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Breastfeeding has been consistently associated with higher intelligence since childhood. However, this relation could be confounded due to maternal selection bias. We estimated the association between predominant breastfeeding and intelligence in school-age children considering potential selection bias and we simulated the intelligence gap reduction between low versus higher socioeconomic status children by increasing breastfeeding. We analysed predominant breastfeeding practices (breastmilk and water-based liquids) of children 0-3 years included in the Mexican Family Life Survey (MxFLS-1). Intelligence was estimated as the z-score of the abbreviated Raven score, measured at 6-12 years in the MxFLS-2 or MxFLS-3. We predicted breastfeeding duration among children with censored data with a Poisson model. We used the Heckman selection model to assess the association between breastfeeding and intelligence, correcting for selection bias and stratified by socioeconomic status. Results show after controlling for selection bias, a 1-month increase in predominant breastfeeding duration was associated with a 0.02 SD increase in the Raven z-score (p < 0.05). The children who were predominantly breastfed for 4-6 months versus <1 month had 0.16 SD higher Raven z-score (p < 0.05). No associations were found using multiple linear regression models. Among low socioeconomic status children, increasing predominantly breastfeeding duration to 6 months would increase their mean Raven z-score from -0.14 to -0.07 SD and reduce by 12.5% the intelligence gap with high socioeconomic status children. In conclusion, predominant breastfeeding duration was significantly associated with childhood intelligence after controlling for maternal selection bias. Increased breastfeeding duration may reduce poverty-driven intelligence inequities.

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PURPOSE: We tested the hypothesis that low institutional trust would be associated with depressive symptom elevation, with attention to potential selection bias. METHODS: The District of Columbia Area Survey (DCAS) was conducted by mail in 2018. Invitations sent to 8800 households resulted in a sample of 1061 adults. Institutional trust questions referenced nonprofit organizations, businesses, and government. Depressive symptom elevation was assessed using PHQ-9. Logistic regression model estimates were compared with and without adjustment for sociodemographic characteristics and neighborhood satisfaction; among complete cases and following multiple imputation of missing covariate data; and with and without survey weights or correction for collider selection bias. RESULTS: Of 968 participants without missing depressive symptom or trust data, 24% reported low institutional trust. Low institutional trust was associated with elevated depressive symptoms (adjusted OR following multiple imputation: 2.0; 95% CI: 1.1, 3.4), although the association was attenuated with use of survey weights (adjusted OR incorporating multiple imputation and survey weights: 1.6; 95% CI: 0.7, 3.2). CONCLUSIONS: Under contrasting scenarios where low institutional trust and depressive symptoms jointly increase nonresponse, selection bias could lead to under- or overestimation of this association. Future research could explore posited selection bias scenarios that differ in direction of bias.

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Selective outcome reporting (SOR) is a type of bias that can compromise the validity of results and affect evidence-based practice. SOR can overestimate the effect of an intervention and lead to conclusions that a treatment is effective when it is not. This study aimed to investigate the prevalence of SOR in publications of RCTs on nonsurgical periodontal therapy (NSPT) and to verify associated factors. The protocols were searched and selected on the www.clinicaltrials.gov platform up to January 16, 2022. Corresponding publications were identified, and data extraction and discrepancy analysis were performed. The risk of bias was assessed according to the RoB2 tool. One hundred forty-five studies (174 publications) were included. The prevalence of SOR was 49.7% and was unclear in nearly one third of studies (27.6%). Only 31.7% of the primary outcomes were completely described in the publications. The overall risk of bias was high in 60% of the included studies. SOR was associated with statistical significance (p < .001), and multiple publications of the same study (p = .005). Our study demonstrated the high prevalence of SOR, highlighting the need to improve the quality of reporting of RCTs on NSPT studies.

