Impact of Molar Incisor Hypomineralization on Oral Health-Related Quality of Life in Brazilian Schoolchildren Aged 8 to 10 Years

ABSTRACT Objective: To assess the impact of Molar Incisor Hypomineralization (MIH) and confounding factors on oral health-related quality of life (OHRQoL) according to the perception of 8 to 10-year-old children and their parents/caregivers. Material and Methods: A cross-sectional study including 403 students aged 8-10 years was carried out, in which OHRQoL was measured using the Child Perceptions Questionnaire administered to both children and parents/caregivers. The diagnosis of MIH was performed according to the previously proposed index. Dental caries experience, malocclusion, and sociodemographic factors were evaluated as confounders. Cluster analysis and Poisson regression with robust variance (p<0.05) were performed. Results: The prevalence of MIH was 13.4%. Parents/caregivers of children with MIH in incisors showed a higher impact prevalence in the emotional well-being domain (PR=1.92; 95%CI=1.16-3.19). Children with hypoplasia had a higher prevalence of negative impact on OHRQoL in the oral symptoms domain (PR=1.51; 95%CI=1.03-2.23). According to the perception of parents/caregivers, dental caries experience had a negative impact on the quality of life of students in the emotional well-being domain (PR=4.19; 95%CI=1.06-16.49) and in the total questionnaire score (PR=3.21; 95%CI=1.06-9.71). Conclusion: According to the perception of parents/caregivers, children with MIH in incisors showed a greater impact on OHRQoL. Additionally, the presence of hypoplasia affected the self-perception of OHRQoL in children, and caries experience influenced the OHRQoL of children, as perceived by parents/caregivers.

Statistical methods of unmeasured confounder control based on negative control theory / 中华流行病学杂志

Controlling unmeasured confounders in non-randomized controlled studies is challenging. Negative control theory is based on the theoretical concept that the test result of negative controls must be negative. Setting appropriate negative control incorporates the specificity of association into population studies for the identification and control of unmeasured confounders. This paper explains the principles to control unmeasured confounders using negative control theory from a statistical perspective. A detailed introduction of derived methods based on negative control theory is also introduced, including adjusted standardized mortality ratio method, calibrating P-value method, generalized difference-in-difference model and double negative control method. The reasonable application of those derived methods is also comprehensively summarized based on representative case studies. Negative control is an important statistical design to identify, revise and control unmeasured confounders and a valuable method for comparative effectiveness research based on real-world data.

The directionality of measurement bias: a directed acyclic graph-based structural perspective / 中华流行病学杂志

Measurement bias (MB) has been described in causal structures but is still not entirely clear. In practice, the correctness of substitution estimate (SE) of effect is a prerequisite for causal inference, usually based on a bidirectionally non-differential misclassification between the measured exposure and the measured outcome. Based on a directed acyclic graph (DAG), this paper proposes a structure for the single-variable measure, where its MB is derived from the choice of an imperfect, "input/output device-like" measurement system. The MB of the SE is influenced both by the measurement system itself and by factors outside the measurement system: while the independence or dependence mechanism of the measurement system still ensures that the MB of the SE is bidirectionally non-differential; however, the misclassification can be bidirectionally non-differential, unidirectionally differential, or bidirectionally differential resulted from the factors outside the measurement system. In addition, reverse causality should be defined at the level of measurement, where measured exposures can influence measured outcomes and vice versa. Combined with temporal relationships, DAGs help elucidate MB's structures, mechanisms, and directionality.

Análisis mediante variables instrumentales para establecer causalidad en investigaciones observacionales / Analysis through instrumental variables to establish causality in observational research

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)

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)

Linfopenia y riesgo de infecciones nosocomiales en ancianos en una institución de salud de Bogotá, Colombia. Estudio de casos y controles / Lymphopenia and risk of nosocomial infections in elderly in a health institution of Bogotá, Colombia. Cases and controls study

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.

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.

Índices triglicéridos-glucosa como estimadores de insulinorresistencia en personas con riesgo de desarrollar diabetes tipo 2 / Triglyceride-glucose indices as estimators of insulin resistance in people at risk of developing type 2 diabetes

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.

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.

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.

State of Mental Health and Associated Factors in Nursing Students from Southeastern Iran

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.

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.

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.

