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Search Results: 1 - 10 of 300887 matches for " Kenneth J Rothman "
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Thrombosis after Travel
Kenneth J Rothman
PLOS Medicine , 2006, DOI: 10.1371/journal.pmed.0030300
Simple estimators of the intensity of seasonal occurrence
M Alan Brookhart, Kenneth J Rothman
BMC Medical Research Methodology , 2008, DOI: 10.1186/1471-2288-8-67
Abstract: We discuss various approaches to the estimation of seasonal intensity assuming Edwards's periodic model, including maximum likelihood estimation (MLE), least squares, weighted least squares, and a new closed-form estimator based on a second-order moment statistic and non-transformed data. Through an extensive Monte Carlo simulation study, we compare the finite sample performance characteristics of the estimators discussed in this paper. Finally, all estimators and confidence interval procedures discussed are compared in a re-analysis of data on the seasonality of monocytic leukemia.We find that Edwards's estimator is substantially biased, particularly for small numbers of events and very large or small amounts of seasonality. For the common setting of rare events and moderate seasonality, the new estimator proposed in this paper yields less finite sample bias and better mean squared error than either the MLE or weighted least squares. For large studies and strong seasonality, MLE or weighted least squares appears to be the optimal analytic method among those considered.Edwards's estimator of the seasonal relative risk can exhibit substantial finite sample bias. The alternative estimators considered in this paper should be preferred.In a classic paper, Edwards [1] describes a geometrically motivated, moment-based method to fit a sine curve to a time series of square-root transformed monthly frequencies. From this basic framework, he derived both a test of the null hypothesis of no seasonality and an estimator of the intensity of seasonal occurrence (i.e., the peak-to-low ratio of the fitted sine curve). Owing to its intuitive appeal and computational simplicity, Edwards's and related methods have been widely used in epidemiology in studies of seasonality, e.g., [2-7].Although there has been considerable discussion of the hypothesis testing procedure described by Edwards and a variety of alternative tests have been proposed [8-12], there has been relatively little dis
Migraine, fibromyalgia, and depression among people with IBS: a prevalence study
J Alexander Cole, Kenneth J Rothman, Howard J Cabral, Yuqing Zhang, Francis A Farraye
BMC Gastroenterology , 2006, DOI: 10.1186/1471-230x-6-26
Abstract: The source of data was a large U.S. health plan from January 1, 1996 though June 30, 2002. We identified all people with a medical claim associated with an ICD-9 code for IBS. A non-IBS cohort was a random sample of people with an ICD-9 code for routine medical care. In the cohorts, we identified all claims for migraine, depression, and fibromyalgia. We estimated the prevalence odds ratios (PORs) of each of the three conditions using the Mantel-Haenszel method. We conducted quantitative sensitivity analyses to quantify the impact of residual confounding and in differential outcome identification.We identified 97,593 people in the IBS cohort, and a random sample of 27,402 people to compose the non-IBS comparison cohort. With adjustment, there was a 60% higher odds in the IBS cohort of having any one of the three disorders relative to the comparison cohort (POR 1.6, 95% CI 1.5 – 1.7). There was a 40% higher odds of depression in the IBS cohort (POR 1.4, 95% CI 1.3 – 1.4). The PORs for fibromyalgia and migraine were similar (POR for fibromyalgia 1.8, 95% CI 1.7 – 1.9; POR for migraine 1.6, 95% CI 1.4 – 1.7). Differential prevalence of an unmeasured confounder, or imperfect sensitivity or specificity of outcome detection would have impacted the observed results.People in the IBS cohort had a 40% to 80% higher prevalence odds of migraine, fibromyalgia, and depression.Irritable bowel syndrome (IBS) is a functional disorder of the gastrointestinal tract, which results in the clinical symptoms of altered bowel habits and abdominal pain [1,2]. It is characterized by three specific forms: diarrhea-predominant, constipation-predominant, and alternating between diarrhea and constipation. While there is no diagnostic instrument to screen and diagnose people with the condition, the Rome II criteria are the established method of diagnosis for inclusion in clinical trials and by some clinicians [3].People with IBS are reportedly more likely to have other disorders including migrain