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ABSTRACT: The improper disposal of pesticide packaging wastes (PPW) has posed serious harm to the environment, including groundwater and soil pollution and even health concerns to the public. To address the environmental concerns and public health issues, there is a need to recycle the pesticides packaging waste (RPPW). Though small farmers in many developing countries have joined the cooperatives to reduce the production costs and increase the product premium, how these cooperatives improve farmers' RPPW behaviors is still sparse. The current study used data collected from 725 apple farmers in Shaanxi and Gansu provinces of China to explore the phenomenon empirically. Recycling decisions and degree are used to portray the farmers' RPPW behaviors. Firstly, the Logit model was used to analyze the effect of joining cooperatives on farmers' recycling decisions. Further, to address the sample selection bias, the present study employed the propensity score matching (PSM) method for empirical analysis concerning the effect of joining cooperatives on farmers' recycling degree. Results showed that joining cooperatives positively and significantly influences farmers' recycling decisions. If farmers join a cooperative, the probability of the recycling decisions and degree will increase by 20.30% and 27.50%, respectively. Moreover, it is also found that some other factors such as education level, environmental and public health risk perception, peer effect, and relationship network also significantly influence farmers' recycling decisions. Moreover, considering the differences in farmers' gender, age, and educational attainment, the study unveiled the heterogeneous effects of joining cooperatives on farmers' RPPW behaviors. The findings revealed that gender and age variables have noticeable masking effects while education level has a typical threshold effect. The overall findings provided insights for policymakers to emphasize the development of agricultural cooperatives, improve the risk and interest linkage mechanism, and build the RPPW system. These implications are also supportive for policymakers in other developing countries.

RESUMO: O descarte inadequado de resíduos de embalagens de pesticidas (PPW) tem causado sérios danos ao meio ambiente, incluindo a poluição das águas subterrâneas e do solo e até mesmo problemas de saúde pública. Para abordar as preocupações ambientais e questões de saúde pública, há a necessidade de reciclar os resíduos de embalagens de pesticidas (RPPW). Embora pequenos agricultores, em muitos países em desenvolvimento, tenham se unido às cooperativas para reduzir os custos de produção e aumentar o prêmio do produto, ainda é escassa a forma como essas cooperativas melhoram os comportamentos de RPPW dos agricultores. O estudo atual usou dados coletados de 725 produtores de maçã nas províncias de Shaanxi e Gansu da China para explorar o fenômeno empiricamente. Decisões e grau de reciclagem são usados para retratar os comportamentos de RPPW dos agricultores. Primeiramente, o modelo Logit foi utilizado para analisar o efeito da adesão às cooperativas nas decisões de reciclagem dos agricultores. Além disso, para abordar o viés de seleção da amostra, o presente estudo empregou o método Propensity Score Matching (PSM) para análise empírica sobre o efeito da associação de cooperativas no grau de reciclagem dos agricultores. Os resultados mostraram que a adesão às cooperativas influencia positiva e significativamente as decisões de reciclagem dos agricultores. Se os agricultores aderirem a uma cooperativa, a probabilidade das decisões de reciclagem aumentará em 20,30%, e o grau de reciclagem aumentará em 27,50%. Além disso, também se constata que alguns outros fatores como nível de escolaridade, percepção de risco ambiental e de saúde pública, efeito de pares e rede de relacionamento também influenciam significativamente as decisões de reciclagem dos agricultores. Além disso, considerando as diferenças de gênero, idade e escolaridade dos agricultores, o estudo também revelou os efeitos heterogêneos da adesão às cooperativas sobre os comportamentos de RPPW dos agricultores. Os resultados revelaram que as variáveis de gênero e idade têm efeitos de mascaramento perceptíveis, enquanto o nível de escolaridade tem um efeito limiar típico. As descobertas gerais fornecem insights para os formuladores de políticas enfatizarem o desenvolvimento de cooperativas agrícolas, melhorar o mecanismo de vinculação de risco e interesse e construir o sistema RPPW. Essas implicações também são favoráveisaos formuladores de políticas em outros países em desenvolvimento.

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Athletes born closer to an arbitrary cut-off date are more likely to reach an elite level in sport, which is supported by a phenomenon called the relative age effect (RAE). It is important to determine whether this phenomenon is present in a sport to minimize this selection bias. This study aimed to investigate the prevalence of RAE in elite volleyball athletes, considering the influence of gender, the playing position (Setter, Middle, Libero, Opposite, and Outside Hitter) and the performance level (attack points, aces, and block points). The sample comprised 203 male and 193 female athletes competing in the Superliga A in the 2020/2021 season, which was equivalent to all of the teams of the championship. The data collection was performed during May and June, 2021. Athletes were organized according to gender, the playing position, and performance in the Superliga. For performance variables, athletes were separated based on the median value (90.0), and classified as high- or low-performance. Chi-squared tests were performed to verify differences between birth date distributions in relation to the aforementioned variables. Results indicated overrepresentation of relatively older male athletes (Q1 = 35.96%; Q2 = 27.59%; Q3 = 19.21%; Q4 = 17.24%), especially in Middles, Opposites, and Outside Hitters, regardless of their performance level. Considering females, no differences were found. Our findings suggest that RAE operates differently for men and women in elite Brazilian volleyball. The characteristics of the games played by male and female elite athletes may lead to different talent selection processes, affecting the likelihood of RAE prevalence.

