RESUMEN

Negative control variables are sometimes used in nonexperimental studies to detect the presence of confounding by hidden factors. A negative control outcome (NCO) is an outcome that is influenced by unobserved confounders of the exposure effects on the outcome in view, but is not causally impacted by the exposure. Tchetgen Tchetgen (2013) introduced the Control Outcome Calibration Approach (COCA) as a formal NCO counterfactual method to detect and correct for residual confounding bias. For identification, COCA treats the NCO as an error-prone proxy of the treatment-free counterfactual outcome of interest, and involves regressing the NCO on the treatment-free counterfactual, together with a rank-preserving structural model, which assumes a constant individual-level causal effect. In this work, we establish nonparametric COCA identification for the average causal effect for the treated, without requiring rank-preservation, therefore accommodating unrestricted effect heterogeneity across units. This nonparametric identification result has important practical implications, as it provides single-proxy confounding control, in contrast to recently proposed proximal causal inference, which relies for identification on a pair of confounding proxies. For COCA estimation we propose 3 separate strategies: (i) an extended propensity score approach, (ii) an outcome bridge function approach, and (iii) a doubly-robust approach. Finally, we illustrate the proposed methods in an application evaluating the causal impact of a Zika virus outbreak on birth rate in Brazil.

Asunto(s)

Puntaje de Propensión , Humanos , Factores de Confusión Epidemiológicos , Infección por el Virus Zika/epidemiología , Causalidad , Modelos Estadísticos , Sesgo , Brasil/epidemiología , Simulación por Computador , Femenino , Embarazo

RESUMEN

La identificación de relaciones causales es uno de los problemas fundamentales de la investigación científica en medicina y es necesaria para poder ejercerla en forma efectiva. Sin embargo, desde el punto de vista práctico es difícil establecer la existencia de relaciones causales en estudios de carácter observacional, en gran parte por la presencia de factores de confusión. El análisis a través de variables instrumentales es una de las estrategias que permite controlar el efecto confundidor y documentar la presencia de relaciones causa-efecto en estas situaciones. En este artículo, el autor resume los principales supuestos del análisis a través de variables instrumentales, haciendo foco en la aleatorización mendeliana. (AU)

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The identification of causal relationships is one of the fundamental challenges in scientific research in medicine and is necessary for its effective practice. However, from a practical standpoint, establishing the existence of causal relationships in observational studies is difficult, largely due to the presence of confounding factors. Analysis through instrumental variables is one of the strategies that allows to control the confounding effect and documenting the presence of cause-and-effect relationships in these situations. In this article, the author summarizes the main assumptions of analysis through instrumental variables, with a focus on Mendelian randomization. (AU)

Asunto(s)

Métodos Epidemiológicos , Factores de Confusión Epidemiológicos , Estudios Observacionales como Asunto , Causalidad , Análisis Multivariante , Análisis Factorial , Análisis de la Aleatorización Mendeliana

Asunto(s)

Humanos , Sesgo , Estadística como Asunto/instrumentación , Proyectos Piloto , Riesgo , Factores de Confusión Epidemiológicos , Ensayos Clínicos como Asunto , Estudios Observacionales como Asunto

RESUMEN

Resumen Objetivo: La linfopenia se ha propuesto como un potencial factor asociado al riesgo de infecciones bacterianas nosocomiales (infección urinaria y neumonía), pero la magnitud y relevancia de este factor no ha sido evaluada formalmente. El objetivo de este estudio es determinar si existe asociación entre linfopenia e infecciones nosocomiales en ancianos hospitalizados en una institución de salud en Bogotá, Colombia. Métodos: Estudio de casos y controles, incluyendo personas mayores de 65 años hospitalizadas en el Hospital Universitario San Ignacio entre junio de 2016 y diciembre de 2017. Se consideraron casos aquellos con diagnóstico de infección nosocomial (neumonía, infección de vías urinarias, bacteriemia, infección de tejidos blandos) y se compararon con controles sin infección emparejados por edad y sexo. Se evaluó la asociación entre linfopenia e infección nosocomial mediante análisis bivariado y multivariado controlando por las variables de confusión. Resultados: Se incluyeron un total de 198 pacientes (99 casos y 99 controles). La prevalencia de linfopenia fue de 34.8%, sin encontrarse diferencia entre los dos grupos (p=0.88). La infección nosocomial se asoció a mayor incidencia de mortalidad (29.3 vs 10.1%, p>0.001) y mayor duración de estancia hospitalaria (Mediana 18 vs 9 días, p<0.01). Se encontró asociación entre infección nosocomial con enfermedad cardiovascular (OR = 2.87; IC 95% 1.37-6.00) y antecedente de cáncer (OR = 6.00; IC 95% 1.28-29.78), sin embargo, no hubo asociación con linfopenia (OR = 1.27; IC 95% 0.61-2.65). Conclusiones: Este estudio sugiere que no existe asociación entre linfopenia y el desarrollo de infecciones nosocomiales en pacientes ancianos.

