Scott D L, Khoshaba B, Choy E H, Kingsley G H
Department of Rheumatology, King's College London School of Medicine, Weston Education Centre, King's College, Cutcombe Road, London SE5 9RS, UK.
Ann Rheum Dis. 2007 Nov;66(11):1534-7. doi: 10.1136/ard.2007.073726. Epub 2007 Jul 27.
There is growing emphasis on the cost-effectiveness of treating rheumatoid arthritis. Few trials directly record the health utility measures, like EuroQol, needed for economic analyses. Consequently linear regression methods have been used to transform Health Assessment Questionnaire (HAQ) scores into utility measures. The authors examined whether this is justified.
The authors compared HAQ and EuroQol in cross-sectional and treatment change observational studies of rheumatoid arthritis patients; they also measured SF-36 and Nottingham Health Profiles.
In the cross-sectional study, HAQ and EuroQol scores were moderately inversely correlated (Spearman rank correlation, r = 0.76). HAQ showed a Gaussian distribution whereas EuroQol was bimodal. In the treatment change study, changes in HAQ and EuroQol were unrelated (r = 0.08); the changes showed similar Gaussian and bimodal distributions.
Not all patient-based measures are analogous, and evidence of clinical equivalence, especially in treatment response, is needed before data transformation is considered. Specifically, as HAQ and EuroQol are demonstrably not equivalent, economic evaluations of treatment cost effectiveness should not be based on EuroQol data transformed from HAQ. The use of such transformed data by regulatory bodies which determine drug availability means that the issue is no longer only of academic interest but a real clinical concern.
类风湿关节炎治疗的成本效益日益受到重视。很少有试验直接记录经济分析所需的健康效用指标，如欧洲五维度健康量表（EuroQol）。因此，线性回归方法已被用于将健康评估问卷（HAQ）评分转换为效用指标。作者研究了这样做是否合理。
作者在类风湿关节炎患者的横断面和治疗变化观察性研究中比较了HAQ和EuroQol；他们还测量了SF-36和诺丁汉健康概况。
在横断面研究中，HAQ和EuroQol评分呈中度负相关（斯皮尔曼等级相关，r = 0.76）。HAQ呈高斯分布，而EuroQol呈双峰分布。在治疗变化研究中，HAQ和EuroQol的变化不相关（r = 0.08）；变化呈现出相似的高斯和双峰分布。
并非所有基于患者的指标都是类似的，在考虑数据转换之前，需要有临床等效性的证据，尤其是在治疗反应方面。具体而言，由于HAQ和EuroQol明显不等效，治疗成本效益的经济评估不应基于从HAQ转换而来的EuroQol数据。监管机构在确定药物可及性时使用此类转换后的数据，这意味着该问题不再仅仅是学术上的兴趣，而是一个实际的临床问题。
