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Disease Control and Prevention
American Journal of Epidemiology - current issue
A Cautionary Note on the Evaluation of Biomarkers of Subtypes of a Single Disease
Adewale, A. J., Liu, Q., Dinu, I., Lampe, P. D., Mitchell, B. L., Yasui, Y. Fri, 05 Sep 2008 00:00:00 -0000
Heterogeneity in the molecular characteristics of a disease presents a challenge to investigators attempting to identify biomarkers of the disease. Preceding the biomarker discovery effort with stratification within a heterogeneous disease group, which amounts to grouping disease cases into more homogeneous subtypes, seems to be a natural strategy for discovering subtype-specific biomarkers. This is because biologically more homogeneous subgroups are presumably easier to distinguish from the nondiseased than the entire heterogeneous disease group. The misleading benefits of this two-step approach are illustrated using an example from a protein biomarker discovery project for breast cancer. A potential analytical pitfall in this framework is explained using a conditional probability argument.
Risk of Complex and Atypical Endometrial Hyperplasia in Relation to Anthropometric Measures and Reproductive History
Epplein, M., Reed, S. D., Voigt, L. F., Newton, K. M., Holt, V. L., Weiss, N. S. Fri, 05 Sep 2008 00:00:00 -0000
The authors sought to test the hypothesis that characteristics and exposures which influence the balance of estrogen and progesterone bear on the incidence of endometrial hyperplasia (EH), a noninvasive proliferation of the lining of the uterus. Cases included all female members of Group Health (Washington State) who were diagnosed with complex EH or EH with atypia during the period 1985–2003 and whose diagnoses were confirmed in a pathology review (n = 446). Controls were selected randomly from Group Health membership files and were matched to the cases by age and enrollment status at the reference date. An increased risk of EH was associated with increasing body mass index and nulliparity. There was a suggestion of a decreased risk of EH with atypia among current smokers. No association with diabetes or hypertension was found. The risk factors observed to be associated with EH in this study are similar to those associated with endometrial cancer. Whether these risk factors predispose women to cancer simply by increasing EH incidence or continue to augment cancer risk even after EH is present is currently unknown.
Invited Commentary: Endometrial Hyperplasia--Getting Back to Normal
Lacey, J. V. Fri, 05 Sep 2008 00:00:00 -0000
Cancer precursors can help to reveal clues about how and when risk factors influence the development of carcinoma. Endometrial carcinoma is well-suited to studies of precursors: Strong risk and protective factors exist, as does a good candidate precursor lesion, called atypical endometrial hyperplasia. Atypical hyperplasia is the most severe type of endometrial hyperplasia, which ranges from mild, reversible proliferation to incipient carcinoma. In this issue of the Journal, Epplein et al. (Am J Epidemiol 2008;168:563–70) report that three established risk factors for endometrial carcinoma—obesity, parity, and smoking—are similarly associated with two types of endometrial hyperplasia: complex hyperplasia and atypical hyperplasia. How much these findings reveal about mechanistic pathways for endometrial carcinoma depends, in part, on three issues that specifically affect endometrial hyperplasia but also affect other precursors. They are: 1) potential misclassification of intermediate endpoints, 2) unsettled thresholds between low-risk and high-risk lesions, and 3) uncertain boundaries between normal tissue and early-stage precursors. In this commentary, the author explores how these issues might influence interpretation of the new data from Epplein et al. and shape future research on endometrial carcinoma precursors.
