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American Journal of Epidemiology - RSS feed of current issue

Cover 25 Aug 2010

Editorial Board 25 Aug 2010

Subscriptions 25 Aug 2010

Table of contents 25 Aug 2010

Blood 25-Hydroxyvitamin D3 Concentrations and Incident Sporadic Colorectal Adenoma Risk: A Pooled Case-Control Study 25 Aug 2010

The authors examined the association between circulating 25-hydroxyvitamin D₃ (25(OH)D₃), the best indicator of total vitamin D exposure, and incident, sporadic colorectal adenoma risk in a pooled analysis of primary data from 3 colonoscopy-based case-control studies conducted in Minnesota, North Carolina, and South Carolina between 1991 and 2002. The pooled study included 616 colorectal adenoma cases and 770 polyp-free controls. Multivariable logistic regression was used to estimate the association between circulating 25(OH)D₃ and colorectal adenoma risk. Stratified analyses and the likelihood ratio test were used to examine effect modification by various risk factors. In the pooled analysis, higher circulating 25(OH)D₃ concentrations were statistically significantly associated with decreased colorectal adenoma risk (highest vs. lowest quartile odds ratio = 0.59, 95% confidence interval: 0.41, 0.84). The observed inverse association was stronger among participants who used nonsteroidal antiinflammatory drugs regularly (highest vs. lowest quartile odds ratio = 0.33, 95% confidence interval: 0.19, 0.56). Inverse associations between 25(OH)D₃ and colorectal adenoma did not differ substantially by other risk factors or by adenoma characteristics. These findings support the hypothesis that greater vitamin D exposure may reduce the risk of colorectal adenoma and suggest that it may do so more strongly in combination with antiinflammatory agents.

Community Programs for the Prevention of Cardiovascular Disease: A Systematic Review 25 Aug 2010

In this systematic review, the authors aimed to assess the effectiveness of community programs for prevention of cardiovascular disease (CVD). They searched numerous electronic databases (CDSR, DARE, HTA, EED, and CENTRAL via the Cochrane Library, MEDLINE, MEDLINE In Process, EMBASE, CINAHL, PsycINFO, HMIC, and ASSIA) and relevant Web sites from January 1970 to mid-July 2008. Controlled studies of community programs for the primary prevention of CVD were included. Net changes in CVD risk factors were used to generate an overall index for net change in 10-year CVD risk. The authors identified 36 relevant community programs that took place between 1970 and 2008. These programs were multifaceted interventions employing combinations of media, screening, and counseling activities and environmental changes and were primarily evaluated using controlled before-after studies. In 7 studies, investigators reported changes in CVD/total mortality rates, and in 5 they reported net changes. In all cases, these net changes were positive but were largely nonsignificant. In 22 studies, investigators reported changes in physiologic CVD risk factors, and there was a positive trend in the calculated CVD risk score. The average net reduction in 10-year CVD risk was 0.65%. Community programs for CVD prevention appear to have generally achieved favorable changes in overall CVD risk and, with adaptation to current circumstances, deserve continued consideration as possible approaches to preventing CVD.

The Emergence of Translational Epidemiology: From Scientific Discovery to Population Health Impact 25 Aug 2010

Recent emphasis on translational research (TR) is highlighting the role of epidemiology in translating scientific discoveries into population health impact. The authors present applications of epidemiology in TR through 4 phases designated T1–T4, illustrated by examples from human genomics. In T1, epidemiology explores the role of a basic scientific discovery (e.g., a disease risk factor or biomarker) in developing a "candidate application" for use in practice (e.g., a test used to guide interventions). In T2, epidemiology can help to evaluate the efficacy of a candidate application by using observational studies and randomized controlled trials. In T3, epidemiology can help to assess facilitators and barriers for uptake and implementation of candidate applications in practice. In T4, epidemiology can help to assess the impact of using candidate applications on population health outcomes. Epidemiology also has a leading role in knowledge synthesis, especially using quantitative methods (e.g., meta-analysis). To explore the emergence of TR in epidemiology, the authors compared articles published in selected issues of the Journal in 1999 and 2009. The proportion of articles identified as translational doubled from 16% (11/69) in 1999 to 33% (22/66) in 2009 (P = 0.02). Epidemiology is increasingly recognized as an important component of TR. By quantifying and integrating knowledge across disciplines, epidemiology provides crucial methods and tools for TR.

