Showing papers in "American Journal of Epidemiology in 2002"
TL;DR: The Multi-Ethnic Study of Atherosclerosis was initiated in July 2000 to investigate the prevalence, correlates, and progression of subclinical cardiovascular disease (CVD) in a population-based sample of 6,500 men and women aged 45-84 years for identification and characterization of CVD events.
Abstract: The Multi-Ethnic Study of Atherosclerosis was initiated in July 2000 to investigate the prevalence, correlates, and progression of subclinical cardiovascular disease (CVD) in a population-based sample of 6,500 men and women aged 45-84 years. The cohort will be selected from six US field centers. Approximately 38% of the cohort will be White, 28% African-American, 23% Hispanic, and 11% Asian (of Chinese descent). Baseline measurements will include measurement of coronary calcium using computed tomography; measurement of ventricular mass and function using cardiac magnetic resonance imaging; measurement of flow-mediated brachial artery endothelial vasodilation, carotid intimal-medial wall thickness, and distensibility of the carotid arteries using ultrasonography; measurement of peripheral vascular disease using ankle and brachial blood pressures; electrocardiography; and assessments of microalbuminuria, standard CVD risk factors, sociodemographic factors, life habits, and psychosocial factors. Blood samples will be assayed for putative biochemical risk factors and stored for use in nested case-control studies. DNA will be extracted and lymphocytes will be immortalized for genetic studies. Measurement of selected subclinical disease indicators and risk factors will be repeated for the study of progression over 7 years. Participants will be followed through 2008 for identification and characterization of CVD events, including acute myocardial infarction and other coronary heart disease, stroke, peripheral vascular disease, and congestive heart failure; therapeutic interventions for CVD; and mortality.
3,367 citations
TL;DR: The authors found a strong association of the temperature-mortality relation with latitude, with a greater effect of colder temperatures on mortality risk in more-southern cities and of warmer temperatures inMore-northern cities.
Abstract: Episodes of extremely hot or cold temperatures are associated with increased mortality. Time-series analyses show an association between temperature and mortality across a range of less extreme temperatures. In this paper, the authors describe the temperature-mortality association for 11 large eastern US cities in 1973-1994 by estimating the relative risks of mortality using log-linear regression analysis for time-series data and by exploring city characteristics associated with variations in this temperature-mortality relation. Current and recent days' temperatures were the weather components most strongly predictive of mortality, and mortality risk generally decreased as temperature increased from the coldest days to a certain threshold temperature, which varied by latitude, above which mortality risk increased as temperature increased. The authors also found a strong association of the temperature-mortality relation with latitude, with a greater effect of colder temperatures on mortality risk in more-southern cities and of warmer temperatures in more-northern cities. The percentage of households with air conditioners in the south and heaters in the north, which serve as indicators of socioeconomic status of the city population, also predicted weather-related mortality. The model developed in this analysis is potentially useful for projecting the consequences of climate-change scenarios and offering insights into susceptibility to the adverse effects of weather.
1,261 citations
TL;DR: Regular physical activity could be an important component of a preventive strategy against Alzheimer's disease and many other conditions, and use of nonsteroidal anti-inflammatory drugs, wine consumption, coffee consumption, and regular physical activity were associated with a reduced risk of Alzheimer's Disease.
Abstract: A prospective analysis of risk factors for Alzheimer's disease was a major objective of the Canadian Study of Health and Aging, a nationwide, population-based study. Of 6,434 eligible subjects aged 65 years or older in 1991, 4,615 were alive in 1996 and participated in the follow-up study. All participants were cognitively normal in 1991 when they completed a risk factor questionnaire. Their cognitive status was reassessed 5 years later by using a similar two-phase procedure, including a screening interview, followed by a clinical examination when indicated. The analysis included 194 Alzheimer's disease cases and 3,894 cognitively normal controls. Increasing age, fewer years of education, and the apolipoprotein E epsilon4 allele were significantly associated with increased risk of Alzheimer's disease. Use of nonsteroidal anti-inflammatory drugs, wine consumption, coffee consumption, and regular physical activity were associated with a reduced risk of Alzheimer's disease. No statistically significant association was found for family history of dementia, sex, history of depression, estrogen replacement therapy, head trauma, antiperspirant or antacid use, smoking, high blood pressure, heart disease, or stroke. The protective associations warrant further study. In particular, regular physical activity could be an important component of a preventive strategy against Alzheimer's disease and many other conditions.
1,240 citations
TL;DR: Findings are presented from the Slone Epidemiology Unit Birth Defects Study, 1992-1997, a case-control study on folic acid supplementation and risk of neural tube defects, which suggests that the crude odds ratio should be used because the adjusted odds ratio is invalid.
Abstract: Common strategies to decide whether a variable is a confounder that should be adjusted for in the analysis rely mostly on statistical criteria. The authors present findings from the Slone Epidemiology Unit Birth Defects Study, 1992-1997, a case-control study on folic acid supplementation and risk of neural tube defects. When statistical strategies for confounding evaluation are used, the adjusted odds ratio is 0.80 (95% confidence interval: 0.62, 1.21). However, the consideration of a priori causal knowledge suggests that the crude odds ratio of 0.65 (95% confidence interval: 0.46, 0.94) should be used because the adjusted odds ratio is invalid. Causal diagrams are used to encode qualitative a priori subject matter knowledge.