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Abstract Objective: Lymphopenia has been proposed as a potential factor associated with the risk of nosocomial bacterial infections (urinary tract infection and pneumonia), but the magnitude and relevance of this factor has not been formally evaluated. Objective is to determine the association between lymphopenia and nosocomial infections in elderly hospitalized in a health institution in Bogotá, Colombia. Methods: Case-control study, including people over 65 hospitalized in the University Hospital San Ignacio - Bogotá, during the period between June 2016 and December 2017. Cases with a diagnosis of nosocomial infection (pneumonia, urinary tract infection, bacteraemia, soft tissue infection) were considered and compared with controls without infection matched by age and sex. The association between lymphopenia and nosocomial infection was evaluated by bivariate and multivariate analysis, controlling for confounding variables. Results: A total of 198 patients (99 cases and 99 controls) were included. The prevalence of lymphopenia was 34.8%, with no difference between the two groups (p = 0.88). Nosocomial infection was associated with a higher incidence of mortality (29.3 vs. 10.1%, p> 0.001) and a longer duration of hospital stay (Median 18 vs. 9 days, p< 0.001). An association was found between nosocomial infection with cardiovascular disease (OR = 2.87; 95% CI 1.37-6.00) and a history of cancer (OR = 6.19; 95% CI 1.28-29.78), however, there was no association with lymphopenia (OR = 1.27 ; 95% CI 0.61-2.65). Conclusions: This study suggests that there is no association between lymphopenia and the development of nosocomial infections in elderly patients.

Asunto(s)

Humanos , Masculino , Anciano , Infecciones Bacterianas , Infecciones Urinarias , Infecciones , Linfopenia , Enfermedades Cardiovasculares , Riesgo , Factores de Confusión Epidemiológicos , Análisis Multivariante , Bacteriemia , Colombia

RESUMEN

EL HOMA-IR (homeostasis model assessment-insulin-resistance) es un estimador de insulinorresistencia (IR) pero depende de la determinación de insulina. Los índices triglicéridos-glucosa (T-G)-circunferencia de la cintura (CC) (T-G-CC) o triglicéridos-glucosa-índice de masa corporal (TG- IMC) podrían ser sustitutos. Los objetivos de este trabajo consistieron en investigar en personas con riesgo de desarrollar diabetes tipo 2 (DT2): a) los índices T-G, T-G-CC y T-G-IMC como estimadores de HOMA-IR>2,1; b) determinar su poder discriminante. Se realizó un estudio prospectivo en el que se estudiaron 223 individuos ≥45 años con riesgo de desarrollar diabetes tipo 2 (DT2). La relación T-G se calculó como ln [triglicéridos (mg/dL) x glucemia (mg/dL)/2]. La relación T-G-CC y T-G-IMC fue el producto de T-G por CC o IMC. Se utilizó análisis de regresión logística y se calcularon las áreas bajo las curvas ROC (receiver operating characteristic curves) (ABC) para comparar las asociaciones de T-G, T-G-CC y T-G-IMC con HOMA-IR>2,1. Mediante análisis discriminante se evaluó la clasificación de los sujetos entre HOMA-IR>2,1 y HOMA-IR≤2,1. ABC, sensibilidad, especificidad, poder predictivo positivo y negativo para T-G-CC y T-G-IMC fueron mayores que para T-G, con los siguientes valores de corte: T-G=8,75, T-G-CC=821 y T-G-IMC=255. Los odds ratios (OR) para HOMA-IR>2,1, ajustados para confusores, fueron: T-G>8,75, OR: 4,85 (IC 95% 2,73-8,62); T-G-CC>821, OR: 10,41 (IC 95% 5,55-19,53); T-GIMC> 255, OR: 10,41 (IC 95% 5,55-19,53). Con el análisis discriminante T-G>8,75 clasificó correctamente 69,2% individuos con HOMA-IR≤2,1 y 68,3% con HOMA-IR>2,1; T-G-CC y T-G-IMC clasificaron 74,4% y 78,2% respectivamente (p<0,001 en todos los casos). Se concluyó que T-GCC> 821 y T-G-IMC>255 fueron mejores estimadores de HOMA-IR>2,1 que T-G>8,75. Estas son determinaciones simples y accesibles y podrían ser útiles en la práctica clínica y en estudios epidemiológicos.

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HOMA-IR ((homeostasis model assessment-insulin-resistance) is a surrogate estimator of insulin resistance (IR) but it depends on insulin determination. Triglyceride-glucose-waist circumference (T-G-WC) or triglyceride-glucose-body mass index (BMI) (T-G-BMI) could be substitutes. The objectives of this work were: to investigate in people at risk of developing type 2 diabetes (T2D): a) T-G, T-G-CC and T-G-BMI as estimators of HOMA-IR>2.1 and b) to determine their discriminating power. A prospective study was conducted studying 223 individuals ≥45 years of age at risk of developing type 2 diabetes (T2D). The T-G ratio was calculated as ln [triglycerides (mg/dL) x glycemia (mg/dL)/2]. The T-G-CC and T-G-BMI ratio was the product of T-G by CC or BMI. Logistic regression analysis was used and the areas under the receiver operating characteristic curves (ROC) curves were calculated to compare the associations of T-G, T-G-CC and T-G-BMI with HOMA-IR>2.1. Using a discriminant analysis, the classification of the subjects between HOMA-IR>2.1 or HOMA-IR≤2.1 was evaluated. AUC, sensitivity, specificity, positive and negative predictive powers for T-G-CC and T-G-BMI were higher than for T-G, with the following cut-off values: TG=8.75, T-G-CC=821 and T-G-BMI=255. Odds ratios (OR) for HOMA-IR>2.1, adjusted for confounders, were: T-G>8.75, OR 4.85 (95% CI 2.73-8.62); T-G-CC>821, OR 10.41 (95% CI 5.55-19.53); T-G-BMI>255, OR 10.41 (95% CI 5.55-19.53). With the discriminant analysis T-G>8.75, 69.2% correctly classified with HOMA-IR≤2.1 and 68.3% with HOMA-IR>2.1; T-G-CC and T-G-BMI correctly classified 74.4% and 78.2% respectively (p <0.001 in all cases). It is concluded that T-G-CC>821 and T-G-BMI>255 were better estimators of HOMA-IR>2.1 than T-G>8.75. T-G-WC and T-G-BMI are simple and reliable determinations and could be useful in clinical practice and epidemiological studies.

