Epidemiologic Reviews - recent issues

The Burden of Mental Disorders

2008-10-29

In the last decade, there has been an increase in interest in the burden of chronic and disabling health conditions that are not necessarily fatal, such as the mental disorders. This review systematically summarizes data on the burden associated with 11 major mental disorders of adults. The measures of burden include estimates of prevalence, mortality associated with the disorders, disabilities and impairments related to the disorders, and costs. This review expands the range of mental disorders considered in a report on the global burden of disease, updates the literature, presents information on the range and depth of sources of information on burden, and adds estimates of costs. The purpose is to provide an accessible guide to the burden of mental disorders, especially for researchers and policy makers who may not be familiar with this subfield of epidemiology.

Dementia of the Alzheimer Type

Jalbert, J. J., Daiello, L. A., Lapane, K. L. — 2008-10-29

Dementia of the Alzheimer type is a progressive, fatal neurodegenerative condition characterized by deterioration in cognition and memory, progressive impairment in the ability to carry out activities of daily living, and a number of neuropsychiatric symptoms. This narrative review summarizes the literature regarding descriptive epidemiology, clinical course, and characteristic neuropathological changes of dementia of the Alzheimer type. Although there are no definitive imaging or laboratory tests, except for brain biopsy, for diagnosis, brief screening instruments and neuropsychiatric test batteries used to assess the disease are discussed. Insufficient evidence exists for the use of biomarkers in clinical practice for diagnosis or disease management, but promising discoveries are summarized. Optimal treatment requires both nonpharmacological and pharmacological interventions, yet none have been shown to modify the disease's clinical course. This review describes the current available options and summarizes promising new avenues for treatment. Issues related to the care of persons with dementia of the Alzheimer type, including caregiver burden, long-term care, and the proliferation of dementia special care units, are discussed. Although advances have been made, more research is needed to address the gaps in our understanding of the disease.

Dementia Prevention: Methodological Explanations for Inconsistent Results

2008-10-29

The prevention of neurodegenerative dementias, such as Alzheimer disease, is a growing public health concern, because of a lack of effective curative treatment options and a rising global prevalence. Various potential risk or preventive factors have been suggested by epidemiologic research, including modifiable lifestyle factors, such as social contacts, leisure activities, physical exercise, and diet, as well as some preventive pharmacologic strategies, such as hormone replacement therapy, nonsteroidal antiinflammatory drugs, and Ginkgo biloba. Some factors have been targeted by interventions tested in randomized controlled trials, but many of the results are in conflict with observational evidence. The aim of this paper is to review the epidemiologic data linking potential protective factors to dementia or cognitive decline and to discuss the methodological limitations that could explain conflicting results. A thorough review of the literature suggests that, even if there are consistent findings from large observational studies regarding preventive or risk factors for dementia, few randomized controlled trials have been designed specifically to prove the protective effects of interventions based on such factors on dementia incidence. Because of the multifactorial origin of dementia, it appears that multidomain interventions could be a suitable candidate for preventive interventions, but designing such trials remains very challenging for researchers.

Schizophrenia: A Concise Overview of Incidence, Prevalence, and Mortality

McGrath, J., Saha, S., Chant, D., Welham, J. — 2008-10-29

Recent systematic reviews have encouraged the psychiatric research community to reevaluate the contours of schizophrenia epidemiology. This paper provides a concise overview of three related systematic reviews on the incidence, prevalence, and mortality associated with schizophrenia. The reviews shared key methodological features regarding search strategies, analysis of the distribution of the frequency estimates, and exploration of the influence of key variables (sex, migrant status, urbanicity, secular trend, economic status, and latitude). Contrary to previous interpretations, the incidence of schizophrenia shows prominent variation between sites. The median incidence of schizophrenia was 15.2/100,000 persons, and the central 80% of estimates varied over a fivefold range (7.7–43.0/100,000). The rate ratio for males:females was 1.4:1. Prevalence estimates also show prominent variation. The median lifetime morbid risk for schizophrenia was 7.2/1,000 persons. On the basis of the standardized mortality ratio, people with schizophrenia have a two- to threefold increased risk of dying (median standardized mortality ratio = 2.6 for all-cause mortality), and this differential gap in mortality has increased over recent decades. Compared with native-born individuals, migrants have an increased incidence and prevalence of schizophrenia. Exposures related to urbanicity, economic status, and latitude are also associated with various frequency measures. In conclusion, the epidemiology of schizophrenia is characterized by prominent variability and gradients that can help guide future research.