1,228 citations
TL;DR: Diverse single-variable and composite area-based socioeconomic measures at the census tract, block group, and zip code level for Massachusetts and Rhode Island indicated that block group and tract socioeconomic measures performed comparably within and across both states, but zip code measures for several outcomes detected no gradients or gradients contrary to those observed with tract and block group measures.
Abstract: Despite the promise of geocoding and use of area-based socioeconomic measures to overcome the paucity of socioeconomic data in US public health surveillance systems, no consensus exists as to which measures should be used or at which level of geography. The authors generated diverse single-variable and composite area-based socioeconomic measures at the census tract, block group, and zip code level for Massachusetts (1990 population: 6,016,425) and Rhode Island (1990 population: 1,003,464) to investigate their associations with mortality rates (1989-1991: 156,366 resident deaths in Massachusetts and 27,291 in Rhode Island) and incidence of primary invasive cancer (1988-1992: 140,610 resident cases in Massachusetts; 1989-1992: 19,808 resident cases in Rhode Island). Analyses of all-cause and cause-specific mortality rates and all-cause and site-specific cancer incidence rates indicated that: 1) block group and tract socioeconomic measures performed comparably within and across both states, but zip code measures for several outcomes detected no gradients or gradients contrary to those observed with tract and block group measures; 2) similar gradients were detected with categories generated by quintiles and by a priori categorical cutpoints; and 3) measures including data on economic poverty were most robust and detected gradients that were unobserved using measures of only education and wealth.
1,125 citations
TL;DR: The authors assessed the sensitivity and specificity of the definitions of the metabolic syndrome for prevalent and incident diabetes mellitus in a Finnish population-based cohort of middle-aged men followed for 4 years since the late 1980s.
Abstract: The World Health Organization (WHO) and the National Cholesterol Education Program (NCEP) recently proposed definitions for the metabolic syndrome. Little is known of their validity, however. The authors assessed the sensitivity and specificity of the definitions of the metabolic syndrome for prevalent and incident diabetes mellitus in a Finnish population-based cohort of middle-aged men (n = 1,005) followed for 4 years since the late 1980s. Four definitions based on the WHO and NCEP recommendations were compared. All definitions identified persons at high risk for developing diabetes during the 4-year follow-up (odds ratios = 5.0-8.8). The WHO definition including waist-hip ratio > 0.90 or body mass index >or= 30 kg/m(2) was the most sensitive (0.83 and 0.67) and least specific (0.78 and 0.80) in detecting the 47 prevalent and 51 incident cases of diabetes. The NCEP definition in which adiposity was defined as waist girth > 102 cm detected only 61% of prevalent and 41% of incident diabetes, although it was the most specific (0.89 and 0.90). The WHO definition seems valid as judged by its relatively high sensitivity and specificity in predicting diabetes. The NCEP definition including waist > 102 cm also identifies persons at high risk for diabetes, but it is relatively insensitive in predicting diabetes.
913 citations
TL;DR: Results confirm previous suggestions that cannabis use increases the risk of both the incidence of psychosis in psychosis-free persons and a poor prognosis for those with an established vulnerability to psychotic disorder.
Abstract: Cannabis use may increase the risk of psychotic disorders and result in a poor prognosis for those with an established vulnerability to psychosis. A 3-year follow-up (1997-1999) is reported of a general population of 4,045 psychosis-free persons and of 59 subjects in the Netherlands with a baseline diagnosis of psychotic disorder. Substance use was assessed at baseline, 1-year follow-up, and 3-year follow-up. Baseline cannabis use predicted the presence at follow-up of any level of psychotic symptoms (adjusted odds ratio (OR) = 2.76, 95% confidence interval (CI): 1.18, 6.47), as well as a severe level of psychotic symptoms (OR = 24.17, 95% CI: 5.44, 107.46), and clinician assessment of the need for care for psychotic symptoms (OR = 12.01, 95% CI: 2.24, 64.34). The effect of baseline cannabis use was stronger than the effect at 1-year and 3-year follow-up, and more than 50% of the psychosis diagnoses could be attributed to cannabis use. On the additive scale, the effect of cannabis use was much stronger in those with a baseline diagnosis of psychotic disorder (risk difference, 54.7%) than in those without (risk difference, 2.2%; p for interaction = 0.001). Results confirm previous suggestions that cannabis use increases the risk of both the incidence of psychosis in psychosis-free persons and a poor prognosis for those with an established vulnerability to psychotic disorder.
907 citations
TL;DR: Results suggest that stimulating activity, either mentally or socially oriented, may protect against dementia, indicating that both social interaction and intellectual stimulation may be relevant to preserving mental functioning in the elderly.
