Abstract
Health status is increasingly used in clinical practice to quantify symptom burden and as a clinical trial endpoint in patients with interstitial lung disease (ILD). The Kings Brief Interstitial Lung Disease (KBILD) questionnaire is a brief validated 15-item, disease-specific, health-related quality of life questionnaire that is increasingly used in clinical trials, but little data exist regarding the minimum clinically important difference (MCID). Using pulmonary rehabilitation as a model, we aimed to determine responsiveness of the KBILD and provide estimates of the MCID.
KBILD, Chronic Respiratory Questionnaire (CRQ), Medical Research Council dyspnoea scale (MRC) and incremental shuttle walk test (ISW) were measured in 209 patients with ILD (105 with idiopathic pulmonary fibrosis (IPF)) before and after an outpatient pulmonary rehabilitation programme. Changes with intervention and Cohen's effect size were calculated. Anchor- (linear regression and Receiver Operating Characteristic plots) or distribution-based approaches (0.5 * standard deviation, standard error of measurement) were used to estimate the MCID of KBILD domain and total scores.
KBILD, CRQ, MRC and ISW improved with intervention and the effect sizes of KBILD domain and total scores ranged from 0.28 to 0.38. Using anchor-based estimates, the MCID estimate for KBILD-Psychological, KBILD-Breathlessness and activities and KBILD-Total score were 5.4, 4.4 and 3.9 respectively. Using distribution-based methods, the MCID estimate for KBILD-Chest symptoms was 9.8. The MCID estimates for KBILD in IPF patients were similar.
In patients with ILD and IPF, KBILD is responsive to intervention with an estimated MCID of 3.9 for the total score.
Footnotes
This manuscript has recently been accepted for publication in the European Respiratory Journal. It is published here in its accepted form prior to copyediting and typesetting by our production team. After these production processes are complete and the authors have approved the resulting proofs, the article will move to the latest issue of the ERJ online. Please open or download the PDF to view this article.
Conflict of interest: Dr. Nolan has nothing to disclose.
Conflict of interest: Dr. Birring reports other from Roche, other from Boehringer Ingleheim, other from Galapogos, outside the submitted work.
Conflict of interest: Dr. Maddocks reports grants from NIHR, outside the submitted work.
Conflict of interest: TMM has, via his institution, received industry-academic funding from GlaxoSmithKline R&D and UCB and has received consultancy or speakers fees from Apellis, Astra Zeneca, aTyr Pharma, Bayer, Biogen Idec, Boehringer Ingelheim, Celgene, Galapagos, GlaxoSmithKline R&D, Indalo, Pliant, ProMetic, Roche, Samumed and UCB.
Conflict of interest: Miss. Patel has nothing to disclose.
Conflict of interest: Ms. Barker has nothing to disclose.
Conflict of interest: Ms. Jones has nothing to disclose.
Conflict of interest: Ms. Walsh has nothing to disclose.
Conflict of interest: Miss. Wynne has nothing to disclose.
Conflict of interest: Dr. George reports personal fees and non-financial support from Boehringer Ingelheim, personal fees and non-financial support from Roche Pharmacueticals, personal fees from Teva, outside the submitted work.
Conflict of interest: Dr. Man reports grants from National Institute for Health Research, during the conduct of the study; grants from Pfizer, non-financial support from GSK, personal fees from Mundipharma, personal fees from Novartis, outside the submitted work.
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