Population-based Cohort Studies on Premorbid Cognitive Function in Schizophrenia

MacCabe, J. H. — 2008-10-29

Many previous studies have found associations between poor cognitive function and schizophrenia. However, the majority of these studies used retrospective data, leading to the possibility of selection and recall biases. Retrospective studies are also unable to distinguish whether cognitive deficits exist prior to the onset of schizophrenia, suggesting that they are important in etiology, or following onset, suggesting that they are secondary to the disorder or its treatment. The current review used a systematic search strategy to identify and summarize the results of all studies that have used population-based cohorts to examine associations between prospectively collected data on premorbid cognitive functioning in childhood or adolescence and subsequent risk for schizophrenia. Three broad categories of study have addressed these questions: birth cohort designs with cognitive testing during childhood, army conscript designs with cognitive performance measured at conscription, and studies using school grades. Birth cohort and conscript studies are consistent in reporting strong associations between poor performance on cognitive batteries and increased risk of schizophrenia. Studies on school performance have been less consistent, although the largest such study showed strong associations across all school subjects. In conclusion, children and adolescents with poor cognitive abilities in childhood are at increased risk of schizophrenia. This suggests that poor cognitive function is either directly causal or associated with causal factors that are involved in etiology.

Psychosis and Place

2008-10-29

One important line of epidemiologic inquiry implicating social context in the etiology of psychosis is the examination of spatial variation in the distribution of psychotic illness. The authors conducted a systematic review of evidence from urbanicity and neighborhood studies regarding spatial variation in the incidence of psychosis in developed countries since 1950. A total of 44 studies (20 of urbanicity and 24 of neighborhood) were culled from three databases with similar time frames: Medline (1950–2007), PsychInfo (1950–2007), and Sociological Abstracts (1952–2007). With a special emphasis on social factors potentially relevant to etiology, the authors elucidated contributions, limitations, and issues related to study design, measurement, and theory. Evidence from both arenas supports a possible etiologic role for social context. Studies of urbanicity indicate that early-life exposure may be important; dose-response relations, spatial patterning of schizophrenia, and interactions with other factors may exist. Neighborhood studies indicate heterogeneity in rates, hint at spatial patterning of schizophrenia, and offer intriguing evidence implying more proximal social (as opposed to physical) exposures. The authors encourage the exploration of social pathways engaging theory, methodological advances, and the life-course perspective. They also propose a conceptual shift from studies of spatial variation in outcomes to research addressing the etiologic effect of exposures shaped by place as a reservoir of risk or resilience.

Blues from the Neighborhood? Neighborhood Characteristics and Depression

Kim, D. — 2008-10-29

Unipolar major depression ranks among the leading contributors to the global burden of disease. Although established risk factors for depression include a variety of individual-level characteristics, neighborhood etiologic factors have been relatively understudied, with several such attributes (neighborhood socioeconomic status, physical conditions, services/amenities, social capital, social disorder) possessing plausible linkages to depression. Using the PubMed database (1966–2008) and the Social Sciences Citation Index database (1956–2008), the author undertook a systematic review of the published literature on the associations between these characteristics and depression in adults. Across studies, the evidence generally supports harmful effects of social disorder and, to a lesser extent, suggests protective effects for neighborhood socioeconomic status. Few investigations have explored the relations for neighborhood physical conditions, services/amenities, and social capital, and less consistently point to salutary effects. The unsupportive findings may be attributed to the lack of representative studies within and across societies or to methodological gaps, including lack of control for other neighborhood/non-neighborhood exposures and lack of implementation of more rigorous methodological approaches. Establishing mediating pathways and effect-modifying factors will vitally advance understanding of neighborhood effects on depression. Overall, addressing these gaps will help to identify what specific neighborhood features matter for depression, how, and for whom, and will contribute to curtailing the burden of disease associated with this major disorder.

The Relation between Work-related Psychosocial Factors and the Development of Depression

2008-10-29

This review is based on a literature search made in January 2007 on request by the Danish National Board of Industrial Injuries. The search in PubMed, EMBASE, and PsycINFO resulted in more than 1,000 publications. This was reduced to 14 after the titles, abstracts, and papers were evaluated by using the following criteria: 1) a longitudinal study, 2) exposure to work-related psychosocial factors, 3) the outcome a measure of depression, 4) relevant statistical estimates, and 5) nonduplicated publication. Of the 14 studies, seven used standardized diagnostic instruments as measures of depression, whereas the other seven studies used self-administered questionnaires. The authors found moderate evidence for a relation between the psychological demands of the job and the development of depression, with relative risks of approximately 2.0. However, indication of publication bias weakens the evidence. Social support at work was associated with a decrease in risk for future depression, as all four studies dealing with this exposure showed associations with relative risks of about 0.6. Even if this literature study has identified work-related psychosocial factors that in high-quality epidemiologic studies predict depression, studies are still needed that assess in more detail the duration and intensity of exposure necessary for developing depression.

