The Editorial Executive Committee welcomes letters, which should be less than 250 words. Before a decision to publish is made, letters which refer to a published article may be sent to the author for a response. Any letter may be sent to an expert for comment. When letters are published, they are usually accompanied in the same issue by their responses or comments. The Committee screens out discourteous, inaccurate or libellous statements. The letters are sub-edited before publication. Authors are required to declare any conflicts of interest. The Committee's decision on publication is final.

The Editorial Executive Committee welcomes letters, which should be less than 250 words. Before a decision to publish is made, letters which refer to a published article may be sent to the author for a response. Any letter may be sent to an expert for comment. When letters are published, they are usually accompanied in the same issue by their responses or comments. The Committee screens out discourteous, inaccurate or libellous statements. The letters are sub-edited before publication. Authors are required to declare any conflicts of interest. The Committee's decision on publication is final.

Letter to the editor

Editor, I believe that there is room for further comment on 'Stimulant treatment for attention deficit hyperactivity disorder' (Aust Prescr 1995;18:60-3) by Dr P. Hazell. I am concerned that his highlighted placebo effect of 35-40% will be taken as gospel.

It was mooted by Dr Russell Barkley in the late 1970s, but is not widely discussed by him lately. It has been mentioned once in the 1990s, but not by other researchers. If one medicates on the basis of pre testing, e.g. with a paired associate learning task, there is little if any room for placebo effect.

Dr Hazell's suggestion that 'drugs do not exert a direct effect on behaviour or learning problems' may be a quibble on the word 'direct'. The statement is in conflict with the article and references quoted by Christopher Gordon.1

Professor Adler's comments on 'an epidemic' are very emotive when Dr Paul Hutchins quoted N.S.W. figures which show that 0.8% of all children/adolescents are on neurostimulants. As with Dr Hazell, paired associate learning testing of the child's responses to medications precludes the need for 'single blind controlled trials' and obviates the need for cumbersome assessments of what works and what does not.

Michael J. Harris
Consultant Paediatrician
Sydney, N.S.W.

Author's comments

Dr P. Hazell, the author of the article, comments:

Dr Harris has questioned the magnitude of placebo response quoted in my paper. One meta analysis2 has addressed this issue adequately, and found a placebo response rate of 30%. This is less than that reported in the narrative review of Barkley, but is still substantial. The question of which method is best for determining treatment efficacy in an individual patient is unresolved. While placebo trials have been recommended on theoretical grounds, there is a lack of evidence that these improve clinical management. I would welcome evidence from Dr Harris that supports the use of the paired associate learning task for the purpose of assessing the clinical response of ADHD children to stimulant treatment.

The important take home message for clinicians in relation to behaviour and learning is that clinicians, educators and parents should not expect conduct or learning problems to respond to stimulants in the absence of ADHD. Even in the presence of ADHD, the effect on learning averaged across 3 published meta analyses was 0.35 standard deviations, which is probably clinically non significant.2

References

  1. Gordon C. ADHD issues for special education. Aust J Special Education 1994;18(2):36-49.
  2. Swanson JM, McBurnett K, Wigal T, et al. Effect of stimulant medication on children with attention deficit disorder: a 'review of reviews'. Exceptional Children 1993;60:154-62.