Association of Apgar score at five minutes with long-term neurologic disability and cognitive function in a prevalence study of Danish conscripts
Vera Ehrenstein, Lars Pedersen, Miriam Grijota, Gunnar Nielsen, Kenneth J Rothman, Henrik S?rensen
BMC Pregnancy and Childbirth , 2009, DOI: 10.1186/1471-2393-9-14
Abstract: We conducted a prevalence study among draft-liable men born in Denmark in 1978–1983 and presenting for the mandatory army evaluation in a northern Danish conscription district. We linked records of this evaluation, which includes medical exam and intelligence testing, with the conscripts' records in the Medical Birth Registry, containing perinatal data. We examined prevalence of neurologic disability and of low cognitive function according to five-minute Apgar score.Less than 1% (136/19,559) of the conscripts had 5-minute Apgar scores <7. Prevalence of neurologic disability was 2.2% (435/19,559) overall; among conscripts with Apgar scores <7, 7–9, and 10 (reference), it was 8.8%, 2.5%, and 2.2% respectively. The corresponding prevalences of low cognitive function (intelligence test score in the bottom quartile) were 34.9%, 27.2%, and 25.0%. The outcomes were more prevalent if Apgar score <7 was accompanied by certain fetal or obstetric adversities. After accounting for perinatal characteristics, 5-mintue Apgar score <7 was associated with prevalence ratios of 4.02 (95% confidence interval: 2.24; 7.24) for neurologic disability and 1.33 (0.94; 1.88) for low cognitive function.A five-minute Apgar score <7 has a consistent association with prevalence of neurologic disability and with low cognitive function in early adulthood.Apgar score [1], used to evaluate infant's condition immediately after birth, is a sum of ratings (0, 1, or 2) of five clinical signs: heart rate, respiration, reflex irritability, muscle tone, and color. Five-minute Apgar scores below 4 are strong predictors of neonatal mortality [2]. Antenatal [3,4] and peripartum [5] adversities associated with five-minute Apgar scores below 7 [6-8] have been implicated in neonatal brain injury, which in turn may lead to neurodevelopmental disability [9-13].Most newborns with Apgar scores below 7 grow up healthy, but risks of neurodevelopmental disability among them are greater than among those with higher Apgar
The relation between amyotrophic lateral sclerosis and inorganic selenium in drinking water: a population-based case-control study
Marco Vinceti, Francesca Bonvicini, Kenneth J Rothman, Luciano Vescovi, Feiyue Wang
Environmental Health , 2010, DOI: 10.1186/1476-069x-9-77
Abstract: To assess the extent to which such association persisted in the decade following its initial observation, we conducted a population-based case-control study encompassing forty-one newly-diagnosed cases of amyotrophic lateral sclerosis and eighty-two age- and sex-matched controls. We measured long-term intake of inorganic selenium along with other potentially neurotoxic trace elements.We found that consumption of drinking water containing ≥ 1 μg/l of inorganic selenium was associated with a relative risk for amyotrophic lateral sclerosis of 5.4 (95% confidence interval 1.1-26) after adjustment for confounding factors. Greater amounts of cumulative inorganic selenium intake were associated with progressively increasing effects, with a relative risk of 2.1 (95% confidence interval 0.5-9.1) for intermediate levels of cumulative intake and 6.4 (95% confidence interval 1.3-31) for high intake.Based on these results, coupled with other epidemiologic data and with findings from animal studies that show specific toxicity of the trace element on motor neurons, we hypothesize that dietary intake of inorganic selenium through drinking water increases the risk for amyotrophic lateral sclerosis.Amyotrophic lateral sclerosis (ALS), a severe neurodegenerative disease, has no established environmental risk factors [1]. Although some studies report that its incidence has been stable, others report changes in incidence over time and geographic variation in occurrence [2,3]. Some environmental factors, particularly neurotoxic elements and pesticides, have been implicated by some investigations [4-6]. Two epidemiologic studies [7,8] have focused on the possible role of selenium (Se), an element of nutritional and toxicological interest [9]. Environmental Se exists in organic and inorganic forms, with the organic forms being virtually the only ones found in food [10]. Dietary Se intake in Italy has been estimated to be about 50 μg/d per person [11]. Inorganic forms of Se are found more c
Apgar score and hospitalization for epilepsy in childhood: a registry-based cohort study
Vera Ehrenstein, Henrik T S?rensen, Lars Pedersen, Helle Larsen, Vibeke Holsteen, Kenneth J Rothman
