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1.
Stat Med ; 38(23): 4574-4582, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31304613

RESUMO

Feature selection is an important initial step of exploratory analysis in biomedical studies. Its main objective is to eliminate the covariates that are uncorrelated with the outcome. For highly correlated covariates, traditional feature selection methods, such as the Lasso, tend to select one of them and eliminate the others, although some of the eliminated ones are still scientifically valuable. To alleviate this drawback, we propose a feature selection method based on covariate space decomposition, referred herein as the "Decomposition Feature Selection" (DFS), and show that this method can lead to scientifically meaningful results in studies with correlated high dimensional data. The DFS consists of two steps: (i) decomposing the covariate space into disjoint subsets such that each of the subsets contains only uncorrelated covariates and (ii) identifying significant predictors by traditional feature selection within each covariate subset. We demonstrate through simulation studies that the DFS has superior practical performance over the Lasso type methods when multiple highly correlated covariates need to be retained. Application of the DFS is demonstrated through a study of bipolar disorders with correlated biomarkers.

2.
BMJ Open ; 9(6): e028151, 2019 06 22.
Artigo em Inglês | MEDLINE | ID: mdl-31230018

RESUMO

OBJECTIVES: Condoms are highly effective in preventing sexually transmitted infections (STIs) but implementation is often inconsistent with use rarely examined across travel transition periods. We examined the prevalence of condom use among ship-assigned US military personnel across an overseas deployment cycle and identified factors associated with condom non-use. METHODS: Longitudinal survey data were collected from ship-assigned US Navy/Marine Corps personnel on 11 ships before (T1), during (T2) and after (T3) an overseas deployment. The anonymous, self-completed survey included demographics, condom use at last sex, STI diagnosis, alcohol misuse and drug use with sex. Descriptive and generalised regression model analyses were conducted. RESULTS: Analysis included 1900 (T1), 549 (T2) and 1168 (T3) personnel who reported age, sex and condom use/non-use at last sex. The proportion reporting condom use was significantly higher during T2 (53%, p<0.0001) than T1 (27%) or T3 (28%), with STI prevalences of 1% (T1), 7% (T2) or 2% (T3), with fewer (29%) sexually active individuals at T2. In adjusted models, condom non-use was associated with hazardous alcohol use (OR 1.44, 95% CI 1.21 to 1.71), or drug use to enhance sex (OR 1.37, 95% CI 1.06 to 1.77), but transactional sex was negatively associated (OR 0.69, 95% CI 0.50 to 0.84). CONCLUSIONS: Condom use was highest during deployment, as was STI prevalence (among non-users), possibly reflecting concentration of high-risk sexual activities/individuals and/or sexual partners more likely to be infected. Higher condom use with transactional sex likely reflects awareness of higher STI risk. These data can be used to facilitate targeted interventions to reduce STI transmission and may extend to similarly aged cohorts travelling outside the US (eg, college students on spring break).

3.
Sensors (Basel) ; 18(5)2018 May 22.
Artigo em Inglês | MEDLINE | ID: mdl-29789475

RESUMO

With the development of wireless sensor networks, IoT devices are crucial for the Smart City; these devices change people's lives such as e-payment and e-voting systems. However, in these two systems, the state-of-art authentication protocols based on traditional number theory cannot defeat a quantum computer attack. In order to protect user privacy and guarantee trustworthy of big data, we propose a new identity-based blind signature scheme based on number theorem research unit lattice, this scheme mainly uses a rejection sampling theorem instead of constructing a trapdoor. Meanwhile, this scheme does not depend on complex public key infrastructure and can resist quantum computer attack. Then we design an e-payment protocol using the proposed scheme. Furthermore, we prove our scheme is secure in the random oracle, and satisfies confidentiality, integrity, and non-repudiation. Finally, we demonstrate that the proposed scheme outperforms the other traditional existing identity-based blind signature schemes in signing speed and verification speed, outperforms the other lattice-based blind signature in signing speed, verification speed, and signing secret key size.