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O HOMA-IR (homeostasis model assessment-insulin-resistance) e um estimador de resistencia a insulina (RI), mas depende da determinacao da insulina. Triglicerideos-glicose (T-G), circunferencia da cintura (CC) (T-G-CC) ou triglicerideos-glicose-indice de massa corporal (T-G-IMC) poderiam ser substitutos. Os objetivos desse trabalho foram investigar em pessoas com risco de desenvolver diabetes tipo 2 (DT2): a) os indices T-G, T-G-CC e T-G-IMC como estimadores de HOMA-IR> 2,1; b) determinar seu poder discriminante. Um estudo prospectivo foi realizado em 223 pessoas ≥45 anos com risco de desenvolver diabetes tipo 2 (DT2). A razao T-G foi calculada como ln [triglicerideos (mg/dL) x glicemia (mg/dL)/2]. A razao T-G-CC e T-G-IMC foi o produto de T-G por CC ou IMC. A analise de regressao logistica foi utilizada e as areas sob as curvas ROC (receiver operating features) ABC foram calculadas para comparar as associacoes de T-G, T-G-CC e T-G-IMC com HOMA-IR>2.1. Por meio de analise discriminante, avaliou-se a classificacao dos sujeitos entre HOMA-IR>2,1 e HOMA-IR≤2,1. ABC, sensibilidade, especificidade, poder preditivo positivo e negativo para TG-CC e TG-IMC foram maiores que para TG, com os seguintes valores de corte: TG=8,75, TG-CC=821 e TG-IMC=255. Odds Ratios (OR) para HOMA-IR>2,1, ajustados para fatores de confusao, foram: TG>8,75, OR 4,85 (IC95% 2,73-8,62); T-G-CC>821, OR 10,41 (IC 95% 5,55-19,53); T-G-IMC>255, OR 10,41 (IC 95% 5,55-19,53). Com a analise discriminante T-G>8,75, 69,2% foram classificados corretamente com HOMA-IR≤2,1 e 68,3% com HOMA-IR>2,1; T-G-CC e T-G-IMC classificaram 74,4% e 78,2%, respectivamente (p<0,001 em todos os casos). Conclui-se que T-G-CC>821 e TG- IMC>255 foram melhores estimadores de HOMA-IR>2,1 que T-G>8,75. Elas sao determinacoes simples e acessiveis e poderiam ser uteis na pratica clinica e em estudos epidemiologicos.

Asunto(s)

Humanos , Triglicéridos , Poder Psicológico , Estudios Epidemiológicos , Modelos Logísticos , Oportunidad Relativa , Factores de Confusión Epidemiológicos , Curva ROC , Sensibilidad y Especificidad , Clasificación , Área Bajo la Curva , Cortejo , Diabetes Mellitus Tipo 2 , Diabetes Mellitus Tipo 2/complicaciones , Glucosa , Objetivos , Insulina , Personas , Organización y Administración , Asociación , Glucemia , Resistencia a la Insulina , Índice de Masa Corporal , Análisis Discriminante , Riesgo , Análisis de Regresión , Circunferencia de la Cintura

RESUMEN

BACKGROUND: Child abuse is a public health and human rights issue that is prevalent worldwide. All forms of abuse against children can have negative physical and mental health consequences. Under post-disaster situations, where there is a potential for increased stress and decreased social support among caregivers, the risk of child abuse may be higher. OBJECTIVE: To explore the association between earthquake-related losses (family-related and property-related) and the experience of emotional, physical, and severe physical child abuse in the household for children aged 2-14 in Haiti. METHODS: A nationally representative sample of Haitian households from the 2012 Demographic and Health Survey (DHS) was used. Descriptive analyses were summarized using frequencies and measures of central tendency. Associations between earthquake-related loss and child abuse was assessed using log-binomial regression modelling. RESULTS: Two years following the earthquake, and after considering potentially confounding variables, death of a household member was associated with a higher likelihood of a child being victim to emotional (RR = 1.11, 95 % CI: 1.05-1.17) and severe physical abuse (RR = 1.50, 95 % CI: 1.15-1.96). Conversely, injury of a household member was associated with a lower likelihood of a child experiencing emotional abuse (RR = 0.93, 95 % CI: 0.87-0.99). CONCLUSIONS: There were associations between earthquake-related losses and some forms of child abuse; the results were not consistent across all exposures and outcomes. The high prevalence of reported child abuse indicates a need for interventions to reduce child abuse in homes overall. There is also need for further research into the aetiology and influences specific to different types of abuse.

