Mishra Eleanor K, Corcoran John P, Hallifax Robert J, Stradling John, Maskell Nicholas A, Rahman Najib M
Oxford Centre for Respiratory Medicine and Oxford Respiratory Trials Unit, Oxford Biomedical Research Centre, Churchill Hospital, Oxford, United Kingdom.
University of Bristol, Bristol, United Kingdom.
PLoS One. 2015 Apr 15;10(4):e0123798. doi: 10.1371/journal.pone.0123798. eCollection 2015.
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.
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.
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.
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.
最小重要差异（MID）对于解释随机对照试验（RCT）的结果至关重要。尽管有多项针对恶性胸腔积液（MPE）患者的RCT使用视觉模拟呼吸困难量表（VASD）作为结局指标，但尚未确定MID。
接受胸膜手术的疑似MPE患者记录其基线VASD和术后VASD（胸腔引流24小时后），并同时用7点李克特量表评估其呼吸困难程度。
报告呼吸困难有“轻微但值得的减轻”（即相当于MID）的MPE患者VASD的平均降低值为19mm（95%CI 14 - 24mm）。产生19mm的VASD变化所需的平均引流量为760ml。
接受胸膜手术的MPE患者VASD的平均MID为19mm（95%CI 14 - 24mm）。因此，在未来MPE研究的设计和分析中，选择VASD改善19mm是合理的。
