Annual Review of Public Health - Volume 37, 2016

Studies in which clusters of individuals are randomized to conditions are increasingly common in public health research. However, the designs utilized for such studies are often suboptimal and inefficient. We review strategies to improve the design of cluster randomized trials. We discuss both older but effective design concepts that are underutilized, such as stratification and factorial designs, as well as emergent ideas including fractional factorial designs and cluster randomized crossover studies. We draw examples from the recent literature and provide resources for sample size and power planning. Given the inherent inefficiencies of cluster randomized trials, these design strategies merit wider consideration and can lead to studies that are more cost-effective and potentially more rigorous than traditional approaches.

This article provides an overview of recent developments in mediation analysis, that is, analyses used to assess the relative magnitude of different pathways and mechanisms by which an exposure may affect an outcome. Traditional approaches to mediation in the biomedical and social sciences are described. Attention is given to the confounding assumptions required for a causal interpretation of direct and indirect effect estimates. Methods from the causal inference literature to conduct mediation in the presence of exposure-mediator interactions, binary outcomes, binary mediators, and case-control study designs are presented. Sensitivity analysis techniques for unmeasured confounding and measurement error are introduced. Discussion is given to extensions to time-to-event outcomes and multiple mediators. Further flexible modeling strategies arising from the precise counterfactual definitions of direct and indirect effects are also described. The focus throughout is on methodology that is easily implementable in practice across a broad range of potential applications.

The timing of puberty has important public health, clinical, and social implications. The plasticity of sexual development onset could be a mechanism that adapts to prevailing environmental conditions. Early-life nutrition may provide cues for the environment's suitability for reproduction. This review focuses on recent developments in our understanding of the role of diet in the timing of sexual maturation. Population-based observational studies consistently indicate that childhood obesity is related to the earlier onset of puberty in girls. Similarly, intake of animal foods has been associated with earlier sexual development, whereas vegetable protein intake is related to delayed maturation. Evidence for prenatal nutrition, infant feeding practices, and childhood intake of fat, carbohydrate, and micronutrients is inconsistent. Secondary analyses of prenatal and early-life randomized nutritional interventions with extended follow-up through peripubertal years would help clarify the role of nutrition in the timing of sexual maturation.

With increasing accessibility to geographic information systems (GIS) software, statisticians and data analysts routinely encounter scientific data sets with geocoded locations. This has generated considerable interest in statistical modeling for location-referenced spatial data. In public health, spatial data routinely arise as aggregates over regions, such as counts or rates over counties, census tracts, or some other administrative delineation. Such data are often referred to as areal data. This review article provides a brief overview of statistical models that account for spatial dependence in areal data. It does so in the context of two applications: disease mapping and spatial survival analysis. Disease maps are used to highlight geographic areas with high and low prevalence, incidence, or mortality rates of a specific disease and the variability of such rates over a spatial domain. They can also be used to detect hot spots or spatial clusters that may arise owing to common environmental, demographic, or cultural effects shared by neighboring regions. Spatial survival analysis refers to the modeling and analysis for geographically referenced time-to-event data, where a subject is followed up to an event (e.g., death or onset of a disease) or is censored, whichever comes first. Spatial survival analysis is used to analyze clustered survival data when the clustering arises from geographical regions or strata. Illustrations are provided in these application domains.

The use and functionality of electronic health records (EHRs) have increased rapidly in the past decade. Although the primary purpose of EHRs is clinical, researchers have used them to conduct epidemiologic investigations, ranging from cross-sectional studies within a given hospital to longitudinal studies on geographically distributed patients. Herein, we describe EHRs, examine their use in population health research, and compare them with traditional epidemiologic methods. We describe diverse research applications that benefit from the large sample sizes and generalizable patient populations afforded by EHRs. These have included reevaluation of prior findings, a range of diseases and subgroups, environmental and social epidemiology, stigmatized conditions, predictive modeling, and evaluation of natural experiments. Although studies using primary data collection methods may have more reliable data and better population retention, EHR-based studies are less expensive and require less time to complete. Future EHR epidemiology with enhanced collection of social/behavior measures, linkage with vital records, and integration of emerging technologies such as personal sensing could improve clinical care and population health.

