Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 20
Filtrar
1.
Emerg Infect Dis ; 30(2): 245-254, 2024 02.
Artigo em Inglês | MEDLINE | ID: mdl-38270128

RESUMO

During January-August 2021, the Community Prevalence of SARS-CoV-2 Study used time/location sampling to recruit a cross-sectional, population-based cohort to estimate SARS-CoV-2 seroprevalence and nasal swab sample PCR positivity across 15 US communities. Survey-weighted estimates of SARS-CoV-2 infection and vaccine willingness among participants at each site were compared within demographic groups by using linear regression models with inverse variance weighting. Among 22,284 persons >2 months of age and older, median prevalence of infection (prior, active, or both) was 12.9% across sites and similar across age groups. Within each site, average prevalence of infection was 3 percentage points higher for Black than White persons and average vaccine willingness was 10 percentage points lower for Black than White persons and 7 percentage points lower for Black persons than for persons in other racial groups. The higher prevalence of SARS-CoV-2 infection among groups with lower vaccine willingness highlights the disparate effect of COVID-19 and its complications.


Assuntos
COVID-19 , Vacinas , Adulto , Criança , Humanos , COVID-19/epidemiologia , SARS-CoV-2 , Estudos Transversais , Prevalência , Estudos Soroepidemiológicos
2.
Epidemiology ; 35(3): 389-397, 2024 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-38079239

RESUMO

BACKGROUND: COVID-19 has placed a disproportionate burden on underserved racial and ethnic groups, community members working in essential industries, those living in areas of high population density, and those reliant on in-person services such as transportation. The goal of this study was to estimate the cross-sectional prevalence of SARS-CoV-2 (active SARS-CoV-2 or prior SARS-CoV-2 infection) in children and adults attending public venues in 15 sociodemographically diverse communities in the United States and to develop a statistical design that could be rigorously implemented amidst unpredictable stay-at-home COVID-19 guidelines. METHODS: We used time-location sampling with complex sampling involving stratification, clustering of units, and unequal probabilities of selection to recruit individuals from selected communities. We safely conducted informed consent, specimen collection, and face-to-face interviews outside of public venues immediately following recruitment. RESULTS: We developed an innovative sampling design that adapted to constraints such as closure of venues, changing infection hotspots, and uncertain policies. We updated both the sampling frame and the selection probabilities over time using information acquired from prior weeks. We created site-specific survey weights that adjusted sampling probabilities for nonresponse and calibrated to county-level margins on age and sex at birth. CONCLUSIONS: Although the study itself was specific to COVID-19, the strategies presented in this article could serve as a case study that can be adapted for performing population-level inferences in similar settings and could help inform rapid and effective responses to future global public health challenges.


Assuntos
COVID-19 , SARS-CoV-2 , Adulto , Criança , Recém-Nascido , Humanos , Estados Unidos/epidemiologia , COVID-19/epidemiologia , Estudos Transversais , Manejo de Espécimes , Inquéritos e Questionários
3.
PLoS Med ; 19(9): e1004097, 2022 09.
Artigo em Inglês | MEDLINE | ID: mdl-36095005

RESUMO

BACKGROUND: In sub-Saharan Africa (SSA), adolescent girls and young women (AGYW) ages 15 to 24 years represent <10% of the population yet account for 1 in 5 new HIV infections. Although oral pre-exposure prophylaxis (PrEP) with tenofovir disoproxil fumarate/emtricitabine (TDF/FTC) can be highly effective, low persistence in PrEP programs and poor adherence have limited its ability to reduce HIV incidence among women. METHODS AND FINDINGS: A total of 336 AGYW participating in the PEPFAR-funded DREAMS PrEP program in western Kenya were enrolled into a study of PrEP use conducted between 6/2019 to 1/2020. AGYW, who used daily oral TDF/FTC, completed interviews and provided dried blood spots (DBS) for measurement of tenofovir-diphosphate (TFV-DP) concentrations at enrollment and 3 months later, and 176/302 (58.3%, 95% confidence interval [95% CI 52.3 to 63.8]) met our definition of PrEP persistence: having expressed intention to use PrEP and attended both the second interview and an interim refill visit. Among AGYW with DBS taken at the second interview, only 9/197 (4.6%, [95% CI 1.6 to 7.5]) had protective TFV-DP levels (≥700 fmol/punch) and 163/197 (82.7%, [95% CI 77.5 to 88]) had levels consistent with no recent PrEP use (<10 fmol/punch). Perception of being at moderate-to-high risk for HIV if not taking PrEP was associated with persistence (adjusted odds ratio, 10.17 [95% CI 5.14 to 20.13], p < 0.001) in a model accounting for county of residence and variables that had p-value <0.1 in unadjusted analysis (age, being in school, initiated PrEP 2 to 3 months before the first interview, still active in DREAMS, having children, having multiple sex partners, partner aware of PrEP use, partner very supportive of PrEP use, partner has other partners, AGYW believes that a partner puts her at risk, male condom use, injectable contraceptive use, and implant contraceptive use). Among AGYW who reported continuing PrEP, >90% indicated they were using PrEP to prevent HIV, although almost all had non-protective TFV-DP levels. Limitations included short study duration and inclusion of only DREAMS participants. CONCLUSIONS: Many AGYW persisted in the PrEP program without taking PrEP frequently enough to receive benefit. Notably, AGYW who persisted had a higher self-perceived risk of HIV infection. These AGYW may be optimal candidates for long-acting PrEP.


