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Journal Cover American Journal of Epidemiology
  [SJR: 3.047]   [H-I: 201]   [179 followers]  Follow
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0002-9262 - ISSN (Online) 1476-6256
   Published by Oxford University Press Homepage  [372 journals]
    • PubDate: Mon, 29 Jan 2018 00:00:00 GMT
    • PubDate: Mon, 29 Jan 2018 00:00:00 GMT
  • Principled Approaches to Missing Data in Epidemiologic Studies
    • Authors: Perkins N; Cole S, Harel O, et al.
      Abstract: Principled methods with which to appropriately analyze missing data have long existed; however, broad implementation of these methods remains challenging. In this and 2 companion papers (Am J Epidemiol. 2018;187(3):576–584 and Am J Epidemiol. 2018;187(3):585–591), we discuss issues pertaining to missing data in the epidemiologic literature. We provide details regarding missing-data mechanisms and nomenclature and encourage the conduct of principled analyses through a detailed comparison of multiple imputation and inverse probability weighting. Data from the Collaborative Perinatal Project, a multisite US study conducted from 1959 to 1974, are used to create a masked data-analytical challenge with missing data induced by known mechanisms. We illustrate the deleterious effects of missing data with naive methods and show how principled methods can sometimes mitigate such effects. For example, when data were missing at random, naive methods showed a spurious protective effect of smoking on the risk of spontaneous abortion (odds ratio (OR) = 0.43, 95% confidence interval (CI): 0.19, 0.93), while implementation of principled methods multiple imputation (OR = 1.30, 95% CI: 0.95, 1.77) or augmented inverse probability weighting (OR = 1.40, 95% CI: 1.00, 1.97) provided estimates closer to the “true” full-data effect (OR = 1.31, 95% CI: 1.05, 1.64). We call for greater acknowledgement of and attention to missing data and for the broad use of principled missing-data methods in epidemiologic research.
      PubDate: Mon, 20 Nov 2017 00:00:00 GMT
  • Multiple Imputation for Incomplete Data in Epidemiologic Studies
    • Authors: Harel O; Mitchell E, Perkins N, et al.
      Abstract: Epidemiologic studies are frequently susceptible to missing information. Omitting observations with missing variables remains a common strategy in epidemiologic studies, yet this simple approach can often severely bias parameter estimates of interest if the values are not missing completely at random. Even when missingness is completely random, complete-case analysis can reduce the efficiency of estimated parameters, because large amounts of available data are simply tossed out with the incomplete observations. Alternative methods for mitigating the influence of missing information, such as multiple imputation, are becoming an increasing popular strategy in order to retain all available information, reduce potential bias, and improve efficiency in parameter estimation. In this paper, we describe the theoretical underpinnings of multiple imputation, and we illustrate application of this method as part of a collaborative challenge to assess the performance of various techniques for dealing with missing data (Am J Epidemiol. 2018;187(3):568–575). We detail the steps necessary to perform multiple imputation on a subset of data from the Collaborative Perinatal Project (1959–1974), where the goal is to estimate the odds of spontaneous abortion associated with smoking during pregnancy.
      PubDate: Mon, 20 Nov 2017 00:00:00 GMT
  • Inverse-Probability-Weighted Estimation for Monotone and Nonmonotone
           Missing Data
    • Authors: Sun B; Perkins N, Cole S, et al.
      Abstract: Missing data is a common occurrence in epidemiologic research. In this paper, 3 data sets with induced missing values from the Collaborative Perinatal Project, a multisite US study conducted from 1959 to 1974, are provided as examples of prototypical epidemiologic studies with missing data. Our goal was to estimate the association of maternal smoking behavior with spontaneous abortion while adjusting for numerous confounders. At the same time, we did not necessarily wish to evaluate the joint distribution among potentially unobserved covariates, which is seldom the subject of substantive scientific interest. The inverse probability weighting (IPW) approach preserves the semiparametric structure of the underlying model of substantive interest and clearly separates the model of substantive interest from the model used to account for the missing data. However, IPW often will not result in valid inference if the missing-data pattern is nonmonotone, even if the data are missing at random. We describe a recently proposed approach to modeling nonmonotone missing-data mechanisms under missingness at random to use in constructing the weights in IPW complete-case estimation, and we illustrate the approach using 3 data sets described in a companion article (Am J Epidemiol. 2018;187(3):568–575).
      PubDate: Mon, 20 Nov 2017 00:00:00 GMT
  • Sudden Unexpected Cardiac Death on Monday in Younger and Older Men: The
           Manitoba Follow-up Study
    • Authors: Tate R; St. John P.