4.
Cancer Epidemiol Biomarkers Prev ; 26(7): 1114-1123, 2017 07.
Artigo em Inglês | MEDLINE | ID: mdl-28341757

RESUMO

Background: We investigated whether an immune system environment characterized by elevated serum levels of B-cell activation molecules was associated with the subsequent development of classical Hodgkin lymphoma (cHL).Methods: We measured serum levels of B-cell-stimulatory cytokines, IL6 and IL10, soluble CD30 (sCD30), and total IgE prior to cHL diagnosis in 103 cases and 206 matched controls with archived specimens in the DoD Serum Repository.Results: Prediagnosis serum sCD30 and IL6 levels had strong positive associations with risk of a cHL diagnosis 0 to 1 year prior to diagnosis [sCD30 OR = 5.5; 95% confidence interval (CI), 3.4-9.0; IL6 OR = 4.6; 95% CI, 2.9-7.5] and >1 year to 2 years pre-cHL diagnosis (sCD30 OR = 3.3; 95% CI, 1.6-6.7; IL6 OR = 2.9; 95% CI, 1.3-6.5). We observed similar, albeit not consistently significant positive associations, over 4 or more years preceding diagnosis. We did not observe a clear association with IgE levels. Of note, detectable IL10 levels were significantly associated with Epstein-Barr virus (EBV)-positive cHL cases compared with EBV-negative cases.Conclusion: In this prospective analysis, elevated sCD30 and IL6 levels and detectable IL10 preceded cHL diagnosis.Impact: The associations of these cytokines with cHL risk may reflect the production of these molecules by proliferating nascent cHL tumor cells, or by immune cells responding to their presence, prior to clinical detection. The stable elevation in cHL risk, 4 or more years prediagnosis, also suggests that a B-cell-stimulatory immune system milieu precedes, and may promote, lymphomagenesis. Cancer Epidemiol Biomarkers Prev; 26(7); 1114-23. ©2017 AACR.


Assuntos
Infecções por Vírus Epstein-Barr/sangue , Doença de Hodgkin/sangue , Interleucina-10/sangue , Interleucina-6/sangue , Antígeno Ki-1/sangue , Adulto , Linfócitos B/imunologia , Linfócitos B/metabolismo , Carcinogênese/imunologia , Estudos de Casos e Controles , Infecções por Vírus Epstein-Barr/diagnóstico , Infecções por Vírus Epstein-Barr/imunologia , Infecções por Vírus Epstein-Barr/virologia , Feminino , Herpesvirus Humano 4/isolamento & purificação , Doença de Hodgkin/diagnóstico , Doença de Hodgkin/imunologia , Doença de Hodgkin/virologia , Humanos , Imunoglobulina E/sangue , Interleucina-10/imunologia , Interleucina-6/imunologia , Antígeno Ki-1/imunologia , Masculino , Militares/estatística & dados numéricos , Estudos Prospectivos , Fatores de Risco , Estados Unidos , United States Department of Defense , Adulto Jovem
5.
Front Public Health ; 4: 207, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27774446

RESUMO

This paper reviews several common challenges encountered in statistical analyses of epidemiological data for epidemiologists. We focus on the application of linear regression, multivariate logistic regression, and log-linear modeling to epidemiological data. Specific topics include: (a) deletion of outliers, (b) heteroscedasticity in linear regression, (c) limitations of principal component analysis in dimension reduction, (d) hazard ratio vs. odds ratio in a rate comparison analysis, (e) log-linear models with multiple response data, and (f) ordinal logistic vs. multinomial logistic models. As a general rule, a thorough examination of a model's assumptions against both current data and prior research should precede its use in estimating effects.

