BACKGROUND: The assessment of asthma control is pivotal to the evaluation of treatment response in individuals and in clinical trials. Previously, asthma control, severity, and exacerbations were defined and assessed in many different ways. PURPOSE: The Task Force was established to provide recommendations about standardization of outcomes relating to asthma control, severity, and exacerbations in clinical trials and clinical practice, for adults and children aged 6 years or older. METHODS: A narrative literature review was conducted to evaluate the measurement properties and strengths/weaknesses of outcome measures relevant to asthma control and exacerbations. The review focused on diary variables, physiologic measurements, composite scores, biomarkers, quality of life questionnaires, and indirect measures. RESULTS: The Task Force developed new definitions for asthma control, severity, and exacerbations, based on current treatment principles and clinical and research relevance. In view of current knowledge about the multiple domains of asthma and asthma control, no single outcome measure can adequately assess asthma control. Its assessment in clinical trials and in clinical practice should include components relevant to both of the goals of asthma treatment, namely achievement of best possible clinical control and reduction of future risk of adverse outcomes. Recommendations are provided for the assessment of asthma control in clinical trials and clinical practice, both at baseline and in the assessment of treatment response. CONCLUSIONS: The Task Force recommendations provide a basis for a multicomponent assessment of asthma by clinicians, researchers, and other relevant groups in the design, conduct, and evaluation of clinical trials, and in clinical practice.
AimAims of the Task Force
The primary aim of the Task Force was:
To provide consensus recommendations on standardized definitions and data collection methods for assessing asthma control, asthma severity, and asthma exacerbations in future clinical trials.
The secondary aims were:
1. To provide consensus recommendations on standardized measures of asthma control and exacerbations that can be
obtained retrospectively from existing clinical trial data, to maximize the potential for pooling of data, and making comparisons between clinical trials.
2. To provide consensus recommendations on the assessment of asthma control, asthma severity, and asthma exacerbations in clinical practice.
The Task Force considered outcome variables from the perspective of their relevance to clinical trials, including those
conducted in primary care, and to clinical practice at all levels from primary care to tertiary care. The focus was primarily on
issues relating to the assessment of asthma in those aged 6 years and over, as the needs for children younger than 6 years were considered to be beyond the scope of the present initiative.
Reddel, Helen K. Taylor, D. Robin Bateman, Eric D. Boulet, Louis-Philippe Boushey, Homer A. Busse, William W. Casale, Thomas B. Chanez, Pascal Enright, Paul L. Gibson, Peter G. de Jongste, Johan C. Kerstjens, Huib A. M. Lazarus, Stephen C. Levy, Mark L. O'Byrne, Paul M. Partridge, Martyn R. Pavord, Ian D. Sears, Malcolm R. Sterk, Peter J. Stoloff, Stuart W. Sullivan, Sean D. Szefler, Stanley J. Thomas, Mike D. Wenzel, Sally E. American Thoracic Society/European Respiratory Society Task Force on Asthma, Control Exacerbations,
Disease Category: Child health, Lungs & airways
Disease Name: Asthma
Age Range: 6 - 100
Sex: Either
Nature of Intervention: Not specified
- Clinical experts
- Researchers
- Pharmaceutical industry representatives
- Governmental agencies
- Methodologists
- Policy makers
- Systematic review of outcomes measured in trials
- COS for clinical trials or clinical research
- COS for practice
- Semi structured discussion
- Literature review
The Cochrane Register of Randomized Controlled Trials was searched for all studies published between 1998 and 2004 that contained the words ‘‘asthma control,’’ ‘‘asthma severity,’’ or ‘‘asthma exacerbation(s).’’ This yielded 440 references, decreasing to 356 after exclusion of non–English-language references and those published only as abstracts, and to 327 after exclusion of duplicates. Papers reporting studies based only within a laboratory, emergency room (ER), or hospital ere also excluded. Thereafter, each paper was allocated to an individual Task Force member to identify the outcome variables that had been used to describe and/or quantify asthma control, severity, and/or exacerbations. This search provided a subset of clinical trial reports that had used outcome variables relevant to previous definitions of asthma control, severity, or exacerbations. Evaluation of Outcome Measures Papers identified by the above process were allocated to the relevant Working Group(s) for joint assessment of the measurement properties, analysis and reporting of the outcome variables, and the information that they provided about treatment response. The Working Groups then performed descriptive reviews of each identified outcome variable. The focus was on the measurement properties of each variable, and its strengths and weaknesses in the assessment of asthma control or exacerbations (as defined by the Task Force). Task Force members were asked to refer where possible to published guidelines or recommendations about methodology relevant to their Working Group, and to identify additional papers that evaluated measurement properties or clinical associations for the nominated outcome variables from further literature searches.
Development of Final Recommendations
Finally, after considering the available outcome measures, the Task Force developed overall recommendations for the assessment of asthma control and exacerbations in clinical trials and clinical practice. The recommendations are based on a balance between:
1. The extent to which each measure provides information that is congruous with the definitions of asthma and of asthma control.
2. The extent to which each measure is reflective of the dual goals of asthma treatment, namely: (a) to achieve good control of the current clinical manifestations of asthma, and (b) to reduce risk to the patient (i.e., the risk of adverse outcomes such as exacerbations, poor control, accelerated decline in lung function, and side-effects of treatment). Some of these future risks may result from lack of control of the underlying disease process.
3. Characteristics of the outcome measures such as reproducibility, responsiveness, and construct validity (association with other measures), all of which will obviously vary to some extent between individual outcome variables within each class.
4. Feasibility of using the outcome measure (including safety, accessibility, and cost).