Invited Commentary: The Epicenter of Translational Science 25 Aug 2010

Epidemiology is at the center of translational science. Uniquely among biomedical disciplines, the methods and perspective of epidemiology span research from discovery to effective interventions and ultimately to their dissemination and implementation. However, shorthand designations for various phases of translational science, such as "T1, T2, T3, and T4," may be proliferating past the level of their usefulness. It is worthwhile to reflect on the actual nature of the science undertaken by epidemiologists along the continuum of discovery to application. The new challenge for epidemiology is the integration of knowledge and effective interventions into various societal settings working with allied disciplines not necessarily in the biomedical domain to ensure that these interventions have their intended effects on individual and public health.

Khoury et al. Respond to "The Epicenter of Translational Science": Crossing All the T's 25 Aug 2010

Birth Weight Standardized to Gestational Age and Intelligence in Young Adulthood: A Register-based Birth Cohort Study of Male Siblings 25 Aug 2010

The authors aimed to determine the relation between birth-weight variations within the normal range and intelligence in young adulthood. A historical birth cohort study was conducted. Data from the Medical Birth Register of Norway were linked with register data from the Norwegian National Conscript Service. The sample comprised 52,408 sibships of full brothers who were born singletons at 37–41 completed weeks’ gestation during 1967–1984 in Norway and were intelligence-tested at the time of mandatory military conscription. Generalized estimating equations were used to fit population-averaged panel data models. The analyses showed that in men with birth weights within the 10th–90th percentile range, a within-family difference of 1 standard deviation in birth weight standardized to gestational age was associated with a within-family difference of 0.07 standard deviation (99% confidence interval: 0.03, 0.09) in intelligence score, after adjustment for a range of background factors. There was no significant between-family association after adjustment for background factors. In Norwegian males, normal variations in intrauterine growth are associated with differences in intelligence in young adulthood. This association is probably not due to confounding by familial and parental characteristics.

Invited Commentary: The Use of Sibship Studies to Detect Familial Confounding 25 Aug 2010

The authors discuss how the sibship design can be used to detect and control for familial confounding. Family-level confounding is especially problematic when estimating modest individual-level effects in the presence of familial confounders with large effects. This circumstance arises frequently in studies which relate indicators of fetal growth, such as birth weight, to outcomes that are strongly associated with parental socioeconomic status and genes. The study by Eriksen et al. in this issue of the Journal (Am J Epidemiol. 2010;172(5):530–536) uses the sibship design to capture the relation between birth weight, gestational age, and intelligence score among Norwegian males born as singletons at 37–41 completed weeks’ gestation during 1967–1984. Their study illustrates how valuable the design can be in this kind of scenario. It also illustrates the potential complexity of sibship studies and the challenges they present for appropriate interpretation.

Midlife Health and Socioeconomic Consequences of Persistent Overweight Across Early Adulthood: Findings From a National Survey of American Adults (1986-2008) 25 Aug 2010

The health consequences of obesity and overweight have been well documented, but less research has examined their social and economic consequences. This paper examines the long-term consequences of early adult overweight for midlife health and socioeconomic attainment using prospective nationally representative panel data from American adults in the Monitoring the Future Study (1986–2008). Growth mixture models identified 2 distinct latent classes of trajectories of body mass index (BMI) from age 19 to 35 years: a persistently overweight class (BMI >25 kg/m²) and a second class exhibiting more moderate growth in BMI to age 35 years. Women (odds ratio (OR) = 2.16, 95% confidence interval (CI): 1.39, 3.36) and those from a lower childhood socioeconomic position (OR = 1.71, 95% CI: 1.30, 2.24) were more likely to be in the persistently overweight class. Compared with those in the moderately increasing BMI class, those in the persistently overweight class were more likely to have a chronic health problem at age 40 years (OR = 2.74, 95% CI: 2.20, 3.43), to have no further education beyond high school (OR = 1.33, 95% CI: 1.04, 1.69), and to have a higher odds of receiving welfare or unemployment compensation at age 40 years (OR = 1.76, 95% CI: 1.49, 2.04). These findings highlight the importance of addressing persistent obesity and overweight early in the life course.

A Study of the Birth Weight-Obesity Relation Using a Longitudinal Cohort and Sibling and Twin Pairs 25 Aug 2010

Sibling and twin study designs provide control for confounding factors that are typically unmeasured in traditional cohort studies. Using nationally representative data from the National Longitudinal Study of Adolescent Health collected at 3 visits during 1994–2002, the authors evaluated the longitudinal association between birth weight and later obesity in a traditional cohort study (n = 13,763; ages 11–21 years at baseline), controlling for sex, age, race/ethnicity, and parental education. Among persons with a nonobese mother, high birth weight (>4 kg) participants were more likely than normal birth weight (≥2.5–≤4 kg) participants to become obese later in life (incidence rate ratio = 1.46, 95% confidence interval: 1.28, 1.67). In a matched sibling pair sample (full siblings: n = 513; monozygotic twins: n = 207; dizygotic twins: n = 189), the authors examined longitudinal within-pair differences. Birth weight difference was positively associated with body mass index difference later in life for female monozygotic pairs only (β = 2.67, 95% confidence interval: 0.99, 4.35). Given the null associations observed in the sibling sample, the commonly observed positive association between birth weight and later obesity from cohort analyses may be attributed to confounding by maternal characteristics. Further research is needed to identify specific factors that contribute to the birth weight–obesity relation.