6.
Front Public Health ; 3: 75, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26000271

RESUMO

Biomarkers have been examined in schizophrenia research for decades. Medical morbidity and mortality rates, as well as personal and societal costs, are associated with schizophrenia patients. The identification of biomarkers and alleles, which often have a small effect individually, may help to develop new diagnostic tests for early identification and treatment. Currently, there is not a commonly accepted statistical approach to identify predictive biomarkers from high dimensional data. We used space decomposition-gradient-regression (DGR) method to select biomarkers, which are associated with the risk of schizophrenia. Then, we used the gradient scores, generated from the selected biomarkers, as the prediction factor in regression to estimate their effects. We also used an alternative approach, classification and regression tree, to compare the biomarker selected by DGR and found about 70% of the selected biomarkers were the same. However, the advantage of DGR is that it can evaluate individual effects for each biomarker from their combined effect. In DGR analysis of serum specimens of US military service members with a diagnosis of schizophrenia from 1992 to 2005 and their controls, Alpha-1-Antitrypsin (AAT), Interleukin-6 receptor (IL-6r) and connective tissue growth factor were selected to identify schizophrenia for males; and AAT, Apolipoprotein B and Sortilin were selected for females. If these findings from military subjects are replicated by other studies, they suggest the possibility of a novel biomarker panel as an adjunct to earlier diagnosis and initiation of treatment.

7.
Schizophr Res ; 151(1-3): 36-42, 2013 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-24139899

RESUMO

INTRODUCTION: Multiple studies have documented immune activation in many individuals with schizophrenia suggesting that antigens capable of generating a prolonged immune response may be important environmental factors in many cases of this disorder. While existing studies have found single-agent associations of antibodies to food and neurotropic infectious agents with schizophrenia, a simultaneous examination of multiple agents may shed light on agent interactions or possible etiopathogenic pathways. METHODS: We used traditional regression and novel statistical techniques to examine associations of single and combined infectious and food antigens with schizophrenia. We tested 6106 serum samples from 855 cases and 1165 matched controls. RESULTS: Higher antibody levels to casein were borderline significant in the prediction of schizophrenia (HR=1.08, p=0.06). Study participants with higher cytomegalovirus (CMV) IgG antibody levels had a reduced risk of developing schizophrenia (HR=0.90; p=0.02). While IgG antibodies to gliadin, Toxoplasma gondii, vaccinia, measles, and human herpesvirus-6 (HHV-6) showed no significant independent associations with schizophrenia, the increase in antibody levels to several combinations of agents, to include casein, measles, CMV, T. gondii and vaccinia, was predictive of an 18-34% increase in the risk of developing schizophrenia. CONCLUSION: Certain patterns of antibodies, involving some agents, were predictive of developing schizophrenia, with the magnitude of association rising when the level of antibodies increased to two or more agents. A heightened antibody response to a combination of several infectious/food antigens might be an indicator of an altered immune response to antigenic stimuli.


Assuntos
Anticorpos/metabolismo , Antígenos Virais/imunologia , Citomegalovirus/imunologia , Alimentos , Herpesvirus Humano 6/imunologia , Esquizofrenia/imunologia , Adolescente , Adulto , Feminino , Humanos , Modelos Logísticos , Masculino , Militares , Modelos de Riscos Proporcionais , Análise de Regressão , Estados Unidos , Adulto Jovem
8.
Genet Epidemiol ; 37(6): 571-80, 2013 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-23740720

RESUMO

Testing association between a genetic marker and multiple-dependent traits is a challenging task when both binary and quantitative traits are involved. The inverted regression model is a convenient method, in which the traits are treated as predictors although the genetic marker is an ordinal response. It is known that population stratification (PS) often affects population-based association studies. However, how it would affect the inverted regression for pleiotropic association, especially with the mixed types of traits (binary and quantitative), is not examined and the performance of existing methods to correct for PS using the inverted regression analysis is unknown. In this paper, we focus on the methods based on genomic control and principal component analysis, and investigate type I error of pleiotropic association using the inverted regression model in the presence of PS with allele frequencies and the distributions (or disease prevalences) of multiple traits varying across the subpopulations. We focus on common alleles but simulation results for a rare variant are also reported. An application to the HapMap data is used for illustration.