      PubDate: Mon, 13 Nov 2017 00:00:00 GMT
  • Invited Commentary: Sex and Race Differences in Diabetes and
           Cardiovascular Disease—Achieving the Promise of Sex and Race Subgroup
           Analyses in Epidemiologic Research
    • Authors: Moise N; Bertoni A.
      Abstract: Diabetes confers a higher risk of cardiovascular disease on women than on men. The reasons for these sex differences, such as poorer cardiovascular risk factor profiles, have received considerable attention. However, a recent report on sex × diabetes interactions on cardiovascular disease identified that few if any prior studies have confirmed these sex differences in black individuals, despite known diabetes-related disparities. In this issue of the Journal, George et al. (Am J Epidemiol. 2018;187(3):403–410.) found marginally significant multiplicative sex × diabetes interactions in black but not white study participants after adjustments for traditional and behavioral risk factors, competing risk, and change in diabetes status over time. This study is notable for its attempt to fill an important literature gap, and it elegantly addressed multiple statistical considerations in assessing sex × diabetes interactions according to race strata. The findings also highlighted several important considerations for conducting race and sex subgroup analyses.
      PubDate: Thu, 05 Oct 2017 00:00:00 GMT
  • George et al. Respond to “Diabetes and Cardiovascular Disease”
    • Authors: George K; Selvin E, Pankow J, et al.
      PubDate: Thu, 05 Oct 2017 00:00:00 GMT
  • Sex Differences in the Association of Diabetes With Cardiovascular Disease
           Outcomes Among African-American and White Participants in the
           Atherosclerosis Risk in Communities Study
    • Authors: George K; Selvin E, Pankow J, et al.
      Abstract: A sex × diabetes interaction in cardiovascular disease (CVD) has been established among white persons; however, it is unknown whether this interaction occurs among African Americans. We hypothesized that there was a multiplicative sex × diabetes interaction for CVD among African Americans participating in the Atherosclerosis Risk in Communities Study (1987–2013). Race-specific Cox models were run in three stages: Stage 1 examined baseline diabetes status; stage 2 examined baseline diabetes status with the competing risk of non-CVD death; and stage 3 examined time-varying diabetes status with a competing risk of non-CVD death. There were 1,073 incident CVD events among 3,767 African Americans and 2,475 among 10,291 white persons. Among African Americans, in stage 1 analysis, the hazard ratio for women with diabetes was 2.3 (95% confidence interval (CI): 2.0, 2.7) compared with women without diabetes after adjustment for age, and the corresponding hazard ratio for men was 1.8 (95% CI: 1.5, 2.1) (P for interaction = 0.014). After full adjustment, the diabetes hazard ratio was attenuated to 2.0 (95% CI: 1.8, 2.3) among women and remained 1.8 (95% CI: 1.5, 2.1) for men (P for interaction = 0.058). A synergistic influence on CVD risk between being a black woman and having diabetes was consistent across stage 2 and stage 3 analyses, with marginally significant interaction, mirroring sex differences seen in whites.
      PubDate: Thu, 05 Oct 2017 00:00:00 GMT
  • Breast Cancer Incidence and Exposure to Metalworking Fluid in a Cohort of
           Female Autoworkers
    • Authors: Garcia E; Bradshaw P, Eisen E.
      Abstract: Breast cancer is the leading cancer diagnosed among women, and environmental studies have produced few leads on modifiable risk factors for breast cancer. Following an Institute of Medicine recommendation for occupational studies of women highly exposed to potential breast cancer risk factors, we took advantage of an existing cohort of 4,503 female autoworkers in Michigan exposed to metalworking fluid (MWF), complex mixtures of oils and chemicals widely used in metal manufacturing worldwide. Cox proportional hazards models were fit to estimate hazard ratios for incident breast cancer (follow-up, 1985–2013) and cumulative exposure (20-year lag) to straight mineral oils (a known human carcinogen) and water-based soluble and synthetic MWF. Because the state cancer registry began decades after the cohort was defined, we restricted our analyses to subcohorts of women hired closer to the start of follow-up. Among those hired after 1969, the hazard ratio associated with a 1 interquartile-range increase in straight MWF exposure was 1.13 (95% confidence interval: 1.03, 1.23). In separate analyses of premenopausal breast cancer, defined by age at diagnosis, the hazard ratio was elevated for exposure to synthetic MWF (chemical lubricants with no oil content), possibly suggesting a different mechanism in the younger women with breast cancer. This study adds to the limited literature regarding quantitative chemical exposures and breast cancer risk.
      PubDate: Wed, 23 Aug 2017 00:00:00 GMT
  • Possible Mediation by Methylation in Acute Inflammation Following Personal
           Exposure to Fine Particulate Air Pollution
    • Authors: Wang C; Chen R, Shi M, et al.