Suicide and Suicidal Behavior

Nock, M. K., Borges, G., Bromet, E. J., Cha, C. B., Kessler, R. C., Lee, S. — 2008-10-29

Suicidal behavior is a leading cause of injury and death worldwide. Information about the epidemiology of such behavior is important for policy-making and prevention. The authors reviewed government data on suicide and suicidal behavior and conducted a systematic review of studies on the epidemiology of suicide published from 1997 to 2007. The authors' aims were to examine the prevalence of, trends in, and risk and protective factors for suicidal behavior in the United States and cross-nationally. The data revealed significant cross-national variability in the prevalence of suicidal behavior but consistency in age of onset, transition probabilities, and key risk factors. Suicide is more prevalent among men, whereas nonfatal suicidal behaviors are more prevalent among women and persons who are young, are unmarried, or have a psychiatric disorder. Despite an increase in the treatment of suicidal persons over the past decade, incidence rates of suicidal behavior have remained largely unchanged. Most epidemiologic research on suicidal behavior has focused on patterns and correlates of prevalence. The next generation of studies must examine synergistic effects among modifiable risk and protective factors. New studies must incorporate recent advances in survey methods and clinical assessment. Results should be used in ongoing efforts to decrease the significant loss of life caused by suicidal behavior.

Comorbid Forms of Psychopathology: Key Patterns and Future Research Directions

Cerda, M., Sagdeo, A., Galea, S. — 2008-10-29

The purpose of this review is to systematically appraise the peer-reviewed literature about clustered forms of psychopathology and to present a framework that can be useful for studying comorbid psychiatric disorders. The review focuses on four of the most prevalent types of mental health problems: anxiety, depression, conduct disorder, and substance abuse. The authors summarize existing empirical research on the distribution of concurrent and sequential comorbidity in children and adolescents and in adults, and they review existing knowledge about exogenous risk factors that influence comorbidity. The authors include articles that used a longitudinal study design and used psychiatric definitions of the disorders. A total of 58 articles met the inclusion criteria and were assessed. Current evidence demonstrates a reciprocal, sequential relation between most comorbid pairs, although the mechanisms that mediate such links remain to be explained. Methodological concerns include the inconsistency of measurement of the disorders across studies, small sample sizes, and restricted follow-up times. Given the significant mental health burden placed by comorbid disorders, and their high prevalence across populations, research on the key risk factors for clustering of psychopathology is needed.

The Global Epidemic of Obesity: An Overview

Caballero, B. — 2007-07-12

The Obesity Epidemic in the United States Gender, Age, Socioeconomic, Racial/Ethnic, and Geographic Characteristics: A Systematic Review and Meta-Regression Analysis

Wang, Y., Beydoun, M. A. — 2007-07-12

This review of the obesity epidemic provides a comprehensive description of the current situation, time trends, and disparities across gender, age, socioeconomic status, racial/ethnic groups, and geographic regions in the United States based on national data. The authors searched studies published between 1990 and 2006. Adult overweight and obesity were defined by using body mass index (weight (kg)/height (m)²) cutpoints of 25 and 30, respectively; childhood "at risk for overweight" and overweight were defined as the 85th and 95th percentiles of body mass index. Average annual increase in and future projections for prevalence were estimated by using linear regression models. Among adults, obesity prevalence increased from 13% to 32% between the 1960s and 2004. Currently, 66% of adults are overweight or obese; 16% of children and adolescents are overweight and 34% are at risk of overweight. Minority and low-socioeconomic-status groups are disproportionately affected at all ages. Annual increases in prevalence ranged from 0.3 to 0.9 percentage points across groups. By 2015, 75% of adults will be overweight or obese, and 41% will be obese. In conclusion, obesity has increased at an alarming rate in the United States over the past three decades. The associations of obesity with gender, age, ethnicity, and socioeconomic status are complex and dynamic. Related population-based programs and policies are needed.

Socioeconomic Status and Obesity

McLaren, L. — 2007-07-12

The objective of this review was to update Sobal and Stunkard's exhaustive review of the literature on the relation between socioeconomic status (SES) and obesity (Psychol Bull 1989;105:260–75). Diverse research databases (including CINAHL, ERIC, MEDLINE, and Social Science Abstracts) were comprehensively searched during the years 1988–2004 inclusive, using "obesity," "socioeconomic status," and synonyms as search terms. A total of 333 published studies, representing 1,914 primarily cross-sectional associations, were included in the review. The overall pattern of results, for both men and women, was of an increasing proportion of positive associations and a decreasing proportion of negative associations as one moved from countries with high levels of socioeconomic development to countries with medium and low levels of development. Findings varied by SES indicator; for example, negative associations (lower SES associated with larger body size) for women in highly developed countries were most common with education and occupation, while positive associations for women in medium- and low-development countries were most common with income and material possessions. Patterns for women in higher- versus lower-development countries were generally less striking than those observed by Sobal and Stunkard; this finding is interpreted in light of trends related to globalization. Results underscore a view of obesity as a social phenomenon, for which appropriate action includes targeting both economic and sociocultural factors.