Asunto(s)

Maltrato a los Niños/estadística & datos numéricos , Desastres , Terremotos , Adolescente , Niño , Preescolar , Factores de Confusión Epidemiológicos , Estudios Transversales , Abuso Emocional/estadística & datos numéricos , Femenino , Haití/epidemiología , Humanos , Masculino , Abuso Físico/estadística & datos numéricos , Prevalencia

Asunto(s)

Cardiomiopatía Hipertrófica , Hipertensión , Factores de Confusión Epidemiológicos , Ventrículos Cardíacos , Humanos , Función Ventricular Izquierda

Asunto(s)

Humanos , Cardiomiopatía Hipertrófica , Hipertensión , Factores de Confusión Epidemiológicos , Función Ventricular Izquierda , Ventrículos Cardíacos

RESUMEN

Case-control studies have been essential to the field of epidemiology and in public health research. In this design, data analysis is carried out from the outcome to the exposure, that is, retrospectively, as the association between exposure and outcome is studied between people who present a condition (cases) and those who do not (controls). They are thus very useful for studying infrequent conditions, or for those that involve a long latency period. There are different case selection methodologies, but the central aspect is the selection of controls. Data collection can be retrospective (obtained from clinical records) or prospective (applying data collection instruments to participants). Depending on the objective of the study, different types of case-control studies are available; however, all present a particular vulnerability to information bias and confounding, which can be controlled at the level of design and in the statistical analysis. This review addresses general theoretical concepts concerning case-control studies, including their historical development, methods for selecting participants, types of case-control studies, association measures, potential biases, as well as their advantages and disadvantages. Finally, concepts about the relevance on this study design are discussed, with a view to aid comprehension for undergraduate and graduate students of the health sciences. This is the third of a methodological series of articles on general concepts in biostatistics and clinical epidemiology developed by the Chair of Scientific Research Methodology at the School of Medicine, University of Valparaíso, Chile.

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Los estudios de casos y controles han sido esenciales en el desarrollo de la epidemiología y de la salud pública. En este diseño, el análisis de los datos se realiza desde el desenlace hacia la exposición, es decir, retrospectivamente, ya que se estudia la asociación entre factores de exposición y un desenlace conocido entre personas que ya presentan una condición (casos) y quienes no la presentan (controles). Por lo tanto, son muy útiles en condiciones infrecuentes o que requieren una larga latencia para ocurrir. Existen distintas metodologías de selección de casos, pero el aspecto central es la adecuada selección de controles. La recolección de los datos puede ser retrospectiva (desde de registros clínicos) o prospectiva (mediante la aplicación de instrumentos de recolección de datos a los participantes). En función del objetivo del estudio, se dispone de distintos tipos de estudios de casos y controles, pero todos presentan una vulnerabilidad particular al sesgo de información y de confusión, los que pueden controlarse a nivel del diseño y del análisis estadístico. En este artículo se abordan conceptos teóricos generales sobre los estudios de casos y controles, considerando aspectos históricos, metodología de selección de participantes, tipos estudios de casos y controles, medidas de asociación, potenciales sesgos, ventajas y desventajas. Finalmente, se discuten algunos conceptos de relevancia sobre este diseño para los estudiantes de pre y posgrado de ciencias de la salud. Esta revisión es la tercera entrega de una serie metodológica sobre conceptos generales en bioestadística y epidemiología clínica desarrollada por la Cátedra de Metodología de la Investigación Científica de la Escuela de Medicina de la Universidad de Valparaíso, Chile.

Asunto(s)

Bioestadística/métodos , Métodos Epidemiológicos , Proyectos de Investigación , Sesgo , Estudios de Casos y Controles , Factores de Confusión Epidemiológicos , Recolección de Datos , Humanos , Estudios Observacionales como Asunto

RESUMEN

INTRODUCTION: There is evidence of an association between inflammatory bowel disease (IBD) and lung conditions such as chronic obstructive pulmonary disease (COPD). This systematic review and meta-analysis explored the risk of new onset IBD in patients with COPD and new onset COPD in IBD patients. METHODS: We performed a systematic review of observational studies exploring the risk of both associations. Two independent reviewers explored the EMBASE, MEDLINE, LILACS and DOAJ databases, and the risk of bias was evaluated using the ROBBINS-I tool. Data from included studies was pooled in a random effect meta-analysis following a DerSimonian-Laird method. The quality of the evidence was ranked using GRADE criteria. RESULTS: Four studies including a pooled population of 1355 new cases were included. We found association between new onset IBD in COPD population. The risk of bias was low in most of them. Only one study reported tobacco exposure as a potential confounding factor. The pooled risk ratio (RR) for a new diagnosis of IBD in COPD patients was 2.02 (CI, 1.56 to 2.63), I2 = 72% (GRADE: low). The subgroup analyses for Crohn's disease and ulcerative colitis yielded RRs of 2.29 (CI, 1.51 to 3.48; I2 = 62%), and 1.79 (CI, 1.39 to 2.29; I2 = 19%.), respectively. DISCUSSION: According to our findings, the risk of new onset IBD was higher in populations with COPD compared to the general population without this condition. Based on our analysis, we suggest a potential association between IBD and COPD; however, further research exploring the potential effect of confounding variables, especially cigarette smoking, is still needed. REVIEW REGISTER: (PROSPERO: CRD42018096624).