Epplein et al. Respond to "Endometrial Hyperplasia--Getting Back to Normal"
Epplein, M., Reed, S. D., Voigt, L. F., Newton, K. M., Holt, V. L., Weiss, N. S. Fri, 05 Sep 2008 00:00:00 -0000
Frequency of Leisure-Time Physical Activity and Serum 25-Hydroxyvitamin D Levels in the US Population: Results from the Third National Health and Nutrition Examination Survey
Scragg, R., Camargo, C. A. Fri, 05 Sep 2008 00:00:00 -0000
The decline in vitamin D status among older people is probably due to decreased synthesis of vitamin D by sun-exposed skin and/or decreased outdoor activity. The authors examined the association between outdoor leisure physical activity and serum 25-hydroxyvitamin D in the Third National Health and Nutrition Examination Survey (1988–1994) (n = 15,148 aged ≥20 years). The mean 25-hydroxyvitamin D concentration declined with increasing age, with 79, 73, and 68 nmol/liter for persons aged 20–39, 40–59, and 60 or more years. The proportion that engaged in outdoor activity in the past month was 80% for persons aged 20–39 and 40–59 years but 71% for those aged 60 or more years. In contrast, the mean difference in 25-hydroxyvitamin D between those who participated in outdoor activities daily compared with those who did not participate in the past month was similar for the youngest and oldest age groups: 13 and 16 nmol/liter, respectively. Those persons aged 60 or more years who participated in daily outdoor activities had a mean 25-hydroxyvitamin D concentration similar to that of persons aged 20–39 years: 77 versus 79 nmol/liter, respectively. These nationally representative data suggest that persons aged 60 or more years can synthesize enough vitamin D from daily outdoor activities to maintain vitamin D levels similar to those of young adults.
Invited Commentary: Physical Activity and Vitamin D
Birrell, F., Francis, R. M. Fri, 05 Sep 2008 00:00:00 -0000
Exercise and vitamin D are both important for musculoskeletal health. In this issue of the Journal, Scragg and Camargo (Am J Epidemiol 2008;168:577–86) provide a new analysis of relatively old data on physical activity and vitamin D from the Third National Health and Nutrition Examination Survey (1988–1994). This commentary considers the methodological strengths and weaknesses of the study and concludes that the findings are as robust as could reasonably be expected from a cross-sectional design. Consideration is given to whether outdoor exercise is the cause of higher vitamin D levels and, if so, whether mortality gains may accrue from more widespread participation. A note of caution is sounded, given the disappointing results on studies of the prevention of falls and fractures with vitamin D supplementation in community-dwelling populations. However, this is an important observation, and more epidemiologic studies are needed, preferably including care home residents. Applied researchers should consider further studies of vitamin D supplementation in older people, possibly combined with an exercise intervention. Public health professionals and practicing clinicians should recognize that there is a rationale for recommending outdoor exercise, and they should seek to improve universal accessibility.
Scragg and Camargo Respond to "Physical Activity and Vitamin D"
Scragg, R., Camargo, C. A. Fri, 05 Sep 2008 00:00:00 -0000
Adolescent Cannabis Problems and Young Adult Depression: Male-Female Stratified Propensity Score Analyses
Harder, V. S., Stuart, E. A., Anthony, J. C. Fri, 05 Sep 2008 00:00:00 -0000
Cannabis use and depression are two of the most prevalent conditions worldwide. Adolescent cannabis use is linked to depression in many studies, but the effects of adolescent cannabis involvement on young adult depression remain unclear and may differ for males versus females. In this cohort study of youth from a mid-Atlantic metropolitan area of the United States, repeated assessments from 1985 (at age 6 years) through 2002 (at age 21 years) were made for 1,494 individuals (55% female). Measured covariate differences between individuals with and without cannabis problems were controlled via propensity score techniques. The estimated risk of young adult depression for adolescents with cannabis problems was not significantly different from that for comparison adolescents for either females (odds ratio = 0.7, 95% confidence interval: 0.2, 2.3) or males (odds ratio = 1.7, 95% confidence interval: 0.8, 3.6). The evidence does not support a causal association linking adolescent-onset cannabis problems with young adult depression.