Compreendendo os métodos de escore de propensão na pesquisa clínica / Understanding the methods of propensity score in clinical research

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

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

Child dietary intake of folate and vitamin B12 and their neurodevelopment at 24 and 30 months of age / Ingesta de folato y vitamina B12 en la dieta del niño y su neurodesarrollo a los 24 y 30 meses de edad

Abstract Objective To evaluate whether child dietary intake of folate and vitamin B12, is associated with mental and psychomotor development in Mexican children, respectively, at 24 and 30 months of age. Materials and methods Information about neurodevelopment and dietary intake of folate and vitamin B12 at 24 and 30 months of age among 229 children belonging to a perinatal cohort was analyzed longitudinally. Dietary information was assessed using a semi-quantitative food frequency questionnaire, and neurodevelopment by Bayley Scale of Infant Development II. Results At 30 months of age, dietary folate intake was marginally associated with increased Mental Development Index (MDI) (β=8.33; 95%CI -0.48, 17.14; p=0.06). Non-significant positive associations of vitamin B12 with MDI were found. Psychomotor Development Index (PDI) was not associated with these nutrients. Conclusion Dietary folate intake in early childhood may benefit the mental development of children.

Resumen Objetivo Evaluar si la ingesta dietética infantil de folato y vitamina B12 se asocia con el desarrollo mental y psicomotor en niños mexicanos de 24 y 30 meses de edad. Material y métodos La información del neurodesarrollo y la ingesta dietética de folato y B12 a los 24 y 30 meses de edad de 229 niños pertenecientes a una cohorte perinantal, se analizó longitudinalmente. La información dietética se obtuvo por un cuestionario de frecuencia de alimentos semicuantitativo y el neurodesarrollo mediante la Escala de Desarrollo Infantil de Bayley II. Resultados A los 30 meses de edad, la ingesta dietética de folato se asoció marginalmente con un incremento del Índice de Desarrollo Infantil (IDM) (β=8.33; IC95% -0.48, 17.14; p=0.06). Se observaron asociaciones positivas no significativas entre la B12 y el IDM. El Índice de Desarrollo Psicomotor (IDP) no se asoció con dichos nutrientes. Conclusión La ingesta dietética infantil de folato puede beneficiar el desarrollo mental.

Aplicación de grafos acíclicos dirigidos en la evaluación de un set mínimo de ajuste de confusores: un complemento al modelamiento estadístico en estudios epidemiológicos observacionales / Directed acyclic graphs in statistical modelling of epidemiological studies

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.

Cognitive deficits in chronic pain patients, in a brief screening test, are independent of comorbidities and medication use / Déficits cognitivos em pacientes com dor crônica, em uma avaliação breve de triagem, são independentes de comorbidades e uso de medicações

ABSTRACT Objective To describe and analyze cognitive aspects in patients with chronic pain and a control group without pain. Method A case-control study was conducted on 45 patients with chronic pain and on 45 control subjects. Data including pain diagnosis, comorbidities and medication used, were evaluated. Cognitive tests, such as the Montreal Cognitive Assessment (MoCA), Verbal Fluency Test, Clock Drawing Test and Stroop Test, were applied. Results Patients with chronic pain showed a poorer performance, as shown by the scores of the MoCA test (p < 0.002), Verbal Fluency Test (p < 0.001), Clock Drawing Test (p = 0.022) and Stroop Test (p < 0.000). Chronic pain variable (p = 0.015, linear regression model) was an independent factor for results obtained with the MoCA. Conclusion Patients with chronic pain showed a poorer performance in a brief screening test for cognitive impairment not related to confounding variables, as comorbidities and pain-medication use.

RESUMO Objetivo Descrever e analisar aspectos cognitivos em pacientes com dor crônica e um grupo controle sem dor. Método Um estudo de caso-controle foi conduzido em 45 pacientes com dor crônica e 45 controles. Dados incluindo diagnóstico da dor, comorbidades e medicações utilizadas foram avaliados. Foram aplicados testes cognitivos, tais comoMontreal Cognitive Assessment, Teste da Fluência verbal, Teste do relógio e Teste de Stroop. Resultados Pacientes com dor crônica apresentaram uma pior performance, em scores do MoCA (p < 0.002), Fluência verbal (p < 0.001), Teste do relógio (p = 0.022) e Stroop (p < 0.000). Dor crônica (p = 0.015, modelo de regressão linear) foi um fator independente para os piores resultados obtidos no MoCA. Conclusão Pacientes com dor crônica apresentaram uma pior performance em uma avaliação breve para comprometimento cognitivo, não relacionada a variáveis confundidoras, como comorbidades e medicações utilizadas para dor.

