Global burden of disease – a race against time – secondary publication

Low-income communities will within the next decades undergo rapid changes. The burden of non-communicable diseases (NCDs), such as diabetes, cardio-vascular disease and cancer, will comprise an increasing proportion of the total disease burden. The results of projections indicate that the already constrained health systems will face a double burden of disease, in which HIV/AIDS and other common infectious diseases will co-exist with the new NCDs. In order for preventive measures directed towards NCD to be cost-effective, these have to be implemented within the next 10-20 years. As previously emphasized by the authors of the present paper [1], there is increasing evidence that many communities in lowand middle income countries are exposed to risk factors which over time will result in an increase in the prevalence and incidence of noncommunicable diseases (NCDs), e.g. diabetes, cardio-vascular disease, chronic respiratory diseases and cancer. This development is a consequence of epidemiological transition, arising as a result of an increase in life expectancies combined with urbanisation, modernization and economical development. The main objective of the present paper is to give an insight into the various aspects of this transition with specific focus on low-income communities and possibilities for intervention. In order to measure and compare disease burdens, the traditional methods have mainly been based on various measures of mortality. However, since many infectious diseases (CDs) and NCDs result in shorter or longer periods of disability which do not necessarily result in death, there are a number of pronounced limitations related to the use of these measures as indicators for burden of disease. In order to develop a more valid alternative, several summary health measures of disease burden have been developed. These measures indicate the sum of life years lost due to premature death and periods of disease. In the present paper, we have primarily chosen to use the summary health measure disability adjusted life years (DALY), which is a measure based on algorithms adjusting for disease-specific differences in the burden of disease and age of the individuals. One DALY is defined as one year lost of an otherwise healthy life. [2]. Of the estimated 1.5 billion DALY’s that comprise the overall global burden of disease, CDs, NCDs and accidents contribute to 41%, 47% and 12%, respectively [3]. Globally 79% of all deaths which are caused by NCDs take place in low-income communities. In this context it is relevant to notice that out of a global population of six billion individuals, 80% live in low-income countries. There is a pronounced variation in the proportional distribution of CDs and NCDs when comparing geographical regions (Figure 1) [2]. It appears the obvious trend is an increasing proportion of disease burden which can be related to NCD with increasing level of economic development and modernization. As a result of the epidemiological transition, these pronounced differences between geographical regions will tend to diminish in the coming decades. A projection of disease burden for low-income countries in 2030, predicts that NCDs will contribute to half of the total burden (Figure 2) [4]. This projection is made when considering the combined effect of demographical transition (population growth and increasing life expectancies) and expected impact of modernisation and economical development. The same model indicates that in 2030, HIV/AIDS will appear as the most important cause of disease and death (12%), followed by perinatal disease (6%), depression (4%) and ischemic heart disease (4%). According to this projection, it is remarkable that depression now and in the future appears as one of the most important contributors to the global burden of the disease. If the measure was based on mortality rather than DALYs, depression would most likely result in an insignificant proportion of the total disease burden. It is furthermore projected that on a global level lung-, stomachand liver cancer will appear as one of the ten most common causes of death in 2020 [2]. On the condition that no interventions will be implemented, the number of deaths caused globally by cardio-vascular disease will increase from three million in 1998 to almost five million in 2020 [5]. In 2020, the number of deaths caused by NCDs in developing countries will equal the deaths caused by CDs [5]. Hence, within the coming 2-3 decades the combined burden of cardio-vascular disease, HIV/AIDS and perinatal disease will comprise the major causes of disease and death in low-income countries. There are good reasons to assume that NCDs will not follow the same trends as observed in the industrialized countries, when the burden of cardio-vascular disease peaked. Cardio-vascular disease in low-income countries is predicted to hit the populations earlier, result in higher age-specific morbidity and mortality rates, and higher incidences in low-income groups than previously observed in the industrialized countries. Hence, the estimated loss of life years related to cardio-vascular disease in the economically productive proportion of the population in India and China (PRC) will increase by 57% and 95% respectively during the period 2002-2030 [5]. A major part of the previously mentioned analyses and projections are based on estimates, extrapolations and projections with questionable relevance and validity. The lack of access to relevant data appears as a major barrier for obtaining a more valid impres-