Objectives: Quality-adjusted life-years (QALYs) and disability-adjusted life-years (DALYs) are commonly used in cost-effectiveness analysis (CEA) to measure health benefits. We sought to quantify and explain differences between QALY- and DALY-based cost-effectiveness ratios, and explore whether using one versus the other would materially affect conclusions about an intervention's cost-effectiveness.
Methods: We identified CEAs using both QALYs and DALYs from the Tufts Medical Center CEA Registry and Global Health CEA Registry, with a supplemental search to ensure comprehensive literature coverage. We calculated absolute and relative differences between the QALY- and DALY-based ratios, and compared ratios to common benchmarks (e.g., 1× gross domestic product per capita). We converted reported costs into US dollars.
Results: Among eleven published CEAs reporting both QALYs and DALYs, seven focused on pharmaceuticals and infectious disease, and five were conducted in high-income countries. Four studies concluded that the intervention was "dominant" (cost-saving). Among the QALY- and DALY-based ratios reported from the remaining seven studies, absolute differences ranged from approximately $2 to $15,000 per unit of benefit, and relative differences from 6-120 percent, but most differences were modest in comparison with the ratio value itself. The values assigned to utility and disability weights explained most observed differences. In comparison with cost-effectiveness thresholds, conclusions were consistent regardless of the ratio type in ten of eleven cases.
Conclusions: Our results suggest that although QALY- and DALY-based ratios for the same intervention can differ, differences tend to be modest and do not materially affect comparisons to common cost-effectiveness thresholds.
Keywords: Cost-effectiveness analysis; DALY; Medical-decision; QALY.
Comparing the cost-per-QALYs gained and cost-per-DALYs averted literatures.Version 2. Gates Open Res. 2018 Mar 5;2:5. doi: 10.12688/gatesopenres.12786.2. eCollection 2018. Gates Open Res. 2018. PMID: 29431169 Free PMC article.
Global Patterns of QALY and DALY Use in Surgical Cost-Utility Analyses: A Systematic Review.PLoS One. 2016 Feb 10;11(2):e0148304. doi: 10.1371/journal.pone.0148304. eCollection 2016. PLoS One. 2016. PMID: 26862894 Free PMC article. Review.
Measuring the Benefits of Healthcare: DALYs and QALYs - Does the Choice of Measure Matter? A Case Study of Two Preventive Interventions.Int J Health Policy Manag. 2018 Feb 1;7(2):120-136. doi: 10.15171/ijhpm.2017.47. Int J Health Policy Manag. 2018. PMID: 29524936 Free PMC article.
Global cost-effectiveness of cataract surgery.Ophthalmology. 2007 Sep;114(9):1670-8. doi: 10.1016/j.ophtha.2006.12.013. Epub 2007 Mar 26. Ophthalmology. 2007. PMID: 17383730
When does quality-adjusting life-years matter in cost-effectiveness analysis?Health Econ. 2004 May;13(5):429-36. doi: 10.1002/hec.853. Health Econ. 2004. PMID: 15127423 Review.