BMC Public Health , 2006, DOI: 10.1186/1471-2458-6-23
Abstract: Using records linked from population registries, we conducted a cohort study among singleton children born alive in the period 1978–2001 in North Jutland County, Denmark. The first hospital discharge diagnosis of epilepsy during the follow-up time was the main outcome. We followed each child for up to 12 years, calculated absolute risks and risk differences, and used a Poisson regression model to estimate risk ratios for epilepsy hospitalization. We adjusted risk ratio estimates for birth weight, gestational age, mode of delivery, birth presentation, mother's age at delivery, and birth defects.One percent of the 131,853 eligible newborns had a 5-minute Apgar score <7. These children were more likely to be hospitalized with epilepsy during the follow-up than were children with an Apgar score of 7 or greater. The crude risk difference for epilepsy hospitalization was 2.5 cases per 100 (95% confidence interval [CI] 1.3 to 3.8). The risk difference estimates were greater in the presence of other perinatal risk factors. The adjusted risk ratio was 2.4 (95% CI 1.5 to 3.8). Half of the 12-year risk for epilepsy hospitalization in those with a depressed Apgar score occurred during the first year of life. The risk ratio during the first year of life was 4.9 (95% CI 2.0 to 12.3).An Apgar score <7 at five minutes predicts an increase in the subsequent risk of epilepsy hospitalization. This association is amplified by other perinatal risk factors.Designed to assess infants' condition immediately after birth, Apgar score [1] is a cumulative ranking of five clinical signs – heart rate, respiratory effort, muscle tone, reflex activity, and color – each assigned a rating of 0, 1, or 2 with lower number corresponding to poorer condition [2]. Apgar scores take on integer values from zero to ten and are measured at one and five minutes of age. A prolonged Apgar score below four is a component of a diagnosis of asphyxia and is a stronger predictor of neonatal death than the pH of umbil
Risk Factors for Venous Thromboembolism in 1.3 Million Pregnancies: A Nationwide Prospective Cohort
Rie Adser Virkus, Ellen L?kkegaard, ?jvind Lidegaard, Jens Langhoff-Roos, Anne Kristine Nielsen, Kenneth J. Rothman, Thomas Bergholt
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0096495
Abstract: Objective To quantify risk factors for venous thromboembolism during pregnancy and the puerperal period. Design In a nationwide prospective cohort study we followed pregnant and puerperal women in Denmark from 1995 to 2009 for venous thromboembolism. Information on risk factors and confounders was retrieved from national registries. The diagnosis of venous thromboembolism was confirmed through medical charts. We calculated adjusted incidence rates per 10,000 women years and used Poisson regression to estimate effects during pregnancy and the puerperal period. Results We studied 1,297,037 pregnancies and related puerperal periods, during which there were 748 venous thromboembolisms. The incidence rate for venous thromboembolism during a pregnancy with and without hospitalization for hyperemesis was 15.2/10,000 yr and 6.3/10,000 yr, respectively, (adjusted rate ratio: 2.5 (95%-confidence interval; 1.4–4.5)). The incidence rate among women with multiple pregnancies was 18.2/10,000 yr and 6.3/10,000 yr in singletons (adjusted rate ratio: 2.8 (1.9–4.2)). Increased risk was found with hospitalization during pregnancy or the puerperal period with incidence rates of 42.1/10.000 and 54.7/10.000, respectively, (rate ratios: 12.2 (8.7–17) and 5.9 (4.0–8.8)). Women hospitalized with infections during pregnancy had incidence rates of 25.9/10,000 yr and 29.3/10,000 yr during pregnancy and the puerperal period, respectively, and of 62.7/10,000 yr if hospitalized with infection in the puerperal period. Puerperal venous thromboembolism was associated with hospitalization for preeclampsia and intrauterine growth restriction/fetal death with incidence rates of 45.8/10,000 yr and 18.3/10,000 yr, respectively (rate ratio: 5.0 (3.1–7.8) and 1.9 (0.9–4.4)). Additionally puerperal venous thromboembolism was associated with obesity, elective and acute caesarean sections and major postpartum bleeding with incidence rates of 25.5/10,000 yr, 23.2/10,000 yr, 34.0/10,000 yr and 20.3/10,000 yr, respectively (rate ratios 1.7 (1.1–2.7), 2.1 (1.4–3.1), 3.0 (2.3–4.0) and 1.4 (1.0–2.1)). Conclusions Important risk factors for venous thromboembolism during pregnancy or the puerperal period were hospitalization, infection, hyperemesis, multiple pregnancies, preeclampsia, obesity, caesarean section, major postpartum bleeding, and intrauterine growth restriction or fetal death.
