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Evidence and belief in ADHD

Informed decisions on stimulants must be based on studies with good methodology

A

ttention deficit hyperactivity disorder (ADHD)generates controversy. Some believe that itdoes not exist, whereas others see the

reluctance of clinicians to diagnose and treat it asdenying effective health care to children.1 Epidemio-logical studiesshowthat3-5% of children of school agemay be classified as having attention deficit hyperactiv-ity disorder.2 No validated diagnostic test exists to con-firm the clinical diagnosis.

It is a complex neurodevelopmental constellationof problems rather than a single disorder. The coresymptoms are inattention, hyperactivity, and impulsiv-ity. These are also, however, normal behavioural traitspresent in unaffected children. The extent to whicheach causes disability varies and should be seen withinthe context of a childs developmental level. For exam-ple, an active 3 year old, impulsive and frequently inter-rupting of others,differs from a disruptive, unfocused 8

year old who is unable to cope educationally. Yet bothmay display core symptoms. Also, it is important toestablish that symptoms exist in various settings andare not better accounted for by another mentaldisorder.2 Specialists should undertake this assessment.

The variability of treatment and concerns aboutoveruse of stimulants has led to the writing of practiceparameters,3 clinical guidelines, and evidence basedbriefings4 to support clinicians in achieving bestpractice. Prescriptions in the United Kingdom rosefrom 183 000 in 1991 to 1.58 million in 1995. 5The useof stimulants varies worldwideit is estimated to be 10to 30 times as high in North America as in the UnitedKingdom.6 Concern has been expressed about the risein the use of psychoactive drugs, especially inpreschool children in the United States.7

For parents and children, getting informationabout ADHD is a lottery that depends on whichprofessional they see and what they read or gatherfrom television and the internet.

What roles should the general practitioner, childpsychiatrist, child psychologist, and paediatrician play?Szatmari suggests that our most important function isthat of interpreting evidence.8 Through dialogue withparents and children the risks and benefits oftreatment may be considered along with the familysvalues and cultural background. Transparency is essen-tial, and requires that clinicians are able adequately tointerpret less than perfect evidence.

Two new studies add to the debate. The collaborativemultimodal treatment study of children with ADHD isthe largest, most rigorous randomised controlled trial inADHD research thus far.9About 579 children aged 7 to9.9 years with ADHD were assigned to four groups:medication management, intensive behavioural treat-ment, medication management plus intensive behav-ioural treatment, and standard community care. Itshowed significantly greater improvement amonggroups that were given medication. These results are inkeeping with other studies examining drug treatment ofADHD with stimulants and confirm that these benefitscontinue during treatment.10 Serious methodological

issues have been raised,11 however, including that of theevaluation of non-drug interventions.6

The systematic review from McMaster University1

reviews 77 randomised controlled trials, including thecollaborative multimodal treatment study, and alsoincorporates results from the systematic review byresearchers at the University of British Columbia.10 Itconcludes that stimulants are effective in the shortterm, are more effective than placebo, compare wellwith each other, and seem to be more effective than tri-cyclics and non-drug treatments.

The short term benefits of stimulants seem to con-tinue into the longer term as long as they are taken, butevidence is limited in this area.9 Little is known, forexample, about outcomes such as educational achieve-ment, employment, or social functioning.1 Adversereactions are usually dose related and no evidenceexists of harmful long term effects of therapeutic use.1

Most importantly, the McMaster review highlightsshortfalls in the published research. Many studies aresmall and do not adequately describe randomisation orblinding,or account for withdrawalsand dropouts.1 Poorreporting of these basic methodological componentslimits our ability to assess the importance of publishedwork, which is important to individual clinicians, system-atic reviewers, and organisations (such as the NationalInstitute of Clinical Excellence in England and Wales)that evaluate and summarise research. Many of the trialswill have included these elements in their protocols andexecution, yet they are absent from the final publication. Authors, peer reviewers, and editors should beencouraged to apply publication standards as recom-mended in the CONSORT (consolidation of the stand-

ards of reporting trials) statement.12Stimulants should be prescribed judiciously and

monitored carefully by specialists in close liaison withprimary care physicians. Informed decision making byclinicians and parents will be aided by more attention toresearch methods and its improved reporting. Theimminent report by the National Institute for ClinicalExcellence on the use of methylphenidate in childhoodhyperactivity will, we hope, assert this principle.

Morris Zwi consultant child and adolescent psychiatrist

Richmond Royal Hospital, Richmond TW9 2TE

Paul Ramchandani specialist registrar, child andadolescent psychiatry

Child and Family Psychiatric Service, Aylesbury HP20 1EG(PaulGulab@aol.com)

Carol Joughin project manager

FOCUS, Royal College of Psychiatrists Research Unit, LondonSW1H 0HW (carol.joughin@virgin.net)

1 Jadad AR, Boyle M, Cunningham C, Kim M, Schachar R. Treatment ofattention-deficit/hyperactivity disorder. Rockville, MD:Agencyfor HealthcareResearch and Quality, 2000.

2 American Psychiatric Association.Diagnostic and statistical manual of mentaldisorders. 4th ed. Washington, DC: American Psychiatric Association, 1994.

3 Dulcan M. Practice parameters for the assessment and treatment of children,adolescents, and adults with attention-deficit/hyperactivity disorder. J Am AcadChild Adolesc Psychiatry 1997;36:85-121S.

4 Joughin C, Zwi M. The use of stimulants in children with attention deficithyperactivity disorder. London:Royal College of Psychiatrists,1999.

Editorials

BMJ 2000;321:9756

975BMJ VOLUME 321 21 OCTOBER 2000 bmj.com

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