Genetic Epidemiology of Obesity

Yang, W., Kelly, T., He, J. — 2007-07-12

Obesity has become a global epidemic and contributes to the increasing burden of type 2 diabetes, cardiovascular disease, stroke, some types of cancer, and premature death worldwide. Obesity is highly heritable and arises from the interactions of multiple genes, environmental factors, and behavior. In this paper, the authors reviewed recent developments in genetic epidemiologic research, focusing particularly on several promising genomic regions and obesity-related genes. Gene-gene and gene-environment interactions of obesity were also discussed. Published studies were accessed through the MEDLINE database. The authors also searched the Obesity Gene Map Database (http://obesitygene.pbrc.edu/) and conducted a manual search using references cited in relevant papers. Heritabilities for obesity-related phenotypes varied from 6% to 85% among various populations. As of October 2005, 253 quantitative trait loci for obesity-related phenotypes have been localized in 61 genome-wide linkage scans, and genetic variants in 127 biologic candidate genes have been reported to be associated with obesity-related phenotypes from 426 positive findings. Gene-gene interactions were also observed in several genes, and some genes were found to influence the effect of dietary intake and physical activity on obesity-related phenotypes. Integration of genetic epidemiology with functional genomics and proteomics studies will be required to fully understand the role of genetic variants in the etiology and prevention of obesity.

Childhood Overweight, Obesity, and the Metabolic Syndrome in Developing Countries

Kelishadi, R. — 2007-07-12

The incidence of chronic disease is escalating much more rapidly in developing countries than in industrialized countries. A potential emerging public health issue may be the increasing incidence of childhood obesity in developing countries and the resulting socioeconomic and public health burden faced by these countries in the near future. In a systematic review carried out through an electronic search of the literature from 1950–2007, the author compared data from surveys on the prevalence of overweight, obesity, and the metabolic syndrome among children living in developing countries. The highest prevalence of childhood overweight was found in Eastern Europe and the Middle East, whereas India and Sri Lanka had the lowest prevalence. The few studies conducted in developing countries showed a considerably high prevalence of the metabolic syndrome among youth. These findings provide alarming data for health professionals and policy-makers about the extent of these problems in developing countries, many of which are still grappling with malnutrition and micronutrient deficiencies. Time trends in childhood obesity and its metabolic consequences, defined by uniform criteria, should be monitored in developing countries in order to obtain useful insights for primordial and primary prevention of the upcoming chronic disease epidemic in such communities.

Abdominal Obesity and Fatty Liver

Jakobsen, M., Berentzen, T, Sorensen, T., Overvad, K — 2007-07-12

It has been hypothesized that visceral fat releases free fatty acids and adipokines and thereby exposes the liver to fat accumulation. The authors aimed to evaluate current epidemiologic evidence for an association between abdominal fat and liver fat content. Clinical and epidemiologic studies with data on abdominal fat and liver fat content were reviewed. Studies using waist circumference to estimate abdominal fat mass suggested a direct association between abdominal fat and liver fat content. Studies using imaging methods suggested a direct association between intraabdominal fat and liver fat content, but not between subcutaneous abdominal fat and liver fat content. In conclusion, clinical and epidemiologic studies of abdominal fat and liver fat content suggest a direct association between abdominal fat and liver fat content which is probably accounted for by visceral fat. However, results from the included studies do not allow strong conclusions regarding the temporal sequence of events. Future longitudinal studies are recommended to obtain additional information on associations and mechanisms. Both abdominal fat depots and other body compartments of interest should be included to further investigate the association between specific fat depots and liver fat content. Biomarkers may provide insight into underlying mechanisms.

Obesity and Prostate Cancer: Making Sense out of Apparently Conflicting Data

Freedland, S. J., Platz, E. A. — 2007-07-12

Both obesity and prostate cancer are epidemic in Western society. Although initial epidemiologic data appeared conflicting, recent studies, especially large prospective studies published in the past 6–12 months, have clarified the association between obesity and prostate cancer. The aim of this paper is to review the epidemiologic data linking obesity and prostate cancer, with an emphasis on new data published since 2005. A PubMed search was done on the keywords, "prostate cancer" and "obesity." Relevant articles and their references were reviewed for data on the association between obesity and prostate cancer. Recent data suggest that obesity is associated with reduced risk of nonaggressive disease but increased risk of aggressive disease. This may in part be explained by an inherent bias in our ability to detect prostate cancer in obese men (lower prostate-specific antigen values and larger sized prostates making biopsy less accurate for finding an existing cancer). Ultimately, this leads to increased risk of cancer recurrence after primary therapy and increased risk of prostate cancer mortality. The biologic causes of these associations are likely multifactorial, although the lower testosterone levels among obese men appear to be one of the most promising explanations. The association between obesity and prostate cancer is complex. Emerging data suggest a differential effect of obesity by disease aggressiveness: obesity may reduce the risk of nonaggressive disease while it may promote aggressive disease.