Assuntos
Fármacos Anti-HIV , Infecções por HIV , Profilaxia Pré-Exposição , Adenina/análogos & derivados , Adolescente , Adulto , Fármacos Anti-HIV/uso terapêutico , Criança , Anticoncepcionais/uso terapêutico , Difosfatos/uso terapêutico , Emtricitabina/uso terapêutico , Feminino , Infecções por HIV/epidemiologia , Infecções por HIV/prevenção & controle , Humanos , Lactente , Quênia/epidemiologia , Masculino , Adesão à Medicação , Organofosfatos , Profilaxia Pré-Exposição/métodos , Estudos Prospectivos , Tenofovir/uso terapêutico , Adulto Jovem
4.
Epigenetics ; 17(13): 2082-2095, 2022 12.
Artigo em Inglês | MEDLINE | ID: mdl-35938852

RESUMO

Postmenopausal women with overweight or obesity have an increased risk of developing breast cancer but many of the mechanisms underlying this association remain to be elucidated. MicroRNAs (miRNAs), short non-coding single-stranded RNAs, regulate many physiological processes by controlling post-transcriptional regulation of mRNA. We measured circulating miRNA from 192 overweight/obese postmenopausal women (50-75 years) who were part of a randomized controlled trial, comparing independent and combined effects of a 12-month reduced-calorie weight-loss diet and exercise programme, versus control. RNA was extracted from stored plasma samples, and 23 a priori selected miRNA targets related to aetiology of breast cancer or obesity were measured using NanoString nCounter miRNA Expression assays. Changes from baseline to 12-months between controls and women in the diet/exercise weight loss arms were analysed using generalized estimating equations modification of linear regression, adjusted for confounders. We next examined changes in levels of circulating miRNA by amount of weight loss (0-10% versus ≥10%). Participants randomized to weight-loss interventions had statistically significantly greater reductions in miR-122 (-7.25%), compared to controls (+ 33.5%, P = 0.009), and miR-122 levels were statistically significantly correlated with weight loss (rho = 0.24; P = 0.001) Increasing weight loss was associated with greater reductions in miR-122 vs. controls (-11.7% (≥10% weight loss); +2.0% (0-10% weight loss) +33.5% (controls); Ptrend = 0.006), though this was not significant after correction for multiple testing (P = 0.05/23) Our study supports the effect of weight loss on regulation of miRNA.


Assuntos
Neoplasias da Mama , MicroRNA Circulante , MicroRNAs , Humanos , Feminino , Sobrepeso/complicações , Sobrepeso/genética , Pós-Menopausa , Neoplasias da Mama/genética , Metilação de DNA , Redução de Peso/genética , Obesidade/complicações , Obesidade/genética , MicroRNAs/genética
5.
Epigenetics ; 17(10): 1070-1079, 2022 10.
Artigo em Inglês | MEDLINE | ID: mdl-34550860

RESUMO

Physical activity reduces risk of colon cancer by 20-30%. Aberrant methylation patterns are common epigenetic alterations in colorectal adenomas, and cancers and play a role in cancer initiation and progression. Alterations identified in normal colon tissue represent apotential 'field cancerization' process, where normal colon is primed for carcinogenesis. Here, we investigate methylation patterns in three genes -Ena/VASP-like (EVL), (CDKN2A (p14, ARF)), and Oestrogen Receptor-1 (ESR1)- in normal colon tissue collected at baseline and 12 months from 202 sedentary men and women, 40-75 years, enrolled in a randomized controlled trial testing an exercise intervention vs. control (http://clinicaltrials.gov/show/NCT00668161). Participants were randomized to moderate-to-vigorous intensity exercise, 60 minutes/day, 6 days/week for 12 months, or usual lifestyle. Sigmoid colon biopsies were obtained at baseline and 12-months, DNA extracted, and bisulphite converted. Droplet digital methylation-specific PCR was performed for EVL, p14ARF, and ESR1. Generalized estimating equations modification of linear regression was used to model relationships between intervention effects and gene methylation levels, adjusting for possible confounders.There were no statistically significant differences between methylation patterns at 12-months between exercisers and controls. ESR1 methylation patterns differed by sex: women -10.58% (exercisers) +11.10% (controls); men +5.54% (exercisers), -8.16% (controls) (P=0.05), adjusting for BMI and age. There were no statistically significant changes in methylation patterns in any gene stratified by change in VO2max or minutes/week of exercise.While no statistically significant differences were found in gene methylation patterns comparing exercises vs. controls, 12-month exercise effects on ESR1 methylation differed by sex, warranting further study.