Inflammatory Markers and Longitudinal Lung Function Decline in the Elderly
Jiang, R., Burke, G. L., Enright, P. L., Newman, A. B., Margolis, H. G., Cushman, M., Tracy, R. P., Wang, Y., Kronmal, R. A., Barr, R. G. Fri, 05 Sep 2008 00:00:00 -0000
Longitudinal studies examining associations of the inflammatory markers fibrinogen and C-reactive protein (CRP) with lung function decline are sparse. The authors examined whether elevated fibrinogen and CRP levels were associated with greater longitudinal lung function decline in the elderly. The Cardiovascular Health Study measured fibrinogen and CRP in 5,790 Whites and African Americans from four US communities aged 65 years or older in 1989–1990 or 1992–1993. Spirometry was performed in 1989–1990 and 4, 7, and 16 years later. Fibrinogen and CRP were inversely associated with lung function at baseline after adjustment for multiple potential confounders. In mixed models, the rate of decline in forced expiratory volume in 1 second (FEV1)/forced vital capacity (FVC) ratio with increasing age was faster among those with higher baseline fibrinogen (–0.032%/year per standard deviation higher fibrinogen (95% confidence interval: –0.057, –0.0074)) but not among those with higher CRP (–0.0037%/year per standard deviation higher CRP (95% confidence interval: –0.013, 0.0056)). Longitudinal analyses for FEV1 and FVC yielded results in the direction opposite of that hypothesized, possibly because of the high mortality rate and strong inverse association of FEV1 and FVC but not FEV1/FVC with mortality. An alternative approach to missing data yielded similar results. In conclusion, higher levels of fibrinogen, but not CRP, independently predicted greater FEV1/FVC decline in the elderly.
Epidemiologic Reviews - current issue
The Global Epidemic of Obesity: An Overview
Caballero, B. Thu, 12 Jul 2007 00:00:00 -0000
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. Thu, 12 Jul 2007 00:00:00 -0000
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. Thu, 12 Jul 2007 00:00:00 -0000
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. Thu, 12 Jul 2007 00:00:00 -0000
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. Thu, 12 Jul 2007 00:00:00 -0000
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 Thu, 12 Jul 2007 00:00:00 -0000
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.
Epidemiology and Infection - Current Issue
Volume 136 Issue 09
Sun, 31 Aug 2008 23:00:00 -0000
Epidemiology and Infection, Volume 136 Issue 09 Increased frequency in 2007 - now 8 issues per year! Epidemiology and Infection publishes original reports and reviews on all aspects of infection in humans and animals. Particular emphasis is given to the epidemiology, prevention and control of infectious diseases. The field covered is broad and includes the zoonoses, tropical infections, food hygiene, vaccine studies, statistics and the clinical, social and public-health aspects of infectious disease. Papers covering microbiology and immunology which have an epidemiological relevance are part of this broad field. Papers come from medical and veterinary scientists worldwide. It has become the key periodical in which to find the latest reports on recently discovered infections and new technology. For those concerned with policy and planning for the control of infections, the papers on mathematical modelling of epidemics caused by historical, current and emergent infections, will be of particular value. To celebrate 100 years of the journal, a series of important papers has been selected and each, together with a modern commentary on the paper by an expert, will be published on-line. This journal has now moved over to electronic submission, using the Scholar One system. Click here to go to the submission website. Guidance on how to upload your manuscript is available on the site by clicking "User Tutorials". Online manuscript submission (now) available, please go to http://mc.manuscriptcentral.com/cup/hyg
The elimination of Chagas' disease from Brazil
Review ArticlesE. MASSAD, Epidemiology and Infection, Volume 136 Issue 09 , pp 1153-1164Abstract
Outbreak of group A streptococcal throat infection: don't forget to ask about food
Research ArticlesG. FALKENHORST, J. BAGDONAITE, M. LISBY, S.B. MADSEN, L. LAMBERTSEN, K.E.P. OLSEN, K. MLBAK, Epidemiology and Infection, Volume 136 Issue 09 , pp 1165-1171Abstract
Evaluation of data quality in a laboratory-based surveillance of M. tuberculosis drug resistance and impact on the prevalence of resistance: France, 2004
Research ArticlesP.M. KHU, A. MALLET, N. VEZIRIS, V. JARLIER, J. ROBERT, Epidemiology and Infection, Volume 136 Issue 09 , pp 1172-1178Abstract
Performance of an interferon-gamma release assay for diagnosing latent tuberculosis infection in children
Research ArticlesK. OKADA, T.E. MAO, T. MORI, T. MIURA, T. SUGIYAMA, T. YOSHIYAMA, S. MITARAI, I. ONOZAKI, N. HARADA, S. SAINT, K.S. KONG, Y.M. CHHOUR, Epidemiology and Infection, Volume 136 Issue 09 , pp 1179-1187Abstract
Seasonality of clinical isolation of rapidly growing mycobacteria
Brief ReportX.Y. HAN, Epidemiology and Infection, Volume 136 Issue 09 , pp 1188-1191Abstract
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