Family history of later-onset breast cancer, breast healthy behavior and invasive breast cancer among postmenopausal women: a cohort study
Robert Gramling, Timothy L Lash, Kenneth J Rothman, Howard J Cabral, Rebecca Silliman, Mary Roberts, Marcia L Stefanick, Rosanne Harrigan, Monica L Bertoia, Charles B Eaton
Breast Cancer Research , 2010, DOI: 10.1186/bcr2727
Abstract: Breast cancer outcomes through August 2003 were analyzed in relationship to lifestyle and risk factors collected by questionnaire during enrollment (between 1993 and 1998) of 85,644 postmenopausal women into the Women's Health Initiative Observational Study.During a mean follow-up of 5.4 years, 1997 women were diagnosed with invasive breast cancer. The rate of invasive breast cancer among women with an FHLBC who participated in all three behaviors was 5.94 per 1,000 woman-years, compared with 6.97 per 1,000 woman-years among women who participated in none of the behaviors. The rate among women with no FHLBC who participated in all three behavioral conditions was 3.51 per 1,000 woman-years compared to 4.67 per 1,000 woman-years for those who participated in none. We did not observe a clinically important departure from additive effects (Interaction Contrast: 0.00014; 95% CI: -0.00359, 0.00388).Participating in breast healthy behaviors was beneficial to postmenopausal women and the degree of this benefit was the same for women with and without an FHLBC.Nearly 15% of postmenopausal women in the US report breast cancer in a first-degree relative [1]. Few women report pedigrees that are suggestive of highly penetrant, single-gene disorders such as hereditary breast and ovarian cancer [2]. Most family histories, particularly those that arise among older relatives, reflect complex risk factors representing the interaction between genes, environments, and behaviors that are often shared within families [3-5]. Under such multi-factorial inheritance conditions, it is plausible that family history is a mutable risk factor. For example, if a woman's family history arose in part because of a predominance of risk-conferring behaviors among women in her family and she adopts breast cancer-preventive behaviors, she will have ameliorated some of her risk attributed to family history.Physical inactivity [6,7], excessive alcohol consumption [8], and patterns of energy consumption and
Weight at Birth and Subsequent Fecundability: A Prospective Cohort Study
Cathrine Wildenschild, Anders H. Riis, Vera Ehrenstein, Berit L. Heitmann, Elizabeth E. Hatch, Lauren A. Wise, Kenneth J. Rothman, Henrik T. S?rensen, Ellen M. Mikkelsen
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0095257
Abstract: Objective To examine the association between a woman's birth weight and her subsequent fecundability. Method In this prospective cohort study, we included 2,773 Danish pregnancy planners enrolled in the internet-based cohort study “Snart-Gravid”, conducted during 2007–2012. Participants were 18–40 years old at study entry, attempting to conceive, and were not receiving fertility treatment. Data on weight at birth were obtained from the Danish Medical Birth Registry and categorized as <2,500 grams, 2,500–2,999 grams, 3,000–3,999 grams, and ≥4,000 grams. In additional analyses, birth weight was categorized according to z-scores for each gestational week at birth. Time-to-pregnancy measured in cycles was used to compute fecundability ratios (FR) and 95% confidence intervals (CI), using a proportional probabilities regression model. Results Relative to women with a birth weight of 3,000–3,999 grams, FRs adjusted for gestational age, year of birth, and maternal socio-demographic and medical factors were 0.99 (95% CI: 0.73;1.34), 0.99 (95% CI: 0.87;1.12), and 1.08 (95% CI: 0.94;1.24) for birth weight <2,500 grams, 2,500–2,999 grams, and ≥4,000 grams, respectively. Estimates remained unchanged after further adjustment for markers of the participant's mother's fecundability. We obtained similar results when we restricted to women who were born at term, and to women who had attempted to conceive for a maximum of 6 cycles before study entry. Results remained similar when we estimated FRs according to z-scores of birth weight. Conclusion Our results indicate that birth weight appears not to be an important determinant of fecundability.
"Is there nothing more practical than a good theory?": Why innovations and advances in health behavior change will arise if interventions are used to test and refine theory
Alexander J Rothman
International Journal of Behavioral Nutrition and Physical Activity , 2004, DOI: 10.1186/1479-5868-1-11
Abstract: Even with the dramatic advances in our understanding of the biological processes that determine health and illness, it has never been more clear that rates of disease morbidity and premature mortality reflect people's behavioral practices. [1] The benefits, both for individuals and the societies in which they live, that would come from systematic improvements in diet, physical activity, and use of substances such as tobacco, alcohol, and illicit drugs are tantalizing and provide ample motivation to develop initiatives to elicit changes in health behavior. Yet, health behavior change has proven a worthy adversary. Despite the commitment of considerable time and effort, innovations and advances in our ability to improve health behaviors have been modest. In particular, the specification of methods that produce sustained improvements in behavior have been elusive [2-5]. At the same time, innovations in theories of health behavior have also been modest. Investigators continue to advocate for a broad range of theories and there has been limited progress in demonstrating the unique value of any specific theory. [6-8]Although there may be consensus in the professional community that there are considerable gaps in our understanding of health behavior change, critiques of the current state of affairs more often that not reflect the professional interests of the critic. Investigators who strive to specify the structural and psychological processes that regulate people's behavior lament the fact that too many interventions are not guided by a theoretical framework that specifies how they are supposed to elicit health behavior change. At the same time, investigators who design and implement health behavior interventions lament that the preponderance of theories of health behavior make it difficult to discern what factors are likely to be the most effective targets for intervention. Moreover, it is argued that theories are not sufficiently specified to determine when or how to m
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