Abstract: Recent findings suggest that a rich social network may decrease the risk of developing dementia. The authors hypothesized that such a protective effect may be due to social interaction and intellectual stimulation. To test this hypothesis, data from the 1987-1996 Kungsholmen Project, a longitudinal population-based study carried out in a central area of Stockholm, Sweden, were used to examine whether engagement in different activities 6.4 years before dementia diagnosis was related to a decreased incidence of dementia. Dementia cases were diagnosed by specialists according to Diagnostic and Statistical Manual of Mental Disorders, Third Edition, Revised, criteria. After adjustment for age, sex, education, cognitive functioning, comorbidity, depressive symptoms, and physical functioning at the first examination, frequent (daily-weekly) engagement in mental, social, or productive activities was inversely related to dementia incidence. Adjusted relative risks for mental, social, and productive activities were 0.54 (95% confidence interval (CI): 0.34, 0.87), 0.58 (95% CI: 0.37, 0.91), and 0.58 (95% CI: 0.38, 0.91), respectively. Similar results were found when these three factors were analyzed together in the same model. Results suggest that stimulating activity, either mentally or socially oriented, may protect against dementia, indicating that both social interaction and intellectual stimulation may be relevant to preserving mental functioning in the elderly.
906 citations
TL;DR: Findings support the protective effects of physical activity on depression for older adults and argue against excluding disabled subjects from similar studies.
Abstract: Previous studies assessing protective effects of physical activity on depression have had conflicting results; one recent study argued that excluding disabled subjects attenuated any observed effects. The authors' objective was to compare the effects of higher levels of physical activity on prevalent and incident depression with and without exclusion of disabled subjects. Participants were 1,947 community-dwelling adults from the Alameda County Study aged 50-94 years at baseline in 1994 with 5 years of follow-up. Depression was measured using criteria from the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (Washington, DC: American Psychiatric Association, 1994). Physical activity was measured with an eight-point scale; odds ratios are based upon a one-point increase on the scale. Even with adjustments for age, sex, ethnicity, financial strain, chronic conditions, disability, body mass index, alcohol consumption, smoking, and social relations, greater physical activity was protective for both prevalent depression (adjusted odds ratio (OR) = 0.90, 95% confidence interval (CI): 0.79, 1.01) and incident depression (adjusted OR = 0.83, 95% CI: 0.73, 0.96) over 5 years. Exclusion of disabled subjects did not attenuate the incidence results (adjusted OR = 0.79, 95% CI: 0.67, 0.92). Findings support the protective effects of physical activity on depression for older adults and argue against excluding disabled subjects from similar studies.
776 citations
TL;DR: Allelic variation in apo var epsilon is consistently associated with plasma concentrations of total cholesterol, LDL cholesterol, and apo B (the major protein of LDL, VLDL, and chylomicrons), and the genotype yields poor predictive values when screening for clinically defined atherosclerosis despite positive, but modest associations with plaque and coronary heart disease outcomes.
Abstract: This review examines the association between the apolipoprotein (apo) var epsilon gene polymorphism (or its protein product (apo E)), metabolic regulation of cholesterol, and cardiovascular disease. The apo var epsilon gene is located at chromosome 19q13.2. Among the variants of this gene, alleles (*) epsilon2, (*) epsilon3, and (*) epsilon4 constitute the common polymorphism found in most populations. Of these variants, apo (*) epsilon3 is the most frequent (>60%) in all populations studied. The polymorphism has functional effects on lipoprotein metabolism mediated through the hepatic binding, uptake, and catabolism of chylomicrons, chylomicron remnants, very low density lipoprotein (VLDL), and high density lipoprotein subspecies. Apo E is the primary ligand for two receptors, the low density lipoprotein (LDL) receptor (also known as the B/E receptor) found on the liver and other tissues and an apo E-specific receptor found on the liver. The coordinate interaction of these lipoprotein complexes with their receptors forms the basis for the metabolic regulation of cholesterol. Allelic variation in apo var epsilon is consistently associated with plasma concentrations of total cholesterol, LDL cholesterol, and apo B (the major protein of LDL, VLDL, and chylomicrons). Apo var epsilon has been studied in disorders associated with elevated cholesterol levels or lipid derangements (i.e., hyperlipoproteinemia type III, coronary heart disease, strokes, peripheral artery disease, and diabetes mellitus). The apo var epsilon genotype yields poor predictive values when screening for clinically defined atherosclerosis despite positive, but modest associations with plaque and coronary heart disease outcomes. In addition to genotype-phenotype associations with vascular disease, the alleles and isoforms of apo var epsilon have been related to dementias, most commonly Alzheimer's disease.
756 citations
TL;DR: To evaluate the impact of default implementation of the gam software on published analyses, the authors reanalyzed data from the National Morbidity, Mortality, and Air Pollution Study using three different methods and found that pooled NMMAPS estimates were very similar under the first and third methods but were biased upward under the second method.
Abstract: The widely used generalized additive models (GAM) method is a flexible and effective technique for conducting nonlinear regression analysis in time-series studies of the health effects of air pollution. When the data to which the GAM are being applied have two characteristics--1) the estimated regression coefficients are small and 2) there exist confounding factors that are modeled using at least two nonparametric smooth functions--the default settings in the gam function of the S-Plus software package (version 3.4) do not assure convergence of its iterative estimation procedure and can provide biased estimates of regression coefficients and standard errors. This phenomenon has occurred in time-series analyses of contemporary data on air pollution and mortality. To evaluate the impact of default implementation of the gam software on published analyses, the authors reanalyzed data from the National Morbidity, Mortality, and Air Pollution Study (NMMAPS) using three different methods: 1) Poisson regression with parametric nonlinear adjustments for confounding factors; 2) GAM with default convergence parameters; and 3) GAM with more stringent convergence parameters than the default settings. The authors found that pooled NMMAPS estimates were very similar under the first and third methods but were biased upward under the second method.
