Chapter 2: Population Health: Definitions, Tensions, and New Directions

INTRODUCTION

Population health has long been a topic of great interest to population-based fields such as epidemiology, social demography, geography, and public health. It is both a set of social indicators and a field of scientific interest and professional practice. Historically, for at least two centuries, population health has primarily been focused on the distributions and patterns of health outcomes and their causes in populations—typically based on geography and/or governmental authority—and sociodemographic subgroups within populations. The overarching objective of population health is to elucidate how social, economic, environmental, and ecological factors and changes within societies manifest—in both positive and negative ways—in health outcomes at the population level.¹

The general foci of population health has historically included: (a) systematically measuring rates of health, morbidity, injury, and mortality in populations; (b) elucidating the determinants of health at both individual and population level; (c) identifying and addressing risks to population health; and (d) identifying and evaluating interventions aimed at improving population health and reducing distributional disparities.^2,3

The key methods and metrics used in population health research and policy (listed in Box 2-1) are defined in a plethora of books and articles.^1–6 Population health data typically come from vital registration systems, censuses, public health reporting systems, numerous public and private administrative databases, and surveys, all with strong attention to capturing data from the entire “denominator” or population base from the which the data are gathered and should validly represent.⁵ Population-level indicators such as life expectancy, mortality rates across the life course, unintentional injury incidence, risk behavior levels, preventable hospitalization rates, etc., represent both exposures and investments at the micro, mezzo, and macro levels, and are important signals regarding the physical, mental, and social health of populations. Surveillance and research using these metrics is a powerful tool for making absolute and relative comparisons within and across countries and their subpopulations in the cross-section and over time.