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BACKGROUND: The minimal important difference (MID) is essential for interpreting the results of randomised controlled trials (RCTs). Despite a number of RCTs in patients with malignant pleural effusions (MPEs) which use the visual analogue scale for dyspnea (VASD) as an outcome measure, the MID has not been established. METHODS: Patients with suspected MPE undergoing a pleural procedure recorded their baseline VASD and their post-procedure VASD (24 hours after the pleural drainage), and in parallel assessed their breathlessness on a 7 point Likert scale. FINDINGS: The mean decrease in VASD in patients with a MPE reporting a 'small but just worthwhile decrease' in their dyspnea (i.e. equivalent to the MID) was 19mm (95% CI 14-24mm). The mean drainage volume required to produce a change in VASD of 19mm was 760ml. INTERPRETATION: The mean MID for the VASD in patients with a MPE undergoing a pleural procedure is 19mm (95% CI 14-24mm). Thus choosing an improvement of 19mm in the VASD would be justifiable in the design and analysis of future MPE studies.

Original publication

DOI

10.1371/journal.pone.0123798

Type

Journal article

Journal

PLoS One

Publication Date

2015

Volume

10

Keywords

Aged, Breast Neoplasms, Carcinoma, Non-Small-Cell Lung, Drainage, Dyspnea, Female, Humans, Male, Mesothelioma, Middle Aged, Ovarian Neoplasms, Pleural Effusion, Malignant, Severity of Illness Index, Surveys and Questionnaires, Visual Analog Scale