Redelmeier D A, Guyatt G H, Goldstein R S
Department of Medicine, University of Toronto, Ontario, Canada.
J Clin Epidemiol. 1996 Nov;49(11):1215-9. doi: 10.1016/s0895-4356(96)00206-5.
We have developed a method for estimating the minimally important difference (MID) for health status measures. Whereas the conventional approach requires patients to judge themselves relative to their memories, our method requires patients to judge themselves relative to others with the same condition. In this study we examined whether our method (based on between-patient differences) and the conventional method (based on within-patient changes) provides comparable estimates of the MID for one health status measure: the Chronic Respiratory Questionnaire. Patients with chronic obstructive pulmonary disease who were participating in a supervised respiratory rehabilitation program were included if they were in stable health (n = 112). Their mean score per question in the Chronic Respiratory Questionnaire was 4.5 (range, 1 to 7; where bigger values indicate better health). Our method estimated that the MID was 0.5 (95% confidence interval 0.4 to 0.7). This estimate was similar to the MID previously found using the conventional method. These observations support the role of the Chronic Respiratory Questionnaire for measuring patient's symptoms, the validity of our approach for assessing the MID, and an estimate on the order of 0.5 as the threshold for this particular health status measure.
我们开发了一种估算健康状况测量中最小重要差异（MID）的方法。传统方法要求患者根据自身记忆进行自我判断，而我们的方法要求患者将自己与患有相同疾病的其他人进行比较来进行自我判断。在本研究中，我们检验了我们的方法（基于患者间差异）和传统方法（基于患者自身变化）对于一种健康状况测量指标——慢性呼吸问卷，是否能提供可比的MID估计值。如果慢性阻塞性肺疾病患者健康状况稳定（n = 112），且正在参加一项有监督的呼吸康复项目，那么他们会被纳入研究。他们在慢性呼吸问卷中每个问题的平均得分是4.5（范围为1至7；分值越高表明健康状况越好）。我们的方法估计MID为0.5（95%置信区间为0.4至0.7）。这个估计值与先前使用传统方法得出的MID相似。这些观察结果支持了慢性呼吸问卷在测量患者症状方面的作用、我们评估MID方法的有效性，以及0.5左右的值作为这一特定健康状况测量指标阈值的估计。
