PHYSICIANS HAVE always measured clinical phenomena. In each clinical encounter, the doctor makes a diagnosis, gauges the severity of disease, and uses this information to guide a therapeutic recommendation or predict what will happen next. Assessing, judging, and then recommending are the art of medicine.
We must codify this art if we are to improve the quality of clinical care. We must accurately observe, record, and communicate information about disease to determine (and learn from others) a disease's natural history, prognosis, and response to therapy. But much important information about disease cannot be quantified easily. For us in dermatology, the challenges are apparent: no laboratory tests exist for most of the diseases we treat, and we most often gauge severity of disease by talking to patients and by examining them. Thus, if we are to improve our care by observing it and studying it in controlled circumstances such as clinical trials, we need to develop accurate measures of patients' reports and of our physical examinations—clinical assays, as it were.