School of Public Health, The University of Hong Kong, 1/F Patrick Manson Building, 7 Sassoon Road, Pokfulam, Hong Kong.
Department of Medical Oncology, National Cancer Center, Singapore, Singapore.
Appl Health Econ Health Policy. 2018 Oct;16(5):685-695. doi: 10.1007/s40258-018-0404-8.
Health-related quality-of-life (HRQoL) measures are commonly mapped to a value that represents a utility for economic evaluation via regression models, which may lead to shrinkage of the variance.
This study aimed to develop and compare conversion functions that map the Functional Assessment of Cancer Therapy-Breast (FACT-B) total score to the EuroQoL 5-Dimensions, 5-Levels (EQ-5D-5L) utility value via four methods.
We used the HRQoL scores of 238 Singapore patients with breast cancer to develop the conversion function for the equipercentile, linear equating, mean rank and ordinary least squares (OLS) methods. We compared the distributions of the observed values and the four sets of mapped values and performed regression analyses to assess whether the association with risk factors was preserved by utility values derived from mapping.
At baseline, the observed EQ-5D-5L utility value had a mean ± standard deviation (SD) of 0.820 ± 0.152, and 24.8% of the respondents attained a value of 1. The OLS method (mean 0.820; SD 0.112; proportion 0%) better agreed with the observed data than the equipercentile (mean 0.831; SD 0.152; proportion 23.5%), linear equating (mean 0.814; SD 0.145; proportion 11.8%) and mean rank method (mean 0.821; SD 0.147; proportion 23.9%). The significance of association was preserved for all parameters involved in the regression analyses by the equipercentile and linear equating methods, but the mean rank and OLS methods were inconsistent with the observed data for one and two parameters, respectively.
The problem of shrinkage in the variance occurred in the OLS method, but it provided an unbiased estimate for the mean and better agreement. Among the other three linking methods, the mean rank method better described the distribution, whereas the equipercentile and linear equating methods better assessed the association with risk factors.
健康相关生活质量（HRQoL）测量通常通过回归模型映射到代表经济评估效用的值，这可能导致方差缩小。
本研究旨在通过四种方法开发和比较将癌症治疗功能评估-乳房（FACT-B）总分映射到欧洲五维健康量表（EQ-5D-5L）效用值的转换函数。
我们使用了 238 名新加坡乳腺癌患者的 HRQoL 评分，为等百分位、线性等价、平均秩和普通最小二乘法（OLS）方法开发了转换函数。我们比较了观察值和四组映射值的分布，并进行了回归分析，以评估通过映射得出的效用值是否保留了与危险因素的关联。
在基线时，观察到的 EQ-5D-5L 效用值的平均值为±标准偏差（SD）0.820±0.152，24.8%的受访者获得了 1 的值。OLS 方法（平均值 0.820；SD 0.112；比例 0%）比等百分位（平均值 0.831；SD 0.152；比例 23.5%）、线性等价（平均值 0.814；SD 0.145；比例 11.8%）和平均秩方法（平均值 0.821；SD 0.147；比例 23.9%）更符合观察数据。在回归分析中，所有涉及的参数的关联意义都被等百分位和线性等价方法保留，但平均秩和 OLS 方法分别对一个和两个参数的观察数据不一致。
OLS 方法中出现了方差缩小的问题，但它提供了平均值的无偏估计值，并更好地吻合。在其他三种链接方法中，平均秩方法更好地描述了分布，而等百分位和线性等价方法更好地评估了与危险因素的关联。