Biomarkers of Obesity and Subsequent Cardiovascular Events

Musaad, S., Haynes, E. N. — 2007-07-12

Obesity is a major risk factor for cardiovascular diseases, but the mechanisms for increased cardiovascular risk in obesity are still unclear. Inflammation and increased oxidative stress are two potential mechanisms proposed to play a major role in the morbidity associated with obesity. Studies that investigate these mechanisms rely on biomarkers, but validated biomarkers for obesity-related cardiovascular outcomes are lacking. By finding optimal biomarkers, diagnostic criteria for cardiovascular diseases can be refined in the obese beyond "traditional" risk factors to identify early pathologic processes. The objective of this review is to identify potential early biomarkers resulting from obesity and associated with cardiovascular disease. Studies were initially identified through the search engine PubMed by using the keywords "obesity" and "biomarker." Subsequently, combinations of the keywords "obesity," "biomarker," "cardiovascular risk," "adipose tissue," "adipokine," "adipocytokine," and "oxidative stress" were used. The SOURCE database and Online Mendelian Inheritance in Man (OMIM) were used to obtain more information on the biomarkers. Results of the searches yielded a large number of potential biomarkers that occur in obesity and which either correlate with traditional cardiovascular risk factors or predict subsequent cardiovascular events. Several biomarkers are promising regarding their biologic properties, but they require further validation in humans.

Comparison of Body Mass Index, Waist Circumference, and Waist/Hip Ratio in Predicting Incident Diabetes: A Meta-Analysis

Vazquez, G., Duval, S., Jacobs, D. R., Silventoinen, K. — 2007-07-12

Body mass index, waist circumference, and waist/hip ratio have been shown to be associated with type 2 diabetes. From the clinical perspective, central obesity (approximated by waist circumference or waist/hip ratio) is known to generate diabetogenic substances and should therefore be more informative than general obesity (body mass index). Because of their high correlation, from the statistical perspective, body mass index and waist circumference are unlikely to yield different answers. To compare associations of diabetes incidence with general and central obesity indicators, the authors conducted a meta-analysis based on published studies from 1966 to 2004 retrieved from a PubMed search. The analysis was performed with 32 studies out of 432 publications initially identified. Measures of association were transformed to log relative risks per standard deviation (pooled across all studies) increase in the obesity indicator and pooled using random effects models. The pooled relative risks for incident diabetes were 1.87 (95% confidence interval (CI): 1.67, 2.10), 1.87 (95% CI: 1.58, 2.20), and 1.88 (95% CI: 1.61, 2.19) per standard deviation of body mass index, waist circumference, and waist/hip ratio, respectively, demonstrating that these three obesity indicators have similar associations with incident diabetes. Although the clinical perspective focusing on central obesity is appealing, further research is needed to determine the usefulness of waist circumference or waist/hip ratio over body mass index.

The Built Environment and Obesity

2007-07-12

Obesity results from a complex interaction between diet, physical activity, and the environment. The built environment encompasses a range of physical and social elements that make up the structure of a community and may influence obesity. This review summarizes existing empirical research relating the built environment to obesity. The Medline, PsychInfo, and Web of Science databases were searched using the keywords "obesity" or "overweight" and "neighborhood" or "built environment" or "environment." The search was restricted to English-language articles conducted in human populations between 1966 and 2007. To meet inclusion criteria, articles had to 1) have a direct measure of body weight and 2) have an objective measure of the built environment. A total of 1,506 abstracts were obtained, and 20 articles met the inclusion criteria. Most articles (84%) reported a statistically significant positive association between some aspect of the built environment and obesity. Several methodological issues were of concern, including the inconsistency of measurements of the built environment across studies, the cross-sectional design of most investigations, and the focus on aspects of either diet or physical activity but not both. Given the importance of the physical and social contexts of individual behavior and the limited success of individual-based interventions in long-term obesity prevention, more research on the impact of the built environment on obesity is needed.

Promoting Physical Activity Participation among Children and Adolescents

Salmon, J., Booth, M. L., Phongsavan, P., Murphy, N., Timperio, A. — 2007-07-12

With global increases in the prevalence of overweight and obesity among children and adolescents, there has never been a more urgent need for effective physical activity programs. The aim of this narrative review is to summarize the evidence of the effectiveness of interventions that report physical activity outcomes in children aged 4–12 years and adolescents aged 13–19 years. A systematic search of electronic databases identified 76 interventions. Most interventions were delivered via the school setting (57 interventions), nine through the family setting, six via primary care, and four in community- or Internet-based settings. Children's physical activity interventions that were most effective in the school setting included some focus on physical education, activity breaks, and family strategies. Interventions delivered in the family setting were not highly effective, but many were pilot studies. The use of motivationally tailored strategies and program delivery in the primary care setting showed promise among adolescents. Many studies had methodological and reporting flaws (e.g., no baseline data, poor study design, physical activity measures of unknown reliability and validity, and poor reporting of sample size, response rates, attrition/retention, compliance, year of intervention, and duration of intervention). Publications reporting the results of evaluations of intervention studies should follow the Consolidated Standards of Reporting Trials guidelines or, for nonrandomized studies, should follow the Transparent Reporting of Evaluations with Nonrandomized Designs guidelines. Further evidence of the effectiveness of interventions promoting young people's physical activity in family and community settings is needed.