      Abstract: Air pollution may increase cardiovascular and respiratory risk through inflammatory pathways, but evidence for acute effects has been weak and indirect. Between December 2014 and July 2015, we enrolled 36 healthy, nonsmoking college students for a panel study in Shanghai, China, a city with highly variable levels of air pollution. We measured personal exposure to particulate matter with an aerodynamic diameter less than or equal to 2.5 μm (PM2.5) continuously for 72 hours preceding each of 4 clinical visits that included phlebotomy. We measured 4 inflammation proteins and DNA methylation at nearby regulatory cytosine-phosphate-guanine (CpG) loci. We applied linear mixed-effect models to examine associations over various lag times. When results suggested mediation, we evaluated methylation as mediator. Increased PM2.5 concentration was positively associated with all 4 inflammation proteins and negatively associated with DNA methylation at regulatory loci for tumor necrosis factor alpha (TNF-α) and soluble intercellular adhesion molecule-1. A 10-μg/m3 increase in average PM2.5 during the 24 hours preceding blood draw corresponded to a 4.4% increase in TNF-α and a statistically significant decrease in methylation at one of the two studied candidate CpG loci for TNF-α. Epigenetics may play an important role in mediating effects of PM2.5 on inflammatory pathways.
      PubDate: Thu, 17 Aug 2017 00:00:00 GMT
  • Sickle Cell Trait and Heat Injury Among US Army Soldiers
    • Authors: Nelson D; Deuster P, O’Connor F, et al.
      Abstract: There is concern that sickle cell trait (SCT) increases risk of exertional collapse, a primary cause of which is heat injury. However, to our knowledge, no population-based studies among active individuals have addressed this, representing a critical evidence gap. We conducted a retrospective cohort study of SCT-tested African-American soldiers who were on active duty in the US Army anytime between January 2011 and December 2014. Using Cox proportional hazards models and adjusting for demographic and medical factors, we observed no significant associations between SCT and either mild heat injury (hazard ratio (HR) = 1.15, 95% confidence interval (CI): 0.84, 1.56; n = 45,999) or heat stroke (HR = 1.11, 95% CI: 0.44, 2.79; n = 46,183). Risk of mild heat injury was substantially higher among soldiers with recent prescriptions for antipsychotic agents (HR = 3.25, 95% CI: 1.33, 7.90). Risk of heat stroke was elevated among those with a prior mild heat injury (HR = 17.7, 95% CI: 8.50, 36.7) and among overweight and obese individuals (HR = 2.91 (95% CI: 1.38, 6.17) and HR = 4.04 (95% CI: 1.72, 9.45), respectively). In a setting where universal precautions are utilized to mitigate risk of exertion-related illnesses, SCT is not associated with either mild heat injury or heat stroke.
      PubDate: Thu, 17 Aug 2017 00:00:00 GMT
  • Association of DNA Methylation-Based Biological Age With Health Risk
           Factors and Overall and Cause-Specific Mortality
    • Authors: Dugué P; Bassett J, Joo J, et al.
      Abstract: Measures of biological age based on blood DNA methylation, referred to as age acceleration (AA), have been developed. We examined whether AA was associated with health risk factors and overall and cause-specific mortality. At baseline (1990–1994), blood samples were drawn from 2,818 participants in the Melbourne Collaborative Cohort Study (Melbourne, Victoria, Australia). DNA methylation was determined using the Infinium HumanMethylation450 BeadChip array (Illumina Inc., San Diego, California). Mixed-effects models were used to examine the association of AA with health risk factors. Cox models were used to assess the association of AA with mortality. A total of 831 deaths were observed during a median 10.7 years of follow-up. Associations of AA were observed with male sex, Greek nationality (country of birth), smoking, obesity, diabetes, lower education, and meat intake. AA measures were associated with increased mortality, and this was only partly accounted for by known determinants of health (hazard ratios were attenuated by 20%–40%). Weak evidence of heterogeneity in the association was observed by sex (P = 0.06) and cause of death (P = 0.07) but not by other factors. DNA-methylation-based AA measures are associated with several major health risk factors, but these do not fully explain the association between AA and mortality. Future research should investigate what genetic and environmental factors determine AA.
      PubDate: Thu, 17 Aug 2017 00:00:00 GMT
  • The Role of Mobile Genetic Elements in the Spread of
           Antimicrobial-Resistant Escherichia coli From Chickens to Humans in
           Small-Scale Production Poultry Operations in Rural Ecuador
    • Authors: Moser K; Zhang L, Spicknall I, et al.
