Health Adjusted Life Years (HALY) - A Promising Measure to Estimate the Burden of Zoonotic Diseases on Human Health?

Abstract

Reliable, comprehensive and comparable information on the impact of (zoonotic) diseases on population health are important for policy decision making in Public Health to support allocation processes of scarce resources with best available evidence. Although the availability and quality of health data has increased in the recent past (Boerma et al. 2007, Murray, 2007), there are still relevant limitations when traditional health indicators are used to prioritize diseases and to allocate resources for intervention measures. Difficulties especially come up when comparisons over time, between sub-groups or even between diseases are intended. In the past, major efforts have been made to describe adverse health effects on population level by using traditional epidemiological indicators such as mortality and the derivative life expectancies (e.g. Greenberg et al. 1989; Shi 1993). Infant mortality rates, life expectancies at birth and other indicators from this group are estimated using information on mortality and thus only reflect the fatal contribution to disease burdens. The morbidity of human populations is usually assessed by using incidence or prevalence measures, giving no information on the severity of the disease for human health. Comparability of disease impacts on the health of populations and health related quality of life is limited due to the characteristics and the large variety of indicators. Composite measures such as Health Adjusted Life Years (HALYs) aspire a comprehensive and comparable description of the burden of disease by integrating the impact of both, mortality and morbidity on population health. Especially for zoonoses which can significantly contribute to mortality as well as morbidity, the concept of HALYs can be a helpful technique to comprehensively assess the burden of disease. In addition HALYs can also be an useful metric for the intangible costs of morbidity and mortality to be used in economic analyses evaluating potential control programs for zoonotic diseases considering also their impact on human health.