Asunto(s)

Enfermedades Inflamatorias del Intestino/epidemiología , Enfermedad Pulmonar Obstructiva Crónica/epidemiología , Comorbilidad , Factores de Confusión Epidemiológicos , Humanos

RESUMEN

Objective. To evaluate the state of mental health and its relation with associated factors among nursing students. Methods. A cross-sectional study was conducted with 130 students from the Nursing and Midwifery College affiliated to the University of Medical Sciences of Shiraz (Iran). Data was collected through a document that included information on the demographic characteristics, the mean grades of the practical assignments and of the total (practical and theoretical assignments), and the Goldberg Health Questionnaire (GHQ-28) that measures symptoms grouped into four dimensions (somatic symptoms, anxiety and insomnia, social dysfunction, and depression). Results. Most of the participants (65.1%) were women; 5.3% were between 21 and 22 years of age, 84.5% were single, and 33.3% were in the sixth semester; 68.5% of the students had problems with mental health. By dimensions of the GHQ-28, it was found that 7.7% had somatic symptoms, 13.8% symptoms of anxiety and sleep disorders, 52.3% social dysfunction, and 6.2% depression. Males had a higher score of depression than females, and being single was related with higher scores of physical symptoms, anxiety and insomnia, and depression, compared with those who were married. An inverse relationship was found between the GHQ-28 average score and the semester, the grade in practical assignments, and the total grade for physical symptoms and anxiety and insomnia. Conclusion. There is a high proportion of nursing students with suspected mental health disorder. Some demographic and academic factors are related with the mental health of students and must be kept in mind by the institutions training future nurses.

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Objetivo. Evaluar el estado de salud mental y su relación con factores asociados entre los estudiantes de enfermería. Métodos. Se realizó un estudio de corte transversal con 130 estudiantes del Colegio de Enfermería y Partería afiliado a la Universidad de Ciencias Médicas de Shiraz (Irán). Para la toma de los datos se empleó un formulario que incluía información sobre las características demográficas, los promedios de calificación de las asignaturas prácticas y del total (asignaturas prácticas más teóricas), y el Cuestionario de Salud Goldberg (GHQ-28) que mide síntomas agrupados en cuatro dimensiones (síntomas somáticos, ansiedad e insomnio, disfunción social, y depresión). Resultados. La mayoría de los participantes (65.1%) fueron mujeres; el 5.3% tenía entre 21 y 22 años; solteros, el 84.5% y el 33.3% estudiaba en el sexto semestre. El 68.5% de los estudiantes tenía problemas con la salud mental. Por dimensiones del GHQ-28, se encontró que el 7.7% tenía síntomas somáticos; 13.8%, síntomas de ansiedad y trastornos del sueño; 52.3%, disfunción social y 6.2% depresión. El sexo masculino tuvo mayor puntaje de depresión que las mujeres, y el estado civil soltero se relacionó con mayores puntajes de síntomas físicos, ansiedad e insomnio y depresión, comparado con los casados. Se encontró una relación inversa entre el promedio del puntaje del GHQ-28 y el semestre, la calificación en las asignaturas prácticas y la calificación total para síntomas físicos y ansiedad e insomnio. Conclusión. Es alta la proporción de estudiantes de enfermería con sospecha de trastorno de la salud mental. Algunos factores demográficos y académicos están relacionados con su salud mental y deben ser tenidos en cuenta por las instituciones formadoras de los futuros enfermeros.

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Objetivo. Avaliar o estado de saúde mental e sua relação com fatores associados entre os estudantes de enfermagem. Métodos. Se realizou um estudo de corte transversal com 130 estudantes do Colégio de Enfermagem e Parteira afiliada à Universidade de Ciências Médicas de Shiraz (Irã). Para a toma dos dados se empregou um formulário que incluía informação sobre as características demográficas, as médias de qualificação das matérias práticas e do total (matérias práticas mais teóricas), e o Questionário de Saúde Goldberg (GHQ-28) que mede sintomas agrupados em quatro dimensões (sintomas somáticos, ansiedade e insônia, disfunção social, e depressão). Resultados. A maioria dos participantes (65.1%) eram mulheres; 5.3% tinham entre 21 e 22 anos, eram solteiros (84.5%) e o 33.3% estudavam no sexto semestre. 68.5% dos estudantes tinham problemas com a saúde mental. Por dimensões de GHQ-28, se encontrou que 7.7% tinham sintomas somáticos, 13.8% sintomas de ansiedade e transtornos do sono, 52.3% disfunção social e 6.2% depressão. O sexo masculino teve maior pontuação de depressão que as mulheres, e o estado civil solteiro se relacionou com maiores pontuações de sintomas físicos, ansiedade e insônia e depressão, comparado com os casados. Se encontrou uma relação inversa entre a média da pontuação de GHQ-28 e o semestre, a qualificação nas matérias práticas e a qualificação total para sintomas físicos e ansiedade e insônia. Conclusão. É alta a proporção de estudantes de enfermagem com suspeita de transtorno da saúde mental. Alguns fatores demográficos e acadêmicos estão relacionados com a saúde mental dos estudantes e devem ser tidos em conta pelas instituições formadoras dos futuros enfermeiros.