      Abstract: Small-scale production poultry operations are increasingly common worldwide. To investigate how these operations influence antimicrobial resistance and mobile genetic elements (MGEs), Escherichia coli isolates were sampled from small-scale production birds (raised in confined spaces with antibiotics in feed), household birds (no movement constraints; fed on scraps), and humans associated with these birds in rural Ecuador (2010–2012). Isolates were screened for genes associated with MGEs as well as phenotypic resistance to 12 antibiotics. Isolates from small-scale production birds had significantly elevated odds of resistance to 7 antibiotics and presence of MGE genes compared with household birds (adjusted odds ratio (OR) range = 2.2–87.9). Isolates from humans associated with small-scale production birds had elevated odds of carrying an integron (adjusted OR = 2.0; 95% confidence interval (CI): 1.06, 3.83) compared with humans associated with household birds, as well as resistance to sulfisoxazole (adjusted OR = 1.9; 95% CI: 1.01, 3.60) and trimethoprim/sulfamethoxazole (adjusted OR = 2.1; 95% CI: 1.13, 3.95). Stratifying by the presence of MGEs revealed antibiotic groups that are explained by biological links to MGEs; in particular, resistance to sulfisoxazole, trimethoprim/sulfamethoxazole, or tetracycline was highest among birds and humans when MGE exposures were present. Small-scale production poultry operations might select for isolates carrying MGEs, contributing to elevated levels of resistance in this setting.
      PubDate: Thu, 17 Aug 2017 00:00:00 GMT
  • Understanding Causal Distributional and Subgroup Effects With the
           Instrumental Propensity Score
    • Authors: Cheng J; Lin W.
      Abstract: To address issues with measured and unmeasured confounding in observational studies, we developed a unified approach to using an instrumental variable in more flexible ways to evaluate treatment effects. The approach is based on an instrumental propensity score conditional on baseline variables, which can then be incorporated in matching, regression, subclassification, or weighting along with various parametric, semiparametric, or nonparametric methods for the assessment of treatment effects. Therefore, the application of the instrumental propensity score allows different methods for outcome effect evaluations in addition to standard 2-stage least square models while controlling for unmeasured confounders. Several properties of the instrumental propensity score are discussed. The approach is then illustrated using subclassification along with a semiparametric density ratio model and empirical likelihood. This method allows us to evaluate distributional and subgroup treatment effects in addition to the overall average treatment effect. Simulation studies showed that the method works well. We applied our method to a study of the effects of attending a Catholic school versus a public school and found that attending a Catholic school had significant beneficial effects on subsequent wages among a subgroup of subjects.
      PubDate: Thu, 17 Aug 2017 00:00:00 GMT
  • The Mental Health Benefits of Acquiring a Home in Older Age: A
           Fixed-Effects Analysis of Older US Adults
    • Authors: Courtin E; Dowd J, Avendano M.
      Abstract: Homeownership is consistently associated with better mental health, but whether becoming a homeowner in later in life has positive psychological benefits has not, to our knowledge, been examined. We assessed whether acquiring a home after age 50 years was associated with depression in a representative sample of older US adults. We used individual fixed-effects models based on data from 20,524 respondents aged ≥50 years from the Health and Retirement Study, who were interviewed biennially during 1993–2010. Depressive symptoms were measured using the 8-item Center for Epidemiologic Studies Depression Scale. Controlling for confounders, becoming a homeowner in later life predicted a decline in depressive symptoms in the same year (β = −0.0768, 95% confidence interval (CI): −0.152, −0.007). The association remained significant after 2 years (β = −0.0556, 95% CI: −0.134, −0.001) but weakened afterward. Buying a home for reasons associated with positive characteristics of the new house or neighborhood drove this association (β = −0.426, 95% CI: −0.786, −0.066), while acquiring a home for reasons associated with characteristics of the previous home or neighborhood, the desire to be closer to relatives, downsizing, or upsizing did not predict mental health improvements. Findings suggest that there are small but significant benefits for mental health associated with acquiring a home in older age.
      PubDate: Fri, 11 Aug 2017 00:00:00 GMT
  • When to Censor'
    • Authors: Lesko C; Edwards J, Cole S, et al.
      Abstract: Loss to follow-up is an endemic feature of time-to-event analyses that precludes observation of the event of interest. To our knowledge, in typical cohort studies with encounters occurring at regular or irregular intervals, there is no consensus on how to handle person-time between participants’ last study encounter and the point at which they meet a definition of loss to follow-up. We demonstrate, using simulation and an example, that when the event of interest is captured outside of a study encounter (e.g., in a registry), person-time should be censored when the study-defined criterion for loss to follow-up is met (e.g., 1 year after last encounter), rather than at the last study encounter. Conversely, when the event of interest must be measured within the context of a study encounter (e.g., a biomarker value), person-time should be censored at the last study encounter. An inappropriate censoring scheme has the potential to result in substantial bias that may not be easily corrected.