Assuntos
Genética Populacional , Modelos Genéticos , Grupo com Ancestrais do Continente Asiático/genética , Frequência do Gene , Marcadores Genéticos , Estudo de Associação Genômica Ampla , Projeto HapMap , Humanos , Herança Multifatorial/genética , Polimorfismo de Nucleotídeo Único , Análise de Componente Principal , Análise de Regressão
9.
J Acquir Immune Defic Syndr ; 62(4): 471-9, 2013 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-23254150

RESUMO

BACKGROUND: President's Emergency Plan for AIDS Relief (PEPFAR) has been criticized for its vertical or "stove-piping" structure, with resources targeting a specific disease rather than working to strengthen the underlying health system. This study aimed to evaluate whether PEPFAR activities were associated with system-wide improvements in both proximal and distal indicators of health systems strengthening. METHODS: The World Bank database provided 12 indicators of health systems strengthening that were analyzed for their relationship to PEPFAR. Poisson and linear regression models were used to estimate the time trend. We evaluated the PEPFAR impact on health outcomes by comparing the time trend in each of the above indicators between 2 time periods: from 1995 to 2002 (pre-PEPFAR) and from 2004 to 2010 (during PEPFAR). RESULTS: PEPFAR activities showed strong and statistically significant associations with improvements in proximal indicators of health systems strengthening, those related directly to HIV, specifically life expectancy (P = 0.003) and tuberculosis incidence, prevalence, and mortality (P < 0.0001). There were nonsignificant associations between PEPFAR and improvements in distal indicators of health systems strengthening, namely infant mortality and under 5 child mortality. CONCLUSIONS: The progressive scale-up of PEPFAR-supported activities was associated with consistent improvements in proximal indicators of health systems strengthening. It was also associated with improvements in broader measures of health system strength, most clearly life expectancy. Given the limited number of health measures available for this type of analysis, more data must be collected for other indicators to evaluate the effectiveness of the many multibillion dollar global health initiatives.


Assuntos
Síndrome de Imunodeficiência Adquirida/terapia , Assistência à Saúde/organização & administração , Emergências , Humanos , Avaliação de Programas e Projetos de Saúde
10.
Sex Transm Dis ; 39(4): 241-50, 2012 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-22421688

RESUMO

BACKGROUND: While population-based seroprevalence studies of herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2) are widespread, seroincidence studies are largely limited to select or high-risk populations. The US military offers a potential population to derive national seroincidence rate estimates for young adults (ages 18-29). METHODS: We used banked, longitudinal serum specimens collected in a cohort of 1094 military personnel aged 18 to 30 years who served between 1989 and 2005 to estimate national HSV-1 and HSV-2 seroincidence and seroprevalence for the young, adult military population, weighted according to the US Census. Serum was tested with indirect ELISA (enzyme-linked immunosorbent assay). RESULTS: Estimated national seroincidence rates for the US young, adult military population were 9.1 per 100 person-years (95% confidence interval: 4.6-13.5) for HSV-1 and 6.2 (95% confidence interval: 3.1-9.3) for HSV-2. Female sex and black race were associated with significantly higher HSV-2 seroconversion rates. Our estimated HSV1/2 seroprevalences were comparable to US national data provided by National Health and Nutrition Examination Surveys' serosurveys except for non-Hispanic blacks and Hispanics. CONCLUSION: Although these US 2000 Census-weighted estimates of HSV-1 and HSV-2 seroincidence apply only to young, military adults, they nonetheless supply, to our knowledge, the only national figures that might be used to predict US national HSV1/2 seroincidence in young adults. Thus, we believe that our findings in this military population can be used to inform the planning of HSV-1 and 2 prevention measures in the general, young-adult US population.


Assuntos
Anticorpos Antivirais/sangue , Herpes Simples/diagnóstico , Herpes Simples/epidemiologia , Herpesvirus Humano 1 , Herpesvirus Humano 2 , Militares/estatística & dados numéricos , Adolescente , Adulto , Grupo com Ancestrais do Continente Africano , Estudos de Coortes , Ensaio de Imunoadsorção Enzimática , Grupo com Ancestrais do Continente Europeu , Feminino , Herpes Simples/etnologia , Herpesvirus Humano 1/imunologia , Herpesvirus Humano 2/imunologia , Hispano-Americanos , Humanos , Estudos Longitudinais , Masculino , Fatores de Risco , Estudos Soroepidemiológicos , Fatores Sexuais , Adulto Jovem
11.
Clin Infect Dis ; 53(3): 234-44, 2011 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-21765072

