Population-Based Health Studies: An Overview of Principles and Methods

Chronic non-communicable diseases (NCDs) are the major causes of premature death and disability in both high-income and low- and middle-income countries (LMICs). However, there is substantial variation in the age and sex-specific rates of major NCDs that are not fully explained by differences in the distributions of established risk factors, suggesting that other important causes remain to be discovered. Population-based epidemiological studies are needed for reliable assessment of lifestyle, biochemical and genetic determinants for NCDs, and for assessing prognosis and clustering of NCDs. Moreover, analysis of genetic variants for particular traits can be used to elucidate the causal relevance of particular exposures with disease and to anticipate the likely effects of treatments. Epidemiological studies conducted in diverse populations with prolonged follow-up for both fatal and non-fatal disease outcomes can provide important evidence about the causes of NCDs that may inform disease prevention strategies globally. The aim of this chapter is to provide readers with an overview of basic concepts and the epidemiological principles that underlie the design and conduct of epidemiological studies, including the chief strengths and limitations of different study designs. Moreover, it will highlight the importance of large prospective biobank studies, which involve assessment of a sufficiently large number of participants, together with strict control of bias and confounding to be able to detect moderate relative risks of major disease outcomes reliably.