TL;DR: Using a population-based cohort of the general Dutch population, the authors studied whether an excessively negative orientation toward pain (pain catastrophizing) and fear of movement/(re)injury (kinesiophobia) are important in the etiology of chronic low back pain and associated disability.
Abstract: By using a population-based cohort of the general Dutch population, the authors studied whether an excessively negative orientation toward pain (pain catastrophizing) and fear of movement/(re)injury (kinesiophobia) are important in the etiology of chronic low back pain and associated disability, as clinical studies have suggested. A total of 1,845 of the 2,338 inhabitants (without severe disease) aged 25-64 years who participated in a 1998 population-based questionnaire survey on musculoskeletal pain were sent a second questionnaire after 6 months; 1,571 (85 percent) participated. For subjects with low back pain at baseline, a high level of pain catastrophizing predicted low back pain at follow-up (odds ratio (OR) = 1.7, 95% confidence interval (CI): 1.0, 2.8) and chronic low back pain (OR = 1.7, 95% CI: 1.0, 2.3), in particular severe low back pain (OR = 3.0, 95% CI: 1.7, 5.2) and low back pain with disability (OR = 3.0, 95% CI: 1.7, 5.4). A high level of kinesiophobia showed similar associations. The significant associations remained after adjustment for pain duration, pain severity, or disability at baseline. For those without low back pain at baseline, a high level of pain catastrophizing or kinesiophobia predicted low back pain with disability during follow-up. These cognitive and emotional factors should be considered when prevention programs are developed for chronic low back pain and related disability.
TL;DR: Former drinkers who had stopped 1-10 years previously had a higher risk of HCC than current drinkers did and a synergism between alcohol drinking and either infection was found, with approximately a twofold increase in the odds ratio for each hepatitis virus infection for drinkers of >60 g per day.
Abstract: The authors investigated the dose-effect relation between alcohol drinking and hepatocellular carcinoma (HCC) in men and women separately, also considering hepatitis B and hepatitis C virus infections. They enrolled 464 subjects (380 men) with a first diagnosis of HCC as cases and 824 subjects (686 men) unaffected by hepatic diseases as controls; all were hospitalized in Brescia, northern Italy, in 1995-2000. Spline regression models showed a steady linear increase in the odds ratio of HCC for increasing alcohol intake, for values of >60 g of ethanol per day, with no substantial differences between men and women. Duration of drinking and age at start had no effect on the odds ratio when alcohol intake was considered. Former drinkers who had stopped 1-10 years previously had a higher risk of HCC than current drinkers did. The effect of alcohol drinking was evident even in the absence of hepatitis B or hepatitis C virus infection. In addition, a synergism between alcohol drinking and either infection was found, with approximately a twofold increase in the odds ratio for each hepatitis virus infection for drinkers of >60 g per day.
TL;DR: The author investigates sample size requirements for studies of G x G interaction, focusing on four study designs: the matched-case-control design, the case-sibling design,The case-parent design, and the cases-only design, which provide an estimate of interaction on a multiplicative scale.
Abstract: In the study of complex diseases, it may be important to test hypotheses related to gene-gene (G x G) interaction. The success of such studies depends critically on obtaining adequate sample sizes. In this paper, the author investigates sample size requirements for studies of G x G interaction, focusing on four study designs: the matched-case-control design, the case-sibling design, the case-parent design, and the case-only design. All four designs provide an estimate of interaction on a multiplicative scale, which is used as a unifying theme in the comparison of sample size requirements. Across a variety of genetic models, the case-only and case-parent designs require fewer sampling units (cases and case-parent trios, respectively) than the case-control (pairs) or case-sibling (pairs) design. For example, the author describes an asthma study of two common recessive genes for which 270 matched case-control pairs would be required to detect a G x G interaction of moderate magnitude with 80% power. By comparison, the same study would require 319 case-sibling pairs but only 146 trios in the case-parent design or 116 cases in the case-only design. A software program that computes sample size for studies of G x G interaction and for studies of gene-environment (G x E) interaction is freely available (http://hydra.usc.edu/gxe).
TL;DR: Older people who reported problematic neighborhood environments had a greater risk of functional deterioration over 1 year compared with those in better neighborhoods and lower-extremity functional loss.
Abstract: Research suggests that neighborhood environment may influence functional health at an older age. This study examined the association between neighborhood problems and incidence of overall and lower-extremity functional loss. A total of 883 participants in the Alameda County Study who were aged 55 years and older and functionally healthy were questioned in 1994 and 1995 as part of an ongoing cohort study. Participants rated the severity of six neighborhood problems: traffic, noise, crime, trash and litter, lighting, and public transportation. Seventeen percent reported multiple neighborhood problems. Functional loss was measured by self-report of severe difficulty with physical tasks (e.g., climbing stairs, lifting 10 pounds (4.54 kg)). After 1 year, 6.1% developed overall functional loss, and 3.9% developed lower-extremity functional loss. Regression models adjusted for demographic, socioeconomic, health, and behavioral risk factors. Compared with those who reported nonproblem neighborhoods, those who reported multiple-problem neighborhoods were at increased risk of overall functional loss (odds ratio = 2.23, 95% confidence interval: 1.08, 4.60) and lower-extremity functional loss (odds ratio = 3.12, 95% confidence interval: 1.15, 8.51). Neighborhood problems associated with the largest increase in risk were excessive noise, inadequate lighting, and heavy traffic. Older people who reported problematic neighborhood environments had a greater risk of functional deterioration over 1 year compared with those in better neighborhoods.
