In cost-effectiveness analysis (CEA), the consequences of interventions (or programs) held as comparators are measured in natural units such as “life years gained” or “hospitalizations avoided.” When observing this ratio incrementally, the investigator can then estimate the incremental cost to achieve a concomitant improvement in outcome, to yield an incremental cost-effectiveness ratio (ICER). For example, in 2003, it was found that higher multiple birth rates occurred in patients receiving in-vitro fertilization (IVF) as compared to the naturally conceiving population. This circumstance held true even when one embryo was replaced because embryos can split in the course of treatment to create twins, or, in rare circumstances, split twice (with or without resorption of one of the embryos) to create triplets or even quadruplets. This finding was followed up with a CEA to estimate the incremental cost to achieve an additional healthy birth under new embryo transfer policies and to predictive algorithms for forward simulation of risks, costs, and outcomes. In light of the growing epidemic of iatrogenic multiple births, this analysis was invited for presentation in the UK Department of Health public consultation. In the UK Parliament, the results of this work had an immediate impact for it led to a national limit on the number of transferred embryos.
In a special form of CEA called cost-utility analysis (CUA), the consequences of alternative interventions are adjusted by health state preference scores called utility weights. These are the states of health associated with the outcomes that are valued relative to one another. When such patient-reported quality of life is combined with expected years of life remaining, a quality-adjusted life year (QALY) is created. Under such circumstances, the CUA or cost/QALY gained can be evaluated across treatments, programs, and diseases. The Panel on Cost Effectiveness in Health and Medicine has recommended the use of QALYs as the most equitable measure of effect in cost-effectiveness analysis, the use of which was first reported by Zeckhauser and Shepard. The latter, a fellow to the HEU, should be particularly useful to investigators interested in QALYs as part of their studies.
One good example of CUA is the study by Stroupe et al., which evaluated the cost-effectiveness of open versus endovascular repair of abdominal aortic aneurysm in the OVER trial. Another example of QALY use was the clinical trial evaluation by Dr. Jones which evaluated the extent to which quality of life was sustainable over time, and found both maintained and sustained quality of life in patients being treated for primary immune deficiency with high versus low doses of immunoglobulin therapy.