Utilização de diagramas causais em epidemiologia: um exemplo de aplicação em situação de confusão / Use of causal diagrams in Epidemiology: application to a situation with confounding / Utilización de diagramas causales en epidemiología: un ejemplo de su aplicación en situación de confusión

Resumo: Apesar do crescente reconhecimento de seu potencial, os diagramas causais ainda são pouco utilizados na investigação epidemiológica. Uma das possíveis razões é que muitos programas de investigação envolvem temas sobre o qual há certo grau de incerteza sobre os mecanismos dos processos que geram os dados. Neste trabalho, a relação entre estresse ocupacional e obesidade é utilizada como um exemplo de aplicação de diagramas causais em questões relacionadas ao confundimento. São apresentadas etapas da seleção de variáveis para ajuste estatístico e da derivação das implicações estatísticas de um diagrama causal. A principal vantagem dos diagramas causais é tornar explícitas as hipóteses adjacentes ao modelo considerado, permitindo que suas implicações possam ser analisadas criticamente, facilitando, dessa forma, a identificação de possíveis fontes de viés e incerteza nos resultados de um estudo epidemiológico.

Abstract: Epidemiological research still rarely uses causal diagrams, despite growing recognition of their explanatory potential. One possible reason is that many research programs involve themes in which there is a certain degree of uncertainty as to mechanisms in the processes that generate the data. In this study, the relationship between occupational stress and obesity is used as an example of the application of causal diagrams to questions related to confounding. The article presents the selection stages for variables in statistical adjustment and the derivation of a causal diagram's statistical implications. The main advantage of causal diagrams is that they explicitly reveal the respective model's underlying hypotheses, allowing critical analysis of the implications and thereby facilitating identification of sources of bias and uncertainty in the epidemiological study's results.

Resumen: A pesar del creciente reconocimiento de su potencial, los diagramas causales todavía se utilizan poco en la investigación epidemiológica. Una de las posibles razones es que muchos programas de investigación están involucrados en temas sobre los cuales existe un cierto grado de incertidumbre acerca de los mecanismos de los procesos que generan los datos. En este trabajo, la relación entre estrés ocupacional y obesidad se utiliza como un ejemplo de aplicación de diagramas causales en cuestiones relacionadas con la confusión. Se presentan etapas de la selección de variables para el ajuste estadístico y de la derivación de las implicaciones estadísticas de un diagrama causal. La principal ventaja de los diagramas causales es hacer explícitas las hipótesis adyacentes al modelo considerado, permitiendo que sus implicaciones puedan ser analizadas críticamente, facilitando, de esta forma, la identificación de posibles fuentes de sesgo e incertidumbre en los resultados de un estudio epidemiológico.

Disponibilidad de Flúor en Saliva y Biofilms en Escolares Expuestos a Leche o Agua Fluorurada / Availability of Fluoride in Saliva and Biofilms in School Children Exposed to Fluoride in Water or Milk

La caries sigue siendo un problema de Salud Pública, por la alta prevalencia y severidad que afecta a la población. En Chile, la incorporación de flúor en el agua y la leche, son medidas de salud pública en la prevención de caries que se distribuye en zonas urbanas y rurales respectivamente. La evidencia científica nos permite sostener que el fluoruro disponible en saliva y placa bacteriana es el principal responsable del efecto preventivo de este compuesto en el proceso de caries. El objetivo fue comparar los niveles de flúor en saliva y placa bacteriana, antes y después de la ingesta de leche, de los escolares que consumen leche fluorurada y de los que consumen leche sin flúor preparada con agua potable fluorurada de la Región de la Araucanía de Chile. Se realizó un estudio de muestras repetidas de saliva y placa bacteriana en 165 niños(as) incorporados(as) en el Programa PAE de 16 escuelas rurales y urbanas. Se tomaron muestras de saliva y placa bacteriana antes del desayuno, muestras de saliva 60 min después y muestras de placa bacteriana 120 minutos después del desayuno. La concentración de fluoruro en saliva se observa muy similar sin importar el vehículo a través del cual se le administre, sea este leche fluorurada o leche sin fluor preparada con agua fluorurada, tanto en las muestras basales como en las muestras obtenidas después del desayuno. En cambio en placa bacteriana si se observan pequeñas diferencias que, siendo estadísticamente significativa, pueden no tener mucha relevancia clínica por ser demasiado pequeñas. Estos resultados refuerzan la hipótesis de que la estrategia de leche fluorurada tiene resultados similares al agua fluorurada.