The Real Contribution of Added Sugars and Fats to Obesity

Drewnowski, A. — 2007-07-12

Obesity rates in the United States are a function of socioeconomic status. Higher rates are found among groups with lower educational and income levels, among racial and ethnic minorities, and in high-poverty areas. Yet, the relation between obesity, nutrition, and diet continues to be viewed in biologic terms, with the search for likely causes focused on consumption of specific macronutrients, foods, or food groups. Epidemiologic evidence linking diet composition and body weight has mostly relied on ecologic comparisons, time trends, and analyses of cross-sectional studies. Plausible physiologic mechanisms have included the metabolic effects of dietary components, mostly sugars and fats, on regulation of food intake and deposition of body fat. However, the evidence could not have been convincing since the blame for rising obesity rates seems to shift regularly, every 10 years or so, from fats to sugars and then back again. This review demonstrates that much of past epidemiologic research is consistent with a single parsimonious explanation: obesity has been linked repeatedly to consumption of low-cost foods. Refined grains, added sugars, and added fats are inexpensive, good tasting, and convenient. The fact that energy-dense foods (megajoules/kilogram) cost less per megajoule than do nutrient-dense foods means that energy-dense diets are not only cheaper but may be preferentially selected by the lower-income consumer. In other words, the low cost of dietary energy (dollars/megajoule), rather than specific food, beverage, or macronutrient choices, may be the main predictor of population weight gain. Examining past studies of the contribution of added sugars and fats to obesity rates through the prism of food prices and diet costs is the purpose of this review.

Editorial: Vaccines and Public Health

Ibrahim, M. A. — 2006-07-20

Immunization to Protect the US Armed Forces: Heritage, Current Practice, and Prospects

Grabenstein, J. D., Pittman, P. R., Greenwood, J. T., Engler, R. J.M. — 2006-07-20

Americans serving with the US Armed Forces need protection from the dangerous infections that they can contract during training, based on occupation, during overseas deployment, or because of underlying health status. For over 230 years, the military health-care system has immunized troops to protect them personally and to help them accomplish their missions. Military researchers have invented, developed, and improved vaccines and immunization delivery methods against more than 20 diseases. This article consolidates content from several previous historical reviews, adds additional sources, and cites primary literature regarding military contributions and accomplishments. Discussion emphasizes smallpox, typhoid fever, tetanus, influenza, meningococcal disease, adenovirus, yellow fever, pneumococcal disease, and anthrax. Delivery issues include documentation, simultaneous immunization, seroscreening, safety surveillance, jet injection, and cold-chain management. Immunization policies for each major US conflict are described. Military immunization programs need to be individualized on the basis of personal contraindications and prior immunity. The proper conduct of military immunization programs respects the need for detailed education of military personnel, maximizes quality in immunization delivery, and supports quality clinical care to prevent and treat adverse events after immunization. Military immunization programs maintain the health of soldiers, marines, sailors, airmen, and coast guardsmen, the resources most critical to military success.

Measuring Immunization Coverage among Preschool Children: Past, Present, and Future Opportunities

2006-07-20

Control of vaccine-preventable diseases depends on maintaining high levels of immunization coverage. Immunization coverage among preschool children remains suboptimal in some areas and sociodemographic subgroups, as well as for more recently introduced vaccines, leaving susceptible young children vulnerable to complications from vaccine-preventable diseases. This paper reviews approaches historically used to measure immunization coverage among preschool children in the United States. The strengths and weaknesses of various approaches to measuring immunization coverage among preschool children are explored, with emphasis on the current means to measure national immunization coverage—the National Immunization Survey. Methods for measuring immunization coverage among preschool children at local and state levels are also evaluated. Future opportunities and challenges for measuring immunization coverage at the local, state, and national levels are explored.

Interdisciplinary Epidemiologic and Economic Research Needed to Support a Universal Childhood Influenza Vaccination Policy

2006-07-20

Recent research indicates that influenza vaccination of children may decrease the influenza disease burden in adults to a greater extent than targeting vaccination to populations at high risk of serious disease. Possible new policies reflecting these results would add groups most likely to transmit disease to existing vaccination recommendations. Interdisciplinary research combining epidemiology with economics is needed to answer critical questions about the desirability and feasibility of potential new policies, such as what additional resources medical providers might need to expand vaccination to larger groups or what opportunity costs parents might incur in vaccinating their children annually. In this paper, the authors provide background for some of the changes in influenza vaccination rates and disease and discuss existing information gaps and research methods capable of closing these gaps. They provide several examples of interdisciplinary studies that have incorporated both economics and epidemiology or health policy issues. These studies are representative of a variety of stakeholder perspectives needed to determine whether community-based, universal childhood vaccination policies would be more efficacious and cost-effective than strategies targeted toward persons at high risk of disease complications.