Assuntos
Moléculas de Adesão Celular , Colo , Inibidor p16 de Quinase Dependente de Ciclina , Metilação de DNA , Receptor alfa de Estrogênio , Exercício Físico , Moléculas de Adesão Celular/genética , Colo/metabolismo , Neoplasias Colorretais/genética , Inibidor p16 de Quinase Dependente de Ciclina/genética , Receptor alfa de Estrogênio/genética , Feminino , Humanos , Masculino , Proteína Supressora de Tumor p14ARF/genética
6.
Cancer Prev Res (Phila) ; 14(1): 85-94, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-32859616

RESUMO

Dietary composition can influence systemic inflammation; higher levels of circulating inflammatory biomarkers are associated with increased risk of breast and other cancers. A total of 438 overweight/obese, healthy, postmenopausal women were randomized to a caloric-restriction diet (goal: 10% weight-loss), aerobic-exercise (225 min/week moderate-to-vigorous activity), combined diet+exercise, or control. Dietary inflammatory index (DII) and energy-adjusted (E-DII) scores were derived from food frequency questionnaires (FFQ) and could be calculated for 365 participants with complete FFQs at baseline and 12 months. Changes from baseline to 12 months in E-DII scores in the intervention arms versus controls were analyzed using generalized estimating equations, adjusted for confounders. We examined associations between changes in previously measured biomarkers and E-DII at 12 months. Participants randomized to diet and diet+exercise arms had greater reductions in E-DII (-104.4% and -84.4%), versus controls (-34.8%, both P < 0.001). Weight change had a more marked effect than E-DII change on biomarkers at 12-months; associations between E-DII and biomarker changes were reduced after adjustment by weight change. Changes in E-DII at 12 months, adjusted for weight change, were negatively associated with changes in ghrelin [r = -0.19; P = 0.05 (diet), r = -0.29; P = 0.02 (diet+exercise)], and positively with VEGF [r = 0.22; P = 0.03 (diet+exercise)], and red blood cell counts [r = 0.30; P = 0.004 (exercise)]. C-reactive protein (CRP) and IL6 levels were not associated with E-DII changes at 12 months. In conclusion, a behavior change of low-calorie, low-fat diet significantly reduces dietary inflammatory potential, modulating biomarkers that are associated with tumorigenesis, such as VEGF, but not CRP or IL6. PREVENTION RELEVANCE: Diets high in saturated fats and low in fruit and vegetable intake are associated with increased inflammation, which increases cancer risk. This study showed that changes in diet quality had effects on factors associated with cancer; however, the majority of beneficial effects were associated with weight loss rather than diet quality.


Assuntos
Neoplasias/prevenção & controle , Obesidade/terapia , Sobrepeso/terapia , Redução de Peso/imunologia , Idoso , Restrição Calórica , Carcinogênese/imunologia , Inquéritos sobre Dietas/estatística & dados numéricos , Exercício Físico/imunologia , Feminino , Humanos , Inflamação/complicações , Inflamação/diagnóstico , Inflamação/imunologia , Inflamação/terapia , Pessoa de Meia-Idade , Neoplasias/imunologia , Neoplasias/metabolismo , Obesidade/complicações , Obesidade/imunologia , Obesidade/metabolismo , Sobrepeso/complicações , Sobrepeso/imunologia , Sobrepeso/metabolismo , Pós-Menopausa/imunologia
7.
Stat Med ; 39(8): 1167-1182, 2020 04 15.
Artigo em Inglês | MEDLINE | ID: mdl-31997385

RESUMO

In many epidemiological and biomedical studies, the association between a response variable and some covariates of interest may change at one or several thresholds of the covariates. Change-point models are suitable for investigating the relationship between the response and covariates in such situations. We present change-point models, with at least one unknown change-point occurring with respect to some covariates of a generalized linear model for independent or correlated data. We develop methods for the estimation of the model parameters and investigate their finite-sample performances in simulations. We apply the proposed methods to examine the trends in the reported estimates of the annual percentage of new human immunodeficiency virus (HIV) diagnoses linked to HIV-related medical care within 3 months after diagnosis using HIV surveillance data from the HIV prevention trial network 065 study. We also apply our methods to a dataset from the Pima Indian diabetes study to examine the effects of age and body mass index on the risk of being diagnosed with type 2 diabetes.