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Resumen Los resultados de diversos hallazgos de investigación han sido objeto de crítica, en especial en los últimos años, debido a presencia de errores sistemáticos (sesgos), los que ponen en duda la validez interna de los resultados obtenidos. Estos sesgos pueden ocurrir en cualquier etapa del curso de una investigación, es decir, desde la planificación del estudio hasta la presentación y publicación de sus resultados. Los sesgos se han clasificado de diferentes formas, intentado agruparlos bajo dimensiones conceptuales, objeto de organizar de mejor forma la información existente, que además es considerable. Los sesgos pueden ocurrir por diversos motivos, pero en general, los más frecuentes son aquellos originados por el observador (él o los que miden), por lo que es observado (sujeto en estudio); y aquello con lo que se observa (instrumento de medición). Por otra parte, varios de los múltiples sesgos existentes, se pueden agrupar en: sesgos de selección, de medición o información, y de confusión. El objetivo de este manuscrito fue comentar la importancia de los sesgos más comunes en la investigación quirúrgica, y su relación con algunos diseños de investigación; así como, conocer las estrategias existentes para minimizar su ocurrencia.

The results of many research findings have come under scrutiny in recent years due to the introduction of systematic errors (biases), which can occur at any stage during an investigation, from planning to presentation of results and their presentation and further publication. Biases have been classified in different ways, trying to group them under conceptual dimensions to better organize the existing information, which is considerable. Biases can occur for various reasons, but in general, the most frequent are those originated by the observer, what is observed; and what is observed with. I.e., the subject that is measured, who measures it and with what it measures it. On the other hand, several of the multiple biases can be grouped into selection, measurement or information, and confounding biases. The aim of this manuscript was to comment on the importance of the most common biases in surgical research, and their relationship with some research designs; as well as know the existing strategies to reduce its occurrence.

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Abstract: Correctly recognizing gender identity in population-based surveys is essential to develop effective public health strategies to improve the living conditions of transgender and gender-diverse populations, as well as to adequately collect data on cisgender individuals. This study aims to present the two-step measure as the best strategy for assessing gender identity in Brazilian surveys, thus we performed two separate analyses. Firstly, we conducted a systematic review concerning HIV-related care among Brazilian transgender and gender-diverse populations to assess the strategy used to identify participants' gender identity. Secondly, we re-analyzed data from a recent survey that included Brazilian transgender populations, comparing characteristics and health outcomes from the sample identified by single-item and by the two-step measure. Concerning the systematic review, from 6,585 references, Brazilian research teams published seven articles, and only one study used the two-step measure. Regarding this survey, the two-step measure recognized 567 cisgender and 773 transgender and gender diverse participants among the 1,340 participants who answered the questionnaire, whereas the single-item measure was able to recognize only 540 transgender and gender diverse people. Furthermore, 31 transgender women self-identified as "transgender men" on the single-item measure. Therefore, although scarcely used in Brazil, the two-step measure is a more accurate strategy to recognize gender identity.

Resumo: O reconhecimento correto da identidade de género em inquéritos populacionais é essencial para desenvolver estratégias eficazes de saúde pública para melhorar as duras condições de vida das populações transgênero e não binárias, além de coletar dados adequados sobre pessoas cisgênero. O estudo tem como objetivo apresentar a medida de dois passos como a melhor estratégia para avaliar a identidade de gênero em inquéritos brasileiros. Para tanto, fizemos duas análises separadas. Primeiro, realizamos uma revisão sistemática sobre a assistência relacionada ao HIV em populações transgênero e não binárias brasileiras para avaliar a estratégia aplicada ao reconhecimento da identidade de gênero dos participantes. Depois, reanalisamos os dados de um inquérito recente que incluiu populações transgênero brasileiras, comparando as características e os desfechos de saúde na amostra identificada com as medidas de item único e de dois passos, respectivamente. Quanto à revisão sistemática, entre 6.585 referências, sete artigos foram publicados por pesquisadores brasileiros, e apenas um estudo aplicou a medida de dois passos. Com relação ao inquérito, a medida de dois passos reconheceu 567 pessoas cisgênero e 773 pessoas transgênero e não binárias entre os 1.340 participantes que iniciaram o questionário, enquanto a medida de item único reconheceu somente 540 pessoas transgênero e não binárias. Além disso, 31 mulheres transgênero se identificaram como "homens transgênero", quando foi usada a medida de item único. Portanto, embora a medida de dois passos seja pouco aplicada no Brasil, é uma estratégia mais precisa para reconhecer a identidade de gênero.

