Kenneth J Rothman's research while affiliated with RTI Health Solutions and other places

Publications (616)

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Background: Little is known about potential health effects of eating organic food in relation to reproduction. Objective: We examined associations between organic food consumption and fecundability. Methods: Data were derived from a preconception cohort study of Danish couples trying to conceive (SnartForaeldre.dk, SF). Participants completed...
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Background Spontaneous abortion, pregnancy loss before the 20th week, has adverse psychological and physical sequelae. Some medical conditions with conditions known to affect insulin sensitivity, including polycystic ovary syndrome and diabetes, may affect risk of spontaneous abortion. No prior studies have examined glycemic load and incidence of s...
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Purpose Evidence on the influence of modifiable risk factors on spontaneous abortion (SAB) is scarce. We investigated associations for adherence to national dietary guidelines and a healthy Nordic diet with first-trimester (≤ 12 weeks’ gestation) SAB in a Danish cohort of couples trying to conceive. Methods Participants completed a questionnaire o...
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Background: Psychological stress is prevalent among reproductive-aged men. Assessment of semen quality for epidemiological studies is challenging as data collection is expensive and cumbersome, and studies evaluating the effect of perceived stress on semen quality are inconsistent. Objective: To examine the association between perceived stress a...
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Background Refusal to participate in studies related to sexual health can compromise the internal and external validity of findings. Research examining non-response to sexual health studies has primarily focused on predictors such as specific sexual attitudes and behaviors. Aim Evaluate predictors of non-response to a supplemental sexual health su...
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Purpose Diet quality is increasingly recognized as important for human reproductive capacity. We studied the association between intake of protein-rich foods and risk of spontaneous abortion (SAB). Methods During 2013–2020, we recruited pregnancy planners from the United States and Canada (Pregnancy Study Online; PRESTO) and Denmark (SnartForaeldr...
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Background Italy was the first country after China to be severely affected by the COVID-19 pandemic, in early 2020. The country responded swiftly to the outbreak with a nationwide two-step lockdown, the first one light, and the second one tight. By analysing 2020 national mobile phone movements, we assessed how lockdown compliance influenced its ef...
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Background: Several studies indicate adverse effects of selected heat exposures on semen quality, but few studies have directly evaluated fertility as an endpoint. Objective: We evaluated prospectively the association between male heat exposures and fecundability, the per-cycle probability of conception. Materials & methods: We analyzed data f...
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Background Reports of perforation risk related to intrauterine devices (IUDs) inserted immediately post partum and among non-post-partum individuals are scarce, and previous studies with only 12-month follow-ups underestimate the risk. Breastfeeding at IUD insertion and insertion within 36 weeks post partum have been associated with increased risk...
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Background Prospectively collected, routine clinical practice-based data on antithrombotic therapy in non-valvular atrial fibrillation (AF) patients are important for assessing real-world comparative outcomes. The objective was to compare the safety and effectiveness of dabigatran versus vitamin K antagonists (VKAs) in patients with newly diagnosed...
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(Abstracted from Hum Reprod 2022;37(4):828–837) Folate is an antioxidant micronutrient present in many vegetables, fruits, whole grains, beans, and the liver. Its synthetic counterpart, folic acid, is used as a dietary supplement for fortification of wheat and other foods.
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Studies about sexual health require accurate information on sexual behaviours, yet there is no gold standard for assessing sexual behaviour. Concordance of partner reports is one way to estimate the reliability and, indirectly, the validity of such data. We aimed to evaluate the inter-partner concordance of self-reported intercourse frequency among...
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In this article, the name of the GLORIA-AF investigator Anastasios Kollias was given incorrectly as Athanasios Kollias in the Acknowledgements. The original article has been corrected.
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Background Accurate estimates of risks of poststroke outcomes from large population–based studies can provide a basis for public health policy decisions. We examined the absolute and relative risks of a spectrum of incident mental disorders following ischemic stroke and intracerebral hemorrhage. Methods During 2004 to 2018, we used Danish registri...
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Background and purpose: Prospectively collected data comparing the safety and effectiveness of individual non-vitamin K antagonists (NOACs) are lacking. Our objective was to directly compare the effectiveness and safety of NOACs in patients with newly diagnosed atrial fibrillation (AF). Methods: In GLORIA-AF, a large, prospective, global registr...
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Purpose: We examined the effect of olodaterol on the risk of myocardial ischaemia, cardiac arrhythmia, and all-cause mortality compared with use of other long-acting beta2-agonists (LABAs). Channelling bias was also explored. Methods: This Danish population-based cohort study used data linked from registries of hospital diagnoses, outpatient dis...
