The Science Journal of the American Association for Respiratory Care

Original Contributions

September 2002 / Volume 47 / Number 9 / Page 986

Clinical Utility of Measures of Breathlessness

Deborah L Cullen EdD RRT FAARC and Bernadette Rodak MSc CLSpH

BACKGROUND: The clinical utility of measures of dyspnea has been debated in the health care community. Although breathlessness can be evaluated with various instruments, the most effective dyspnea measurement tool for patients with chronic lung disease or for measuring treatment effectiveness remains uncertain. Understanding the evidence for the validity and reliability of these instruments may provide a basis for appropriate clinical application. OBJECTIVE: Evaluate instruments designed to measure breathlessness, either as single-symptom or multidimensional instruments, based on psychometrics foundations such as validity, reliability, and discriminative and evaluative properties. Classification of each dyspnea measurement instrument will recommend clinical application in terms of exercise, benchmarking patients, activities of daily living, patient outcomes, clinical trials, and responsiveness to treatment. METHODS: Eleven dyspnea measurement instruments were selected. Each instrument was assessed as discriminative or evaluative and then analyzed as to its psychometric properties and purpose of design. RESULTS: Descriptive data from all studies were described according to their primary patient application (ie, chronic obstructive pulmonary disease, asthma, or other patient populations). The Borg Scale and the Visual Analogue Scale are applicable to exertion and thus can be applied to any cardiopulmonary patient to determine dyspnea. All other measures were determined appropriate for chronic obstructive pulmonary disease, whereas the Shortness of Breath Questionnaire can be applied to cystic fibrosis and lung transplant patients. The most appropriate utility for all instruments was measuring the effects on activities of daily living and for benchmarking patient progress. Instruments that quantify function and health-related quality of life have great utility for documenting outcomes but may be limited as to documenting treatment responsiveness in terms of clinically important changes. CONCLUSIONS: The dyspnea measurement instruments we studied meet important standards of validity and reliability. Discriminative measures have limited clinical utility and, when used for populations or conditions for which they are not designed or validated, the data collected may not be clinically relevant. Evaluative measures have greater clinical utility and can be applied for outcome purposes. Measures should be applied to the populations and conditions for which they were designed. The relationship between clinical therapies and the measurement of dyspnea as an outcome can develop as respiratory therapists become more comfortable with implementing dyspnea measurement instruments and use the data to improve patient treatment. Dyspnea evaluation should be considered for all clinical practice guidelines and care pathways.
Key words: breathlessness, dyspnea, Borg Scale, Visual Analogue Scale, Oxygen Cost Diagram, Baseline/Transition Dyspnea Index, BDI, TDI, Chronic Respiratory Questionnaire, St George's Respiratory Questionnaire, SGRQ, Shortness of Breath Questionnaire, SOBQ, Breathing Problems Questionnaire, Pulmonary Functional Status and Dyspnea Questionnaire, Pulmonary Function Status Scale.
[Respir Care 2002;47(9):986–993]

Introduction

Respiratory therapists provide many treatments to relieve shortness of breath, including oxygen therapy and ventilator care. Yet current clinical practice guidelines rarely recommend dyspnea measurement instruments as a means of patient evaluation. The reason for that omission is uncertain. Perhaps dyspnea evaluation has not been demonstrated to be beneficial in today's fast-paced health care environment? Given the emphasis on patient outcomes in health care, the clinical utility of dyspnea measures should be explored and a paradigm for their administration developed.

During the infancy of inhalation therapy, respiratory treatments consisted of high volumes of aerosol and medication therapy to soothe mucosa and provide bronchodilation. There was limited interest in quantifying breathlessness, and more consideration was given to treatment of breathing difficulties. That emphasis on treatment continues today. Without emphasis on assessing the patient's improvement in pulmonary function and oxygenation, little documentation of treatment outcomes is available to clinicians.

Dyspnea measures have been used to assess patient response to exercise, activities of daily living (ADL), and rehabilitation, and have been included in assessment of health-related quality of life. For example, recent attention has been given to dyspnea treatment and assessment during mechanical ventilation in the context of patient-centered care.

Although many methods are available to evaluate breathlessness, the most effective measure for a specific patient condition or treatment remains largely unexplored in the respiratory care literature. The American Thoracic Society Consensus Guideline on Dyspnea states that dyspnea instruments should be applied as related to the purpose for which they were intended. That consensus statement presents valuable scientific evidence on the mechanisms, assessment, and management of dyspnea. Additionally the statement noted, "Inventories that embrace aspects of dyspnea related to quality of life are not yet a routine part of the history and physical examination, but have demonstrated a useful role in the clinic and in pulmonary rehabilitation." Although no specific recommendations were forthcoming, the consensus statement does describe dyspnea inventories used for exercise as well as the broader context of instruments for dyspnea in regards to quality of life. It is necessary to differentiate between a breathing function and breathing as it affects ADL. One can have the ability to breathe and yet not have adequate oxygenation to perform ADL such as dressing and climbing stairs. It is also possible for a patient to show no change in limited objective measures of breathing function and yet to show increased ability to cope with ADL.

Mishoe and MacLean recommend that only those tools that have documented sound psychometric properties be applied to clinical practice and research. Psychometric properties include validity, reliability, and responsiveness, among others. Tables 1 and 2 provide definitions of some commonly used psychometric terms.

Important questions include:

The purpose of this study is to evaluate and then to classify the clinical utility of measures of breathlessness, either as single-symptom or multidimensional instruments, based on psychometric foundations such as validity and reliability, as well as discriminative or evaluative properties. We make recommendations for clinical application of each dyspnea measure, in terms of exercise, benchmarking patients, ADL, patient outcomes, clinical trials, and response to treatment. Evaluation of each dyspnea measure analyzed can guide assessment of patient progress, treatment effectiveness, and short-term or long-term therapy goals. This template will assist respiratory clinicians to identify the best measures for clinical practice guideline inclusion or clinical application.

The entire text of this article is available in the printed version of the September 2002 RESPIRATORY CARE.

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