Background

We propose a modified quality-adjusted life year (QALY) calculation that aims to be consistent with guidance for interpreting change in patient-reported outcomes. This calculation incorporates the minimally important difference (MID) in generic preference-based health-related quality of life (HRQL) change scores to reflect what might be considered meaningful HRQL improvement/deterioration. In doing so, we review common issues in QALY calculations such as adjustment for baseline scores and standardizing for between-group differences.

Methods

Using EQ-5D-5L outcome data from the Alberta TEAMCare-Primary Care Network trial in the management of depression for patients with type 2 diabetes (n = 98), this study compared results from different QALY calculation methods to investigate the impact of (i) adjusting for baseline HRQL score, (ii) standardizing between-group differences at baseline, and (iii) adjusting for ‘meaningful’ HRQL changes. The following QALY calculation methods are examined: area under curve (QALY-AUC), change from baseline (QALY-CFB), regression modelling (QALY-R), and incorporating an MID for HRQL changes from baseline (QALY-MID).

Results

The incremental QALY-AUC estimate favoured the Collaborative Care group (0.031) while the incremental QALY-CFB (−0.028) estimate favoured Enhanced Care. Adjusting for meaningful HRQL changes resulted in a crude incremental QALY-MID of −0.023; however, after adjusting for between-group differences at baseline, QALY-R and adjusted incremental QALY-MID estimates were −0.007 and −0.001, respectively. In addition, recursive regression analyses showed that very low baseline HRQL scores impact incremental QALY estimates.

Conclusions

Uncertainty in incremental QALY estimates reflects uncertainty in the value of small within-individual change as well as the impact of small differences between groups at baseline. Applying a responder-definition approach yielded crude and adjusted QALY-MID estimates that were more in favour of Collaborative Care than QALY-CFB and QALY-R estimates, respectively, suggesting that ambiguous small changes in HRQL scores have the potential to influence QALY outcomes used in economic or non-economic applications.

中文翻译：

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修改质量调整生命年计算以考虑健康相关生活质量的有意义变化：来自实用临床试验的见解

背景

我们提出了一种改进的质量调整生命年 (QALY) 计算，旨在与解释患者报告结果变化的指南保持一致。该计算结合了基于一般偏好的健康相关生活质量 (HRQL) 变化评分的最小重要差异 (MID)，以反映可能被认为有意义的 HRQL 改善/恶化。在此过程中，我们回顾了 QALY 计算中的常见问题，例如基线分数的调整和组间差异的标准化。

方法

本研究使用来自 Alberta TEAMCare-Primary Care Network 试验的 EQ-5D-5L 结果数据来管理 2 型糖尿病患者的抑郁症（n  = 98），比较了不同 QALY 计算方法的结果，以调查（i ) 调整基线 HRQL 评分，(ii) 标准化基线组间差异，以及 (iii) 调整“有意义的” HRQL 变化。检查了以下 QALY 计算方法：曲线下面积 (QALY-AUC)、基线变化 (QALY-CFB)、回归建模 (QALY-R)，以及合并用于 HRQL 从基线变化的 MID (QALY-MID)。

结果

增量 QALY-AUC 估计有利于协作护理组 (0.031)，而增量 QALY-CFB (-0.028) 估计有利于增强护理。调整有意义的 HRQL 变化导致 QALY-MID 的粗增量为 -0.023；然而，在调整基线组间差异后，QALY-R 和调整后的增量 QALY-MID 估计值分别为 -0.007 和 -0.001。此外，递归回归分析表明，非常低的基线 HRQL 分数会影响增量 QALY 估计。

结论

增量 QALY 估计的不确定性反映了个体内部小变化价值的不确定性以及基线组间小差异的影响。应用响应者定义方法得到粗略和调整后的 QALY-MID 估计值，分别比 QALY-CFB 和 QALY-R 估计值更支持协作护理，这表明 HRQL 分数的模糊小变化有可能影响使用的 QALY 结果在经济或非经济应用中。