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Background: Up to 30% of pregnancies end in spontaneous abortion, yet few risk factors have been identified. Examining seasonal patterns in risk of spontaneous abortion can generate new hypotheses regarding environmental and lifestyle determinants. Methods: We used data from Pregnancy Study Online (PRESTO), a preconception cohort study of pregna...
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Purpose To evaluate the relationships among history of asthma, asthma severity, and spontaneous abortion (SAB). Methods Pregnancy Study Online (PRESTO) is a preconception cohort study of North American couples. During the preconception period, female participants reported their history of physician-diagnosed asthma, age at first diagnosis, and use...
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We examined the associations of male depression and psychotropic medication use with fecundability in a North American preconception cohort study (2013–2020). Men aged ≥21 years completed a baseline questionnaire with questions on history of diagnosed depression, the Major Depression Inventory (MDI), and psychotropic medication use. Pregnancy statu...
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Study question: To what extent is dietary folate intake and total folate intake (dietary and supplemental intakes) associated with fecundability, the per cycle probability of conception? Summary answer: Preconception dietary folate intake was positively associated with fecundability in a monotonic pattern. What is known already: Supplemental f...
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Some reproductive-aged individuals remain unvaccinated against COVID-19 due to concerns about potential adverse effects on fertility. We examined the associations of COVID-19 vaccination and SARS-CoV-2 infection with fertility among couples trying to conceive spontaneously using data from an internet-based preconception cohort study. We enrolled 2,...
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Background Animal and epidemiologic studies indicate that air pollution may adversely affect fertility. Epidemiologic studies have been restricted largely to couples undergoing fertility treatment or have retrospectively ascertained time-to-pregnancy among pregnant women. Objectives We examined the association between residential ambient air pollu...
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Purpose: Evidence is insufficient to infer whether topical calcineurin inhibitors (TCIs; tacrolimus and pimecrolimus) cause malignancy. The study objective was to estimate the long-term risk of skin cancer and lymphoma associated with topical TCI use in adults and children, separately. Patients and methods: A cohort study in Denmark, Sweden, UK,...
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Background and Objectives To examine risks of stroke recurrence and mortality after first and recurrent stroke. Methods Using Danish nationwide health registries, we included patients (age ≥18 years) with first-time ischemic stroke (N = 105,397) or intracerebral hemorrhage (N = 13,350) during 2004–2018. Accounting for the competing risk of death,...
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Background The relation between the magnitude of successive waves of the COVID-19 outbreak within the same communities could be useful in predicting the scope of new outbreaks. Methods We investigated the extent to which COVID-19 mortality in Italy during the second wave was related to first wave mortality within the same provinces. We compared da...
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The role of occupational stress on male fertility is understudied. We examined associations between male occupational stress and fecundability. We used data from Pregnancy Study Online (PRESTO), a North American preconception cohort study. At baseline (2013-2019), male participants aged ≥ 21 years completed a baseline questionnaire on employment st...
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Background Prescribing patterns for stroke prevention in atrial fibrillation (AF) patients evolved with approval of non-Vitamin K antagonist oral anticoagulants (NOACs) over time. Objectives To assess changes in anticoagulant prescription patterns in various geographical regions upon first approval of a NOAC and to analyze the evolution of oral an...
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Objectives Previous studies suggest a beneficial effect of supplemental folic acid use and dietary folate intake on fertility, while results for fetal loss are conflicting. Most previous research on fetal loss focused on folic acid supplement use. We therefore, investigated the association between dietary folate intake and spontaneous abortion (SAB...
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Background Prospective data on nonvitamin-K-antagonist oral anticoagulant (NOAC) management during cardiovascular interventions are limited. We therefore evaluated the safety and effectiveness of uninterrupted dabigatran therapy as well as dabigatran management during atrial fibrillation (AF)-cardioversions, AF-ablations, pacemaker implantations an...
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Purpose This post-authorisation safety study estimated the risk of anaphylaxis in patients receiving intravenous (IV) iron in Europe, with interest in iron dextran and iron non-dextrans. Studies conducted in the United States have reported risk of anaphylaxis to intravenous iron ranging from 2.0 to 6.8 per 10 000 first treatments. Methods Cohort s...
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Background: The accuracy of birth outcome data provided by Internet-based cohort study participants has not been well studied. Methods: We compared self-reported data on birth characteristics in Pregnancy Study Online (PRESTO), an Internet-based prospective cohort study of North American pregnancy planners, with birth certificate data. At enrolm...
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Objective To evaluate the associations of a history of diagnosed depression, current depressive symptoms, and recent use of psychotropic medications with semen quality and to consider mediation of the association between depression and semen quality by medication use. Design Prospective cohort study. Setting United States. Patient(s) The patient...
