At the same time, several strengths of this study are notable. Apart from the limitations noted above, our inclusion criteria were broad, and our sample was diagnostically heterogeneous, suggesting that use of the MDP in the ED is not diagnosis-specific. We believe that enhances its potential usefulness in the ED. In conjunction with previous evidence of internal validity of the MDP (e.g., that items Inhibitors,research,lifescience,medical can discriminate between different dyspnea stimuli in controlled experiments [26] and that “now” ratings are responsive to clinical change in the ED [28]), results of the present study support its external validity. In addition, as recommended by Broderick and

colleagues [5], we used a multiple-item instrument, gave clear and consistent instructions as to the rating task and dimensions to be rated, and Inhibitors,research,lifescience,medical recall was referenced to a specific

point in time, the decision to come to the ED. Our results demonstrate high reliability in dyspnea recall when using the MDP during an ED visit and a high degree of similarity in factorial structure to MDP “now” ratings obtained after initiation of treatment [28]. However, we also found that test–retest Inhibitors,research,lifescience,medical reliability was poor for individual items and markedly decreased for domain scores over a 4- to 6-week recall interval between the ED and follow-up visits. Conclusion At a fundamental level, reliability estimates can be thought of as signal-to-noise ratios [18]. Undoubtedly, there is greater noise in symptom self-reports than in many measures of more objective data. However, Inhibitors,research,lifescience,medical at least some of the noise in symptom self-reports comes from asking noisy (e.g., ambiguous or poorly focused) questions, a problem that is potentially treatable by using a reliable and valid questionnaire such as the Inhibitors,research,lifescience,medical MDP [26-28]. Although it might seem intuitive that one should ask patients to recall pre-visit events or perceptions as soon as possible after arrival in the ED, the results of this study suggest that within the

span of an ED visit, recall of dyspnea is sufficiently stable that the actual time lag between arrival and a more detailed assessment with the MDP may not be critical while the patient is in the ED and should not be viewed as a barrier to the use of this measure in the ED. mafosfamide Competing interests MBP, PMM, DS, JA, and PB have no competing interests. Authors’ contributions MBP and PMM conceived of the study and participated in all aspects of its design and coordination, and planned and PF-06463922 mw conducted the statistical analysis. DS and JA participated in the design of the study protocol, data acquisition, and interpretation of results. PB participated in data acquisition and study coordination. MBP wrote the initial draft, and all authors participated in revision of the manuscript for important intellectual content.