Caries continue to be a public health problem, due to their high prevalence and their severe effect on people. Currently in Chile, adding fluoride to water and milk are public health measures to prevent caries that are distributed in urban and rural areas respectively. Scientific evidence supports the availability of fluoride in saliva and bacterial plaque being the most effective prevention against caries. The goal was to compare the levels of fluoride in saliva and bacterial plaque before and after drinking milk, among school-children who consume fluoridated milk and those who consume un-fluoridated milk prepared with fluoridated drinking water, in the La Araucanía Region of Chile. A study was conducted of repeated samples of saliva and bacterial plaque in 165 children within the PAE program at 16 rural and urban schools. Saliva and bacterial plaque samples were taken before breakfast, saliva samples were taken 60 minutes after breakfast and bacterial plaque samples were taken 120 min after breakfast. The concentration of fluoride in saliva was found to be very similar regardless of the manner in which it was administered. So it was similar in children drinking fluoridated milk and un-fluoridated milk prepared with fluoridated water, and similar both before and after breakfast. In contrast, we found small differences for bacterial plaque, that are statistically significant. However, they may not be clinically significant as they are too small. These results reinforce the hypothesis that the strategy of adding fluoride to milk has similar results to adding fluoride to water.

Fatores de risco relacionados à mortalidade fetal / Risk factors related to fetal mortality

Introdução: Pouca atenção tem sido dada às mortes que ocorrem antes do nascimento, apesar da mortalidade fetal ser influenciada pelas mesmas circunstâncias e ter as mesmas etiologias que a mortalidade neonatal precoce. O objetivo deste estudo foi analisar os fatores de risco associados à mortalidade fetal. Métodos: Estudo do tipo caso-controle, incluindo os partos ocorridos entre Março/1998 e Maio/2004. Foram incluídos 183 casos (natimortos) e 342 controles (nativivos). Para testar a associação entre as variáveis independente (preditoras) e dependente (natimortos), foi utilizado o teste qui-quadrado e o teste exato de Fisher, quando indicado, considerando-se o nível de significância de 5%. Para determinação da força da associação foi utilizada a estimativa do risco relativo para os estudos de caso-controle, Odds Ratio (OR), calculando seu intervalo de confiança a 95%. Foi realizada análise de regressão logística seguindo o modelo hierarquizado para controle dos fatores de confusão. Resultados: A taxa de mortalidade fetal correspondeu a 16,8/1.000 nascimentos vivos. Depois da análise multivariada, as variáveis que persistiram significativamente associadas ao óbito fetal foram: presença de malformações (OR= 9,7; IC95%=4,7-20,2), número de consultas durante o pré-natal inferior a seis (OR=5,1; IC95%=3,3-7,8), síndromes hipertensivas (OR=2.7; IC95%=1,5-4,7), menos do que oito anos de estudo (OR=1,6; IC95%=1,0-2,6) e natimortalidade prévia (OR=11,5; IC95%=3,2-41,7). Conclusão: Os fatores de risco identificados e que estiveram relacionados com a morte fetal foram a presença de malformações congênitas, números de consultas de pré-natal inferior a seis, síndromes hipertensivas, menos do que oito anos de estudo e natimortalidade prévia.

Introduction: Little attention has been given to deaths that occur before birth, although fetal mortality is influenced by the same circumstances and has the same causes as early neonatal mortality. The aim of this study was to analyze the risk factors associated with fetal mortality. Methods: A case-control study including births between March 1998 and May 2004. The study included 183 cases (stillbirths) and 342 controls (live births). To test the association between independent (predictors) and dependent (stillborn) variables, we used the chi-square and Fisher’s exact tests, when indicated, considering the significance level of 5%. To determine the strength of association we used an estimate of relative risk for case-control studies, odds ratio (OR), calculating the confidence interval at 95%. A logistic regression analysis was performed following the hierarchy model to control for confounding factors. Results: The fetal mortality rate amounted to 16.8/1,000 live births. After multivariate analysis, the variables that remained significantly associated with fetal death were malformation (OR = 9.7, 95% CI 4.7 to 20.2), fewer than six visits during the prenatal period (OR = 5.1, 95% CI 3.3 to 7.8), hypertensive disorders (OR = 2.7, 95% CI 1.5 to 4.7), fewer than eight years of schooling (OR = 1.6 , 95% CI 1.0 to 2.6) and prior stillbirth (OR = 11.5, 95% CI 3.2 to 41.7). Conclusion: The identified risk factors for fetal death were congenital malformations, fewer than six prenatal consultations, hypertensive disorders, fewer than eight years of schooling, and previous stillbirth.

Sensitivity analysis for unmeasured confounders using an electronic spreadsheet

In studies assessing the effects of a given exposure variable and a specific outcome of interest, confusion may arise from the mistaken impression that the exposure variable is producing the outcome of interest, when in fact the observed effect is due to an existing confounder. However, quantitative techniques are rarely used to determine the potential influence of unmeasured confounders. Sensitivity analysis is a statistical technique that allows to quantitatively measuring the impact of an unmeasured confounding variable on the association of interest that is being assessed. The purpose of this study was to make it feasible to apply two sensitivity analysis methods available in the literature, developed by Rosenbaum and Greenland, using an electronic spreadsheet. Thus, it can be easier for researchers to include this quantitative tool in the set of procedures that have been commonly used in the stage of result validation.