      PubDate: Fri, 11 Aug 2017 00:00:00 GMT
  • Invited Commentary: “Bedroom Light Exposure at Night and the Incidence
           of Depressive Symptoms: A Longitudinal Study of the HEIJO-KYO Cohort”
    • Authors: Hasler B.
      Abstract: In modern society, we are increasingly disconnected from natural light/dark cycles and beset by round-the-clock exposure to artificial light. Light has powerful effects on physical and mental health, in part via the circadian system, and thus the timing of light exposure dictates whether it is helpful or harmful. In their compelling paper, Obayashi et al. (Am J Epidemiol. 2018;187(3):427–434.) offer evidence that light at night can prospectively predict an elevated incidence of depressive symptoms in older adults. Strengths of the study include the longitudinal design and direct, objective assessment of light levels, as well as accounting for multiple plausible confounders during analyses. Follow-up studies should address the study’s limitations, including reliance on a global self-report of sleep quality and a 2-night assessment of light exposure that may not reliably represent typical light exposure. In addition, experimental studies including physiological circadian measures will be necessary to determine whether the light effects on depression are mediated through the circadian system or are so-called “direct” effects of light. In any case, these exciting findings could inform novel approaches to preventing depressive disorders in older adults.
      PubDate: Mon, 31 Jul 2017 00:00:00 GMT
  • Obayashi et al. Respond to “Light at Night Predicts
           Depression—What Next'”
    • Authors: Obayashi K; Saeki K, Kurumatani N.
      PubDate: Mon, 31 Jul 2017 00:00:00 GMT
  • Bedroom Light Exposure at Night and the Incidence of Depressive Symptoms:
           A Longitudinal Study of the HEIJO-KYO Cohort
    • Authors: Obayashi K; Saeki K, Kurumatani N.
      Abstract: Previous studies have indicated that minimal exposure to light at night (LAN) increases depression risk, even at 5 lux, in nocturnal and diurnal mammals. Although such low-level LAN may affect human circadian physiology, the association between exposure to LAN and depressive symptoms remains uncertain. In the present study, bedroom light intensity was measured objectively, and depressive symptoms were assessed, during 2010–2014 in Nara, Japan. Of 863 participants (mean age = 71.5 years) who did not have depressive symptoms at baseline, 73 participants reported development of depressive symptoms during follow-up (median, 24 months). Compared with the “dark” group (average of <5 lux; n = 710), the LAN group (average of ≥5 lux; n = 153) exhibited a significantly higher depression risk (hazard ratio = 1.89; 95% CI: 1.13, 3.14), according to a Cox proportional hazards model adjusting for age, sex, body mass index, and economic status. Further, the significance remained in a multivariable model adjusting for hypertension, diabetes, and sleep parameters (hazard ratio = 1.72; 95% CI: 1.03, 2.89). Sensitivity analyses using bedroom light data with a cutoff value of ≥10 lux suggested consistent results. In conclusion, these results indicated that exposure to LAN in home settings was independently associated with subsequent depression risk in an elderly general population.
      PubDate: Mon, 31 Jul 2017 00:00:00 GMT
  • Associations Between Sedentary Behaviors and Cognitive Function:
           Cross-Sectional and Prospective Findings From the UK Biobank
    • Authors: Bakrania K; Edwardson C, Khunti K, et al.
      Abstract: We investigated the cross-sectional and prospective associations between different sedentary behaviors and cognitive function in a large sample of adults with data stored in the UK Biobank. Baseline data were available for 502,643 participants (2006–2010, United Kingdom). Cognitive tests included prospective memory (baseline only: n = 171,585), visual-spatial memory (round 1: n = 483,832; round 2: n = 482,762), fluid intelligence (n = 165,492), and short-term numeric memory (n = 50,370). After a mean period of 5.3 years, participants (numbering from 12,091 to 114,373, depending on the test) also provided follow-up cognitive data. Sedentary behaviors (television viewing, driving, and nonoccupational computer-use time) were measured at baseline. At baseline, both television viewing and driving time were inversely associated with cognitive function across all outcomes (e.g., for each additional hour spent watching television, the total number of correct answers in the fluid intelligence test was 0.15 (99% confidence interval: 0.14, 0.16) lower. Computer-use time was positively associated with cognitive function across all outcomes. Both television viewing and driving time at baseline were positively associated with the odds of having cognitive decline at follow-up across most outcomes. Conversely, computer-use time at baseline was inversely associated with the odds of having cognitive decline at follow-up across most outcomes. This study supports health policies designed to reduce television viewing and driving in adults.