Assuntos
Diabetes Mellitus Tipo 2 , Infecções por HIV , Índice de Massa Corporal , Diabetes Mellitus Tipo 2/epidemiologia , HIV , Infecções por HIV/epidemiologia , Humanos , Modelos Lineares
8.
Int J Biostat ; 15(2)2019 04 06.
Artigo em Inglês | MEDLINE | ID: mdl-30954972

RESUMO

Many biomedical or epidemiological studies often aim to assess the association between the time to an event of interest and some covariates under the Cox proportional hazards model. However, a problem is that the covariate data routinely involve measurement error, which may be of classical type, Berkson type or a combination of both types. The issue of Cox regression with error-prone covariates has been well-discussed in the statistical literature, which has focused mainly on classical error so far. This paper considers Cox regression analysis when some covariates are possibly contaminated with a mixture of Berkson and classical errors. We propose a simulation extrapolation-based method to address this problem when two replicates of the mismeasured covariates are available along with calibration data for some subjects in a subsample only. The proposed method places no assumption on the mixture percentage. Its finite-sample performance is assessed through a simulation study. It is applied to the analysis of data from an AIDS clinical trial study.


Assuntos
Modelos de Riscos Proporcionais , Bioestatística , Contagem de Linfócito CD4 , Calibragem , Simulação por Computador , Interpretação Estatística de Dados , Infecções por HIV/tratamento farmacológico , Infecções por HIV/imunologia , Humanos , Ensaios Clínicos Controlados Aleatórios como Assunto/estatística & dados numéricos , Análise de Regressão
9.
Menopause ; 26(4): 417-422, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30461557

RESUMO

OBJECTIVE: We tested the effects of weight loss on serum estradiol, estrone, testosterone, and sex hormone-binding globulin (SHBG) in overweight/obese women 18 months after completing a year-long, 4-arm, randomized-controlled dietary weight loss and/or exercise trial. METHODS: From 2005 to 2008, 439 overweight/obese, postmenopausal women (BMI >25 kg/m), 50 to 75 years, were randomized to a year-long intervention: diet (reduced calorie, 10% weight loss, N = 118), exercise (225 min/wk moderate-to-vigorous activity, N = 117), combined diet + exercise (N = 117), or control (N = 87). At 12 months, 399 women provided blood; of these, 156 returned at 30 months and gave a blood sample. Hormones and SHBG were measured by immunoassay. Changes were compared using generalized estimating equations, adjusting for confounders. RESULTS: At 30 months, participants randomized to the diet + exercise intervention had statistically significant increases in SHBG levels versus controls (P = 0.001). There was no statistically significant change in SHBG in the exercise or diet intervention arms. Hormone levels did not vary by intervention arm from baseline to 30 months. Participants who maintained weight loss at 30 months had statistically significantly greater decreases in free estradiol and free testosterone (Ptrend = 0.02 and Ptrend = 0.04, respectively) and increases in SHBG (Ptrend < 0.0001) versus those who did not have sustained weight loss. Levels of other analytes did not vary by weight loss at 30 months. CONCLUSIONS: Sustained weight loss results in reductions in free estradiol and testosterone and increases in SHBG 18-month post-intervention.


Assuntos
Estradiol/sangue , Estrona/sangue , Globulina de Ligação a Hormônio Sexual/análise , Testosterona/sangue , Redução de Peso , Idoso , Dieta Redutora , Exercício Físico , Feminino , Humanos , Pessoa de Meia-Idade , Pós-Menopausa
10.
Cancer Epidemiol Biomarkers Prev ; 27(7): 829-837, 2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-29743162

RESUMO

Background: Accumulating evidence suggests that short telomere length is associated with increased overall mortality, but the relationship with cancer mortality is less clear. We examined whether telomere length (global, and chromosome arm 5p- and 13q-specific) is associated with lung cancer mortality among cases from the ß-Carotene and Retinol Efficacy Trial of heavy smokers.Methods: Telomere length was measured on average 6 years before diagnosis for 788 lung cancer cases. Adjusted Cox proportional hazards models of all-cause and lung cancer-specific mortality were assessed for lung cancer overall and by histotype.Results: Short telomere length was associated with increased mortality for small cell lung cancer (SCLC), particularly stage III/IV SCLC [HR and 95% confidence interval for shortest vs. longest telomere length tertile: 3.32 (1.78-6.21)]. Associations were strongest for those randomized to the active intervention and when telomere length was measured ≤5 years before diagnosis. All-cause mortality patterns were similar. Short chromosome 5p telomere length was suggestively associated with lung cancer mortality, but there was no association with chromosome 13q telomere length.Conclusions: Our large prospective study suggests that among heavy smokers who developed lung cancer, short prediagnosis telomere length is associated with increased risk of death from SCLC.Impact: This is the first study to examine telomere length and mortality in lung cancer cases by histotype. If the association between short telomere length and SCLC mortality is replicated, elucidation of mechanisms through which telomere length influences survival for this highly aggressive cancer may inform more effective use of telomere-targeted therapeutics. Cancer Epidemiol Biomarkers Prev; 27(7); 829-37. ©2018 AACR.


