Real-world experience: correlation of three dyspnoea questionnaires with measures of disease severity and progression in patients with interstitial lung diseases

BACKGROUND: Dyspnoea is an important clinical and research outcome in patients with interstitial lung diseases (ILD) and idiopathic pulmonary fibrosis (IPF).We evaluated the correlation of the British Medical Research Council (MRC) dyspnoea scale, University of California, San Diego Shortness of Breath (UCSD) questionnaire and St. George's Respiratory Questionnaire (SGRQ) with measures of disease severity and progression in patients with ILD and IPF. METHODS: We applied the three questionnaires to all patients with ILD during initial assessment (baseline visit), at 3-6 months (visit 2) and 9-12 months (visit 3). We used univariate analyses and multiple regression adjusting for age, sex, pulmonary hypertension, ILD diagnosis and forced vital capacity (FVC) to estimate the correlations of questionnaires with pulmonary function tests, 6 min walk test (6MWT) parameters and perceived dyspnoea at baseline visit (disease severity). We assessed the correlation between change (Δ) in dyspnoea questionnaires with change in functional variables between baseline and follow-up visits (progression). RESULTS: We enrolled 151 patients with ILD, 57 of them had IPF. At baseline, all questionnaires significantly correlated with FVC%, total lung capacity (TLC%), carbon monoxide diffusing capacity (DLCO%) and 6MWT metrics. Between visits 1 and 2, MRC-Δ correlated with TLC%-Δ and perceived dyspnoea-Δ and UCSD-Δ with perceived dyspnoea-Δ. Between visits 1 and 3, MRC-Δ correlated with FVC%-Δ and 6MWT distance-Δ; UCSD-Δ correlated with TLC%-Δ . SGRQ-Δ did not correlate with any variables in multivariable analyses. CONCLUSIONS: All questionnaires correlated well with ILD/IPF disease severity at baseline but not with disease progression. Improved questionnaires are needed for patients with ILD.