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Accumulating evidence from both experimental and nonexperimental human studies in the last 15 years indicates that exposure to high levels of the trace element selenium increases the risk of type 2 diabetes. However, the relation of dose to effect is not well understood because randomized controlled trials used only one dose (200 μg/day) of seleniu...
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Study question: Do daughters of older mothers have lower fecundability? Summary answer: In this cohort study of North American pregnancy planners, there was virtually no association between maternal age ≥35 years and daughters' fecundability. What is known already: Despite suggestive evidence that daughters of older mothers may have lower fert...
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Background Patients with AF often have multimorbidity (the presence of ≥2 concomitant chronic conditions). Objective To describe baseline characteristics, patterns of antithrombotic therapy, and factors associated with oral anticoagulant (OAC) prescription in patients with AF and ≥2 concomitant, chronic, comorbid conditions. Methods Phase III of...
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Study question: Is a history of periodontitis among women associated with reduced fecundability? Summary answer: A history of periodontitis, as assessed by three different self-reported measures, may be associated with reduced fecundability. What is known already: Periodontitis is a chronic inflammatory condition affecting the hard and soft ti...
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Purpose: To use medical record adjudication and predictive modeling methods to develop and validate an algorithm to identify anaphylaxis among adults with type 2 diabetes (T2D) in administrative claims. Methods: A conventional screening algorithm that prioritized sensitivity to identify potential anaphylaxis cases was developed and consisted of...
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We assessed the relation between Covid-19 waves in Italy, which was severely affected during the pandemic. We evaluated the hypothesis that a larger impact from the first wave (February-March 2020) predicts a smaller peak during the second wave (September-October), in the absence of local changes in public health interventions and area-specific dif...
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To extend previous simulations on the performance of propensity score (PS) weighting and trimming methods to settings without and with unmeasured confounding, Poisson outcomes, and various strengths of treatment prediction (PS c-statistic), we simulated studies with a binary intended treatment T as a function of 4 measured covariates. We mimicked t...
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Study question: To what extent is exposure to cellular telephones associated with male fertility? Summary answer: Overall, we found little association between carrying a cell phone in the front pants pocket and male fertility, although among leaner men (BMI <25 kg/m2), carrying a cell phone in the front pants pocket was associated with lower fec...
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Objective: To investigate the extent to which the incidence and mortality of a first-time stroke among younger and older adults changed from 2005 to 2018 in Denmark using nationwide registries. Methods: We used the Danish Stroke Registry and the Danish National Patient Registry to identify patients aged 18-49 years (younger adults) and those age...
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Objective Anticoagulation management in patients with atrial fibrillation (AF) and impaired renal function is challenging. This study aimed to evaluate anticoagulation prescription patterns in relation to renal function and to describe 2-year clinical outcomes among dabigatran users. Methods Global Registry on Long-Term Oral Antithrombotic Treatmen...
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Background: Inverse probability of treatment weighting (IPTW) may be biased by influential observations, which can occur from misclassification of strong exposure predictors. Methods: We evaluated bias and precision of IPTW estimators in the presence of a misclassified confounder and assessed the effect of propensity score (PS) trimming. We gene...
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Confounding can cause substantial bias in nonexperimental studies that aim to estimate causal effects. Propensity score methods allow researchers to reduce bias from measured confounding by summarizing the distributions of many measured confounders in a single score based on the probability of receiving treatment. This score can then be used to mit...
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Objective To evaluate the association between pregravid use of a variety of contraceptive methods and subsequent fecundability. Design Prospective cohort study. Setting Denmark and North America, 2007-19. Participants 17 954 women who had tried to conceive for up to six menstrual cycles at study entry. At baseline, participants reported their co...
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Emerging evidence from animal and human studies indicates that exposure to traffic-related air pollution may adversely affect fertility. Methods: Among 7,342 female pregnancy planners from the United States and 1,448 from Canada, we examined the association between residential proximity to major roads and fecundability, the per-cycle probability...
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Background: Male marijuana use has increased steadily over the last decade, but its effect on risk of spontaneous abortion to our knowledge has not been studied. Methods: We analyzed data from Pregnancy Study Online (PRESTO), a North American prospective cohort study of pregnancy planners (2013-2019). During the preconception period, male and fe...
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After the appearance of COVID-19 in China last December 2019, Italy was the first European country to be severely affected by the outbreak. The first diagnosis in Italy was on February 20, 2020, followed by the establishment of a light and a tight lockdown on February 23 and on March 8, 2020, respectively. The virus spread rapidly, particularly in...