Assuntos
Neoplasias Pulmonares/genética , Fumar/efeitos adversos , Fumar/genética , Telômero/genética , Adulto , Feminino , Humanos , Neoplasias Pulmonares/mortalidade , Masculino , Pessoa de Meia-Idade , Fumar/mortalidade
11.
Cancer Epidemiol Biomarkers Prev ; 26(12): 1788-1794, 2017 12.
Artigo em Inglês | MEDLINE | ID: mdl-29042415

RESUMO

Background: We tested the effect of weight loss on circulating levels of the angiogenic factors VEGF and pigment epithelium-derived factor (PEDF) in postmenopausal overweight/obese women, 18 months after completing a year-long 4-arm randomized controlled trial of behavioral weight loss and/or exercise versus control (i.e., 30 months postrandomization).Methods: The 439 overweight/obese, postmenopausal women, ages 50 to 75 years, were randomized to: diet (goal: 10% weight loss, N = 118), exercise (225 min/wk moderate-to-vigorous activity, N = 117), diet + exercise (N = 117), or control (N = 87). At 12 months, 399 women gave a blood sample; 156 returned at 30 months. Biomarkers were measured by immunoassay. Changes were compared using generalized estimating equations, adjusting for baseline BMI, age, and race/ethnicity.Results: Participants randomized to diet, exercise, and diet + exercise arms had greater reductions in VEGF at 30 months (-14.1% P = 0.02; -19.7% P = 0.003; -14.5% P = 0.002, respectively) versus controls (-4.5%). There were no statistically significant changes in PEDF in any intervention arm. Participants maintaining ≥10% of baseline weight loss at 30 months had greater reductions in VEGF versus those who gained weight/had no weight change (-22.3% vs. -10.2% respectively, P = 0.002). Participants maintaining any weight loss had significantly lower levels of PEDF at 30 months versus those who gained weight/no weight change.Conclusions: Sustained weight loss via diet and/or exercise results in reductions in angiogenic factors, and can be maintained up to 30-month follow-up. Limitations include relatively small numbers, and possible bias toward more successful weight loss among women who returned at 30 months.Impact: Maintaining weight loss can achieve long-term reductions in biomarkers of angiogenesis that can persist up to 18 months after completion of a weight loss intervention. Cancer Epidemiol Biomarkers Prev; 26(12); 1788-94. ©2017 AACR.


Assuntos
Proteínas do Olho/sangue , Fatores de Crescimento Neural/sangue , Obesidade/sangue , Sobrepeso/sangue , Serpinas/sangue , Fator A de Crescimento do Endotélio Vascular/sangue , Redução de Peso , Controle Comportamental/métodos , Biomarcadores/sangue , Dieta Redutora , Terapia por Exercício , Feminino , Humanos , Pessoa de Meia-Idade , Neovascularização Fisiológica , Obesidade/terapia , Sobrepeso/terapia , Pós-Menopausa , Fatores de Tempo
12.
Cancer Prev Res (Phila) ; 9(11): 835-843, 2016 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-27803047

RESUMO

Oxidative stress, a potential mechanism linking obesity and cancer, results from an imbalance between activation/inactivation of reactive oxygen species, byproducts of cellular metabolism. In a randomized controlled trial, we investigated effects of diet and/or exercise on biomarkers of oxidative stress. A total of 439 overweight/obese [body mass index (BMI) > 25 kg/m2] postmenopausal women, ages 50 of 75 years, were randomized to 12 months of (i) reduced-calorie weight loss diet ("diet"; n = 118); (ii) moderate-to-vigorous intensity aerobic exercise ("exercise"; n = 117); (iii) combined diet and exercise intervention ("diet + exercise"; n = 117); or (iv) control (n = 87). Outcomes were circulating markers of oxidative stress, including fluorescent oxidation products (FOP), F2-isoprostanes, and oxidized low-density lipoprotein (LDL). On average, participants were 57.9 years, with a BMI of 30.9 kg/m2 F2-isprostanes were significantly reduced in the diet (-22.7%, P = 0.0002) and diet + exercise (-23.5%, P < 0.0001) arms versus controls (-2.99%) and nonsignificantly reduced in the exercise arm (-14.5%, P = 0.01). Participants randomized to the diet and diet + exercise arms had significant increases in levels of FOP [control -5.81%; diet +14.77% (P = 0.0001); diet + exercise +17.45%, (P = 0.0001)]. In secondary analyses, increasing weight loss was statistically significantly associated with linear trends of greater reductions in oxidized LDL and in F2-isoprostanes and increases in FOP. Compared with controls, exercise participants whose maximal oxygen consumption increased had significant decreases in levels of F2-isoprostanes and in oxidized LDL and increases in FOP. Dietary weight loss, with or without exercise, significantly reduced some markers of oxidative stress in postmenopausal women. Cancer Prev Res; 9(11); 835-43. ©2016 AACR.


