Conclusion
At a fundamental level, reliability estimates can be thought of as signal-to-noise ratios. Undoubtedly, there is greater noise in symptom self-reports than in many measures of more objective data. However, 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 MDP. 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.