Asunto(s)

Humanos , Ansiedad , Estudiantes de Enfermería , Salud Mental , Factores de Confusión Epidemiológicos , Encuestas y Cuestionarios , Trastornos de la Transición Sueño-Vigilia , Depresión

RESUMEN

Avin et al (2005) showed that, in the presence of exposure-induced mediator-outcome confounding, decomposing the total causal effect (TCE) using standard conditional exchangeability assumptions is not possible even under a nonparametric structural equation model with all confounders observed. Subsequent research has investigated the assumptions required for such a decomposition to be identifiable and estimable from observed data. One approach was proposed by VanderWeele et al (2014). They decomposed the TCE under three different scenarios: (1) treating the mediator and the exposure-induced confounder as joint mediators; (2) generating path-specific effects albeit without distinguishing between multiple distinct paths through the exposure-induced confounder; and (3) using so-called randomised interventional analogues where sampling values from the distribution of the mediator within the levels of the exposure effectively marginalises over the exposure-induced confounder. In this paper, we extend their approach to the case where there are multiple mediators that do not influence each other directly but which are all influenced by an exposure-induced mediator-outcome confounder. We provide a motivating example and results from a simulation study based on from our work in dental epidemiology featuring the 1982 Pelotas Birth Cohort in Brazil.

Asunto(s)

Causalidad , Factores de Confusión Epidemiológicos , Algoritmos , Brasil , Interpretación Estadística de Datos , Femenino , Humanos , Masculino , Modelos Estadísticos

RESUMEN

Os métodos de escore de propensão são a probabilidade de um sujeito receber um tratamento condicional em um conjunto de características de base (confundidores), sendo usado para comparar pacientes com distribuição similar de fatores de confusão, de modo que a diferença nos resultados forneça estimativa imparcial do efeito do tratamento. Esta revisão mostra os conceitos básicos dos escore de propensão e fornece orientação na implementação de métodos de propensão, além de outros, como estratificação, ponderação e ajuste de covariáveis, tornando-se uma guia prático para o clínico

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The propensity score methods are the probability of a subject receiving conditional treatment on a set of baseline characteristics (confounders), and are used to compare patients with similar confounding distributions, so that the difference in results provides an unbiased estimate of the treatment effect. This review shows the basic concepts of propensity scores, and provides guidelines for the implementation of propensity methods, and others based on it, such as stratification, weighting, and adjustment of covariables, becoming a practical guide for the clinician

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Ensayos Clínicos Controlados Aleatorios como Asunto/métodos , Estudios Observacionales como Asunto/métodos , Puntaje de Propensión , Factores de Confusión Epidemiológicos , Estadística como Asunto/métodos , Metodología como un Tema

RESUMEN

BACKGROUND: Atrial fibrillation and obstructive sleep apnea are common conditions, but little is known about obstructive sleep apnea and cardiovascular risk among atrial fibrillation patients. METHODS: Using the Truven Health MarketScan databases, we constructed a prospective cohort of atrial fibrillation patients from 2007 to 2014. Atrial fibrillation, obstructive sleep apnea, stroke, myocardial infarction, and confounders were defined using the International Classification of Disease-9-CM codes. We matched individuals with an obstructive sleep apnea diagnosis with up to five individuals without a diagnosis by age, sex, and enrollment date. Cox proportional hazards models adjusted for confounders and high-dimensional propensity scores. We included migraines as a control outcome. Bias analysis used published sensitivities and specificities to generate rate ratios adjusted for obstructive sleep apnea misclassification. RESULTS: We matched 56,969 individuals with an obstructive sleep apnea diagnosis to 323,246 without. During a mean follow-up of 16 months, 3234 incident strokes and 4639 incident myocardial infarctions occurred. After adjustment, obstructive sleep apnea diagnosis was strongly associated with reduced risk of incident stroke (hazard ratio = 0.48, 95% confidence interval = 0.43, 0.53) and myocardial infarction (0.40, [0.37, 0.44]) and a smaller reduced risk of migraines (0.82, [0.68, 0.99]). Bias analysis produced wide-ranging or inestimable rate ratios adjusted for misclassification of obstructive sleep apnea. CONCLUSIONS: Obstructive sleep apnea diagnosis in atrial fibrillation patients was strongly associated with reduced risk of incident cardiovascular disease. We discuss misclassification, selection bias, and residual confounding as potential explanations.

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Fibrilación Atrial/epidemiología , Isquemia Encefálica/epidemiología , Infarto del Miocardio/epidemiología , Apnea Obstructiva del Sueño/epidemiología , Accidente Cerebrovascular/epidemiología , Anciano , Enfermedades Cardiovasculares/epidemiología , Estudios de Cohortes , Factores de Confusión Epidemiológicos , Bases de Datos Factuales , Femenino , Humanos , Incidencia , Masculino , Persona de Mediana Edad , Modelos de Riesgos Proporcionales , Estudios Prospectivos , Riesgo , Sesgo de Selección , Apnea Obstructiva del Sueño/diagnóstico , Estados Unidos/epidemiología

RESUMEN

Mass gatherings exacerbate infectious disease risks by creating crowded, high-contact conditions and straining the capacity of local infrastructure. While mass gatherings have been extensively studied in the context of epidemic disease transmission, the role of gatherings in incidence of high-burden, endemic infections has not been previously studied. Here, we examine diarrheal incidence among 17 communities in Esmeraldas, Ecuador, in relation to recurrent gatherings characterized using ethnographic data collected during and after the epidemiologic surveillance period (2004-2007). Using distributed-lag generalized estimating equations, adjusted for seasonality, trend, and heavy rainfall events, we found significant increases in diarrhea risk in host villages, peaking 2 weeks after an event's conclusion (incidence rate ratio, 1.21; confidence interval, adjusted for false coverage rate of ≤0.05: 1.02, 1.43). Stratified analysis revealed heightened risks associated with events where crowding and travel were most likely (2-week-lag incidence rate ratio, 1.51; confidence interval, adjusted for false coverage rate of ≤0.05: 1.09, 2.10). Our findings suggest that community-scale mass gatherings might play an important role in endemic diarrheal disease transmission and could be an important focus for interventions to improve community health in low-resource settings.