Assuntos
Exercício Físico , Estresse Oxidativo , Redução de Peso , Idoso , Dieta Redutora , F2-Isoprostanos/sangue , Feminino , Humanos , Lipoproteínas LDL/sangue , Pessoa de Meia-Idade , Obesidade , Sobrepeso , Pós-Menopausa
13.
Am J Hum Genet ; 99(2): 352-65, 2016 08 04.
Artigo em Inglês | MEDLINE | ID: mdl-27486777

RESUMO

Few gene-environment interactions (G × E) have been discovered in cancer epidemiology thus far, in part due to the large number of possible G × E to be investigated and inherent low statistical power of traditional analytic methods for discovering G × E. We consider simultaneously testing for interactions between several related exposures and a genetic variant in a genome-wide study. To improve power, constrained testing strategies are proposed for multivariate gene-environment interactions at two levels: interactions that have the same direction (one-sided or bidirectional hypotheses) or are proportional to respective exposure main effects (a variant of Tukey's one-degree test). Score statistics were developed to expedite the genome-wide computation. We conducted extensive simulations to evaluate validity and power performance of the proposed statistics, applied them to the genetic and environmental exposure data for esophageal adenocarcinoma and Barrett's esophagus from the Barretts Esophagus and Esophageal Adenocarcinoma Consortium (BEACON), and discovered three loci simultaneously interacting with gastresophageal reflux, obesity, and tobacco smoking with genome-wide significance. These findings deepen understanding of the genetic and environmental architecture of Barrett's esophagus and esophageal adenocarcinoma.


Assuntos
Esôfago de Barrett/genética , Interação Gene-Ambiente , Predisposição Genética para Doença , Variação Genética/genética , Estudo de Associação Genômica Ampla , Adenocarcinoma/genética , Fatores Etários , Neoplasias Esofágicas/genética , Feminino , Refluxo Gastroesofágico/genética , Humanos , Masculino , Modelos Genéticos , Obesidade/genética , Razão de Chances , Polimorfismo de Nucleotídeo Único/genética , Reprodutibilidade dos Testes , Fatores de Risco , Tamanho da Amostra , Fatores Sexuais , Fumar/genética
14.
Cancer Res ; 76(14): 4226-35, 2016 07 15.
Artigo em Inglês | MEDLINE | ID: mdl-27417562

RESUMO

Obese and sedentary persons have an increased risk for cancer, but underlying mechanisms are poorly understood. Angiogenesis is common to adipose tissue formation and remodeling, and to tumor vascularization. A total of 439 overweight/obese, healthy, postmenopausal women [body mass index (BMI) > 25 kg/m(2)] ages 50-75 years, recruited between 2005 and 2008 were randomized to a 4-arm 12-month randomized controlled trial, comparing a caloric restriction diet arm (goal: 10% weight loss, N = 118), aerobic exercise arm (225 minutes/week of moderate-to-vigorous activity, N = 117), a combined diet + exercise arm (N = 117), or control (N = 87) on circulating levels of angiogenic biomarkers. VEGF, plasminogen activator inhibitor-1 (PAI-1), and pigment epithelium-derived factor (PEDF) were measured by immunoassay at baseline and 12 months. Changes were compared using generalized estimating equations, adjusting for baseline BMI, age, and race/ethnicity. Participants randomized to the diet + exercise arms had statistically significantly greater reductions in PAI-1 at 12 months compared with controls (-19.3% vs. +3.48%, respectively, P < 0.0001). Participants randomized to the diet and diet + exercise arms had statistically significantly greater reductions in PEDF (-9.20%, -9.90%, respectively, both P < 0.0001) and VEGF (-8.25%, P = 0.0005; -9.98%, P < 0.0001, respectively) compared with controls. There were no differences in any of the analytes in participants randomized to the exercise arm compared with controls. Increasing weight loss was statistically significantly associated with linear trends of greater reductions in PAI-1, PEDF, and VEGF. Weight loss is significantly associated with reduced circulating VEGF, PEDF, and PAI-1, and could provide incentive for reducing weight as a cancer prevention method in overweight and obese individuals. Cancer Res; 76(14); 4226-35. ©2016 AACR.