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Study question: To what extent does the use of mobile computing apps to track the menstrual cycle and the fertile window influence fecundability among women trying to conceive? Summary answer: After adjusting for potential confounders, use of any of several different apps was associated with increased fecundability ranging from 12% to 20% per cy...
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Purpose Evaluate the association between psychotropic medication use during pregnancy and gestational age at delivery, after adjusting for depressive symptom and perceived stress severity. Methods We analyzed data on singleton live births from 2,914 female PRESTO participants, aged 21-45, with a reported conception from 6/2013-6/2018. Women report...
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Background: Seafood is an important source of omega-3 fatty acids, which have been associated with improved oocyte quality and embryo morphology in some studies. However, seafood is also a source of persistent organic pollutants and heavy metals, which may adversely affect fecundity. Previous studies of seafood intake and fecundity have generated...
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Background: Little is known about the influence of the post-partum interval-defined as the time between giving birth and attempting to conceive again-on subsequent fecundability. Objectives: We evaluated the association between the post-partum interval and fecundability in Pregnancy Study Online (PRESTO), a web-based prospective preconception co...
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P values are often taken to be something they are not, a probability measure regarding the truth of the null hypothesis. P values work well if we interpret them as an index of compatibility between the data and a spectrum of parameter values, as graphed in the P value function. But the proclivity to degrade P values into dichotomous bins correspond...
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Aims This study aimed to describe baseline characteristics of patients with atrial fibrillation (AF) at risk of stroke with and without history of heart failure (HF) and report 2‐year outcomes in the dabigatran‐treated subset of a prospective, global, observational study (GLORIA‐AF). Methods and results Newly diagnosed patients with AF and CHA2DS2...
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Background Italy's severe COVID-19 outbreak was addressed by a lockdown that gradually increased in space, time and intensity. The effectiveness of the lockdown has not been precisely assessed with respect to the intensity of mobility restriction and the time until the outbreak receded. Methods We used processed mobile phone tracking data to measu...
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Purpose To evaluate socioeconomic determinants of fecundability. Methods Among 8,654 female pregnancy planners from Pregnancy Study Online, a North American prospective cohort study (2013-2019), we examined associations between socioeconomic status and fecundability (the per-cycle probability of conception). Information on income and education was...
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Background: We aimed to assess the extent to which drug persistence is better with non-vitamin K antagonist oral anticoagulants (NOACs) than vitamin K antagonists (VKAs) in atrial fibrillation (AF) patients and to estimate the difference in therapy persistence depending on NOAC dosing regimen (once daily (QD) vs. twice daily (BID)). Methods: Consec...
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Pain reliever use has been associated with both lower and higher risks of adverse reproductive outcomes in animals. The sole investigation of male pain reliever use and fertility in humans reported a 35% reduction in fecundability among men with urinary acetaminophen concentrations in the highest (>73.5 ng/ml) vs. lowest (<5.4 ng/ml) quartile. We a...
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Purpose: Asthma has been positively associated with irregular menses and infertility in some studies, but data are limited on the relation between asthma medication use and fecundability (i.e., average per-cycle probability of conception among non-contracepting couples). This study examines the extent to which a history of asthma, asthma medicatio...
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Intake of conventionally-grown fruits and vegetables with higher levels of pesticide residue contamination has been associated with poorer semen quality and lower probability of live birth among couples undergoing fertility treatment. We examined the association between dietary intake of pesticide residues and fecundability, the per cycle probabili...
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Following the outbreak of Severe Acute Respiratory Syndrome CoronaVirus 2 (SARS-CoV-2) last December 2019 in China, Italy was the first European country to be severely affected, with the first local case diagnosed on 20 February 2020. The virus spread quickly, particularly in the North of Italy, with three regions (Lombardy, Veneto and Emilia-Romag...
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Background: The extent to which couples change their behaviors with increasing pregnancy attempt time is not well documented. Methods: We examined change in selected behaviors over pregnancy attempt time in a North American preconception cohort study. Eligible females were aged 21-45 years and not using fertility treatment. Participants complete...
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To the Editor We disagree with the analysis and interpretation of the findings presented by Dr O’Brien and colleagues.¹ The increased risk of ovarian cancer in women with intact genital tracts exposed to powder (HR, 1.13) is actually greater than the estimated 10% increased incidence of ovarian cancer attributable to cumulative talc exposure with 1...
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Although e-cigarette aerosol contains similar toxicants to combustible cigarettes, few studies have examined the association between e-cigarettes and fecundability. We assessed the association between e-cigarettes and fecundability, overall and by combustible cigarette smoking history, in a cohort of 4,586 North American women (21-45 years) enrolle...