Reliability and Validity of the Multidimensional Dyspnea Profile
Background: Most measures of dyspnea assess a single aspect (intensity or distress) of the symptom. We developed the Multidimensional Dyspnea Profile (MDP) to measure qualities and intensities of the sensory dimension and components of the affective dimension. The MDP is not indexed to a particular activity and can be applied at rest, during exertion, or during clinical care. We report on the development and testing of the MDP in patients with a variety of acute and chronic cardiopulmonary conditions.
Methods: One hundred fifty-one adults admitted to the ED with breathing symptoms completed the MDP three times in the ED, twice at least 1 h apart (T1, T2), and near discharge from the ED (T3). Measures were repeated in 68 patients twice in a follow-up session 4 to 6 weeks later (T4-T5). The ED sample was 56% men with a mean age of 53 ± 15 years; the follow-up sample was similar.
Results: Factor analysis resulted in a two-factor solution with a total explained variance of 63%, 74%, and 72% at T1, T2, and T3, respectively. One domain related to primary sensory qualities and immediate unpleasantness, and the second encompassed emotional response. For the two domains, Cronbach α ranged from 0.82 to 0.95, and the intraclass correlation coefficient ranged from 0.91 to 0.98. Repeated-measures analysis was significant for change (T1, T3, T4), showing responsiveness to change in MDP domains with treatment (F[2,66] = 19.67, P > .001).
Conclusions: These analyses support the reliability, validity, and responsiveness to clinical change of the MDP with two domains in an acute care and follow-up setting.
Mechanoreceptors, chemoreceptors, and awareness of motor output continuously convey information about breathing to the cerebral cortex and contribute to producing a variety of specific sensory perceptions. Perceived threats to respiratory homeostasis are unpleasant and are accompanied by emotional responses. Dyspnea has been defined as "a subjective experience of breathing discomfort that consists of qualitatively distinct sensations that vary in intensity," and the experience "derives from interactions among multiple physiologic, psychologic, social, and environmental factors." Although this definition recognizes the complexity of dyspnea perception, commonly used dyspnea measures do not adequately assess this complexity.
Dyspnea research is currently hampered by the lack of a single instrument to measure different aspects of respiratory discomfort in a variety of settings. A number of clinical dyspnea instruments provide indirect measurement of several aspects of patients' experience of dyspnea. Most clinical questionnaires rely on patient recall to assess daily activities and do not directly scale sensation. Single-dimension scales (eg, visual analog, Borg, number) are widely used to measure dyspnea, especially in experimental settings. The rating of the perceptual dimension often is poorly defined in published reports, and the meaning can vary across studies (eg, a laboratory subject breathing against a resistive load and rating the intensity of effort, a patient in an ED rating emotional distress). Specifically, the original descriptor list developed by Simon et al has been used by several investigators in the exploration of how individuals would describe breathlessness in various conditions and settings. However, others have modified the list such that comparison across investigations is difficult.
The Multidimensional Dyspnea Profile (MDP) is a comprehensive instrument designed to measure sensory and affective dimensions of dyspnea. The conceptual model we proposed for dyspnea asserts that each item in the MDP has the potential to vary separately from the others under some circumstances. Our approach in developing this instrument was based on the multidimensional model of pain. Intensity (strength of sensation), quality, unpleasantness, and emotion are distinct aspects of pain perception, with evidence accumulating that these dimensions are also relevant to dyspnea perception. Advances in the ability to understand and measure the several dimensions of dyspnea could facilitate comparison of different laboratory models and different disease states based on quantifiable data rather than on intuition and argument; thus, it can lead to better experimental design and clinical practice.
Data thus far support the model concept that the component items can vary with some independence. An earlier laboratory experiment confirmed that the sensory quality of work/effort can vary independently from the sensory quality of air hunger and showed that sensory intensity can vary independently from immediate unpleasantness. Another laboratory investigation confirmed that the MDP is responsive to treatment with morphine. The MDP is rooted in these findings and the model because it is designed to measure sensory and affective dimensions of dyspnea while supporting the relative independence of these dimensions. The purpose of this study was to provide initial reliability and validity estimates of the MDP when administered to the same individuals in two settings: during an ED visit and at an outpatient follow-up visit 4 to 6 weeks later.
