The University of California in San Diego Shortness of Breath Questionnaire (UCSD SOBQ) has been used to assess dyspnea-related activity limitation in patients with airway and parenchymal lung disease. We sought to assess the construct validity and responsiveness of the UCSD SOBQ in systemic sclerosis (SSc; scleroderma) patients with incident pulmonary hypertension (PH) and those at high risk of developing PH.
We used data from 179 patients enrolled in the Pulmonary Hypertension Assessment and Recognition of Outcomes in Scleroderma Registry with pre-PH (defined by criteria on pulmonary function tests and/or echocardiogram) or definite PH with mean pulmonary artery pressure ≥25 mm Hg by right-sided heart catheterization within 6 months of enrollment. For this analysis, we included those subjects with complete data for self-reported measures at baseline and at 12 months.
At baseline, the UCSD SOBQ had strong correlations in the expected direction with the disability index (DI) of the Health Assessment Questionnaire (HAQ) (r = 0.71, P < 0.0001), dyspnea assessment by visual analog scale (r = 0.71, P < 0.0001), and the Short Form 36 (SF-36) health survey physical component summary (PCS) score (r = -0.77, P < 0.0001), as well as a moderate correlation with the 6-minute walk test distance (r = -0.33, P < 0.0001), Borg dyspnea score (r = 0.47, P < 0.0001), and diffusing capacity of carbon monoxide (r = -0.33, P < 0.0001). Change in the UCSD SOBQ at 12 months correlated in the expected direction with change in the HAQ DI (r = 0.54, P < 0.0001) and change in the SF-36 PCS (r = -0.44, P < 0.0001). Multivariate analysis adjusting for age, sex, and race identified male sex as a significant predictor of death (odds ratio [OR] 7.00, 95% confidence interval [95% CI] 1.55-31.76), while the UCSD SOBQ showed a strong trend toward significance (OR 1.82, 95% CI 0.97-3.41).
The UCSD SOBQ demonstrates good construct validity and responsiveness to change in SSc patients with pulmonary vascular disease.