Quantifying burden of disease to support public health policy in Belgium: opportunities and constraints

The main goal of public health policy is to promote, enhance and protect the population’s health. This requires information on the health status of the population, often referred to as the “burden of disease”. More than just the presence/absence of specific diseases and conditions, disease burden encompasses a comprehensive quantification of the physical and psychosocial health impact of diseases, conditions, and risk factors [1].

Evidence on the disease burden is important for decision-making processes within the health sector. In order to make relevant decisions and set appropriate priorities, policy makers need to be informed about the size of health problems in the population, the groups that are particularly at risk, and the trends in the state of health over time. In addition, an accurate estimate of the population’s health status can be used for determining the expected health care use and is vital for prioritizing effective interventions and evaluating their impact and cost-effectiveness (e.g., by integrating them in generalized cost-effectiveness analyses [2]).

The disease burden of the population can be described by a variety of indicators. Indeed, public health is a multifactorial phenomenon with many facets and different ways to measure it. Typical indicators of population health are life expectancy, cause-specific mortality rates, numbers of new and existing cases of specific diseases (i.e., incidence and prevalence), perceived health, the occurrence of physical and mental limitations and disability, but also more indirect measures, such as absenteeism, incapacity of work, and the use of medical facilities and the associated costs. However, all these indicators highlight only one facet of public health, i.e., either mortality or morbidity.

Summarizing public health in terms of mortality-based indicators, such as life expectancy, dates from the time when only reliable data for mortality existed. In many countries, however, one has been confronted with an epidemiological transition of public health problems. The importance of early mortality due to plagues and famines has been replaced by chronic, non-communicable diseases, while communicable diseases remain a real threat, causing a “double burden” [3]. Cardiovascular diseases and cancers have replaced infectious diseases as the main causes of death. However, these diseases are also associated with an important morbidity component, due to the life prolonging effect of continuously improving medical practice [4]. Moreover, not only an extended life expectancy per se is aimed for, living these extra years in good health has become just as important [5]. As a result, current health policy requires a global overview of public health, one that combines morbidity and mortality and takes account of health-related quality of life (HRQoL; [6]).

Given the importance of combining morbidity and mortality, the last few decades have seen important methodological advances in so-called summary measures of population health (SMPH; [7]). By and large, SMPHs may be divided into two broad families, namely health expectancies and health gaps. Metrics of each family combine morbidity and mortality into a single figure. Health expectancy-based metrics, such as Disability-Free Life Expectancy (DFLE), Healthy Life Years (HLY), and Disability-Adjusted Life Expectancy (DALE), translate these indicators into a health-adjusted life expectancy; health gap metrics, such as the Disability-Adjusted Life Year (DALY), translate these indicators into a number of life years lost due to bad health and mortality.

Driven by the influential Global Burden of Disease (GBD) projects initiated in the early 1990s, the DALY has become the dominant SMPH [8‐12]. In the remainder of this debate, we will therefore outline the composition of the DALY metric and its data needs. Next, we will summarize existing DALY estimates for Belgium, providing an overview of the current state-of-knowledge on the burden of disease in Belgium. We will conclude by discussing the added value and potential hurdles of routine DALY calculation for Belgian public health policy.

By quantifying the total disease burden and the contribution of different diseases and risk factors, DALYs are a highly valuable measure to set priorities for public health research and policy. Furthermore, if data allow, DALYs may be calculated for different socioeconomic groups or geographic regions, allowing for a more detailed perspective on public health. By regularly updating the DALY estimates based on the best available data, trends in public health may be monitored over time, and the impact of macro-level policies may be evaluated. As a result, DALYs may be important tools to support policy that aims to improve general population health and reduce health inequalities [39]. For this reason, the IHME is initiating national and subnational burden of disease studies, worldwide [40]. The WHO Regional Office for Europe is collaborating with IHME to facilitate national burden of disease study in the European region and enhance consistency of burden estimates.

Current DALY estimates for Belgium highlight the importance of non-communicable diseases and injuries. However, several constraints can be identified that might hamper the policy relevance of the currently available estimates. First, most DALY estimations remained academic exercises, with little or no direct knowledge transfer to the concerned policy instances. Indirect knowledge transfer may have occurred by referring to existing burden estimates in research proposals, but the effect is difficult to assess. Second, while global estimates provide a broad overview of the health status in Belgium, it remains a question to what extent these estimates are grounded in the best available local data. There may also be issues related to timeliness and ownership of these global estimates. Third, while national research groups did more efforts to apply local data sources, there appears to be little consistency in the applied DALY calculation methodology. As a result, the individual DALY studies cannot be combined to obtain a comparable evaluation of Belgians’ health. Researchers are therefore advised to calculate DALYs under different social weighting scenarios, and to present at least relative DALY estimates (e.g., DALYs per 100,000 people-year).

To overcome these limitations and generate a systematic and truly comparable measurement of Belgians’ health, DALYs should be integrated in the different official data collection systems. This is already the case in the Netherlands and Australia, where DALYs are guiding health policy since the past 10–20 years [34, 41]. In Belgium, various large and important data generation systems are in place that could provide the data required for calculating DALYs. However, there are also some potential hurdles, such as a lack of timeliness of certain databases, a restricted access to hospital data for routine use, a limited harmonization between regional databases, and the absence of certain diseases from the major databases. Given the increasing importance of neurological, mental and musculoskeletal disorders, the absence of comprehensive, harmonized databases for these disorders is particularly striking. Nevertheless, we believe that the routine quantification of disease burden in terms of DALYs would provide a significant added value to public health policy in Belgium and should be integrated in all national mechanisms for the translation of evidence into policy.