TL;DR: It is suggested that symptomatic hand osteoarthritis is a common disease among elders and frequently impairs hand function.
Abstract: Osteoarthritis is one of the most common joint disorders in the elderly, yet few studies have targeted symptomatic osteoarthritis, especially symptomatic hand osteoarthritis. The authors conducted a survey in 1992-1993 among an elderly population to estimate the prevalence of symptomatic hand osteoarthritis and to assess its impact on grip strength and functional activities. Framingham Study subjects received hand radiographs and answered queries on joint symptoms. Functional activities were assessed using an interviewer-administered questionnaire. Grip strength and observed functional performance were evaluated using standard procedures. A hand joint was defined as having symptomatic osteoarthritis if both symptoms and radiographic evidence of osteoarthritis were present. Of 1,041 subjects aged 71-100 years (36% men), the prevalence of symptomatic hand osteoarthritis was higher in women (26.2%) than in men (13.4%). Compared with those without symptomatic hand osteoarthritis, subjects with the disease had 10% reduced maximal grip strength, reported more difficulty writing, handling, or fingering small objects (odds ratio = 3.4), and showed more self-reported and observed difficulty carrying a 10-pound (4.5-kg) bundle (odds ratio = 1.7 and 1.6, respectively). In conclusion, in the context of a remarkable paucity of data on the epidemiology of symptomatic hand osteoarthritis, this study suggests that symptomatic hand osteoarthritis is a common disease among elders and frequently impairs hand function.
TL;DR: Levels of two biomarkers of lipid peroxidation, malondialdehyde and F(2)-isoprostanes, in 298 healthy adults aged 19-78 years are presented to permit a better understanding of the role that oxidants and antioxidants play in the health of human populations.
Abstract: Oxidation of biomolecules may play a role in susceptibility to a number of diseases. However, there are few large-scale survey data describing oxidative damage that occurs in humans and the demographic, physical, or nutritional factors that may be associated with it. Such information is essential for the design and analysis of studies investigating the role of oxidative stress in health and disease. This paper presents data on levels of two biomarkers of lipid peroxidation, malondialdehyde and F(2)-isoprostanes, in 298 healthy adults aged 19-78 years. The study was conducted in Berkeley and Oakland, California, in 1998-1999. Sex was the strongest predictor of lipid peroxidation as measured by both biomarkers (p < 0.0001); it was stronger than smoking. C-reactive protein was positively associated with lipid peroxidation (p = 0.004), as was plasma cholesterol. Plasma ascorbic acid had a strong inverse relation (p < 0.001) with both biomarkers. Plasma beta-carotene was also associated with F(2)-isoprostanes. Other plasma antioxidants were not associated with lipid peroxidation biomarkers, once ascorbic acid was included in the multivariate model. Future surveys and epidemiologic studies should measure at least one marker of oxidative damage, as well as plasma ascorbic acid. These data would permit a better understanding of the role that oxidants and antioxidants play in the health of human populations.
TL;DR: Overall, a woman's recall of menarcheal age and body size was better than recall of cycle length and occurrence of regularity, and the failure to identify certain menstrual characteristics as exposures for subsequent disease may reflect limitations in the accuracy and precision of the recalled measures.
Abstract: The validity of recall of early menstrual characteristics is of interest because of their putative role in the etiology of breast cancer and other diseases A retrospective follow-up of the Newton Girls Study (1965-1975) provided an opportunity to assess the accuracy and precision of recall of several early menstrual characteristics In 1998-1999, 57 percent of the original 793 Newton Girls Study participants completed a mailed questionnaire to assess the accuracy of recall for age and body size at menarche, usual cycle length during the first 2 years, and age at regularity Recalled and original age at menarche were highly correlated (r = 079, p < 0001) The body mass index percentile at menarche was well correlated with recalled body size at menarche (r = 061, p < 0001), but with some evidence of systematic bias Overall, a woman's recall of menarcheal age and body size was better than recall of cycle length and occurrence of regularity The failure to identify certain menstrual characteristics as exposures for subsequent disease may reflect limitations in the accuracy and precision of the recalled measures
TL;DR: Maternal depressive symptoms in this sample of African-American women were independently associated with spontaneous preterm birth, suggesting effective treatment of depression in pregnant women could ultimately result in a reduction of spontaneous pre term births.
Abstract: The purpose of this study was to examine the relation between maternal depressive symptoms and spontaneous preterm birth. From 1991 to 1993, pregnant, African-American women were prospectively enrolled at four hospital-based clinics in Baltimore, Maryland, that serve low-income areas of the city. The Center for Epidemiologic Studies Depression (CES-D) Scale was used to assess depressive symptoms. Multiple logistic regression analysis estimated the independent contribution of maternal depressive symptoms to spontaneous preterm birth, controlling for behavioral, clinical, and demographic variables. Among the 1,399 women in the sample, 117 (8.4%) had a spontaneous preterm delivery. Spontaneous preterm birth occurred among 12.7% of those with a CES-D score in the upper 10th percentile and among 8.0% of those with a lower score (relative risk = 1.59). The adjusted odds ratio for an elevated CES-D score was 1.96 (95% confidence interval: 1.04, 3.72); hence, maternal depressive symptoms in this sample of African-American women were independently associated with spontaneous preterm birth. Effective treatment of depression in pregnant women could ultimately result in a reduction of spontaneous preterm births.