Resumen: Reconocer correctamente la identidad de género en las encuestas basadas en población es esencial para desarrollar estrategias públicas de salud efectivas, con el objeto de mejorar las duras condiciones de vida de las poblaciones transgénero y de género diverso, así como recabar adecuadamente datos sobre personas cisgénero. El objetivo de este estudio es presentar un modelo de dos etapas como la mejor estrategia para evaluar la identidad de género en encuestas brasileñas. Para tal fin, se realizaron dos análisis separados. En primer lugar, se llevó a cabo una revisión sistemática relacionada con los cuidados recibidos por la población transgénero brasileña con VIH y poblaciones de género diverso, con el fin de evaluar la estrategia aplicada para reconocer la identidad de género de los participantes. En segundo lugar, volvimos a analizar los datos de una encuesta reciente, que incluyó a poblaciones transgénero brasileñas, comparando características y resultados de salud de la muestra identificada por un modelo de ítem único y por el modelo de dos etapas. Respecto a la revisión sistemática, de las 6.585 referencias se publicaron siete artículos por parte de equipos de investigación brasileños, y solamente un estudio donde se aplicó el modelo de dos etapas. Respecto a esta encuesta, el modelo de dos etapas reconoció a 567 cisgénero y 773 transgénero, así como a participantes de género diverso, entre los 1.340 participantes que realizaron el cuestionario, aunque el modelo de un único ítem fue capaz de reconocer solo a 540 personas transgénero y de género diverso. Además, 31 mujeres transgénero se autoidentificaron como "hombres transgéneros" en el modelo de un único ítem. Por consiguiente, a pesar de que se aplicó escasamente en Brasil, el modelo de dos etapas es una estrategia más precisa para reconocer la identidad de género.

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Data derived from electronic health records (EHR) are heterogeneous with availability of specific measures dependent on the type and timing of patients' healthcare interactions. This creates a challenge for research using EHR-derived exposures because gold-standard exposure data, determined by a definitive assessment, may only be available for a subset of the population. Alternative approaches to exposure ascertainment in this case include restricting the analytic sample to only those patients with gold-standard exposure data available (exclusion); using gold-standard data, when available, and using a proxy exposure measure when the gold standard is unavailable (best available); or using a proxy exposure measure for everyone (common data). Exclusion may induce selection bias in outcome/exposure association estimates, while incorporating information from a proxy exposure via either the best available or common data approaches may result in information bias due to measurement error. The objective of this paper was to explore the bias and efficiency of these three analytic approaches across a broad range of scenarios motivated by a study of the association between chronic hyperglycemia and five-year mortality in an EHR-derived cohort of colon cancer survivors. We found that the best available approach tended to mitigate inefficiency and selection bias resulting from exclusion while suffering from less information bias than the common data approach. However, bias in all three approaches can be severe, particularly when both selection bias and information bias are present. When risk of either of these biases is judged to be more than moderate, EHR-based analyses may lead to erroneous conclusions.

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BACKGROUND: Large-scale health surveys often consider sociodemographic characteristics and several health indicators influencing physical activity that often vary across subpopulations. Data in a survey for some small subpopulations are often not representative of the larger population. OBJECTIVE: We developed a multilevel regression and poststratification (MRP) model to estimate leisure-time physical activity across Brazilian state capitals and evaluated whether the MRP outperforms single-level regression estimates based on the Brazilian cross-sectional national survey VIGITEL (2018). METHODS: We used various approaches to compare the MRP and single-level model (complete-pooling) estimates, including cross-validation with various subsample proportions tested. RESULTS: MRP consistently had predictions closer to the estimation target than single-level regression estimations. The mean absolute errors were smaller for the MRP estimates than single-level regression estimates with smaller sample sizes. MRP presented substantially smaller uncertainty estimates compared to single-level regression estimates. Overall, the MRP was superior to single-level regression estimates, particularly with smaller sample sizes, yielding smaller errors and more accurate estimates. CONCLUSION: The MRP is a promising strategy to predict subpopulations' physical activity indicators from large surveys. The observations present in this study highlight the need for further research, which could, potentially, incorporate more information in the models to better interpret interactions and types of activities across target populations.

