The article by Polley et al1 in this issue of CHEST (see page 295) illustrates the use of symptom questionnaires to quantify cough and gain a better understanding about its relationship to the underlying diseases. Its findings are predicated on the validity of the instruments that were used.
Laboratory measurements and biomarkers of disease have turned medicine from a profession that was solely skilled based to one that is founded on solid science. However, the ultimate outcome of treatment is to improve clinical outcomes. These are things that are identified by the patients themselves: symptoms, well-being, and ability to perform daily tasks and function as healthy people do.2 Laboratory measurements of disease severity are only markers of outcome. Indeed many may be surrogate markers (ie, markers of other markers), for example diffusion capacity of the lung for carbon monoxide as a marker for CT lung densitometry as a marker of emphysema.