6.G. Scientific session: The importance of using country-specific severity distributions in burden of disease indicators
Authors:   Organised by: European Burden of Disease Network, EUPHA-CHR, -PHMR,   Chair persons: Elena von der Lippe (Germany), Hanna Tolonen (EUPHA-PHMR)
Published: October 2024

Abstract

One of the most commonly used health gap summary measures in the field of public health is the Disability-adjusted life year (DALY). It has become the key metric for quantifying the burden of disease (BoD) and is used as an information source for setting priorities for health care and health service planning. The DALY metric quantifies gaps between a theoretical population in perfect health and the current health status related to both morbidity and mortality. It is the sum of the number of healthy life years lost due to disability (YLD) and death (YLL). The YLD summarises the loss of healthy life time using the frequency of diseases differentiated by severities or related health states (including sequelae). Depending on each health state, it converts the time spent with diseases into YLD by weighting each year with health limitation with so-called disability weights. This allows the two indicators YLL and YLD to be added to the DALY. Consequently, severity distributions are a means of describing the range of health loss along specific health states, which enables an accurate mapping with disability weights. For most of the diseases, these distributions are usually categorised as mild, moderate, severe, or no health loss (asymptomatic). Conditions with higher severity levels contribute more to the YLD and thus, to the overall disease specific BoD. The severity distributions are highly dependent on utilization at the individual level, but also on available health care services at the society level, which indicates that differences by settings are to be expected. Changes over time in the share of severe cases, for instance, may reflect the effectiveness of health interventions and policies. This underlines the importance of severity distributions, as they also reflect information about the quality of healthcare for those affected. The Global Burden of Disease (GBD) study applies for a significant proportion of their considered diseases uniform severity distributions across countries and broader regions. They acknowledge concerns over applying estimates of severity distributions based on limited data, noting that it is the only available information that they were able to use. As the YLD estimates are often utilized to develop and prioritize health policy interventions, there is a necessity for country-specific estimates that are evidence based and less susceptible to model assumptions. In most cases, the estimation of severity distributions involves complex methodology as data for such assessments are very limited or hardly reliable. In the following workshop, general concepts and country cases from Germany, Scotland, and Belgium will be presented covering a variety of diseases. The examples underline the importance of estimating national and even regional severity distributions when identifying the importance of diseases or comparing the health conditions of populations across time.

Key messages
• As the Burden of disease indicators are predominantly used to prioritize health interventions and allocate resources, it is crucial to use accurate information in the severity levels of disease.
• Severity distributions reflect the health care services and vary across different settings. Utilising country-specific severity distributions when estimating Burden of Disease indicators is essential.