Changes in Weight at the End of Life: Characterizing Weight Loss by Time to Death in a Cohort Study of Older Men 25 Aug 2010

The purpose of this analysis was to characterize the natural history of weight change in the years prior to death among older persons and to examine how this pattern varies according to longevity and cause of death. Weight trajectories were analyzed by using data from 800 male decedents from the Baltimore Longitudinal Study of Aging (Maryland, 1958–2005) observed beginning an average of 19 years before death. A model including 3 distinct periods of weight change (weight stability/gain, mild weight loss, and accelerated weight loss before death) provided the best fit for all age-at-death groups. Approximately 9 years before death, the rate of weight loss increased to an average of 0.39 kg/year (P < 0.001) for all-cause mortality. For cancer deaths, weight loss accelerated significantly 3 years before death, regardless of age group. For cardiovascular deaths, the best-fitting inflection point increased with age, from 5 years for participants aged 60–69 years to 9–10 years before death for those aged 80 years or older. Results suggest that weight loss in older persons may begin earlier than previously believed. The duration of weight loss for noncancer deaths suggests that even distal changes in energy balance may be linked to risk of death.

Diet, Supplement Use, and Prostate Cancer Risk: Results From the Prostate Cancer Prevention Trial 25 Aug 2010

The authors examined nutritional risk factors for prostate cancer among 9,559 participants in the Prostate Cancer Prevention Trial (United States and Canada, 1994–2003). The presence or absence of cancer was determined by prostate biopsy, which was recommended during the trial because of an elevated prostate-specific antigen level or an abnormal digital rectal examination and was offered to all men at the trial's end. Nutrient intake was assessed using a food frequency questionnaire and a structured supplement-use questionnaire. Cancer was detected in 1,703 men; 127 cancers were high-grade (Gleason score 8–10). There were no associations of any nutrient or supplement with prostate cancer risk overall. Risk of high-grade cancer was associated with high intake of polyunsaturated fats (quartile 4 vs. quartile 1: odds ratio = 2.41, 95% confidence interval (CI): 1.33, 4.38). Dietary calcium was positively associated with low-grade cancer but inversely associated with high-grade cancer (for quartile 4 vs. quartile 1, odds ratios were 1.27 (95% CI: 1.02, 1.57) and 0.43 (95% CI: 0.21, 0.89), respectively). Neither dietary nor supplemental intakes of nutrients often suggested for prostate cancer prevention, including lycopene, long-chain n-3 fatty acids, vitamin D, vitamin E, and selenium, were significantly associated with cancer risk. High intake of n-6 fatty acids, through their effects on inflammation and oxidative stress, may increase prostate cancer risk.

Use of Aspirin and Other Nonsteroidal Antiinflammatory Medications in Relation to Prostate Cancer Risk 25 Aug 2010

Recent interest has focused on the role that inflammation may play in the development of prostate cancer and whether use of aspirin or other nonsteroidal antiinflammatory drugs (NSAIDs) affects risk. In a population-based case-control study designed to investigate the relation between these medications and prostate cancer risk, detailed exposure data were analyzed from 1,001 cases diagnosed with prostate cancer between January 1, 2002, and December 31, 2005, and 942 age-matched controls from King County, Washington. A significant 21% reduction in the risk of prostate cancer was observed among current users of aspirin compared with nonusers (95% confidence interval (CI): 0.65, 0.96). Long-term use of aspirin (>5 years: odds ratio = 0.76, 95% CI: 0.61, 0.96) and daily use of low-dose aspirin (odds ratio = 0.71, 95% CI: 0.56, 0.90) were also associated with decreased risk. There was no evidence that the association with aspirin use varied by disease aggressiveness, but there was effect modification (P_interaction = 0.02) with a genetic variant in prostaglandin-endoperoxide synthase 2 (PTGS2) (rs12042763). Prostate cancer risk was not related to use of either nonaspirin NSAIDs or acetaminophen. These results contribute further evidence that aspirin may have chemopreventive activity against prostate cancer and highlight the need for additional research.