TL;DR: The authors' results are supported by the specificity of the timing of the effect and some evidence from animal data, and this is the first known study to link ambient air pollution during a vulnerable window of development to human malformations.
Abstract: The authors evaluated the effect of air pollution on the occurrence of birth defects ascertained by the California Birth Defects Monitoring Program in neonates and fetuses delivered in southern California in 1987-1993. By using measurements from ambient monitoring stations of carbon monoxide (CO), nitrogen dioxide, ozone, and particulate matter <10 microm in aerodynamic diameter, they calculated average monthly exposure estimates for each pregnancy. Conventional, polytomous, and hierarchical logistic regression was used to estimate odds ratios for subgroups of cardiac and orofacial defects. Odds ratios for cardiac ventricular septal defects increased in a dose-response fashion with increasing second-month CO exposure (odds ratio (OR)(2nd quartile) CO = 1.62, 95% confidence interval (CI): 1.05, 2.48; OR(3rd quartile) CO = 2.09, 95% CI: 1.19, 3.67; OR(4th quartile) CO = 2.95, 95% CI: 1.44, 6.05). Similarly, risks for aortic artery and valve defects, pulmonary artery and valve anomalies, and conotruncal defects increased with second-month ozone exposure. The study was inconclusive for other air pollutants. The authors' results are supported by the specificity of the timing of the effect and some evidence from animal data; however, this is the first known study to link ambient air pollution during a vulnerable window of development to human malformations. Confirmation by further studies is needed.
TL;DR: It is concluded that sharing of injection equipment other than syringe-sharing may be an important cause of HCV transmission between IDUs.
Abstract: Designing studies to examine hepatitis C virus (HCV) transmission via the shared use of drug injection paraphernalia other than syringes is difficult because of saturation levels of HCV infection in most samples of injection drug users (IDUs). The authors measured the incidence of HCV infection in a large cohort of young IDUs from Chicago, Illinois, and determined the risk of HCV seroconversion associated with specific forms of sharing injection paraphernalia. From 1997 to 1999, serum samples obtained from 702 IDUs aged 18-30 years were screened for HCV antibodies; prevalence was 27%. Seronegative participants were tested for HCV antibodies at baseline, at 6 months, and at 12 months. During 290 person-years of follow-up, 29 participants seroconverted (incidence: 10.0/100 person-years). The adjusted relative hazard of seroconversion, controlling for demographic and drug-use covariates, was highest for sharing "cookers" (relative hazard = 4.1, 95% confidence interval: 1.4, 11.8), followed by sharing cotton filters (relative hazard = 2.4, 95% confidence interval: 1.1, 5.0). Risks associated with syringe-sharing and sharing of rinse water were elevated but not significant. After adjustment for syringe-sharing, sharing cookers remained the strongest predictor of seroconversion (relative hazard = 3.5, 95% confidence interval: 1.3, 9.9). The authors conclude that sharing of injection equipment other than syringes may be an important cause of HCV transmission between IDUs.
TL;DR: In analyses of change in social network components restricted to older men, each categorical unit increase in number of close friends was significantly associated with a 29% decrease in risk of death.
Abstract: The authors prospectively examined the effects of social ties and change in social ties, as measured by a well-known social network index, on total and cause-specific mortality and on coronary heart disease incidence in 28,369 US male health professionals aged 42-77 years in 1988. Over 10 years, the relative risk of total mortality for men in the lower two levels of social integration compared with more socially integrated men was 1.19 (95% confidence interval: 1.06, 1.34) after controlling for age, occupation, health behaviors, general physical condition, coronary risk factors, and dietary habits. In multivariate analysis, deaths from accidents and suicide and from other noncancer, noncardiovascular causes were significantly increased among less socially connected men. Socially isolated men also had an increased risk of fatal coronary heart disease (multivariate relative risk = 1.82, 95% confidence interval: 1.02, 3.23). An increase in the overall social network index between 1988 and 1996 was not significantly associated with subsequent 2-year mortality. In analyses of change in social network components restricted to older men, each categorical unit increase in number of close friends was significantly associated with a 29% decrease in risk of death. Increase in religious service attendance over time was also significantly predictive of decreased mortality.
TL;DR: The results of this study suggest a substantial increase in substance use in the acute postdisaster period after the September 11th attacks, which may be associated with the presence of different comorbid psychiatric conditions.
