Validity and Prognostic Value of the UCSD Dyspnea Questionnaire in Fibrotic Hypersensitivity Pneumonitis: A Multicenter Prospective Study

RATIONALE: Dyspnea is a prominent symptom of fibrotic hypersensitivity pneumonitis (fHP), limiting patients' activity and impairing their quality of life. The University of California San Diego Shortness of Breath questionnaire (UCSD-SOBQ) is a 24-item instrument used to assess dyspnea severity in patients with various respiratory conditions. OBJECTIVES: This study aimed to examine the reliability and responsiveness of the UCSD-SOBQ score, its validity as a measure of dyspnea severity, and its prognostic value in a prospective cohort with fHP. METHODS: We conducted psychometric analyses on UCSD-SOBQ response data and assessed the association between score changes and survival in patients with fHP who completed the UCSD-SOBQ and other HP severity metrics at baseline, 6 and 12 months. We introduce the reliable change index (RCI) and the likely change index (LCI) to assess the statistical significance of within-individual change in UCSD scores. RESULTS: At baseline, internal consistency was high (Cronbach's alpha = 0.97). Significant moderately strong correlations were observed between UCSD-SOBQ scores and percent predicted forced vital capacity (FVC%), r = -0.46, percent predicted diffusing capacity of the lung for carbon monoxide (DLCO%), r = -0.32, and Borg dyspnea scores r = 0.56. UCSD-SOBQ scores were significantly different between the lowest and highest strata of FVC% (64.9 ± 18.9 vs. 36.2 ± 22.9), DLCO% and Borg scores. The threshold for worsening within-individual change in the UCSD-SOBQ score at 95% confidence was 12 points. A 1-point higher baseline UCSD-SOBQ score was associated with a 2% increase in the risk of death or transplant (HR 1.02, 95% CI 1.00, 1.04). CONCLUSIONS: In fHP, the UCSD-SOBQ score is a reliable and valid measure of dyspnea severity, is responsive to change, discriminates patients with differing severities, and is associated with transplant free survival. Additional qualitative data and psychometric analyses could tailor the UCSD-SOBQ to fHP and may further improve its measurement properties.