Abstract and Introduction
Abstract
Background: Most measures of dyspnea assess a single aspect (intensity or distress) of the symptom. We developed the Multidimensional Dyspnea Profile (MDP) to measure qualities and intensities of the sensory dimension and components of the affective dimension. The MDP is not indexed to a particular activity and can be applied at rest, during exertion, or during clinical care. We report on the development and testing of the MDP in patients with a variety of acute and chronic cardiopulmonary conditions.
Methods: One hundred fifty-one adults admitted to the ED with breathing symptoms completed the MDP three times in the ED, twice at least 1 h apart (T1, T2), and near discharge from the ED (T3). Measures were repeated in 68 patients twice in a follow-up session 4 to 6 weeks later (T4-T5). The ED sample was 56% men with a mean age of 53 ± 15 years; the follow-up sample was similar.
Results: Factor analysis resulted in a two-factor solution with a total explained variance of 63%, 74%, and 72% at T1, T2, and T3, respectively. One domain related to primary sensory qualities and immediate unpleasantness, and the second encompassed emotional response. For the two domains, Cronbach α ranged from 0.82 to 0.95, and the intraclass correlation coefficient ranged from 0.91 to 0.98. Repeated-measures analysis was significant for change (T1, T3, T4), showing responsiveness to change in MDP domains with treatment (F[2,66] = 19.67, P > .001).
Conclusions: These analyses support the reliability, validity, and responsiveness to clinical change of the MDP with two domains in an acute care and follow-up setting.
Introduction
Mechanoreceptors, chemoreceptors, and awareness of motor output continuously convey information about breathing to the cerebral cortex and contribute to producing a variety of specific sensory perceptions. Perceived threats to respiratory homeostasis are unpleasant and are accompanied by emotional responses. Dyspnea has been defined as "a subjective experience of breathing discomfort that consists of qualitatively distinct sensations that vary in intensity," and the experience "derives from interactions among multiple physiologic, psychologic, social, and environmental factors." Although this definition recognizes the complexity of dyspnea perception, commonly used dyspnea measures do not adequately assess this complexity.
Dyspnea research is currently hampered by the lack of a single instrument to measure different aspects of respiratory discomfort in a variety of settings. A number of clinical dyspnea instruments provide indirect measurement of several aspects of patients' experience of dyspnea. Most clinical questionnaires rely on patient recall to assess daily activities and do not directly scale sensation. Single-dimension scales (eg, visual analog, Borg, number) are widely used to measure dyspnea, especially in experimental settings. The rating of the perceptual dimension often is poorly defined in published reports, and the meaning can vary across studies (eg, a laboratory subject breathing against a resistive load and rating the intensity of effort, a patient in an ED rating emotional distress). Specifically, the original descriptor list developed by Simon et al has been used by several investigators in the exploration of how individuals would describe breathlessness in various conditions and settings. However, others have modified the list such that comparison across investigations is difficult.
The Multidimensional Dyspnea Profile (MDP) is a comprehensive instrument designed to measure sensory and affective dimensions of dyspnea. The conceptual model we proposed for dyspnea asserts that each item in the MDP has the potential to vary separately from the others under some circumstances. Our approach in developing this instrument was based on the multidimensional model of pain. Intensity (strength of sensation), quality, unpleasantness, and emotion are distinct aspects of pain perception, with evidence accumulating that these dimensions are also relevant to dyspnea perception. Advances in the ability to understand and measure the several dimensions of dyspnea could facilitate comparison of different laboratory models and different disease states based on quantifiable data rather than on intuition and argument; thus, it can lead to better experimental design and clinical practice.
Data thus far support the model concept that the component items can vary with some independence. An earlier laboratory experiment confirmed that the sensory quality of work/effort can vary independently from the sensory quality of air hunger and showed that sensory intensity can vary independently from immediate unpleasantness. Another laboratory investigation confirmed that the MDP is responsive to treatment with morphine. The MDP is rooted in these findings and the model because it is designed to measure sensory and affective dimensions of dyspnea while supporting the relative independence of these dimensions. The purpose of this study was to provide initial reliability and validity estimates of the MDP when administered to the same individuals in two settings: during an ED visit and at an outpatient follow-up visit 4 to 6 weeks later.