Assuntos
Exercício Físico , Proteínas do Olho/sangue , Fatores de Crescimento Neural/sangue , Sobrepeso/terapia , Inibidor 1 de Ativador de Plasminogênio/sangue , Serpinas/sangue , Fator A de Crescimento do Endotélio Vascular/sangue , Redução de Peso , Idoso , Biomarcadores/sangue , Feminino , Humanos , Pessoa de Meia-Idade , Sobrepeso/sangue , Pós-Menopausa
15.
Am J Clin Nutr ; 103(2): 366-74, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26718418

RESUMO

BACKGROUND: Mexican immigrants are disproportionally affected by diet-related risk of metabolic dysfunction. Whether adhering to a traditional Mexican diet or adopting a US diet contributes to metabolic changes associated with future risk of type 2 diabetes and other chronic diseases has not been investigated. OBJECTIVE: The purpose of this study was to test in a randomized crossover feeding trial the metabolic responses to a Mexican diet compared with a commonly consumed US diet. DESIGN: First- and second-generation healthy women of Mexican descent (n = 53) were randomly assigned in a crossover design to consume a Mexican or US diet for 24 d each, separated by a 28-d washout period. Diets were eucaloric and similar in macronutrient composition. The metabolic responses to diets were assessed by measuring fasting serum concentrations of glucose, insulin, insulin-like growth factor 1 (IGF-1), insulin-like growth factor binding protein 3 (IGFBP-3), adiponectin, C-reactive protein (CRP), and interleukin 6 (IL-6), as well as the homeostasis model assessment of insulin resistance (HOMA-IR) at the beginning and end of each period. Linear mixed models tested the intervention effect on the biomarkers, while adjusting for diet sequence, feeding period, baseline and washout biomarker concentrations, age, acculturation, and BMI. RESULTS: Compared with the US diet, the Mexican diet reduced insulin by 14% [geometric means (95% CIs): 9.3 (8.3, 10.3) compared with 8.0 (7.2, 8.9) µU/mL; P = 0.02], HOMA-IR by 15% [2.0 (1.8, 2.3) compared with 1.7 (1.6, 2.0); P = 0.02], and IGFBP-3 by 6% (mean ± SEM: 2420 ± 29 compared with 2299 ± 29 ng/mL; P < 0.01) and tended to reduce circulating concentrations of IGF-1 by 4% (149 ± 2.6 compared with 144 ± 2.5 ng/mL; P = 0.06). There was no significant intervention effect on serum concentrations of glucose, adiponectin, CRP, or IL-6 in the US compared with the Mexican diet. CONCLUSION: Compared with the commonly consumed US diet, the traditional Mexican diet modestly improved insulin sensitivity under conditions of weight stability in healthy women of Mexican descent, while having no impact on biomarkers of inflammation. This trial was registered at clinicaltrials.gov as NCT01369173.


Assuntos
Aculturação , Diabetes Mellitus Tipo 2/etiologia , Dieta Ocidental/efeitos adversos , Dieta/efeitos adversos , Resistência à Insulina , Adolescente , Adulto , Biomarcadores/sangue , Estudos Cross-Over , Diabetes Mellitus Tipo 2/epidemiologia , Diabetes Mellitus Tipo 2/etnologia , Diabetes Mellitus Tipo 2/metabolismo , Dieta/etnologia , Dieta Ocidental/etnologia , Emigrantes e Imigrantes , Ingestão de Energia , Feminino , Humanos , Mediadores da Inflamação/sangue , Modelos Lineares , Americanos Mexicanos , Risco , Estados Unidos/epidemiologia , Adulto Jovem
16.
Stat Med ; 35(10): 1676-88, 2016 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-26593772

RESUMO

In many biomedical studies, covariates of interest may be measured with errors. However, frequently in a regression analysis, the quantiles of the exposure variable are often used as the covariates in the regression analysis. Because of measurement errors in the continuous exposure variable, there could be misclassification in the quantiles for the exposure variable. Misclassification in the quantiles could lead to bias estimation in the association between the exposure variable and the outcome variable. Adjustment for misclassification will be challenging when the gold standard variables are not available. In this paper, we develop two regression calibration estimators to reduce bias in effect estimation. The first estimator is normal likelihood-based. The second estimator is linearization-based, and it provides a simple and practical correction. Finite sample performance is examined via a simulation study. We apply the methods to a four-arm randomized clinical trial that tested exercise and weight loss interventions in women aged 50-75 years.


Assuntos
Modelos Lineares , Idoso , Viés , Calibragem , Simulação por Computador , Feminino , Humanos , Pessoa de Meia-Idade , Ensaios Clínicos Controlados Aleatórios como Assunto , Projetos de Pesquisa , Redução de Peso
17.
PLoS One ; 9(10): e110348, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25333822

RESUMO

Incidence of esophageal adenocarcinoma (EAC) has increased sharply in Western Europe and United States over the past three decades. Nearly all cases of EAC in the west are thought to be associated with Barrett's esophagus (BE) at the time of diagnosis. Regions in the Henan province of China have one of world's highest incidences of esophageal cancer, yet recent temporal trends in the relative rates of EAC with respect to esophageal squamous-cell carcinoma (ESCC), as well as its association with Barrett's esophagus (BE), have not been reported. In this report, we present large-scale longitudinal clinical and histological data on 5401 esophageal cancers (EC) patients diagnosed during the recent 10-year period (2002-2011) at Henan Cancer Hospital, China. All 217 esophageal adenocarcinoma (EAC) patients from these 5401 EC patients were examined to better understand the relationship between Barrett's esophagus (BE) and EAC. We found that EAC was relatively rare and accounted for approximately 5% of all esophageal cancers each year during 2002-2011. There is no evidence of significant temporal trends in the rate of EAC relative to ESCC. Only 10 out of 217 (4.6%) EAC cases were detected to have any evidence of Barrett's esophagus. This result raises the possibility of a different etiological basis for EAC in China motivating more detailed epidemiological, clinical and molecular characterization of EAC in China in order to better understand the neoplastic development of EAC.


