Guest Editorial: Strengthening NCD prevention through risk factor surveillance

T he burden of chronic non-communicable diseases (NCD), especially heart disease, stroke, hypertension, diabetes, cancer and chronic respiratory disease, is rising in low and middle-income countries, particularly in Asia (1). NCD deaths account for 60% of all deaths in the world and one in two deaths in the Asian region. Prevention programmes and policies are in their infancy in this region (2) and struggle to achieve priority because of the more established and pressing needs of infectious disease control; the recent outbreaks of Avian and H1N1 influenza are immediate examples (3). Comprehensive prevention programmes are underpinned by an understanding of the population levels of the major NCD risk factors which explain the occurrence of the vast majority of new episodes of NCD in all regions of the world. The papers in this supplement on NCD risk factor distributions in nine Health and Demographic Surveillance System (HDSS) sites of the INDEPTH Network (www.indepth-network.org) in five countries in Asia (Bangladesh, India, Indonesia, Thailand and Vietnam) are welcome. The surveillance sites have been described as ‘ . . .vibrant hotbeds, grounded in high quality research and training’ (4), and these papers mark a notable shift from the traditional emphasis on communicable diseases in rural populations in low and middle-income countries to the growing problem of NCD. The series begins with a description of the methodology used in the multi-site cross-sectional study (5) and the following papers provide strong support for public health efforts to reduce the harmful effects of tobacco (6), alcohol (7), low fruit and vegetable intake (8) and physical inactivity (9). The series continues with a focus on blood pressure (10), obesity (11), the way in which many of the risk factors cluster (12), and ends with an example of how one of the HDSS sites has used the surveillance process to stimulate actions at a broader societal level (13). Ongoing surveillance of changes in population levels of the major NCD risk factors is crucial if we are to understand the success or otherwise of preventive efforts. Many countries embark on a one-off survey, often with their own definitions, which are not designed to measure secular trends. To address this problem, WHO developed a STEPwise approach to Surveillance (WHO STEPS) of a few key modifiable risk factors suitable for use in low and middle-income settings (14, 15); this methodology is used in this series of papers. The WHO STEPS approach offers standard methods and measures, as well as accompanying detailed manuals and training materials to ensure that age and sex trends can be addressed adequately, as well as to guide quality control (16). Above all, the WHO STEPS approach establishes a baseline against which trends in these key risk factors can be measured through repeated cross-sectional surveys drawn from the same populations. WHO STEPS had its origins in the WHO Monitoring the Trends and Determinants of Cardiovascular Disease (MONICA) Project which, during the 1980s and early 1990s, monitored the trends and determinants of cardiovascular disease by developing ongoing populationbased heart disease and stroke registers as well as three risk factor surveys in the same populations at the beginning, middle and end of the duration of the disease registers (17). This was essentially a research project to understand how the changes in incidence and case fatality of heart disease and stroke related to the changing profile of risk factors. Because the restrictive nature of casefinding methods required access to vital statistics and clinical records, most of the 38 collaborating centres of the MONICA project were based in Europe; only one centre, Beijing, was in a developing country. Even so, the WHO MONICA project was the largest of its kind, monitoring the risk factor profile (tobacco use, serum cholesterol, blood pressure and body mass index) of over 100,000 adults 35 64 years of age. In the process it trained a large group of epidemiologists. In building on the MONICA experience, WHO STEPS placed the focus on obtaining data on a few key risk factors in adults 25 64 years of age which would predict trends in disease incidence, rather than focussing on disease incidence. One of the features of WHO STEPS is that it is designed to ensure the inclusion of core items into existing surveillance systems in an attempt to move towards encouraging the reporting of core indicators in a standardised manner. For example, national health surveys in India, Thailand, Iran, Philippines, Chile, USA, France, Singapore and Indonesia, now incorporate selected items from WHO STEPS; 77 countries have completed at least one baseline national survey, 16 have completed the second survey and two have completed the third survey. The INDEPTH Network was formed in 1998 and formally constituted in 2002 to bring together HDSS sites in low and middle-income countries. Today, INDEPTH GUEST EDITORIAL NCD SUPPLEMENT