RESUMO

BACKGROUND: The interferon-γ release assays (IGRAs) are increasingly being used as an alternative to the tuberculin skin test (TST). Although IGRAs may have better specificity and certain logistic advantages to the TST, their use may contribute to overtesting of low-prevalence populations if testing is not targeted. The objective of this study was to evaluate the accuracy of a risk factor questionnaire in predicting a positive test result for latent tuberculosis infection using the 3 commercially available diagnostics. METHODS: A cross-sectional comparison study was performed among recruits undergoing Army basic training at Fort Jackson, South Carolina, from April through June 2009. The tests performed included: (1) a risk factor questionnaire; (2) the QuantiFERON Gold In-Tube test (Cellestis Limited, Carnegie, Victoria, Australia); (3) the T-SPOT.TB test (Oxford Immunotec Limited, Abingdon, United Kingdom); and (4) the TST (Sanofi Pasteur Ltd., Toronto, Ontario, Canada). Prediction models used logistic regression to identify factors associated with positive test results. RFQ prediction models were developed independently for each test. RESULTS: Use of a 4-variable model resulted in 79% sensitivity, 92% specificity, and a c statistic of 0.871 in predicting a positive TST result. Targeted testing using these risk factors would reduce testing by >90%. Models predicting IGRA outcomes had similar specificities as the skin test but had lower sensitivities and c statistics. CONCLUSIONS: As with the TST, testing with IGRAs will result in false-positive results if the IGRAs are used in low-prevalence populations. Regardless of the test used, targeted testing is critical in reducing unnecessary testing and treatment. CLINICAL TRIAL REGISTRATION: NCT00804713.


Assuntos
Técnicas de Laboratório Clínico/métodos , Tuberculose Latente/diagnóstico , Adolescente , Adulto , Estudos Transversais , Feminino , Humanos , Imunoensaio/métodos , Masculino , Valor Preditivo dos Testes , Medição de Risco/métodos , Sensibilidade e Especificidade , South Carolina , Inquéritos e Questionários , Adulto Jovem
12.
Mil Med ; 176(5): 519-23, 2011 May.
Artigo em Inglês | MEDLINE | ID: mdl-21634296

RESUMO

Selective accession waivers for medically disqualifying conditions like spinal curvature are one way the military meets its manpower needs. We evaluated retention patterns during the first 2 years of service of a cohort of military recruits with waivers for pathological curvature of the spine (spinal curvature). Recruits waived for spinal curvature (n = 417), who accessed from 1998 to 2005 were identified and matched with 3 qualified recruits. Kaplan-Meier survival analysis and Cox proportional hazards model were used to compare survival patterns and adjusted attrition hazard estimates. Waived recruits experienced significantly increased risk of "all cause" discharge (relative risk = 1.3; 95% confidence interval: 1.1, 1.5) and "existing prior to service" discharge (relative risk = 2.4; confidence interval: 1.6, 3.5). Despite the increased risk of discharge, current waiver criteria allowed a majority with spinal curvature to complete at least 2 years of service. Policy makers must consider risks and benefits before modifying the current accession standard for spinal curvature.


Assuntos
Militares , Seleção de Pessoal , Curvaturas da Coluna Vertebral/epidemiologia , Adolescente , Adulto , Estudos de Coortes , Feminino , Humanos , Masculino , Modelos de Riscos Proporcionais , Curvaturas da Coluna Vertebral/patologia , Estados Unidos/epidemiologia
13.
Mil Med ; 176(5): 537-43, 2011 May.
Artigo em Inglês | MEDLINE | ID: mdl-21634299

RESUMO

The estimated incidence of idiopathic venous thromboembolism (IVTE) cases in the United States ranges from 24,000 to 282,000/year. This analysis explores the incidence and prevalence of IVTE in the military and if cases experience increased attrition. The Defense Medical Surveillance System was searched for incident IVTE cases from 1998 through 2007. Enlisted cases were each matched to 3 controls. Kaplan-Meier survival analysis and Cox proportional hazard modeling were performed. We matched 463 cases to 1,389 controls. Outpatient IVTE rates have increased markedly from 1998 through 2007. Cases of all-cause attrition risk (0.56 [95% CI = 0.44, 0.72]) and rates were significantly less than controls (p < 0.0001), and cases of medical attrition risk (1.64 [95% CI = 1.13, 2.37]) and rates were significantly higher (p < 0.01). Increasing rates with lower attrition suggests increasing case prevalence. Health care providers must maintain a high index of suspicion for venous thromboembolism to minimize adverse sequelae affecting health, unit readiness, and medical costs.


