From surveys to surveillance

Surveillance of noncommunicable diseases (NCDs) has been neglected inmodern epidemiology and public health. Silva et al. are to be congratu-lated for their willingness to work towards improving surveys as poten-tial tools for surveillance purposes, as evidenced by their article on thissubject last month in this journal (1) and by their follow-up case study inthis issue (2). Such efforts are crucial in the context of the emerging NCDdisease burden in developing or newly industrialized countries, whichwill have significant social and economic consequences for governmentsand health systems. Preventive programs are needed to halt the rapid risein risk factor levels responsible for increasing disease burdens. Such pre-ventive programs require information on the distribution of major riskfactors in populations and regular, ongoing data collection to evaluateand refine interventions. Surveillance has been defined as the systematic collection, analy-sis, and interpretation of health data and the timely dissemination of suchdata to policymakers and others. While this definition has been modeledon the body of science related specifically to surveillance of infectious dis-eases, it is equally relevant to surveillance of NCDs. In particular, surveil-lance provides the knowledge to support health promotion and diseaseprevention, and it should take place in the context of efforts to improvepopulation health.In contrast, surveys are often done only once, to determine the distri-bution of risk factors in a population at a point in time. In many developedcountries, surveillance of major NCD risk factors is already quite advanced.Often an appropriate first step towards initiating surveillance is to conduct abaseline survey of sufficient sample size to have the power to detect mean-ingful changes over time. If well conducted, such a survey can provide im-portant information for determining priorities for intervention, and for raisingpublic and political awareness of the extent of public health problems.Nonetheless, a baseline survey is only the first step in what ideally should be-come an ongoing surveillance system that builds on multiple sources of healthinformation.The World Health Organization (WHO) is pursuing surveillance aspart of a global strategy for preventing and controlling NCDs and the majorrisk factors that predict them. The WHO's “STEPwise” approach to surveil-lance for NCD risk factors is based on standardized data collection and amethodology that can be adapted to a variety of country settings. The STEP-wise approach encourages the development of an increasingly comprehensivesurveillance system that meets local needs. Moreover, for sustainable surveil-lance, the STEPwise approach emphasizes small amounts of good quality dataover large amounts of poor quality data. Unfortunately, all too many cross-sectional surveys employ differentapproaches, definitions, and methodologies. Silva et al. (1) question how use-ful many prevalence studies are for surveillance. The authors are frustrated bythe continuing proliferation of studies that do not meet minimum criteria forproviding useful information for decision-making. This concern has led theauthors to a call for a uniform, standardized methodology that would allowcomparisons between studies and over time

Computer Science · Food Security and Health in Diverse Populations · Global Public Health Policies and Epidemiology

• Prevalence estimates for hypertension in Latin America and the Caribbean

  Open Access•Pedro Orduñez, Luis Carlos Silva et al.•Revista Panamericana de Salud…•2001

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• A tool for assessing the usefulness of prevalence studies done for surveillance purposes

  Open Access•Luis Carlos Silva, Pedro Orduñez et al.•Revista Panamericana de Salud…•2001

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