Many communities are located near multiple sources of pollution, including current and former industrial sites, major roadways, and agricultural operations. Populations in such locations are predominantly low-income, with a large percentage of minorities and non-English speakers. These communities face challenges that can affect the health of their residents, including limited access to health care, a shortage of grocery stores, poor housing quality, and a lack of parks and open spaces. Environmental exposures may interact with social stressors, thereby worsening health outcomes. Age, genetic characteristics, and preexisting health conditions increase the risk of adverse health effects from exposure to pollutants. There are existing approaches for characterizing cumulative exposures, cumulative risks, and cumulative health impacts. Although such approaches have merit, they also have significant constraints. New developments in exposure monitoring, mapping, toxicology, and epidemiology, especially when informed by community participation, have the potential to advance the science on cumulative impacts and to improve decision making.

Ambient heat exposure is a well-known health hazard, which reduces human performance and work capacity at heat levels already common in tropical and subtropical areas. Various health problems have been reported. Increasing heat exposure during the hottest seasons of each year is a key feature of global climate change. Heat exhaustion and reduced human performance are often overlooked in climate change health impact analysis. Later this century, many among the four billion people who live in hot areas worldwide will experience significantly reduced work capacity owing to climate change. In some areas, 30–40% of annual daylight hours will become too hot for work to be carried out. The social and economic impacts will be considerable, with global gross domestic product (GDP) losses greater than 20% by 2100. The analysis to date is piecemeal. More analysis of climate change–related occupational health impact assessments is greatly needed.

The research community has shown increasing interest in developing and using metrics to determine the relationships between urban living and health. In particular, we have seen a recent exponential increase in efforts aiming to investigate and apply metrics for urban health, especially the health impacts of the social and built environments as well as air pollution. A greater recognition of the need to investigate the impacts and trends of health inequities is also evident through more recent literature. Data availability and accuracy have improved through new affordable technologies for mapping, geographic information systems (GIS), and remote sensing. However, less research has been conducted in low- and middle-income countries where quality data are not always available, and capacity for analyzing available data may be limited. For this increased interest in research and development of metrics to be meaningful, the best available evidence must be accessible to decision makers to improve health impacts through urban policies.

Public health law has roots in both law and science. For more than a century, lawyers have helped develop and implement health laws; over the past 50 years, scientific evaluation of the health effects of laws and legal practices has achieved high levels of rigor and influence. We describe an emerging model of public health law that unites these two traditions. This transdisciplinary model adds scientific practices to the lawyerly functions of normative and doctrinal research, counseling, and representation. These practices include policy surveillance and empirical public health law research on the efficacy of legal interventions and the impact of laws and legal practices on health and health system operation. A transdisciplinary model of public health law, melding its legal and scientific facets, can help break down enduring cultural, disciplinary, and resource barriers that have prevented the full recognition and optimal role of law in public health.

Today's global tobacco epidemic may represent one of the first instances of the globalization of a noninfectious cause of disease. This article focuses on the first century of the global tobacco epidemic and its current status, reviewing the current and projected future of the global tobacco epidemic and the steps that are in progress to end it. In the United States and many countries of Western Europe, tobacco consumption peaked during the 1960s and 1970s and declined as tobacco control programs were initiated, motivated by the evidence indicting smoking as a leading cause of disease. Despite this policy advancement and the subsequent reductions in tobacco consumption, the global tobacco epidemic continued to grow exponentially in the later years of the twentieth century, as the multinational companies sought new markets to replace those shrinking in high-income countries. In response, between 2000 and 2004, the World Health Organization developed its first public health treaty, the Framework Convention on Tobacco Control, which entered into force in 2005. An accompanying package of interventions has been implemented. New approaches to tobacco control, including plain packaging and single representation of brands, have been implemented by Australia and Uruguay, respectively, but have been challenged by the tobacco industry.

Residents of rural jurisdictions face significant health challenges, including some of the highest rates of risky health behaviors and worst health outcomes of any group in the country. Rural communities are served by smaller local health departments (LHDs) that are more understaffed and underfunded than their suburban and urban peers. As a result of history and current need, rural LHDs are more likely than their urban peers to be providers of direct health services, leading to relatively lower levels of population-focused activities. This review examines the double disparity faced by rural LHDs and their constituents: pervasively poorer health behaviors and outcomes and a historical lack of investment by local, state, and federal public health entities.

