Stein Ken, Dyer Matthew, Milne Ruairidh, Round Alison, Ratcliffe Julie, Brazier John
Peninsula Technology Assessment Group, Peninsula Medical School, University of Exeter, Exeter, UK.
Qual Life Res. 2009 May;18(4):509-18. doi: 10.1007/s11136-009-9446-6. Epub 2009 Mar 3.
Precision is a recognised requirement of patient-reported outcome measures but no previous studies of the precision of methods for obtaining health state values from the general public, based on specific health state descriptions or vignettes, have been carried out. The methodological requirements of policy makers internationally is driving growth in the use of methods to obtain utilities from the general public to inform cost per quality-adjusted life-year (QALY) analyses of health technologies being considered for adoption by health systems.
The precision of five comparisons of the outcomes of treatments, based on health state descriptions, was assessed against the results of clinical trials which showed a statistically and clinically significant improvement using an internet panel of members of the UK general public. Health states were developed to depict the baseline and post-treatment states from these exemplar clinical trials. Preferences for health states were obtained using bottom-up titrated standard gamble over the internet, and differences between summary health state values corresponding to the treatment and comparator groups within each exemplar study were compared. Results are considered in the context of various estimates for the minimally important difference in utility values.
Participation among members of the internet panel in the five exemplars ranged from 27 to 59. In four of the five exemplars, the utility-based estimates of treatment benefit showed significant differences between groups and were greater than an assumed minimally important difference of 0.1. Mean utility differences between groups were: 0.23 (computerised cognitive behavioural therapy for depression, P < 0.001), 0.11 (hip resurfacing for hip osteoarthritis, P < 0.001), 0.0005 (cognitive behavioural therapy for insomnia, P = 0.98), 0.15 (pulmonary rehabilitation for COPD, P < 0.001) and 0.11 (infliximab for Crohn's disease, P < 0.001). The confidence intervals around the estimates of utility-based treatment effect in three of the five examples did not exclude the possibility of a difference smaller than a minimally important difference of 0.1. Recent empirical evidence suggests a lower minimally important difference (0.03) may be more appropriate, in which case our results provide further reassurance of preservation of precision in health state description and valuation.
The precision of estimates of treatment effects based on preference data obtained from disease-specific measurements in clinically significant studies of health technologies was acceptable using an internet-based panel of members of the general public and the standard gamble. Definition of the minimally important difference in utility estimates is required to adequately assess precision and should be the subject of further research.
精准度是患者报告结局测量的一项公认要求，但此前尚未开展过基于特定健康状态描述或案例，从普通公众中获取健康状态值的方法的精准度研究。国际上政策制定者的方法学要求推动了从普通公众中获取效用值以用于卫生系统考虑采用的卫生技术的质量调整生命年（QALY）成本分析的方法使用的增长。
基于健康状态描述，对五种治疗结局比较的精准度进行评估，并与临床试验结果进行对比，该临床试验显示使用英国普通公众成员的互联网小组有统计学和临床意义的改善。开发健康状态以描述这些示例性临床试验的基线和治疗后状态。通过互联网使用自下而上滴定的标准博弈法获得对健康状态的偏好，并比较每个示例性研究中对应治疗组和对照组合并健康状态值之间的差异。在效用值最小重要差异的各种估计背景下考虑结果。
互联网小组的成员在五个示例中的参与率从27%到59%不等。在五个示例中的四个中，基于效用的治疗益处估计显示组间存在显著差异，并且大于假设的最小重要差异0.1。组间平均效用差异为：0.23（抑郁症的计算机化认知行为疗法，P < 0.001），0.11（髋骨关节炎的髋关节表面置换术，P < 0.001），0.0005（失眠的认知行为疗法，P = 0.98），0.15（慢性阻塞性肺疾病的肺康复，P < 0.001）和0.11（克罗恩病的英夫利昔单抗，P < 0.001）。五个示例中的三个基于效用的治疗效果估计周围的置信区间并未排除差异小于最小重要差异0.1的可能性。最近的经验证据表明较低的最小重要差异（0.03）可能更合适，在这种情况下，我们的结果进一步保证了健康状态描述和估值中精准度的保持。
在对卫生技术进行具有临床意义的研究中，使用基于互联网的普通公众成员小组和标准博弈法，基于从疾病特异性测量中获得的偏好数据的治疗效果估计的精准度是可以接受的。需要定义效用估计中的最小重要差异以充分评估精准度，并且这应该是进一步研究的主题。