      PubDate: Thu, 13 Jul 2017 00:00:00 GMT
  • Does Type of Residential Housing Matter for Depressive Symptoms in the
           Aftermath of a Disaster' Insights From the Great East Japan Earthquake
           and Tsunami
    • Authors: Sasaki Y; Aida J, Tsuji T, et al.
      Abstract: The 2011 Great East Japan Earthquake and Tsunami resulted in widespread property destruction and over 250,000 displaced residents. We sought to examine whether the type of housing arrangement available to the affected victims was associated with a differential incidence of depressive symptoms. In this prospective cohort study, which comprised participants aged ≥65 years from Iwanuma as a part of the Japan Gerontological Evaluation Study, we had information about the residents’ mental health both before the disaster in 2010 and 2.5 years afterward. The Geriatric Depression Scale was used. Type of accommodation after the disaster was divided into 5 categories: no move, prefabricated housing (temporary housing), existing private accommodations (temporary apartment), newly established housing, and other. Poisson regression analysis was adopted, with and without multiple imputation. Among the 2,242 participants, 16.2% reported depressive symptoms at follow-up. The adjusted rate ratio for depressive symptoms among persons moving into prefabricated housing, compared with those who did not, was 2.07 (95% confidence interval: 1.45, 2.94). Moving into existing private accommodations or other types of accommodations was not associated with depression. The relationship between living environment and long-term mental health should be considered for disaster recovery planning.
      PubDate: Thu, 13 Jul 2017 00:00:00 GMT
  • Childhood Health Outcomes in Term, Large-for-Gestational-Age Babies With
           Different Postnatal Growth Patterns
    • Authors: Lei X; Zhao D, Huang L, et al.
      Abstract: Large-for-gestational-age (LGA) babies have a higher risk of metabolic disease later in life, and their postnatal growth in early childhood may be associated with long-term adverse outcomes. This study aimed to determine childhood health outcomes of term LGA babies with different growth patterns. Data were obtained from the US Collaborative Perinatal Project for the years between 1959 and 1976. The growth trajectories of 3,316 term LGA babies were identified and odds ratios of obesity, growth restriction, low intelligence quotient (IQ), and high blood pressure (HBP) were calculated by logistic regression. Compared with term appropriate-for-gestational-age infants, term LGA babies without catch-down growth had increased risks of obesity (adjusted odds ratio (aOR) = 6.37, 95% confidence interval (CI): 5.24, 7.73) and HBP (aOR = 1.67, 95% CI: 1.37, 2.03). Those with high catch-down growth had higher risks of growth restriction (aOR = 2.21, 95% CI: 1.66, 2.95) and low IQ (aOR = 1.61, 95% CI: 1.04, 2.49). Nevertheless, infants with small catch-down growth had lower risks of obesity (aOR = 0.78, 95% CI: 0.63, 0.95), growth restriction (aOR = 0.28, 95% CI: 0.17, 0.46), low IQ (aOR = 0.66, 95% CI: 0.41, 1.06), and HBP (aOR = 0.89, 95% CI: 0.77, 1.04). According to our data, term LGA infants with small catch-down growth had no increased risks of adverse outcomes.
      PubDate: Thu, 13 Jul 2017 00:00:00 GMT
  • A Prospective Study of Inflammatory Markers and Risk of Endometriosis
    • Authors: Mu F; Harris H, Rich-Edwards J, et al.
      Abstract: Much evidence suggests a role for inflammation in the pathogenesis of endometriosis. Although investigators in numerous case-control studies have found elevation of inflammatory markers in patients with endometriosis, results were not consistent, and no prior prospective study is known to exist. We conducted a case-control study nested within the Nurses’ Health Study II in which we examined associations between levels of plasma inflammatory markers (interleukin-1 beta, interleukin-6, soluble tumor necrosis factor α receptors 1 and 2, and high-sensitivity C-reactive protein) and the risk of laparoscopically confirmed endometriosis. From blood collections in 1996–1999 and 2007, we ascertained 350 cases patients with incident endometriosis and 694 matched controls. Women with interleukin-1 beta levels in quintiles 2–4 had a higher risk of endometriosis (for the second quintile, relative risk (RR) = 3.30, 95% confidence interval (CI): 1.06, 10.3; for the third quintile, RR = 3.36, 95% CI: 1.09, 10.4; and for the fourth quintile, RR = 4.64, 95% CI: 1.58, 13.6; P for trend = 0.62), which suggested an association beginning at 0.47 pg/mL or greater. A significant nonlinear association with levels of soluble tumor necrosis factor α receptor 2 was observed, with elevated risk of endometriosis at concentrations greater than 3,400 pg/mL. Plasma interleukin-6, soluble tumor necrosis factor α receptor 1, and high-sensitivity C-reactive protein levels were not associated with endometriosis risk. Further research in larger studies with younger age at blood collection and longer time from blood to surgical diagnosis are required to confirm these associations.