To improve health in the twenty-first century, to promote both access to and quality of health care services and delivery, and to address significant health disparities, legal and policy approaches, specifically those focused on civil rights, could be used more intentionally and strategically. This review describes how civil rights laws, and their implementation and enforcement, help to encourage health in the United States, and it provides examples for peers around the world. The review uses a broad lens to define health for both classes of individuals and their communities—places where people live, learn, work, and play. Suggestions are offered for improving health and equity broadly, especially within societal groups and marginalized populations. These recommendations include multisectorial approaches that focus on the social determinants of health.

War and other forms of armed conflict have profound adverse effects on population health. It is important to document these effects to inform the general public and policy makers about the consequences of armed conflict, provide services to meet the needs of affected populations, protect human rights and document violations of international humanitarian law, and help to prevent future armed conflict. Documentation can be accomplished with surveillance, epidemiological surveys, and rapid assessment. Challenges include inadequate or absent data systems, social breakdown, forced migration, reporting biases, and the fog of war. The adverse effects of the Iraq War on population health demonstrate how the effects of armed conflict on population health can be documented. We recommend the establishment of an independent mechanism, operated by the United Nations or a multilateral organization, to investigate and document the effects of armed conflict on population health.

This article provides an analysis of novel topics emerging in recent years in research on Latino immigrants, acculturation, and health. In the past ten years, the number of studies assessing new ways to conceptualize and understand how acculturation-related processes may influence health has grown. These new frameworks draw from integrative approaches testing new ground to acknowledge the fundamental role of context and policy. We classify the emerging body of evidence according to themes that we identify as promising directions—intrapersonal, interpersonal, social environmental, community, political, and global contexts, cross-cutting themes in life course and developmental approaches, and segmented assimilation—and discuss the challenges and opportunities each theme presents. This body of work, which considers acculturation in context, points to the emergence of a new wave of research that holds great promise in driving forward the study of Latino immigrants, acculturation, and health. We provide suggestions to further advance the ideologic and methodologic rigor of this new wave.

In recent years, the nudge approach to behavior change has emerged from the behavioral sciences to challenge the traditional use of regulation in public health strategies to address modifiable individual-level behaviors related to the rise of noncommunicable diseases and their treatment. However, integration and testing of the nudge approach as part of more comprehensive public health strategies aimed at making healthy choices easier are being threatened by inadequate understandings of its scientific character, its relationship with regulation, and its ethical implications. This article reviews this character and its ethical implication with a special emphasis on the compatibility of nudging with traditional regulation, special domains of experience, and the need for a more nuanced approach to the ethical debate. The aim is to advance readers' understanding and give guidance to those who have considered working with or incorporating the nudge approach into programs or policies aimed at making healthful choices easier.

To prevent the intergenerational transfer of obesity and end the current epidemic, interventions are needed across the early life stages, from preconception to prenatal to infancy through the age of 2 years. The foundation for obesity is laid in early life by actions and interactions passed from parent to child that have long-lasting biologic and behavioral consequences. The purpose of this paper is to examine the best evidence about (a) factors in parents and offspring that promote obesity during the early life stages, (b) the social determinants and dimensions of obesity in early life, (c) promising and effective interventions for preventing obesity in early life, and (d) opportunities for future research into strategies to disrupt the intergenerational cycle of obesity that begins early in life. The pathway for halting the intergenerational obesity epidemic requires the discovery and development of evidence-based interventions that can act across multiple dimensions of influence on early life.

Temporal trends in the epidemic of childhood obesity have been paralleled by increases in the consumption of sugar-sweetened beverages (SSB) during childhood. Consumption has increased dramatically over the past several decades in all age ranges, with some moderation over the past 10 years. Evidence from cross-sectional, longitudinal, and interventional studies supports links between SSB consumption in childhood and unhealthy weight gain, as well as other untoward health outcomes. These data have stimulated public health efforts to curtail consumption as a means of improving childhood weight status and related health outcomes. Reducing ready access to SSBs, changing the message environment to which children are exposed, and replacing SSBs with healthier beverages have had moderate success in decreasing SSB consumption and curbing unhealthy weight gain.

Over the past two decades, there has been growing interest in improving black men's health and the health disparities affecting them. Yet, the health of black men consistently ranks lowest across nearly all groups in the United States. Evidence on the health and social causes of morbidity and mortality among black men has been narrowly concentrated on public health problems (e.g., violence, prostate cancer, and HIV/AIDS) and determinants of health (e.g., education and male gender socialization). This limited focus omits age-specific leading causes of death and other social determinants of health, such as discrimination, segregation, access to health care, employment, and income. This review discusses the leading causes of death for black men and the associated risk factors, as well as identifies gaps in the literature and presents a racialized and gendered framework to guide efforts to address the persistent inequities in health affecting black men.

