Interstitial Lung Disease Patients' Global Impressions of Symptoms, Severity Ratings, and Meaningfulness of Changes Over Time

Rationale: In interstitial lung disease (ILD), symptoms drive impairments in health-related quality of life. Patient-reported outcome measures (PROMs) can assess whether interventions change symptom severity. The meaningfulness of change in a PROM score is estimated by anchoring it to a related variable for which meaningful change has been previously established. Patient global impressions of severity (PGISs) are single-item PROMs that may make trustworthy anchors, but, for ILD, the meaningfulness of change in PGIS items for shortness of breath (SOB), cough, and fatigue/low energy are unknown. Objectives: To improve understanding of how patients with ILD rate and categorize symptoms, how differing levels of symptom severity affect lived experiences, and how patients derive and apply meaningfulness to change in symptoms. Methods: We used one-on-one interviews and an electronic survey to collect data from patients with various forms of ILD. Interviews were conducted to provide richness and context to survey responses. We conducted certain analyses with respondents stratified by supplemental oxygen use. Results: Interviewees (N = 18) confirmed SOB, cough, and fatigue/low energy as the most bothersome symptoms of ILD. Among 298 survey respondents, on a PGIS for SOB with a 0-4 numeric rating scale, on average, those who used supplemental O₂ had more severe SOB than nonusers, and most respondents considered a 2-point change meaningful for worsening (45.5%) or improvement (47.2%). On a PGIS with a five-option ordinal response scale, for SOB, most considered a 1-category change meaningful for worsening (49.8%) and a 2-category change meaningful for improvement (42.3); for cough frequency, most respondents considered a 1-category change on the five-option ordinal response scale meaningful for worsening (48.2%) or improvement (45.0%). Survey responses for SOB at the present time versus 3 months earlier (patient global impressions of change) were biased toward the present state. Conclusions: PGISs can be used as anchors for meaningful change analyses of PROMs that assess SOB or cough in patients with ILD. Patient global impressions of change demonstrate present-state bias and should not be used. Patients' descriptions paint a vivid picture of lived experience with varying levels of symptom severity and can help contextualize change scores.