Assuntos
Adenocarcinoma/epidemiologia , Esôfago de Barrett/epidemiologia , Carcinoma de Células Escamosas/epidemiologia , Neoplasias Esofágicas/epidemiologia , Adulto , Idoso , China/epidemiologia , Carcinoma de Células Escamosas do Esôfago , Feminino , Humanos , Incidência , Masculino , Pessoa de Meia-Idade
18.
Am J Epidemiol ; 179(10): 1264-72, 2014 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-24723002

RESUMO

Secondary trait genetic association provides insight into the genetic architecture of disease etiology but requires caution in estimation. Ignoring case-control sampling may introduce bias into secondary trait association. In this paper, we compare the efficiency and robustness of various inverse probability weighted (IPW) estimators and maximum likelihood (ML) estimators. ML methods have been proposed but require correct modeling of both the secondary and the primary trait associations for valid inference. We show that ML methods using a misspecified primary trait model can severely inflate the type I error. IPW estimators are typically less efficient than ML estimators but are robust against model misspecification. When the secondary trait is available for the entire cohort, the IPW estimator with selection probabilities estimated nonparametrically and the augmented IPW estimator improve efficiency over the simple IPW estimator. We conclude that in large genetic association studies with complex sampling schemes, IPW-based estimators offer flexibility and robustness, and therefore are a viable option for analysis.


Assuntos
Estudos de Casos e Controles , Predisposição Genética para Doença , Modelos Estatísticos , Humanos , Funções Verossimilhança
19.
Stat Med ; 33(4): 675-92, 2014 Feb 20.
Artigo em Inglês | MEDLINE | ID: mdl-24009099

RESUMO

Data collected in many epidemiological or clinical research studies are often contaminated with measurement errors that may be of classical or Berkson error type. The measurement error may also be a combination of both classical and Berkson errors and failure to account for both errors could lead to unreliable inference in many situations. We consider regression analysis in generalized linear models when some covariates are prone to a mixture of Berkson and classical errors, and calibration data are available only for some subjects in a subsample. We propose an expected estimating equation approach to accommodate both errors in generalized linear regression analyses. The proposed method can consistently estimate the classical and Berkson error variances based on the available data, without knowing the mixture percentage. We investigated its finite-sample performance numerically. Our method is illustrated by an application to real data from an HIV vaccine study.


Assuntos
Ensaios Clínicos como Assunto/métodos , Modelos Lineares , Vacinas contra a AIDS/normas , Simulação por Computador , Feminino , HIV/crescimento & desenvolvimento , Infecções por HIV/prevenção & controle , Humanos , Masculino , Análise de Regressão
20.
Stat Med ; 30(3): 232-49, 2011 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-21213341

RESUMO

Joint models are frequently used in survival analysis to assess the relationship between time-to-event data and time-dependent covariates, which are measured longitudinally but often with errors. Routinely, a linear mixed-effects model is used to describe the longitudinal data process, while the survival times are assumed to follow the proportional hazards model. However, in some practical situations, individual covariate profiles may contain changepoints. In this article, we assume a two-phase polynomial random effects with subject-specific changepoint model for the longitudinal data process and the proportional hazards model for the survival times. Our main interest is in the estimation of the parameter in the hazards model. We incorporate a smooth transition function into the changepoint model for the longitudinal data and develop the corrected score and conditional score estimators, which do not require any assumption regarding the underlying distribution of the random effects or that of the changepoints. The estimators are shown to be asymptotically equivalent and their finite-sample performance is examined via simulations. The methods are applied to AIDS clinical trial data.


Assuntos
Estudos Longitudinais/métodos , Modelos Estatísticos , Modelos de Riscos Proporcionais , Análise de Sobrevida , Síndrome da Imunodeficiência Adquirida/sangue , Síndrome da Imunodeficiência Adquirida/diagnóstico , Síndrome da Imunodeficiência Adquirida/mortalidade , Síndrome da Imunodeficiência Adquirida/prevenção & controle , Algoritmos , Viés , Contagem de Linfócito CD4 , Simulação por Computador , Método Duplo-Cego , Infecções por HIV/sangue , Infecções por HIV/tratamento farmacológico , Infecções por HIV/mortalidade , Humanos , Modelos Lineares , Método de Monte Carlo , Ensaios Clínicos Controlados Aleatórios como Assunto , Distribuições Estatísticas
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...