Abstract: The September 11, 2001, terrorist attacks were the largest human-made disaster in the United States since the Civil War. Studies after earlier disasters have reported rates of psychological disorders in the acute postdisaster period. However, data on postdisaster increases in substance use are sparse. A random digit dial telephone survey was conducted to estimate the prevalence of increased cigarette smoking, alcohol consumption, and marijuana use among residents of Manhattan, New York City, 5-8 weeks after the attacks. Among 988 persons included, 28.8% reported an increase in use of any of these three substances, 9.7% reported an increase in smoking, 24.6% reported an increase in alcohol consumption, and 3.2% reported an increase in marijuana use. Persons who increased smoking of cigarettes and marijuana were more likely to experience posttraumatic stress disorder than were those who did not (24.2% vs. 5.6% posttraumatic stress disorder for cigarettes; 36.0% vs. 6.6% for marijuana). Depression was more common among those who increased than for those who did not increase cigarette smoking (22.1 vs. 8.2%), alcohol consumption (15.5 vs. 8.3%), and marijuana smoking (22.3 vs. 9.4%). The results of this study suggest a substantial increase in substance use in the acute postdisaster period after the September 11th attacks. Increase in use of different substances may be associated with the presence of different comorbid psychiatric conditions.
TL;DR: The authors' findings increase understanding of dengue virus transmission and disease severity in a well-defined cohort population and offer a study design in which to test the efficacy of potential d Dengue vaccines.
Abstract: Dengue viruses are a major cause of morbidity in tropical and subtropical regions of the world. Knowledge about the epidemiology and host determinants of inapparent and severe dengue virus infections is limited. In this paper, the authors report findings from the first 3 years of a prospective study of dengue virus transmission and disease severity conducted in a cohort of 2,119 elementary school children in northern Thailand. A total of 717,106 person-school days were observed from 1998 to 2000. The incidence of inapparent and of symptomatic dengue virus infection was 4.3% and 3.6% in 1998, 3.2% and 3.3% in 1999, and 1.4% and 0.8% in 2000, respectively. Symptomatic dengue virus infection was responsible for 3.2%, 7.1%, and 1.1% of acute-illness school absences in 1998, 1999, and 2000, respectively. The early symptom complex of acute dengue virus infection is protean and difficult to distinguish from other causes of febrile childhood illnesses. The authors' results illustrate the spatial and temporal diversity of dengue virus infection and the burden of dengue disease in schoolchildren in Thailand. Their findings increase understanding of dengue virus transmission and disease severity in a well-defined cohort population and offer a study design in which to test the efficacy of potential dengue vaccines.
TL;DR: It was concluded that obesity was related to development of asthma in women but not in men, and baseline BMI was a significant predictor for asthma incidence in women.
Abstract: To investigate the possibility of gender specificity for the effect of body mass index (BMI) on development of asthma, the authors used the longitudinal data from the first and second cycles of the National Population Health Survey, conducted in Canada in 1994-1995 and 1996-1997, respectively. Data from 9,149 subjects (4,266 men and 4,883 women) aged 20-64 years who reported no asthma at baseline were used in this analysis. The 2-year cumulative incidence of asthma was estimated by using a bootstrap procedure to take sampling weights and design effects into account. During the 2-year study period, 1.6% of the men and 2.9% of the women developed asthma. Average changes in body weight and BMI over the 2-year observation period were relatively small and were not associated with asthma incidence. However, baseline BMI was a significant predictor for asthma incidence in women. The adjusted odds ratio for women whose baseline BMI was at least 30.0 kg/m(2) versus 20.0-24.9 kg/m(2) was 1.9 (95% confidence interval: 1.1, 3.4), whereas the corresponding odds ratio of 1.1 (95% confidence interval: 0.3, 3.6) for men was not significantly different from unity. The authors concluded that obesity was related to development of asthma in women but not in men.
TL;DR: Data suggest a role for specific biologic causes of infertility, but not for fertility drugs in overall risk for ovarian cancer, as suggested in case-control studies conducted between 1989 and 1999.
Abstract: Controversy surrounds the relations among infertility, fertility drug use, and the risk of ovarian cancer. The authors pooled interview data on infertility and fertility drug use from eight case-control studies conducted between 1989 and 1999 in the United States, Denmark, Canada, and Australia. Odds ratios and 95% confidence intervals were calculated, adjusting for age, race, family history of ovarian cancer, duration of oral contraception use, tubal ligation, gravidity, education, and site. Included in the analysis were 5,207 cases and 7,705 controls. Among nulligravid women, attempts for more than 5 years to become pregnant compared with attempts for less than 1 year increased the risk of ovarian cancer 2.67-fold (95% confidence interval (CI): 1.91, 3.74). Among nulliparous, subfertile women, neither any fertility drug use (odds ratio (OR) = 1.60, 95% CI: 0.90, 2.87) nor more than 12 months of use (OR = 1.54, 95% CI: 0.45, 5.27) was associated with ovarian cancer. Fertility drug use in nulligravid women was associated with borderline serous tumors (OR = 2.43, 95% CI: 1.01, 5.88) but not with any invasive histologic subtypes. Endometriosis (OR = 1.73, 95% CI: 1.10, 2.71) and unknown cause of infertility (OR = 1.19, 95% CI: 1.00, 1.40) increased cancer risk. These data suggest a role for specific biologic causes of infertility, but not for fertility drugs in overall risk for ovarian cancer.
TL;DR: A checklist for reporting and appraising studies of genotype prevalence and studies of gene-disease associations was developed and focuses on selection of study subjects, analytic validity of genotyping, population stratification, and statistical issues.
