Such practices appear to contravene the World Medical Association’s
Declaration of Helsinki on Ethical Principles for Medical Research
Including Human Subjects” explains study lead Dr Allan Cyna, a
consultant anaesthetist from the Women’s and Children’s Hospital in
North Adelaide and a Clinical Senior Lecturer at the the University of
Adelaide.
“The Declaration, first published in 1964 and last amended in 2008,
states that ‘patients who receive placebo or no treatment will not be
subject to any risk of serious or irreversible harm’.
“More than half of the research papers we looked at for the scale
development study, published in 2011, subjected control group patients
to risks of moderate or major harm and ill health without apparently
considering the use of a less invasive placebo.”
The initial 2011 study showed how the authors tested the zero to
four-point scale by grading 59 studies. This showed that 31 studies
covering 913 patients represented moderate or major risks, including six
studies involving 183 children.
For the latest study, the 43 consultant anaesthetists, who were not
involved in the development of SHAM, tested the scale by grading ten
published clinical papers chosen at random from the 59 used in the
original study. Their results were then analysed using Fleiss kappa,
which assesses the reliability
of agreement between a fixed number of raters using a scale of zero
(no agreement) to 1.0 (total agreement).
Overall agreement between the assessors was 0.50 and the score was 0.60
when it came to assessors agreeing whether studies were high risk or low
risk. When anaesthetists were given clinical examples to illustrate the
scale, the scores rose even higher and they were much more likely to
agree with each other than those who were not given examples (0.76
versus 0.45). Agreement was also significantly higher among those in
academic posts (0.60) than those who did not hold such posts (0.46).
Explaining the rationale behind the development of the scale, Dr Cyna
says: “Placebos, such as sugar pills or saline injections, are
frequently used in research to assess new techniques or drugs. Because
they contain no active ingredients they provide a useful control.
However in the context of a placebo local anaesthetic control, the
technique itself may risk complications that could be avoided with a
less invasive alternative without reducing scientific validity.”
“The results of our latest study suggest that the SHAM scale can be
successfully used to grade the severity of potential complications of
placebo-controlled interventions in local anaesthesia research and this
represents a first step towards the score’s validation” concludes
co-author and senior registrar Dr James Jarman.
“The SHAM scale draws attention to the potential for harm and it is
important to point out that actual harm is rare in anaesthesia research.
We believe that if clinicians involved in anaesthesia research were to
use the SHAM scale to assess the potential harm caused by their placebo
control, it could lead to them choosing less invasive options. Our study
emphasises that in local anaesthesia research we should be using the
least invasive placebo that is consistent with maintaining scientific
rigour, so as to make research as safe as possible.”
Full details of the scale and the papers studied are included in the
April 2012 paper, which is free online at: http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2044.2011.06998.x/pdf
The scale development study, published in February 2011, is also free
online at: http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2044.2010.06560.x/pdf
