Epidemiology is the scientific study of factors affecting the health and illness of individuals and populations, and serves as the foundation and logic of interventions made in the interest of public health and preventive medicine. It is considered a cornerstone methodology of public health research, and is highly regarded in evidence-based medicine for identifying risk factors for disease and determining optimal treatment approaches to clinical practice. The acting epidemiologist works on issues ranging from the practical, such as outbreak investigation, environmental exposure, and health promotion, to the theoretical, including the development of statistical, mathematical, philosophical, and biological theory. To this end, epidemiologists employ a range of study designs from the observational to experimental, with the purpose of revealing unbiased relationships between exposures such as nutrition, biological agents, stress, or chemicals to outcomes such as disease, wellness and health indicators.

Epidemiologic studies are generally categorized as descriptive, analytic (aiming to examine associations, commonly hypothesized causal relationships), and experimental (a term often equated with clinical or community trials of treatments and other interventions).

Epidemiologists work in a variety of settings. Some epidemiologists work 'in the field', i.e., in the community, commonly in a public health service, and are often at the forefront of investigating and combating disease outbreaks.

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American Journal of Epidemiology - current issue

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The Association Between Obesity and Low Back Pain: A Meta-Analysis
Shiri, R., Karppinen, J., Leino-Arjas, P., Solovieva, S., Viikari-Juntura, E. This meta-analysis assessed the association between overweight/obesity and low back pain. The authors systematically searched the Medline (National Library of Medicine, Bethesda, Maryland) and Embase (Elsevier, Amsterdam, the Netherlands) databases until May 2009. Ninety-five studies were reviewed and 33 included in the meta-analyses. In cross-sectional studies, obesity was associated with increased prevalence of low back pain in the past 12 months (pooled odds ratio (OR) = 1.33, 95% confidence interval (CI): 1.14, 1.54), seeking care for low back pain (OR = 1.56, 95% CI: 1.46, 1.67), and chronic low back pain (OR = 1.43, 95% CI: 1.28, 1.60). Compared with nonoverweight people, overweight people had a higher prevalence of low back pain but a lower prevalence of low back pain compared with obese people. In cohort studies, only obesity was associated with increased incidence of low back pain for ≥1 day in the past 12 months (OR = 1.53, 95% CI: 1.22, 1.92). Results remained consistent after adjusting for publication bias and limiting the analyses to studies that controlled for potential confounders. Findings indicate that overweight and obesity increase the risk of low back pain. Overweight and obesity have the strongest association with seeking care for low back pain and chronic low back pain.
Impact of Improved Classification on the Association of Human Papillomavirus With Cervical Precancer
Castle, P. E., Schiffman, M., Wheeler, C. M., Wentzensen, N., Gravitt, P. E. Misclassification of exposure and surrogate endpoints of disease can obscure causal relations. Using data from the Atypical Squamous Cells of Undetermined Significance/Low-Grade Squamous Intraepithelial Lesion Triage Study (ALTS, 1997–2001), the authors explored the impact of exposure (human papillomavirus (HPV) detection) and endpoint (histologic cervical precancer) classification on their mutual association. Women referred into this study with an atypical squamous cells of undetermined significance Papanicolaou test with satisfactory results for all 4 HPV tests were included in this analysis (n = 3,215; 92.2%). HPV testing results were related to different definitions of cervical precancer, based on paired, worst 2-year histologic diagnoses, by calculating clinical sensitivity, specificity, and odds ratios. The authors found that HPV test sensitivity increased and specificity decreased with increasing certainty of cervical precancer, with HPV testing having the highest sensitivity (92%–98%) and lowest specificity (46%–54%) for consensus cervical intraepithelial neoplasia grade 3 (CIN 3). The overall accuracy of each HPV test, as measured by odds ratios, was greatest for consensus CIN-3 diagnoses, from 2- to 4-fold greater than for a less stringent precancer definition of any diagnosis of CIN 2 or more severe. In summary, there was convergence of greater certainty of carcinogenic HPV with greater certainty of a precancerous diagnosis, such that all 4 HPV tests almost always tested positive in women most likely to have cervical precancer. Finding increasingly strong associations when both test and diagnostic misclassification are reduced is a useful sign of "true association" in molecular epidemiology.