      PubDate: Thu, 13 Jul 2017 00:00:00 GMT
  • Using Sensitivity Analyses for Unobserved Confounding to Address Covariate
           Measurement Error in Propensity Score Methods
    • Authors: Rudolph K; Stuart E.
      Abstract: Propensity score methods are a popular tool with which to control for confounding in observational data, but their bias-reduction properties—as well as internal validity, generally—are threatened by covariate measurement error. There are few easy-to-implement methods of correcting for such bias. In this paper, we describe and demonstrate how existing sensitivity analyses for unobserved confounding—propensity score calibration, VanderWeele and Arah’s bias formulas, and Rosenbaum’s sensitivity analysis—can be adapted to address this problem. In a simulation study, we examine the extent to which these sensitivity analyses can correct for several measurement error structures: classical, systematic differential, and heteroscedastic covariate measurement error. We then apply these approaches to address covariate measurement error in estimating the association between depression and weight gain in a cohort of adults in Baltimore, Maryland. We recommend the use of VanderWeele and Arah’s bias formulas and propensity score calibration (assuming it is adapted appropriately for the measurement error structure), as both approaches perform well for a variety of propensity score estimators and measurement error structures.
      PubDate: Thu, 13 Jul 2017 00:00:00 GMT
  • Blood Concentrations of Persistent Organic Pollutants and Unhealthy
           Metabolic Phenotypes in Normal-Weight, Overweight, and Obese Individuals
    • Authors: Gasull M; Castell C, Pallarès N, et al.
      Abstract: Factors underlying metabolic phenotypes, such as the metabolically healthy but obese phenotype, remain unclear. Differences in metabolic phenotypes—particularly, among individuals with a similar body mass index—could be related to concentrations of persistent organic pollutants (POPs). To our knowledge, no studies have analyzed POPs and metabolic phenotypes in normal-weight persons. We investigated the relationships between serum concentrations of POPs and metabolic phenotypes in 860 normal-weight, overweight, and obese participants in the 2002 Catalan Health Interview Survey (Spain). POP concentrations were significantly higher in metabolically unhealthy than in metabolically healthy individuals. In models adjusting for body mass index and other confounders, hexachlorobenzene, β-hexachlorocyclohexane, and polychlorinated biphenyls were associated with the unhealthy metabolic phenotype and metabolic syndrome. Among normal-weight individuals, the adjusted prevalence ratio of having an unhealthy phenotype for the upper category of the sum of orders of the 6 mentioned POPs (all individually associated with metabolic phenotypes) was 4.1 (95% confidence interval: 1.7, 10.0). Among overweight and obese individuals, the corresponding prevalence ratio for the sum of polychlorinated biphenyls was 1.4 (95% confidence interval: 1.0, 1.8). Our results supported the hypothesis that POP concentrations are associated with unhealthy metabolic phenotypes, not only in obese and overweight individuals but also (and probably more strongly) in normal-weight individuals.
      PubDate: Fri, 30 Jun 2017 00:00:00 GMT
  • Joint Effects of Age, Period, and Cohort on Conduct Problems Among
           American Adolescents From 1991 Through 2015
    • Authors: Keyes K; Gary D, Beardslee J, et al.
      Abstract: Although arrest rates among juveniles have substantially decreased since the 1990s, US national trends in conduct problems are unknown. Population variation in conduct problems would imply changes in the social environment, which would include emergent or receding risk factors. In the present study, we separated age, period, and cohort effects on conduct problems using nationally representative surveys of 375,879 US students conducted annually (1991–2015). The summed score of 7 items measuring the frequency of conduct problems was the outcome. Conduct problems have decreased during the past 25 years among boys; the total amount of the decrease was approximately 0.4 standard deviations (P < 0.01), and by item prevalence, the total amount of the decrease was 8%–11%. Declines are best explained by period effects beginning approximately in 2008, and a declining cohort effect beginning among those born after 1992, which suggests not only declines in population levels, but more rapid declines among younger cohorts of boys. Trends were also consistent with age-period-cohort effects on evenings spent out, which suggest a possible mechanism. Conduct problems among girls were lower than boys and did not demonstrate trends across time. These changes may reflect the changing nature of adolescence toward less unsupervised interaction.
