Visual analogue scores for interstitial lung disease: a prospective validation study

Abstract

Background: Visual analogue scores (VAS) are simple symptom assessment tools which have not been validated in interstitial lung disease (ILD). There is a need for valid measures of ILD progression and therapeutic response. Aims and objectives: - To validate VAS to assess change in dyspnoea, cough and fatigue in ILD - To define the minimal clinically important difference (MCID) for change in these Methods: 64 patients with ILD completed VAS for dyspnoea, cough and fatigue. Baseline K-BILD scores, pulmonary function and 6-minute walk test results were collected. Tests were repeated 3-6 months later, in addition to a 7-point Likert scale. The MCID was estimated using median change in VAS in patients who reported a “small but significant change” in symptoms at follow- up, and confirmed against other objective and subjective measurements. The process was repeated in a validation cohort of 31 ILD patients to confirm findings. Results: VAS scores were significantly higher for patients who reported a “small but significant change” in symptoms versus “no change” or “not significant” change (p Change in VAS Dyspnoea correlated with change in KBILD (r=-0.51, p=0.000), FVC (r=-0.32, p=0.010) and 6MWD (r=-0.37, p=0.007), but not with change in DLCO. Conclusion: The VAS is valid for assessing change in dyspnoea and fatigue in ILD. The MCID is estimated as 22mm for dyspnoea and 14.5mm for fatigue. This could be used to detect treatment response or disease progression.