Invited Commentary: Human Papillomavirus Infection and Risk of Cervical Precancer--Using the Right Methods to Answer the Right Questions
Franco, E. L., Tota, J. Epidemiologists are well aware of the negative consequences of measurement error in exposure and outcome variables to their ability to detect putative causal associations. However, empirical proof that remedying the misclassification problem improves estimates of epidemiologic effect is seldom examined in detail. Of all areas in cancer epidemiology, perhaps the best example of the consequences of misclassification and of the steps taken to circumvent them was the pursuit, beginning in the mid-1980s, of the human papillomavirus (HPV) infection–cervical cancer association. The stakes were high: Had the wrong conclusions been reached epidemiologists would have been led astray in the search for competing hypotheses for the sexually transmissible agent causing cervical cancer or in ascribing to HPV infection a mere ancillary role among many lifestyle, hormonal, and environmental factors. The article by Castle et al. in this issue of the Journal (Am J Epidemiol. 2010;171(2):155–163) provides a detailed account of the joint influences of improved HPV and cervical precancer measurements in gradually unveiling the strong magnitude of the underlying association between viral exposure and cervical lesion risk. In this commentary, the authors extend the findings of Castle et al. by providing additional empirical evidence in support of their arguments.
Between-Strain Competition in Acquisition and Clearance of Pneumococcal Carriage--Epidemiologic Evidence From a Longitudinal Study of Day-Care Children
Auranen, K., Mehtala, J., Tanskanen, A., S. Kaltoft, M. The state of pneumococcal carriage—that is, pneumococcal colonization in the nasopharynx of healthy persons—represents a reservoir for the spread of pneumococci among individuals. In light of the introduction of new pneumococcal conjugate vaccines, further knowledge on the dynamics of pneumococcal carriage is important. Different serotypes (strains) of pneumococcus are known to compete with each other in colonizing human hosts. Understanding the strength and mode of between-serotype competition is important because of its implications for vaccine-induced changes in the ecology of pneumococcal carriage. Competition may work through reduced acquisition of new serotypes, due to concurrent carriage in the individual, or through enhanced clearance of serotypes in carriers who harbor more than 1 serotype simultaneously. The authors employed longitudinal data (1999–2001) on pneumococcal carriage in Danish day-care children to analyze between-serotype competition. The data included observations of carriage in children who had not been vaccinated against pneumococcus, and the level of pneumococcal antibiotic resistance and antibiotic usage in the community was very low. Clearance of any single serotype was not affected by simultaneous carriage of other serotypes. In contrast, acquisition of other serotypes in already-colonized hosts was weak (relative rate of acquisition = 0.09, 95% credible interval: 0.05, 0.15).
Near Real-Time Surveillance for Influenza Vaccine Safety: Proof-of-Concept in the Vaccine Safety Datalink Project
Greene, S. K., Kulldorff, M., Lewis, E. M., Li, R., Yin, R., Weintraub, E. S., Fireman, B. H., Lieu, T. A., Nordin, J. D., Glanz, J. M., Baxter, R., Jacobsen, S. J., Broder, K. R., Lee, G. M. The emergence of pandemic H1N1 influenza in 2009 has prompted public health responses, including production and licensure of new influenza A (H1N1) 2009 monovalent vaccines. Safety monitoring is a critical component of vaccination programs. As proof-of-concept, the authors mimicked near real-time prospective surveillance for prespecified neurologic and allergic adverse events among enrollees in 8 medical care organizations (the Vaccine Safety Datalink Project) who received seasonal trivalent inactivated influenza vaccine during the 2005/06–2007/08 influenza seasons. In self-controlled case series analysis, the risk of adverse events in a prespecified exposure period following vaccination was compared with the risk in 1 control period for the same individual either before or after vaccination. In difference-in-difference analysis, the relative risk in exposed versus control periods each season was compared with the relative risk in previous seasons since 2000/01. The authors used Poisson-based analysis to compare the risk of Guillian-Barré syndrome following vaccination in each season with that in previous seasons. Maximized sequential probability ratio tests were used to adjust for repeated analyses on weekly data. With administration of 1,195,552 doses to children under age 18 years and 4,773,956 doses to adults, no elevated risk of adverse events was identified. Near real-time surveillance for selected adverse events can be implemented prospectively to rapidly assess seasonal and pandemic influenza vaccine safety.