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Aglomeración , Diarrea/epidemiología , Factores de Confusión Epidemiológicos , Brotes de Enfermedades , Ecuador/epidemiología , Monitoreo Epidemiológico , Femenino , Humanos , Incidencia , Masculino , Modelos Estadísticos , Factores de Riesgo , Población Rural , Viaje

RESUMEN

OBJECTIVE: To investigate the influence of maternal depression on child health-care services utilization. METHODOLOGY: Data from The Pelotas 2004 Birth Cohort collected at birth and at 12- and 24-month follow-ups were used. Four outcomes occurring in the second year of life were investigated: number of well-baby visits, number of medical appointments, number of visits to emergency rooms, and number of hospitalizations. The main exposure was maternal depression symptoms at 12-month post-partum as assessed by the Edinburgh Postpartum Depression Scale (EPDS). Adjusted prevalence ratios (PR) with 95% confidence intervals (95% CI) were calculated by Poisson regression. RESULTS: The prevalence of mothers with depressive symptoms was 27.6% (95% CI: 26.2-29.0%). These mothers showed a 10% lower probability of taking their children to well-baby visits (0.90; 0.85-0.95; p = 0.001); 16% higher probability to seek medical consultations (1.16; 1.09-1.25, p = 0.001); and they sought emergency services for their children more often (1.30; 1.17-1.45, p < 0.001) as compared to mothers who did not present depressive symptoms. Although the PR for hospitalizations was 26% higher for children from mothers with depressive symptoms, the association did not achieve statistical significance (1.26; 0.98-1.63; p = 0.072). CONCLUSION: Children from mothers with depressive symptoms attend fewer number of preventive consultations. In contrast, they are taken to medical and emergency care more often, suggesting that these children are given healthcare when they are at more advanced stages of their illnesses.

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Servicios de Salud del Niño/estadística & datos numéricos , Depresión Posparto , Madres/psicología , Aceptación de la Atención de Salud/estadística & datos numéricos , Adulto , Brasil/epidemiología , Preescolar , Factores de Confusión Epidemiológicos , Depresión Posparto/epidemiología , Servicio de Urgencia en Hospital/estadística & datos numéricos , Femenino , Hospitalización/estadística & datos numéricos , Humanos , Lactante , Cuidado del Lactante/estadística & datos numéricos , Masculino , Prevalencia , Escalas de Valoración Psiquiátrica , Adulto Joven

RESUMEN

We develop a Bayesian approach to estimate the average treatment effect on the treated in the presence of confounding. The approach builds on developments proposed by Saarela et al in the context of marginal structural models, using importance sampling weights to adjust for confounding and estimate a causal effect. The Bayesian bootstrap is adopted to approximate posterior distributions of interest and avoid the issue of feedback that arises in Bayesian causal estimation relying on a joint likelihood. We present results from simulation studies to estimate the average treatment effect on the treated, evaluating the impact of sample size and the strength of confounding on estimation. We illustrate our approach using the classic Right Heart Catheterization data set and find a negative causal effect of the exposure on 30-day survival, in accordance with previous analyses of these data. We also apply our approach to the data set of the National Center for Health Statistics Birth Data and obtain a negative effect of maternal smoking during pregnancy on birth weight.

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Teorema de Bayes , Sesgo , Peso al Nacer , Cateterismo Cardíaco/estadística & datos numéricos , Simulación por Computador , Factores de Confusión Epidemiológicos , Femenino , Humanos , Recién Nacido , Estudios Observacionales como Asunto , Embarazo , Puntaje de Propensión , Tamaño de la Muestra , Fumar/efectos adversos , Análisis de Supervivencia

RESUMEN

Accumulating evidence indicates that oxidative and nitrosative stress (O&NS) pathways play a key role in the pathophysiology of bipolar disorder (BD) and major depressive disorder (MDD). However, only a handful of studies have directly compared alterations in O&NS pathways among patients with MDD and BD types I (BPI) and BPII. Thus, the current study compared superoxide dismutase (SOD1), lipid hydroperoxides (LOOH), catalase, nitric oxide metabolites (NOx), malondialdehyde (MDA), and advanced oxidation protein products (AOPP) between mood disorder patients in a clinically remitted state. To this end 45, 23, and 37 participants with BPI, BPII, and MDD, respectively, as well as 54 healthy controls (HCs) were recruited. Z-unit weighted composite scores were computed as indices of reactive oxygen species (ROS) production and nitro-oxidative stress driving lipid or protein oxidation. SOD1, NOx, and MDA were significantly higher in MDD than in the other three groups. AOPP was significantly higher in BPI than in HCs and BPII patients. BPII patients showed lower SOD1 compared to all other groups. Furthermore, MDD was characterized by increased indices of ROS and lipid hydroperoxide production compared to BPI and BPII groups. Indices of nitro-oxidative stress coupled with aldehyde production or protein oxidation were significantly different among the three patient groups (BDII > BDI > MDD). Finally, depressive symptom scores were significantly associated with higher LOOH and AOPP levels. In conclusion, depression is accompanied by increased ROS production, which is insufficiently dampened by catalase activity, thereby increasing nitro-oxidative damage to lipids and aldehyde production. Increased protein oxidation with formation of AOPP appeared to be hallmark of MDD and BPI. In addition, patients with BPII may have protection against the damaging effects of ROS including lipid peroxidation and aldehyde formation. This study suggests that biomarkers related to O&NS could aid in the differentiation of MDD, BPI, and BPII.