Assuntos
Militares , Tromboembolia Venosa/epidemiologia , Adulto , Distribuição de Qui-Quadrado , Feminino , Humanos , Incidência , Masculino , Pessoa de Meia-Idade , Vigilância da População , Prevalência , Fatores de Risco , Estatísticas não Paramétricas , Estados Unidos/epidemiologia
14.
Schizophr Res ; 128(1-3): 51-5, 2011 May.
Artigo em Inglês | MEDLINE | ID: mdl-21376538

RESUMO

Schizophrenia is a pervasive neuropsychiatric disorder of uncertain etiology. Multiple studies have documented immune activation in individuals with schizophrenia. One antigen capable of inducing a prolonged immune response is bovine casein derived from ingested milk products. Increased levels of casein antibodies have been found in individuals with schizophrenia after diagnosis. This study was directed at determining the potential association between schizophrenia and pre-illness onset levels of immunoglobulin G (IgG) antibodies to bovine casein. Parallel analyses for casein antibody levels with bipolar disorder were included as comparison. Cases were service members who received medical discharges from the military with a schizophrenia diagnosis from 1992 to 2005. Serum specimens were selected for 855 cases and 1165 matched healthy controls. IgG antibodies to bovine whole-casein were measured by solid phase enzyme-linked immunosorbent assays (ELISAs). Hazard ratios (HR) were calculated to examine the associations of casein IgG level with risk of schizophrenia by time to diagnosis and by subjects' initial level. Increasing casein IgG antibody levels among those with a high initial level, drawn before diagnosis, was associated with an 18% increase in the hazard risk of schizophrenia per unit increase (value of low-positive standard) in IgG antibody levels (HR=1.18; 95% CI 1.04, 1.34). This is the first report to identify an association between the risk of schizophrenia and elevated antibodies to bovine casein prior to disease onset. Additional research is required to elucidate the complex genetic environmental interactions involved in the pathogenesis of schizophrenia and to identify potentially modifiable risk factors.


Assuntos
Caseínas/imunologia , Imunoglobulina G/sangue , Esquizofrenia/sangue , Esquizofrenia/epidemiologia , Adolescente , Adulto , Animais , Transtorno Bipolar/sangue , Transtorno Bipolar/imunologia , Estudos de Casos e Controles , Bovinos , Ensaio de Imunoadsorção Enzimática/métodos , Feminino , Humanos , Masculino , Militares , Modelos de Riscos Proporcionais , Estudos Retrospectivos , Esquizofrenia/imunologia , Estados Unidos , Adulto Jovem
15.
Aviat Space Environ Med ; 81(2): 107-11, 2010 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-20131650

RESUMO

INTRODUCTION: Heat illness has not declined in the U.S. military despite preventive measures. The increase in overweight recruits entering the U.S. military may lead to an increase in heat-related events. This study compares the risk of heat illness among U.S. Army recruits who exceeded body fat standards at accession to those who met standards. METHODS: Recruits with excess body fat and qualified applicants to the Army were required to take a preaccession fitness test during the study period (February 2005 through September 2006). The test included a 5-min step test and 1-min push-up challenge, scored as pass or fail. Incidence and outpatient usage for heat illness (any heat illness, heat stroke, heat exhaustion, and other heat illness) at 90 d of service were compared in 9667 male recruits of whom 826 had excess body fat and 8841 were qualified. There were too few heat events among women for analysis. RESULTS: The incidence odds ratio among male recruits with excess body fat compared to qualified male recruits was 3.63 (95% CI: 1.92, 6.85). Men with excess body fat had an increased incidence of heat illness with a rate ratio of 7.25 (95% CI: 4.17, 12.61). DISCUSSION: Although there were few heat illness events, the results indicate a significantly increased risk of heat illness and outpatient utilization among male recruits with excess body fat. It was estimated that approximately 70% of the relative risk for heat illnesses in men with excess body fat during basic training was associated with exceeding body fat standards. These findings may have implications for military accession and training.