Delivering Influenza Vaccine to Pregnant Women

Naleway, A. L., Smith, W. J., Mullooly, J. P. — 2006-07-20

Pregnant women have an increased risk of influenza infection and complications. The Advisory Committee on Immunization Practices currently recommends vaccination for women who are pregnant during influenza season. The authors review the literature concerning influenza vaccine safety, effectiveness, and coverage rates during pregnancy, as well as opportunities to improve vaccination rates during pregnancy. No study has demonstrated an increased risk of maternal complications or adverse fetal outcomes associated with inactivated influenza vaccine. Few studies have examined the effectiveness of vaccination during pregnancy, and the results from these studies are inconsistent, with some showing a protective effect and others showing no effect. Despite the proven safety of vaccination and the possible benefits to women and their infants, reported vaccination rates during pregnancy are generally less than 10%. Mothers frequently cite concerns about vaccine safety as a barrier to vaccination. Lack of adequate information about the risks and benefits of vaccination is reported by both patients and obstetric care providers. Organizational factors such as lack of vaccine storage facilities may also limit vaccination during pregnancy. Effective interventions should target factors pertaining to patients or providers, or they should address organizational or logistic barriers. The Advisory Committee on Immunization Practices currently recommends standing orders programs or reminders for patients and providers as strategies to improve vaccination rates.

Distribution of Influenza Vaccine to High-Risk Groups

Ompad, D. C., Galea, S., Vlahov, D. — 2006-07-20

Vaccine distribution programs have historically targeted individuals at high risk of complications due to influenza. Despite recommendations from the Advisory Committee on Immunization Practices, vaccination coverage among high-risk populations has been generally low. This review systematically summarizes the recent literature evaluating programs in different settings, from within medical settings to venue-based and community-based approaches, in an effort to identify successful program components. The published literature was identified by using the MEDLINE database from 1990 to 2006 covering studies that reported on interventions or programs aimed at vaccinating high-risk populations. The authors reviewed 56 studies. In the United States, the Healthy People 2010 goals included 90% vaccination coverage for adults aged ≥65 years and 60% for high-risk adults aged 18–64 years. Only a handful of the studies reviewed managed to meet those goals. Interventions that increased vaccination coverage to Healthy People 2010 goals included advertising, provider and patient mailings, registry-based telephone calls, patient and staff education, standing orders coupled with standardized forms, targeting of syringe exchange customers, and visiting nurses. Few studies evaluated the impact of vaccination programs by race/ethnicity and socioeconomic status. Few studies targeted individuals outside of the health-care and social services sectors. Given the growing disparities in health and health-care access, understanding the way in which interventions can remedy disparities is crucial.

Vaccine Preventable Diseases and Vaccination Policy for Indigenous Populations

Menzies, R., McIntyre, P. — 2006-07-20

Compared with nonindigenous people, indigenous people in first-world countries have experienced much higher rates of many vaccine preventable diseases. This systematic review of published scientific literature, government reports, and immunization guidelines from Australia, Canada, New Zealand, and the United States compares pre- and postvaccination disease rates and vaccination policy for indigenous people in these four countries. Nationally funded universal vaccination programs are clearly the most effective way of reducing disease in indigenous populations. Most successful have been programs for viral diseases in which strain variations are not important and herd immunity is high, such as measles and hepatitis B. For bacterial infections, strain variations (pneumococcal disease), heavy nasopharyngeal colonization of young infants (pneumococcal and Haemophilus influenzae type b disease), low vaccine effectiveness in adults with a high prevalence of risk factors (polysaccharide pneumococcal vaccine), and waning immunity (pertussis) have been associated with continuing or widening disparities between indigenous and nonindigenous populations. However, universal vaccination programs are not always possible. Geographic targeting of all persons in certain regions with high disease rates has been successful, as has targeting of indigenous populations in regions where they constitute larger proportions of the population. In national programs targeting only indigenous people, it has been difficult to achieve high coverage, particularly in urban areas. Innovative program approaches are particularly needed in these situations.

Prevention of Congenital Rubella Syndrome--What Makes Sense in 2006?

Robinson, J. L., Lee, B. E., Preiksaitis, J. K., Plitt, S., Tipples, G. A. — 2006-07-20

This review summarizes the practical aspects of rubella immunization programs in both developed and developing countries. Routine use of rubella vaccine is gradually resulting in the elimination of endemic rubella and congenital rubella syndrome (CRS) in the developed world, and routine use of vaccine in young children is now being implemented in many developing countries. However, such programs must achieve high immunization rates or be supplemented by the immunization of seronegative women of childbearing age to prevent a paradoxical increase in CRS as the burden of illness is shifted to an older age group. There are many successful prenatal screening programs for rubella immunity in developed countries, but screening prior to pregnancy could theoretically prevent even more cases of CRS. Enzyme-linked immunosorbent assay is the most commonly used laboratory test for screening, but the protective titer remains to be established. The need for reimmunization of women who serorevert or who remain seronegative following rubella vaccine has not been established. Surveillance for rubella cases and for CRS is vital in assessment of the ongoing success of rubella immunization programs.