In the past decade, many constituencies have questioned the efficacy, cost, and unintended consequences of mass incarceration in the United States. Although substantial evidence now demonstrates that US incarceration policies have had unintended adverse health consequences, we know less about the strategies and policies that can prevent or reduce these problems for justice-involved individuals and how the criminal justice system (CJS) can contribute to the Healthy People 2020 national goal of eliminating inequities in health. This review examines strategies that have been used to improve the health of people at various stages of CJS involvement, including diversion from jail and prison stays into community settings, improvements to the social and physical environments within correctional facilities, provision of health and other services to inmates, assistance for people leaving correctional facilities to make the transition back to the community, and systems coordination and integration.

Given the broad scope and intersectoral nature of public health structures and practices, there are inherent difficulties in defining which services fall under the public health remit and in assessing their capacity and performance. The aim of this study is to analyze how public health functions and practice have been defined and operationalized in different countries and regions around the world, with a specific focus on assessment tools that have been developed to evaluate the performance of essential public health functions, services, and operations. Our review has identified nearly 100 countries that have carried out assessments, using diverse analytical and methodological approaches. The assessment processes have evolved quite differently according to administrative arrangements and resource availability, but some key contextual factors emerge that seem to favor policy-oriented follow-up. These include local ownership of the assessment process, policymakers' commitment to reform, and expert technical advice for implementation.

In May 2014, the World Health Assembly, of the World Health Organization (WHO), unanimously adopted a palliative care (PC) resolution, which outlines clear recommendations to the United Nations member states, such as including PC in national health policies and in the undergraduate curricula for health care professionals, and highlights the critical need for countries to ensure that there is an adequate supply of essential PC medicines, especially those needed to alleviate pain. This resolution also carries great challenges: Every year over 20 million patients (of which 6% are children) need PC at the end of life (EOL). However, in 2011, approximately three million patients received PC, and only one in ten people in need is currently receiving it. We describe this public health situation and systems failure, the history and evolution of PC, and the components of the WHO public health model. We propose a role for public health for PC integration in community settings to advance PC and relieve suffering in the world.

The annual National Healthcare Quality and Disparities Reports document widespread and persistent racial and ethnic disparities. These disparities result from complex interactions between patient factors related to social disadvantage, clinicians, and organizational and health care system factors. Separate and unequal systems of health care between states, between health care systems, and between clinicians constrain the resources that are available to meet the needs of disadvantaged groups, contribute to unequal outcomes, and reinforce implicit bias. Recent data suggest slow progress in many areas but have documented a few notable successes in eliminating these disparities. To eliminate these disparities, continued progress will require a collective national will to ensure health care equity through expanded health insurance coverage, support for primary care, and public accountability based on progress toward defined, time-limited objectives using evidence-based, sufficiently resourced, multilevel quality improvement strategies that engage patients, clinicians, health care organizations, and communities.

Compared to their urban counterparts, rural and remote inhabitants experience lower life expectancy and poorer health status. Nowhere is the worldwide shortage of health professionals more pronounced than in rural areas of developing countries. Sub-Saharan Africa (SSA) includes a disproportionately large number of developing countries; therefore, this article explores SSA in depth as an example. Using the conceptual framework of access to primary health care, sustainable rural health service models, rural health workforce supply, and policy implications, this article presents a review of the academic and gray literature as the basis for recommendations designed to achieve greater health equity. An alternative international standard for health professional education is recommended. Decision makers should draw upon the expertise of communities to identify community-specific health priorities and should build capacity to enable the recruitment and training of local students from underserviced areas to deliver quality health care in rural community settings.

Much research has investigated the association of income inequality with average life expectancy, usually finding negative correlations that are not very robust. A smaller body of work has investigated socioeconomic disparities in life expectancy, which have widened in many countries since 1980. These two lines of work should be seen as complementary because changes in average life expectancy are unlikely to affect all socioeconomic groups equally. Although most theories imply long and variable lags between changes in income inequality and changes in health, empirical evidence is confined largely to short-term effects. Rising income inequality can affect individuals in two ways. Direct effects change individuals' own income. Indirect effects change other people's income, which can then change a society's politics, customs, and ideals, altering the behavior even of those whose own income remains unchanged. Indirect effects can thus change both average health and the slope of the relationship between individual income and health.