Cigarette Smoking in Relation to Risk of Ductal Carcinoma In Situ of the Breast in a Cohort of Postmenopausal Women 25 Aug 2010

In numerous studies, investigators have examined the association of active smoking with risk of invasive breast cancer, but to the authors’ knowledge, no cohort study has assessed smoking in relation to the risk of in situ breast cancer, the postulated penultimate stage preceding invasive breast cancer. The authors examined the latter association using data collected at baseline from 63,393 women in the Women's Health Initiative Clinical Trial. A total of 486 cases of ductal carcinoma in situ (DCIS) of the breast were identified during 8 years of follow-up between 1993 and 2005. Cox proportional hazards models were used to estimate hazard ratios and 95% confidence intervals. For the primary analysis, invasive breast cancer was treated as a competing risk. After adjustment for covariates, associations with smoking status, smoking intensity, duration, pack-years, and age at quitting were all close to the null value and showed few meaningful trends. Sensitivity analyses performed to address different possibilities with respect to the natural history of breast cancer also did not provide consistent evidence of an association of smoking with DCIS. The results of this large cohort study provide little support for an association of cigarette smoking with risk of DCIS in postmenopausal women.

Risk of Incident Cardiovascular Disease Among Users of Smokeless Tobacco in the Atherosclerosis Risk in Communities (ARIC) Study 25 Aug 2010

Use of smokeless tobacco in the United States has been relatively constant in recent years, as tobacco companies continue aggressive marketing campaigns. The health effects of smokeless tobacco use need further documentation. Thus, the authors examined whether current use of smokeless tobacco was associated with increased incidence of cardiovascular disease (CVD) in 14,498 men and women aged 45–64 years at baseline (1987–1989) in the Atherosclerosis Risk in Communities (ARIC) Study. There were 2,572 incident CVD events (myocardial infarction, coronary revascularization, coronary death, or stroke) during a median of 16.7 years of follow-up (maximum = 19.1 years). Current use of smokeless tobacco at baseline was associated with 1.27-fold greater CVD incidence (95% confidence interval: 1.06, 1.52) than was nonuse, independently of demographic, socioeconomic, and lifestyle and other tobacco-related variables. Past use of smokeless tobacco was not associated with CVD incidence. In conclusion, current use of smokeless tobacco was associated with increased risk of CVD incidence in ARIC cigarette nonsmokers. Current users of smokeless tobacco should be informed of its harm and advised to quit the practice. Current cigarette smokers should also be given sufficient information on safe, therapeutic methods of quitting which do not include switching to smokeless tobacco.

Assessment of Changes in Condom Use Among Female Sex Workers in a Prospective Cohort Study Introducing Diaphragm Use for Disease Prevention 25 Aug 2010

Changes in the rates of condom use and number of sexual partners were evaluated among 140 female sex workers in Kibera, Kenya, participating in a 6-month study of diaphragm safety and acceptability for prevention of sexually transmitted infections conducted in 2004–2005. Analyses were stratified by partner type. Multivariable Tobit regression modeling was used to assess the association between study visit and proportion of acts protected. Participants completed 140 baseline visits and 390 bimonthly follow-up visits. The mean percentage of coital acts reported as protected by a condom increased from 56% at baseline to 68% at the 6-month visit (P < 0.01). Similar increases were observed for condom use by all partner types. Additionally, the mean number of sexual partners decreased over the study. Furthermore, consistent (i.e., 100%) diaphragm use during follow-up was associated with a higher proportion of coital acts protected by a condom in analyses adjusted for study visit and coital frequency. These findings suggest that, despite concerns that introduction of the diaphragm would result in more risky sexual behaviors, reported condom use increased and number of partners decreased.

From Cancer to Transplantation: An Evaluation of Period Analysis for Calculating Up-to-date Long-term Survival Estimates 25 Aug 2010

The timeliness of survival monitoring is particularly important in a field such as transplantation medicine, where progress occurs rapidly. Period analysis, a method successfully applied for improving the timeliness of survival monitoring in population-based cancer survival analysis, could potentially be useful in the field of transplantation as well. Using data from the Collaborative Transplant Study, the authors compared the ability of traditional, cohort-based analysis methods and the period analysis method to provide timely 5-year graft and patient survival estimates for kidney, heart, and liver transplants in 6 age groups (0–17, 18–29, 30–39, 40–49, 50–59, ≥60 years) on 378 occasions between 1990–1992 and 2000–2002. Overall, period estimates provided superior predictions for the survival of most recent transplants on 344 of 378 occasions (91%); in the organ-specific analysis, this proportion ranged between 83% for heart and 100% for kidney graft survival. This evaluation provides evidence that the period analysis method can improve the timeliness of survival monitoring in solid organ transplantation. The method appears useful for providing more up-to-date long-term survival estimates than traditional methods, and its use in pertinent studies is encouraged.

American Journal of Epidemiology - current issue