Epidemiologic Reviews - current issue

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Epidemiologic Research on Health Disparities: Some Thoughts on History and Current Developments
James, S. A. In this introduction to volume 31 of Epidemiologic Reviews, the author traces the history of health disparities research in epidemiology and situates the 10 review articles comprising this edition within this history. With the aid of a conceptual model describing the key determinants of health disparities, he offers several suggestions for improving future epidemiologic research on health disparities.
Built Environments and Obesity in Disadvantaged Populations
Lovasi, G. S., Hutson, M. A., Guerra, M., Neckerman, K. M. In the United States, health disparities in obesity and obesity-related illnesses have been the subject of growing concern. To better understand how obesity-related health disparities might relate to obesogenic built environments, the authors conducted a systematic review of the published scientific literature, screening for studies with relevance to disadvantaged individuals or areas, identified by low socioeconomic status, black race, or Hispanic ethnicity. A search for related terms in publication databases and topically related resources yielded 45 studies published between January 1995 and January 2009 with at least 100 participants or area residents that provided information on 1) the built environment correlates of obesity or related health behaviors within one or more disadvantaged groups or 2) the relative exposure these groups had to potentially obesogenic built environment characteristics. Upon consideration of the obesity and behavioral correlates of built environment characteristics, research provided the strongest support for food stores (supermarkets instead of smaller grocery/convenience stores), places to exercise, and safety as potentially influential for disadvantaged groups. There is also evidence that disadvantaged groups were living in worse environments with respect to food stores, places to exercise, aesthetic problems, and traffic or crime-related safety. One strategy to reduce obesity would involve changing the built environment to be more supportive of physical activity and a healthy diet. Based on the authors' review, increasing supermarket access, places to exercise, and neighborhood safety may also be promising strategies to reduce obesity-related health disparities.

Epidemiology and Infection - Current Issue

Volume 138 Issue 02
Mon, 01 Feb 2010 00:00:00 -0000
Epidemiology and Infection, Volume 138 Issue 02 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
Transmission routes and risk factors for autochthonous hepatitis E virus infection in Europe: a systematic review
Review ArticlesH. C. LEWIS, O. WICHMANN, E. DUIZER, Epidemiology and Infection, Volume 138 Issue 02 , pp 145-166Abstract
Prevalence of hepatitis C virus infection in patients with COPD
Research ArticlesD. R. SILVA, J. STIFFT, H. CHEINQUER, M. M. KNORST, Epidemiology and Infection, Volume 138 Issue 02 , pp 167-173Abstract
National mortality rates from chronic liver disease and consumption of alcohol and pig meat
Research ArticlesH. R. DALTON, R. P. BENDALL, C. PRITCHARD, W. HENLEY, D. MELZER, Epidemiology and Infection, Volume 138 Issue 02 , pp 174-182Abstract
Pandemic (H1N1) 2009 virus outbreak in a school in London, April–May 2009: an observational study
Research ArticlesL. CALATAYUD, S. KURKELA, P. E. NEAVE, A. BROCK, S. PERKINS, M. ZUCKERMAN, M. SUDHANVA, A. BERMINGHAM, J. ELLIS, R. PEBODY, M. CATCHPOLE, R. HEATHCOCK, H. MAGUIRE, Epidemiology and Infection, Volume 138 Issue 02 , pp 183-191Abstract
Lessons from Nigeria: the role of roads in the geo-temporal progression of avian influenza (H5N1) virus
Brief ReportA. L. RIVAS, G. CHOWELL, S. J. SCHWAGER, F. O. FASINA, A. L. HOOGESTEIJN, S. D. SMITH, S. P. R. BISSCHOP, K. L. ANDERSON, J. M. HYMAN, Epidemiology and Infection, Volume 138 Issue 02 , pp 192-198Abstract

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