      PubDate: Fri, 30 Jun 2017 00:00:00 GMT
  • Demographic and Operational Factors Predicting Study Completion in a
           Multisite Case-Control Study of Preschool Children
    • Authors: Bradley C; Browne E, Alexander A, et al.
      Abstract: Participant attrition can limit inferences drawn from study results and inflate research costs. We examined factors associated with completion of the Study to Explore Early Development (2007–2011), a multiple-component, case-control study of risk factors for autism spectrum disorder in preschoolers, conducted in California, Colorado, Georgia, Maryland, North Carolina, and Pennsylvania. Participants (n = 3,769) were asked to complete phone interviews, questionnaires, an in-person evaluation, and biologic sampling. We examined whether participant demographic and administrative factors predicted completion using mixed-effects logistic regression models. Completion of individual key study components was generally 70% or higher. However, 58% of families completed all per-protocol data elements (defined a priori as key study components). Per-protocol completion differed according to mother’s age, race, educational level, driving distance to clinic, number of contact attempts to enroll, and number of telephone numbers provided (all P < 0.05). Case status was not associated with completion, despite additional data collection for case-confirmation. Analysis of a subset that completed an early interview revealed no differences in completion by household factors of income, primary language spoken, number of adults, or number of children with chronic conditions. Differences in completion by race and education were notable and need to be carefully considered in developing future recruitment and completion strategies.
      PubDate: Tue, 27 Jun 2017 00:00:00 GMT
  • Height, Weight, and Aerobic Fitness Level in Relation to the Risk of
           Atrial Fibrillation
    • Authors: Crump C; Sundquist J, Winkleby M, et al.
      Abstract: Tall stature and obesity have been associated with a higher risk of atrial fibrillation (AF), but there have been conflicting reports of the effects of aerobic fitness. We conducted a national cohort study to examine interactions between height or weight and level of aerobic fitness among 1,547,478 Swedish military conscripts during 1969–1997 (97%–98% of all 18-year-old men) in relation to AF identified from nationwide inpatient and outpatient diagnoses through 2012 (maximal age, 62 years). Increased height, weight, and aerobic fitness level (but not muscular strength) at age 18 years were all associated with a higher AF risk in adulthood. Positive additive and multiplicative interactions were found between height or weight and aerobic fitness level (for the highest tertiles of height and aerobic fitness level vs. the lowest, relative excess risk = 0.51, 95% confidence interval (CI): 0.40, 0.62; ratio of hazard ratios = 1.50, 95% CI: 1.34, 1.65). High aerobic fitness levels were associated with higher risk among men who were at least 186 cm (6 feet, 1 inch) tall but were protective among shorter men. Men with the combination of tall stature and high aerobic fitness level had the highest risk (for the highest tertiles vs. the lowest, adjusted hazard ratio = 1.70, 95% CI: 1.61, 1.80). These findings suggest important interactions between body size and aerobic fitness level in relation to AF and may help identify high-risk subgroups.
      PubDate: Wed, 21 Jun 2017 00:00:00 GMT
  • An Olympic Legacy' Did the Urban Regeneration Associated With the
           London 2012 Olympic Games Influence Adolescent Mental Health'
    • Authors: Clark C; Smuk M, Cummins S, et al.
      Abstract: Public expenditure on large events such as the London 2012 Olympic Games is often justified by the potential legacy of urban regeneration and its associated health and well-being benefits for local communities. In the Olympic Regeneration in East London Study, we examined whether there was an association between urban regeneration related to the 2012 Games and improved mental health in young people. Adolescents aged 11–12 years attending schools in the Olympic host borough of Newham in London or in 3 adjacent comparison London boroughs completed a survey before the 2012 Games and 6 and 18 months after the Games (in 2013 and 2014, respectively). Changes in depressive symptoms and well-being between baseline and each follow-up were examined. A total of 2,254 adolescents from 25 randomly selected schools participated. Adolescents from Newham were more likely to have remained depressed between baseline and the 6- and 18-month follow-up surveys (for 6-month follow-up, relative risk = 1.78, 95% confidence interval: 1.12, 2.83; for 18-month follow-up, relative risk = 1.93, 95% confidence interval: 1.01, 3.70) than adolescents from the comparison boroughs. No differences in well-being were observed. There was little evidence that urban regeneration had any positive influence on adolescent mental health and some suggestion that regeneration may have been associated with maintenance of depressive symptoms. Such programs may have limited short-term impact on the mental health of adolescents.
      PubDate: Thu, 08 Jun 2017 00:00:00 GMT
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