Background Quality-adjusted life years (QALYs) are widely used to measure the impact of various diseases on both the quality and quantity of life and in their economic valuations. It will be clinically important and informative if we can estimate QALYs based on measurements of depression severity. Objective To construct a conversion table from the Patient Health Questionnaire-9 (PHQ-9), the most frequently used depression scale in recent years, to the Euro-Qol Five Dimensions Three Levels (EQ-5D-3L), one of the most commonly used instruments to assess QALYs. Methods We obtained individual participant data of randomised controlled trials of internet cognitive-behavioural therapy which had administered depression severity scales and the EQ-5D-3L at baseline and at end of treatment. Scores from depression scales were all converted into the PHQ-9 according to the validated algorithms. We used equipercentile linking to establish correspondences between the PHQ-9 and the EQ-5D-3L. Findings Individual-level data from five trials (total N=2457) were available. Subthreshold depression (PHQ-9 scores between 5 and 10) corresponded with EQ-5D-3L index values of 0.9–0.8, mild major depression (10–15) with 0.8–0.7, moderate depression (15–20) with 0.7–0.5 and severe depression (20 or higher) with 0.6–0.0. A five-point improvement in PHQ-9 corresponded approximately with an increase in EQ-5D-3L score by 0.03 and a ten-point improvement by approximately 0.25. Conclusions and Clinical Implications The conversion table between the PHQ-9 and the EQ-5D-3L scores will enable fine-grained assessment of burden of depression at its various levels of severity and of impacts of its various treatments. Data are available upon reasonable request. The overall database used for this IPD is restricted due to data sharing agreements with the research institutes where the studies were conducted. IPD from individual studies are available from the individual study authors.

中文翻译：

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我们如何根据 PHQ-9 分数估算 QALYs？PHQ-9 和 EQ-5D 的等百分位链接分析

背景 质量调整生命年 (QALY) 被广泛用于衡量各种疾病对生活质量和数量及其经济价值的影响。如果我们可以根据抑郁症严重程度的测量值来估计 QALYs，这将具有临床重要性和信息量。目的 构建从近年来最常用的抑郁量表患者健康问卷 9（PHQ-9）到 Euro-Qol 五维三级（EQ-5D-3L）的转换表，这是最常用的抑郁量表之一。评估 QALY 的常用工具。方法 我们获得了互联网认知行为疗法随机对照试验的个体参与者数据，这些试验在基线和治疗结束时进行了抑郁严重程度量表和 EQ-5D-3L。根据经过验证的算法，抑郁量表的分数全部转换为 PHQ-9。我们使用等百分位链接来建立 PHQ-9 和 EQ-5D-3L 之间的对应关系。结果 来自五项试验（总 N=2457）的个体水平数据可用。阈下抑郁（PHQ-9 评分在 5 到 10 之间）对应于 EQ-5D-3L 指数值 0.9-0.8，轻度重度抑郁 (10-15) 对应 0.8-0.7，中度抑郁 (15-20) 对应 0.7-0.5和严重抑郁症（20 或更高），0.6-0.0。PHQ-9 的 5 分提高大约对应于 EQ-5D-3L 得分提高 0.03 和 10 分提高约 0.25。结论和临床意义 PHQ-9 和 EQ-5D-3L 分数之间的转换表将能够对抑郁症的各种严重程度的负担及其各种治疗的影响进行细粒度的评估。可应合理要求提供数据。由于与开展研究的研究机构签订了数据共享协议，用于本 IPD 的整个数据库受到限制。个别研究的 IPD 可从个别研究作者处获得。