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Trastorno Bipolar/patología , Trastorno Depresivo Mayor/patología , Estrés Nitrosativo , Estrés Oxidativo , Adulto , Biomarcadores/metabolismo , Estudios de Casos y Controles , Factores de Confusión Epidemiológicos , Femenino , Humanos , Modelos Lineales , Masculino , Persona de Mediana Edad , Análisis Multivariante , Superóxidos/metabolismo , Adulto Joven

RESUMEN

BACKGROUND: Studies have shown that cytokines play a role in bone remodeling. METHODS: In 1993, all hospital births occurred in Pelotas (Brazil) were identified and a total of 5249 newborns were included in the present cohort. Sub-samples of this cohort were visited during childhood and all members were traced at 11, 15, 18 and 22 years old. At 18 and 22 years the following biomarkers were measured: IL-6, CRP and adiponectin (the last one in a sub-sample) and bone mineral density (BMD-mg/cm2) was evaluated at 22 years. Crude regression analysis as well as adjusted for confounders (birth weight, pregnancy maternal smoking, gestational age, skin color, schooling, income, smoking, alcohol, physical activity, medical diagnosis of asthma, diabetes and hypertension, BMI, height, calcium intake, corticosteroid use, age at menarche, insulin and testosterone) were performed between the three biomarkers and the whole-body, lumbar spine and femoral BMD. RESULTS: No statistical significant association was found between IL-6 and CRP with BMD, in males. Significant inverse association in the adjusted analysis, among females, was found for the highest tertiles of CRP at 22 y (beta - 15.2 mg/cm2; 95% CI: -25.4; - 4.9; p = 004), of CRP and IL-6 at 22 years (beta - 20.0 mg/cm2; 95% CI: -31.7; - 8.3; p = 0.003), and of IL-6 and CRP at both ages (beta - 20.3 mg/cm2; 95% CI: -38.0; - 2.5; p = 0.001) with total body BMD. Significant association, among males, was also found between the highest tertile of adiponectin at 22 y (beta - 23.3 mg/cm2; 95% CI: -35.5; - 11.1; p = < 001; beta - 22.5 mg/cm2; 95% CI: -42.9; - 2.2; p = 0.03; and beta - 31.8 mg/cm2; 95% CI: -55.5; - 9.1; p = 0.006) and total body, lumbar spine and femur neck BMD, respectively; and, among females, - 17.8 mg/cm2; 95% CI: -34.9; - 0.9; p = 0.033, with lumbar spine BMD. CONCLUSION: CRP at 22 years, in females, seems to be a marker for total body BMD; adiponectin at 22 years is also a marker for BMD at the three sites, in males, and for lumbar spine BMD, in females.

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Adiponectina/sangre , Densidad Ósea , Proteína C-Reactiva/análisis , Interleucina-6/sangre , Adolescente , Antropometría , Biomarcadores/sangre , Niño , Factores de Confusión Epidemiológicos , Femenino , Cuello Femoral/fisiología , Humanos , Estudios Longitudinales , Vértebras Lumbares/fisiología , Masculino , Factores Sexuales , Factores Socioeconómicos , Adulto Joven

RESUMEN

BACKGROUND: Confusion in observational epidemiological studies distorts the relationship between exposure and event. "Step by step" regression models, diverts the decision to a statistical algorithm with little causal basis. Directed Acyclic Graphs (DAGs), qualitatively and visually assess the confusion. They can complement the decision on confounder control during statistical modeling. AIM: To evaluate the minimum set of confounders to be controlled in a cause-effect relationship with the use of "step-by-step regression" and DAGs, in a study of arsenic exposure. MATERIAL AND METHODS: We worked with data from Cáceres et al., 2010 in 66 individuals from northern Chile. The interindividual variability in the urinary excretion of dimethyl arsenic acid attributable to the GSTT1 polymorphism was estimated. A causal DAG was constructed using DAGitty v2.3 with the list of variables. A multiple linear regression model with the step-by-step backwards methodology was carried out. RESULTS: The causal diagram included 12 non-causal open pathways. The minimum adjustment set corresponded to the variables "sex", "body mass index" and "fish and seafood ingest". Confusion retention of the multivariate model included normal and overweight status, gender and the interaction between "water intake" and GSTT1. CONCLUSIONS: The use of DAG prior to the modeling would allow a more comprehensive, coherent and biologically plausible analysis of causal relationships in public health.

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Factores de Confusión Epidemiológicos , Estudios Epidemiológicos , Análisis de Regresión , Chile , Humanos , Modelos Lineales