Defining the minimal important difference for the visual analogue scale assessing dyspnea in patients with malignant pleural effusions.

Journal article

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.

Authors: Mishra, E; Corcoran, J; Hallifax, R; Stradling, J; Maskell, N

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: PLOS
• Journal: PLoS ONE
• Volume: 10
• Issue: 4
• Article number: e0123798
• Publication date: 2015-01-01
• DOI: 10.1371/journal.pone.0123798
• EISSN: 1932-6203
• Language: English