HALYs and QALYs and DALYs, Oh My: Similarities and Differences in Summary Measures of Population Health

Abstract

Key Words burden of disease, cost-effectiveness analysis, health-related quality of life s Abstract Health-adjusted life years (HALYs) are population health measures permitting morbidity and mortality to be simultaneously described within a single number. They are useful for overall estimates of burden of disease, comparisons of the relative impact of specific illnesses and conditions on communities, and in economic analyses. Quality-adjusted life years (QALYs) and disability-adjusted life years (DALYs) are types of HALYs whose original purposes were at variance. Their growing importance and the varied uptake of the methodology by different U.S. and international entities makes it useful to understand their differences as well as their similarities. A brief history of both measures is presented and methods for calculating them are reviewed. Methodological and ethical issues that have been raised in association with HALYs more generally are presented. Finally, we raise concerns about the practice of using different types of HALYs within different decision-making contexts and urge action that builds and clarifies this useful measurement field.

Optimization of Prostate Biopsy Referral Decisions

“…In the sensitivity analysis, the lower bound of λ takes 0.97, the most commonly used value in the health economics literature for cost effectiveness studies (Gold et al 2002) (note that no upper bound is evaluated in this case). When λ reduced to 0.97 the optimal biopsy threshold increased significantly, implying more aggressive prostate cancer screening when a greater discount applies to the future QALYs.…”

“…In this sense, the optimal value is the most sensitive to λ. The use of a discount factor, particularly over long time frames, has been a highly debated topic for decades (see Gold et al 2002 for a discussion of this). From Figure 6, Figure 6 One-way sensitivity analysis on optimal values for model parameters: dt (annual probability of death from other causes), wt (annual probability of prostate cancer incidence), zt (annual probability of death from metastatic prostate cancer), γ (annual disutility of having metastasis), e (annual probability of developing metastasis from state C), (annual disutility of treatment), µ (disutility of biopsy), f (biopsy detection rate), and b (annual probability of developing metastasis from state T ).…”

“…QALYs are commonly employed in the health policy literature and are based on a decrement (from a nominal life year of 1.0) to represent the patient's perceived value of a year of life in a particular health state. Gold et al (2002) provide a review of QALYs, and Packer (1968) and Fanshel and Bush (1970) are early references on the use of QALYs in the operations research literature. We used QALYs as the criteria for our study because they are the standard used in the medical decision making literature.…”

Economic context analysis in mental health care. Usability of health financing and cost of illness studies for international comparisons

“…They measure, for example, the number of years lived with disability or impaired quality of life. They help establish a 'classification (Gold et al 2002;Ayuso-Mateos et al 2006) and would not be treated here. The consideration of the relevance of mental health needs displayed by BoD measurements would certainly impact the amount required for expenditure on health as well as to guide allocation of resources, both national or those linked to aid, key questions in all environments (Health Affairs, 2007;Savedoff, 2007).…”

The structure of optimal statin initiation policies for patients with Type 2 diabetes

“…Quality-adjusted life years (QALYs) are commonly used for treatment evaluation and health policy investigations (Gold et al, 2002). We use QALYs to adjust raw life years to account for the reduction in quality of life associated with side effects from statin treatment and consider the question of if and when to initiate statin treatment to maximize a Type 2 diabetes patient's QALYs prior to the occurrence of the first CHD or stroke event, or death from all other causes.…”