Evidence Report/Technology Assessment: Number 11

Treatment of Attention-Deficit/Hyperactivity Disorder

Summary


Under its Evidence-based Practice Program, the Agency for Health Care Policy and Research (AHCPR) is developing scientific information for other agencies and organizations on which to base clinical guidelines, performance measures, and other quality improvement tools. Contractor institutions review all relevant scientific literature on assigned clinical care topics and produce evidence reports and technology assessments, conduct research on methodologies and the effectiveness of their implementation, and participate in technical assistance activities.

Overview / Methodology / Findings / Future Research / Availability of Full Report


Overview

Attention-deficit/hyperactivity disorder (ADHD) is one of the most common disorders diagnosed in children and adolescents. The American Psychiatric Association (APA) describes the essential feature as "a persistent pattern of inattention and/or hyperactivity-impulsivity that is more frequent and severe than is typically observed in individuals at a comparable level of development."

Terms that have been used to describe children with "distractability, impulsivity, and usually overactivity" include minimal brain dysfunction/damage (MBD), hyperkinetic reaction, and hyperkinesis.

ADHD has been surrounded by great controversy involving clinicians, teachers, policymakers, parents, and the media. The range of opinion regarding the validity of ADHD extends from those who do not believe it exists and regard it as a myth, to those who believe that there is genetic and physiological evidence supporting its existence.

Prevalence estimates of ADHD vary according to the methods of ascertainment, diagnostic criteria, informants, and population sampled. According to the Diagnostic and Statistical Manual of Mental Disorders IV (DSM-IV), the prevalence of ADHD in school-age children is 3 to 5 percent. However, prevalence studies using the two previous versions of the DSM (DSM-III and DSM-III-R) in the United States, Canada, United Kingdom, Germany, and New Zealand have shown rates that vary from 1.7 to 16.1 percent.

Although it was previously thought that ADHD remitted before or during adolescence, it has been estimated that more than 70 percent of hyperactive children continue to meet criteria for ADHD as adolescents and up to 65 percent as adults.

Problems with the diagnosis and treatment of this condition can also arise because approximately 65 percent of ADHD patients may have at least one comorbid disorder in the form of:

ADHD has been associated with impaired academic achievement, rejection by peers, and family resentment and antagonism. The rich terminology may reflect the broad spectrum and the high frequency with which it is described with other comorbid conditions.

There is also variation and controversy around the treatment of ADHD, which often includes stimulant medication. To reduce inappropriate variation in treatment, major organizations in North America have developed, or are in the process of developing, practice parameters or clinical practice guidelines to guide treatment decisions.

In 1997, the Agency for Health Care Policy and Research (AHCPR) charged the McMaster University Evidence-based Practice Center (MU-EPC) with producing an evidence report on the treatment of ADHD. The objectives of this work were to:

Reporting the Evidence

A multidisciplinary research team was assembled, with participation of members of the nominating organizations, the American Academy of Pediatrics (AAP) and the APA, local experts, and research staff. After multiple consultations and the evaluation of published systematic reviews and meta-analyses, the following general questions were selected as the focus of the evidence report:

To answer these questions, while avoiding the duplication of work, making efficient use of the resources available, and ensuring maximum added value, the scope of the evidence report focused on the following seven categories of research studies:

Numerous systematic reviews and meta-analyses have examined placebo-controlled trials of stimulant medication and have established consistently the short-term efficacy of these agents for core symptoms. Consequently, placebo-controlled trials evaluating stimulant medication were reviewed in this report only if they met the criteria for inclusion in any of the other six categories. In addition, the report focuses on head-to-head comparisons of pharmacological interventions; and on head-to-head comparisons of pharmacological and nonpharmacological interventions. This was identified as the area of prime interest to clinicians rather than effectiveness of stand-alone interventions—either pharmacological or nonpharmacological.

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Methodology

Inclusion and Exclusion Criteria

In preparing the Report, we followed current standards for assessing and distilling research evidence. Citations of individual studies were regarded as potentially eligible and selected for further evaluation if:

If the studies included conditions other than ADHD, they were included only if they provided separate analyses for patients with ADHD. We acknowledge that randomized controlled trials are imperfect tools, but so far they are our best probe to evaluate health care interventions. Non-RCTs were included if they provided data on adverse effects of interest collected over more than 16 weeks. More refined inclusion and exclusion criteria defined within each of the seven categories of research studies are described in the body of the report.

Inclusion of a study in the evidence report was decided by two members of the research team, by consensus, and on the basis of the information available in the full published articles.

Literature Search

Citations of potentially eligible studies were identified through a systematic search of:

Data Extraction

Data extraction forms were especially developed and tested for this project. The local research team, partner organizations, and the Task Order Officer (TOO) were consulted and the forms approved for content. More than 41 different variables describing the general characteristics of the study were recorded. In addition, detailed information on interventions, outcomes, and tests were extracted from each of the full reports, independently by two reviewers, with differences resolved by consensus or by a third member of the research team.

Data Synthesis

Descriptive statistics were calculated for all the variables. Evidence tables were constructed to summarize, globally and question by question, all the information extracted from the study reports. The local research team, in consultation with members of the partner organizations and the TOO, evaluated the overall quantity and quality of the data available and decided that meta-analysis would be inappropriate to summarize the evidence on each of the research questions and for each of the main categories of interest. The main reasons for this decision were:

Therefore, this report represents a systematic qualitative review of the existing evidence, emphasizing the implications for clinical practice and the opportunities for future research to fill existing knowledge gaps.

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Findings

The following is a description of the main conclusions from each of the seven categories of interest:

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Future Research

Areas needing further research include the following:

In summary, this report includes seven systematic reviews that incorporate state-of-the-art methodology, represent the most rigorous systematic review conducted to date, and are ready for incorporation into evidence-based clinical practice guidelines or performance measures. The report also provides a detailed description of the many limitations of the evidence available and provides recommendations to fill existing knowledge gaps. Filling such gaps will not be easy and will require highly innovative efforts and collaboration among different groups of decisionmakers. The MTA study confirms that large-scale, long-term collaboration among researchers is possible. If this field continues to produce small, incompletely reported studies with heterogeneous designs, instead of the high-quality collaborative efforts required, research in this area will continue to be abundant but will be of little value to guide most clinically relevant decisions.

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Availability of the Full Report

The full evidence report from which this summary was taken was prepared by McMaster University, an AHCPR Evidence-based Practice Center, Ontario, Canada, under Contract No. 290-97-0017. Print copies may be obtained free of charge from the Publications Clearinghouse by calling 1-800-358-9295. Requesters should ask for Evidence Report/Technology Assessment No.11, Treatment of Attention-Deficit/Hyperactivity Disorder (AHCPR Publication No. 99-E018).

The Evidence Report is available online on the National Library of Medicine Bookshelf.

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AHCPR Publication No. 99-E017
Current as of December 1999


Internet Citation:

Treatment of Attention-Deficit/Hyperactivity Disorder. Summary, Evidence Report/Technology Assessment: Number 11. AHCPR Publication No. 99-E017, December 1999. Agency for Health Care Policy and Research, Rockville, MD. http://www.ahrq.gov/clinic/epcsums/adhdsum.htm


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