Assuntos
Transtornos de Estresse por Calor/epidemiologia , Militares , Sobrepeso/epidemiologia , Adolescente , Adulto , Humanos , Masculino , Aptidão Física , Fatores de Risco , Estados Unidos , Adulto Jovem
16.
Soc Sci Res ; 38(3): 622-34, 2009 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-19856700

RESUMO

Using data from 19,839 adolescents from the National Education Longitudinal Study, this study investigates whether the effects of parental divorce on adolescents' academic test performance vary by sibship size. Analyses show that the negative effect of divorce on adolescent performance attenuates as sibship size increases. On the other side of the interaction, the inverse relationship between sibship size and test performance is weaker in disrupted than in two-biological-parent families. Trends of such interactions are evident when sibship size is examined either as a continuous or a categorical measure. Finally, the observed interactions on adolescents' academic performance are completely explained by variations in parental financial, human, cultural, and social resources. In sum, this study underlines the importance of treating the effect of parental divorce as a variable and calls for more research to identify child and family features that may change the magnitude of such an effect.


Assuntos
Divórcio/psicologia , Escolaridade , Características da Família , Psicologia do Adolescente , Adolescente , Avaliação Educacional , Humanos , Acontecimentos que Mudam a Vida , Estudos Longitudinais , Casamento/psicologia , Matemática , Análise Multivariada , Leitura , Análise de Regressão , Fatores Socioeconômicos
17.
Mil Med ; 174(7): 695-701, 2009 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-19685840

RESUMO

The Assessment of Recruit Motivation and Strength (ARMS) project evaluated whether active duty Army enlistees who exceeded weight and body-fat standards but were able to pass the ARMS physical fitness test were at elevated risk of early attrition relative to the traditional recruit population. Attrition among 1146 overweight and overbody-fat (OBF) recruits who passed ARMS was compared to 10,514 fully qualified (FQ) recruits who began service in February 2005 through September 2006. The ARMS test includes a 5-minute step test and a 1-minute pushup test. There were no significant differences in attrition between OBF and FQ at 180 days: adjusted hazard ratios were 1.17 (95% CI: 0.83, 1.65) among females and 1.23 (95% CI: 0.95, 1.58) among males. This study indicates that physically fit recruits who exceeded weight/body-fat standards were equally capable of serving at least 180 days compared to those who met standards.


Assuntos
Militares , Reorganização de Recursos Humanos , Aptidão Física , Adiposidade , Adolescente , Adulto , Composição Corporal , Índice de Massa Corporal , Intervalos de Confiança , Teste de Esforço , Feminino , Humanos , Masculino , Análise Multivariada , Obesidade , Sobrepeso , Modelos de Riscos Proporcionais , Estudos Prospectivos , Risco , Fatores de Tempo , Estados Unidos , Adulto Jovem
18.
Soc Sci Res ; 37(2): 449-60, 2008 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-19069054

RESUMO

Although a substantial amount of social science research has examined the consequences of various life events, much less has been done to examine how the effect may be unevenly distributed. The present research takes children's experiences of parents' marital disruption as an example and demonstrates how a contaminated-distribution model may simulate a scenario in which the effect of parents' marital disruption on children's academic performance is unevenly distributed. Using test performance data from a nationally representative sample of 10,045 American adolescents, the study partitions the overall performance distribution among adolescents of divorce into an unaffected and a severe-effect distribution. The analyses report the estimated proportions of adolescents whose academic performance is severely affected by various levels. The findings also show that the proportions of adolescents whose school performance is affected by a fixed level remain relatively stable in three consecutive post-divorce waves.