Mathematical Models for Predicting the Epidemiologic and Economic Impact of Vaccination against Human Papillomavirus Infection and Disease

Dasbach, E. J., Elbasha, E. H., Insinga, R. P. — 2006-07-20

Infection with human papillomavirus (HPV) is the primary cause of cervical cancer, other anogenital cancers, genital warts, and recurrent respiratory papillomatosis. Clinical studies have demonstrated that a prophylactic HPV vaccine can prevent infection, genital warts, and the precancerous lesions that lead to cervical cancer. Given the absence of data on the long-term effectiveness of HPV vaccination, a number of mathematical models have been developed to provide insight to policy makers by projecting the long-term epidemiologic and economic consequences of vaccination and evaluate alternative vaccination policies. This paper reviews the state of these models. Three types of HPV mathematical models have been reported in the literature: cohort, population dynamic, and hybrid. All have demonstrated that vaccination can significantly reduce the incidence of cervical cancer in the long term. However, only the cohort and hybrid models have evaluated the cost-effectiveness of vaccination strategies for preventing cervical cancer. These models have generally shown that vaccinating females can be cost-effective. None has accounted for the potential benefits of vaccinating the population to reduce the burden of recurrent respiratory papillomatosis and cancers of the vagina, vulva, anus, penis, and head/neck. Given that only the population dynamic model can account for both the direct and indirect (i.e., herd immunity effects) benefits of vaccination in the population, future research should focus on further development of dynamic models by expanding the range of epidemiologic outcomes tracked and including the ability to assess the cost-effectiveness of alternative vaccination policies.

Hepatitis A in the Era of Vaccination

Wasley, A., Fiore, A., Bell, B. P. — 2006-07-20

The World Health Organization estimates an annual total of 1.5 million clinical cases of hepatitis A worldwide, but seroprevalence data indicate that tens of millions of hepatitis A virus infections occur each year. In the United States in the 1980s–1990s, an average of 26,000 acute hepatitis A cases were reported per year, representing approximately 270,000 infections annually. Since licensure of effective hepatitis A vaccines in the mid-1990s, US hepatitis A rates have fallen precipitously—particularly since 1999, when routine childhood vaccination was recommended in states with consistently elevated rates. By 2004, the overall rate had declined to 1.9/100,000 population, the lowest rate ever recorded and 79% lower than any previously recorded nadir. These marked declines occurred with relatively modest vaccination coverage, suggesting that strong herd immunity accompanies the initiation of routine vaccination programs. Routine childhood vaccination has produced similar results in Israel and selected regions of Italy, Spain, and Australia. Hepatitis A vaccination will probably remain a low priority for some time in the poorest countries, where most persons are infected as young children. However, shifts in the epidemiologic patterns of disease associated with declining hepatitis A virus transmission are occurring in many regions of the world. These shifts are likely to create circumstances where strategically targeted vaccination of children could produce substantial public health benefits.

Hepatitis B Virus Infection: Epidemiology and Vaccination

Shepard, C. W., Simard, E. P., Finelli, L., Fiore, A. E., Bell, B. P. — 2006-07-20

Worldwide, two billion people have been infected with hepatitis B virus (HBV), 360 million have chronic infection, and 600,000 die each year from HBV-related liver disease or hepatocellular carcinoma. This comprehensive review of hepatitis B epidemiology and vaccines focuses on definitive and influential studies and highlights current trends, policies, and directions. HBV can be transmitted vertically, through sexual or household contact, or by unsafe injections, but chronic infections acquired during infancy or childhood account for a disproportionately large share of worldwide morbidity and mortality. Vaccination against HBV infection can be started at birth and provides long-term protection against infection in more than 90% of healthy people. In the 1990s, many industrialized countries and a few less-developed countries implemented universal hepatitis B immunization and experienced measurable reductions in HBV-related disease. For example, in Taiwan, the prevalence of chronic infection in children declined by more than 90%. Many resource-poor nations have recently initiated universal hepatitis B immunization programs with assistance from the Global Alliance for Vaccines and Immunization. Further progress towards the elimination of HBV transmission will require sustainable vaccination programs with improved vaccination coverage, practical methods of measuring the impact of vaccination programs, and targeted vaccination efforts for communities at high risk of infection.

Nationwide Hepatitis B Vaccination Program in Taiwan: Effectiveness in the 20 Years After It Was Launched

Chien, Y.-C., Jan, C.-F., Kuo, H.-S., Chen, C.-J. — 2006-07-20

The national hepatitis B vaccination program in Taiwan is considered one of the most successful and effective public health programs to control chronic hepatitis B infection in the past 20 years. This review illustrates how to implement a successful hepatitis B vaccination program based on Taiwan's experience. Several important controlled randomized clinical trials on hepatitis B immunoglobulin and vaccine in Taiwan demonstrated an 80–90% protective effect among infants of mothers who were positive for either hepatitis B envelope antigen or hepatitis B surface antigen. A series of prevalence surveys on children born before and after the national vaccination program began disclosed a steady decrease in seroprevalence of hepatitis B surface antigen in Taiwan, with 78–87% effectiveness after the national vaccination program was launched. Studies on the secular trend of liver disease risk also documented a 68% decline in mortality from fulminant hepatitis in infants and a 75% decrease in the incidence of hepatocellular carcinoma in children 6–9 years of age after the national vaccination program began. In conclusion, since 1984, the national hepatitis B vaccination program has been successful in preventing acute and chronic liver diseases in Taiwan.