Using Bookmarking to Reveal Dyspnea Severity Categorizations According to Patients with Interstitial Lung Disease and the Physicians Who Treat Them.

Dyspnea impairs the quality of life of patients with interstitial lung disease (ILD). To deliver the best care to patients with ILD, practitioners must understand how patients view and categorize dyspnea severity. Item response theory (IRT) analyses use a probabilistic model to explain the association between an abstract construct (here, dyspnea severity) and observed data (e.g., responses to a dyspnea questionnaire). Bookmarking is a method for establishing cut-points along the range of a questionnaire's score to define severity categories. We performed an IRT analysis on response data from the University of California San Diego Shortness of Breath questionnaire administered at the time of enrollment into the Pulmonary Fibrosis Foundation Patient Registry (PFF-PR). Results of the IRT were used to generate a book of hypothetical patient vignettes, which were ordered from no dyspnea (first page) to most severe dyspnea (last page). Convenience samples of patients with ILD and ILD physicians were recruited to work in groups to decide where bookmarks should be placed to divide the vignette book into categories of overall dyspnea severity. Data from 1,760 patients in the PFF-PR were used in the IRT analysis. Twenty-one vignettes were generated to cover the full spectrum of dyspnea severity. There appeared to be no differences in bookmark positions between female and male ILD physicians or between patient groups based on supplemental oxygen use. Patients and physicians bookmarked dyspnea similarly at the mild end of the dyspnea severity spectrum, but at the severe end, patients rated dyspnea more severely than physicians. When applied back to the registrants in the PFF-PR, patients' bookmarks categorized 177 (10%) registrants with more severe dyspnea than physicians' bookmarks, including 159 (9%) registrants who would be classified with "severe" dyspnea according to patients but only "moderate" dyspnea according to the physicians. Patients and ILD physicians categorize dyspnea similarly at the milder end of the severity spectrum, but patients view dyspnea more severely than physicians at the higher end. Remaining aware of this in clinical encounters could improve understanding of patients' experiences living with ILD and enhance empathy in the patient-physician relationship.