Assuntos
Divórcio/psicologia , Escolaridade , Acontecimentos que Mudam a Vida , Adolescente , Avaliação Educacional , Feminino , Humanos , Estudos Longitudinais , Masculino , Casamento , Modelos Psicológicos , Psicologia do Adolescente , Estados Unidos
19.
Mil Med ; 173(6): 555-62, 2008 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-18595419

RESUMO

BACKGROUND: The Assessment of Recruit Motivation and Strength (ARMS) study was designed to pilot-test the use of a physical fitness screening tool for Army applicants before basic training. METHODS: The ARMS test consists of two components, namely, a 5-minute step test and push-ups. Attrition among 7,612 recruits who underwent preaccession ARMS testing and began service between May 2004 and December 2005 was studied. RESULTS: ARMS test performance was found to be significantly related to risk of attrition within 180 days; the hazard ratios for failing relative to passing the ARMS test were 2.27 (95% confidence interval, 1.70-3.04) among female subjects and 1.36 (95% confidence interval, 1.13-1.64) among male subjects. The attributable risk of attrition associated with failing the ARMS test was approximately 40% among female subjects and approximately 30% among male subjects. DISCUSSION: The ARMS study is the first prospective study conducted in the U.S. Army to assess physical fitness before accession. Physical fitness and motivation to serve were shown to correlate with attrition during initial entry training.


Assuntos
Militares , Motivação , Seleção de Pessoal/métodos , Aptidão Física , Adolescente , Adulto , Teste de Esforço , Feminino , Humanos , Capacitação em Serviço , Masculino , Militares/psicologia , Militares/estatística & dados numéricos , Força Muscular , Resistência Física , Valor Preditivo dos Testes , Estudos Prospectivos
20.
J Trauma ; 64(6): 1459-63; discussion 1463-5, 2008 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-18545109

RESUMO

BACKGROUND: Recent civilian studies have documented a relationship between increased mortality and the presence of an early coagulopathy of trauma diagnosed in the emergency department (ED). We hypothesized that acute coagulopathy (international normalized ratio >/=1.5) in combat casualties was associated with increased injury severity and mortality as is seen in civilian trauma patients. METHODS: A retrospective study of combat casualties who received a blood transfusion at a single combat support hospital between September 2003 and December 2004 was performed. Coagulation status, pH, base deficit, and temperature were recorded at arrival to the ED. These were analyzed by Injury Severity Score (ISS), associated injury patterns, and mortality. RESULTS: A total of 3,287 patients were treated at the combat support hospital during the study period. Of these, 391 patients were transfused and primarily admitted, thus meeting the study criteria, 347 had coagulation data, and 92% had a penetrating mechanism. The prevalence of acute coagulopathy in transfused casualties measured with point-of-care devices at arrival in the ED was 38%. Mortality in those who were coagulopathic at arrival to the ED was 24% (32/133) versus 4% (8/214) in those not presenting with coagulopathy (p < 0.001). The prevalence of mortality by coagulopathy increased as ISS increased. Coagulopathy and acidosis were associated with mortality, odds ratio (OR), 5.38 [95% confidence interval (CI), 1.55-11.37] and 6.9 (95% CI, 2.1-19.5), respectively. Temperature did not affect outcomes (OR, 1.1; 95% CI, 0.4-2.6). CONCLUSIONS: The early coagulopathy of trauma was rapidly diagnosed in the ED and present in more than one-third of combat casualties who received a transfusion, similar to the incidence found in civilian trauma patients. Coagulopathy, independent of hypothermia but strongly correlated with acidosis and ISS, was associated with mortality in combat casualties, similar to that found in civilian trauma patients. Early diagnosis and treatment of acute traumatic coagulopathy with new resuscitation paradigms may improve outcomes.


Assuntos
Transtornos da Coagulação Sanguínea/mortalidade , Transfusão de Sangue , Causas de Morte , Militares , Ferimentos e Lesões/mortalidade , Ferimentos e Lesões/terapia , Adolescente , Adulto , Análise de Variância , Transtornos da Coagulação Sanguínea/diagnóstico , Estudos de Coortes , Intervalos de Confiança , Feminino , Seguimentos , Humanos , Escala de Gravidade do Ferimento , Masculino , Prevalência , Probabilidade , Estudos Retrospectivos , Medição de Risco , Análise de Sobrevida , Fatores de Tempo , Guerra , Ferimentos e Lesões/diagnóstico
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