Abstract: The recent completion of the first draft of the human genome sequence and advances in technologies for genomic analysis are generating tremendous opportunities for epidemiologic studies to evaluate the role of genetic variants in human disease. Many methodological issues apply to the investigation of variation in the frequency of allelic variants of human genes, of the possibility that these influence disease risk, and of assessment of the magnitude of the associated risk. Based on a Human Genome Epidemiology workshop, a checklist for reporting and appraising studies of genotype prevalence and studies of gene-disease associations was developed. This focuses on selection of study subjects, analytic validity of genotyping, population stratification, and statistical issues. Use of the checklist should facilitate the integration of evidence from these studies. The relation between the checklist and grading schemes that have been proposed for the evaluation of observational studies is discussed. Although the limitations of grading schemes are recognized, a robust approach is proposed. Other issues in the synthesis of evidence that are particularly relevant to studies of genotype prevalence and gene-disease association are discussed, notably identification of studies, publication bias, criteria for causal inference, and the appropriateness of quantitative synthesis.
TL;DR: It is concluded that both fitness and fatness are risk factors for mortality, and that being fit does not completely reverse the increased risk associated with excess adiposity.
Abstract: The relative size of the effects of fitness and fatness on longevity has been studied in only one cohort. The authors examined this issue using data from 2,506 women and 2,860 men in the Lipid Research Clinics Study. The mean age was 46.6 years in women and 45.1 years in men at baseline (1972-1976). Fitness was assessed using a treadmill test, and fatness was assessed as body mass index calculated from measured height and weight. Participants were followed for vital status through 1998. Hazard ratios were calculated using proportional hazard models that included covariates for age, education, smoking, alcohol intake, and the dietary Keys score. Fitness and fatness were both associated with mortality from all causes and from cardiovascular disease. For mortality from all causes, the adjusted hazard ratios were 1.32 among the fit-fat, 1.30 among the unfit-not fat, and 1.57 among the unfit-fat women compared with fit-not fat women. Among men the same hazard ratios were 1.25, 1.44, and 1.49 [corrected]. There were no significant interactions between fitness and fatness in either men or women. The authors conclude that both fitness and fatness are risk factors for mortality, and that being fit does not completely reverse the increased risk associated with excess adiposity.
TL;DR: A dose-dependent association between overweight/obesity and maternal smoking during pregnancy was observed that could not be explained by a wide range of confounders, suggesting that intrauterine exposure to inhaled smoke products rather than lifestyle factors associated with maternal smoking accounts for this finding.
Abstract: A recent cohort study suggested that maternal smoking during pregnancy might be a risk factor for childhood obesity. Data from the obligatory school entry health examination in six Bavarian (Germany) public health offices in 1999-2000 were used to assess the relation between maternal smoking during pregnancy and childhood obesity (n = 6,483 German children aged 5.00-6.99 years). A body mass index greater than the 90th percentile was defined as overweight, and a body mass index greater than the 97th percentile was defined as obesity. The main exposure was maternal smoking during pregnancy. The prevalences of overweight and obesity, expressed as percentages, increased in the following order: never smoked (overweight: 8.1, 95% confidence interval (CI): 7.2, 9.0; obesity: 2.2, 95% CI: 1.7, 2.7); less than 10 cigarettes daily (overweight: 14.1, 95% CI: 11.1, 17.7; obesity: 5.7, 95% CI: 3.7, 8.2); and 10 or more cigarettes daily (overweight: 17.0, 95% CI: 10.1, 26.2; obesity: 8.5, 95% CI: 3.7, 16.1). The adjusted odds ratios for maternal smoking during pregnancy were 1.43 (95% CI: 1.07, 1.90) for overweight and 2.06 (95% CI: 1.31, 3.23) for obesity. A dose-dependent association between overweight/obesity and maternal smoking during pregnancy was observed that could not be explained by a wide range of confounders, suggesting that intrauterine exposure to inhaled smoke products rather than lifestyle factors associated with maternal smoking accounts for this finding.
TL;DR: New epidemiologic evidence is offered on the sequences that link earlier use of alcohol and tobacco to later illegal drug involvement and among young people with a cocaine opportunity, those who had used marijuana were more likely to use cocaine than were those with no history of marijuana use.
Abstract: Drawing upon an "exposure opportunity" concept described by Wade Hampton Frost, the authors studied two mechanisms to help account for prior observations about the "stepping-stone" or "gateway" sequences that link the use of alcohol, tobacco, marijuana, and cocaine. Data were obtained from four nationally representative and independent cross-sectional samples of US household residents (n = 44,624 persons aged 12-25 years). Data were gathered using standardized self-report methods and were analyzed via survival methods. Results indicated that users of tobacco and alcohol were more likely than nonusers to have an opportunity to try marijuana and were more likely to actually use marijuana once a marijuana opportunity had occurred. Opportunity to use cocaine was associated with prior marijuana smoking. Among young people with a cocaine opportunity, those who had used marijuana were more likely to use cocaine than were those with no history of marijuana use. The observed associations did not seem to arise solely as a result of young drug users' seeking out opportunities to use drugs. Applying Frost's epidemiologic concept of exposure opportunity, the authors offer new epidemiologic evidence on the sequences that link earlier use of alcohol and tobacco to later illegal drug involvement.