Em estudos que avaliam o efeito de uma dada variável de exposição e um determinado desfecho de interesse, uma situação de confusão pode ser caracterizada pela falsa aparência de que a variável de exposição produz o desfecho de interesse quando, de fato, o efeito observado se deve a um fator de confundimento que está presente. Entretanto, é pouco freqüente a utilização de técnicas quantitativas para determinar a influência potencial de confundidores não mensurados. A análise de sensibilidade é uma técnica estatística que permite uma medida quantitativa do impacto de uma variável confundidora não mensurada na associação de interesse que está sendo avaliada. O objetivo do artigo foi viabilizar a aplicação, por meio de planilha eletrônica, de dois métodos de análise de sensibilidade disponíveis na literatura, desenvolvidos por Rosenbaum e Greenland. Dessa forma, é possível facilitar ao pesquisador a incorporação desse ferramental quantitativo ao conjunto de procedimentos que já são comuns na etapa de validação dos resultados.

Which factors could explain the low birth weight paradox? / Quais fatores podem explicar o paradoxo do baixo peso ao nascer?

OBJECTIVE: Low birth weight children are unusual among well-off families. However, in Brazil, low birth weight rate was higher in a more developed city than in a less developed one. The study objective was to find out the reasons to explain this paradox. METHODS: A study was carried out in two municipalities, Ribeirão Preto (Southeastern Brazil) and São Luís (Northeastern Brazil), which low birth weight rates were 10.7 percent and 7.6 percent respectively. Data from two birth cohorts were analyzed: 2,839 newborns in Ribeirão Preto in 1994 and 2,439 births in São Luís in 1997-1998. Multiple logistic regression analysis was performed, adjusted for confounders. RESULTS: Low birth weight risk factors in São Luís were primiparity, maternal smoking and maternal age less than 18 years. In Ribeirão Preto, the associated variables were family income between one and three minimum wages, maternal age less than 18 and equal to or more than 35 years, maternal smoking and cesarean section. In a combined model including both cohorts, Ribeirão Preto presented a 45 percent higher risk of low birth weight than São Luís. When adjusted for maternal smoking habit, the excess risk for low birth weight in Ribeirão Preto compared to São Luís was reduced by 49 percent, but the confidence interval was marginally significant. Differences in cesarean section rates between both cities contributed to partially explain the paradox. CONCLUSIONS: Maternal smoking was the most important risk factor for explaining the difference in low birth weight between both cities. The other factors contributed little to explain the difference in low birth weight rates.

OBJETIVO: O baixo peso ao nascer é incomum em recém-nascidos de maior nível socioeconômico. Contudo, no Brasil, a taxa de baixo peso ao nascer foi maior em cidade mais desenvolvida do que em município menos desenvolvido. O objetivo do estudo foi buscar razões para explicar este paradoxo. MÉTODOS: O estudo foi realizado em Ribeirão Preto (SP) e em São Luís (MA), cujas taxas de baixo peso ao nascer eram 10,7 por cento e 7,6 por cento, respectivamente. Foram analisados dados de duas coortes de nascimentos: 2.839 recém-nascidos em Ribeirão Preto em 1994 e 2.439 em São Luís em 1997/98. Foi realizada análise de regressão logística múltipla, ajustada para efeito de confusão. RESULTADOS: Os fatores de risco associados em São Luís foram primiparidade, idade materna menor que 18 anos e tabagismo materno. Em Ribeirão Preto, os fatores de risco foram: renda familiar entre um e três salários-mínimos, idade materna menor que 18 e igual ou maior que 35 anos, tabagismo materno e parto cesáreo. Em modelo conjunto incluindo ambas as coortes, Ribeirão Preto apresentou risco 45 por cento maior para em relação a São Luís. Quando ajustado para tabagismo materno, o excesso de risco em Ribeirão Preto, reduziu-se em 49 por cento, mas o intervalo de confiança esteve marginalmente significante. Diferenças nas taxas de cesárea entre as duas cidades contribuíram para explicar uma porção adicional desse paradoxo. CONCLUSÕES: O tabagismo materno foi o fator de risco mais importante capaz de explicar a diferença no baixo peso ao nascer entre as duas cidades. Os outros fatores pouco contribuíram para explicar a diferença nas taxas de baixo peso ao nascer.