PURPOSE: The UCSD Shortness-of-Breath Questionnaire (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 SOBQ in scleroderma patients with incident pulmonary hypertension (PH) and those at high risk for developing PH.
METHODS: We used data from 140 patients enrolled in the Pulmonary Hypertension Assessment and Recognition of Outcomes in Scleroderma (PHAROS) study. Criteria for enrollment include age >18, clinical diagnosis of scleroderma (limited or diffuse), and either PH diagnosed by right heart catheterization (mean pulmonary artery pressure ≥25mmHg) OR evidence of "early" PH defined as: either right ventricular systolic pressure of ≥40mmHg on echocardiogram OR either FVC >70% and DLCO < 55% of predicted OR a FVC/DLCO ratio >1.6. For this analysis, we included those subjects with complete data for self-reported measures at baseline and 12 months. Construct validity of the SOBQ was assessed in relation to the Health Assessment Questionnaire (HAQ), the SF-36 physical component summary (SF-PCS), and 6-minute walk distance (6MWD). Responsiveness of the SOBQ was assessed relative to changes in the HAQ, SF-PCS, and 6MWD between baseline and 12 months.
RESULTS: At baseline, the SOBQ (mean±SD, 1.32±1.09) correlated in the expected direction with all measures. Higher SOBQ (greater dyspnea) scores correlated strongly with higher HAQ (worse disability, Spearman’s rho[r< SUB>s< /SUB>]=0.74, p< 0.001) and lower SF-PCS (worse physical health status, r< SUB>s< /SUB>=-0.79, p< 0.001) scores. Higher SOBQ scores had a weak inverse correlation with 6MWD (n=104, r< SUB>s< /SUB>=-0.28, p=0.004). Change in SOBQ over 12 months correlated in the expected direction with changes in self-reported measures (HAQ: r< SUB>s< /SUB>=0.45, p< 0.001; SF-PCS: r< SUB>s< /SUB>=-0.42, p< 0.001), but not with changes in 6MWD (n=70, r< SUB>s< /SUB>=-0.07, p=0.55).
CONCLUSION: The SOBQ demonstrates good construct validity and responsiveness to change in relation to established self-reported measures of health status, but is not responsive to changes in 6MWD.
CLINICAL IMPLICATIONS: The SOBQ may be a useful tool for assessing dyspnea in scleroderma patients with or at risk for developing PH.
DISCLOSURE: Hubert Chen, No Financial Disclosure Information; No Product/Research Disclosure Information