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ABSTRACT: Objective: The study aimed to validate the estimates of adult smokers determined by Vigitel for small areas, defined by the Health Vulnerability Index (IVS). Methods: The database of the Health Survey of the Metropolitan Region of Belo Horizonte (RMBH) carried out in 2010 and the data from Vigitel in the period from 2010 to 2013 were used to obtain estimates of adult smokers by IVS. With Vigitel, the estimate of smokers by IVS was obtained by the indirect estimation method in small areas. The prevalence of adult smokers was compared, considering RMBH as the gold standard. The t test was used to evaluate the difference between the means and the Pearson correlation, with a significance level of 5%. Results: When stratifying by IVS in the household survey, the prevalence of adult smokers ranged from 13.39% (95%CI 11.88 - 14.91) for residents in a low-risk area to 22.9% (95%CI 12.33 - 33.48) among residents in a very high-risk area. With Vigitel, according to IVS, the prevalence of adult smokers ranged from 11.98% (95%CI 10.75 - 13.21) for residents in the low-risk area to 22.31% (95%CI 18.25 - 26.1) in very high-risk areas. The prevalence was similar between the two surveys, showing good Pearson correlation (r = 0.93). Conclusion: The study points out that the estimates of smokers were similar in both surveys, showing the external validity of Vigitel. There was a gradient in prevalence, with progressive increase, identifying a higher proportion of smokers in high-risk areas.

RESUMO: Objetivo: Validar as estimativas de adultos fumantes produzidas pelo Sistema de Vigilância de Fatores de Risco e Proteção para Doenças Crônicas por inquérito telefônico (Vigitel) para pequenas áreas, definidas pelo Índice de Vulnerabilidade à Saúde (IVS). Métodos: A base de dados do Inquérito de Saúde da Região Metropolitana de Belo Horizonte (RMBH), realizado em 2010, e os dados do Vigitel Belo Horizonte, no período de 2010 a 2013, foram utilizados para obter as estimativas de adultos fumantes por IVS, mediante uso do método indireto de estimação em pequenas áreas. As prevalências de adultos fumantes foram comparadas, considerando-se o Inquérito de Saúde da RMBH como padrão-ouro. Foi utilizado o Teste de hipótese para diferença entre as médias e a correlação de Pearson, sendo considerado o nível de significância de 5%. Resultados: Ao estratificar por IVS no inquérito domiciliar, a prevalência de adultos fumantes variou de 13,39% (intervalo de confiança de 95% — IC95% 11,88 - 14,91), para residentes em área de baixo risco, a 22,9% (IC95% 12,33 - 33,48), entre residentes em área de muito alto risco. No Vigitel, segundo IVS, a prevalência de adultos fumantes variou de 11,98% (IC95% 10,75 - 13,21), para residentes em área de baixo risco, a 22,31% (IC95% 18,25 - 26,1), para residentes nas áreas de muito alto risco. As prevalências foram semelhantes entre os dois inquéritos, mostrando boa correlação de Pearson (r = 0,93). Conclusão: O estudo aponta que as estimativas de fumantes foram semelhantes em ambos os inquéritos, mostrando validade externa do Vigitel. Ocorreu gradiente nas prevalências, com aumento progressivo, identificando-se proporção mais elevada de fumantes em áreas de risco elevado.

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Abstract: Using data collected by the Brazilian National Household Sample Survey - COVID-19 (PNAD-COVID19) and semi-Bayesian modelling developed by Wu et al., we have estimated the effect of underreporting of COVID-19 cases in Brazil as of December 2020. The total number of infected individuals is about 3 to 8 times the number of cases reported, depending on the state. Confirmed cases are at 3.1% of the total population and our estimate of total cases is at almost 15% of the approximately 212 million Brazilians as of 2020. The method we adopted from Wu et al., with slight modifications in prior specifications, applies bias corrections to account for incomplete testing and imperfect test accuracy. Our estimates, which are comparable to results obtained by Wu et al. for the United States, indicate that projections from compartmental models (such as SEIR models) tend to overestimate the number of infections and that there is considerable regional heterogeneity (results are presented by state).

Resumo: Estimamos o efeito da subnotificação de casos de COVID-19 no Brasil até dezembro de 2020, com base nos dados coletados pela Pesquisa Nacional de Amostra de Domicílios sobre COVID-19 (PNAD-COVID19) e a modelagem semi-bayesiana desenvolvida por Wu et al. O número total de indivíduos infectados é cerca de 3 a 8 vezes o número de casos notificados, a depender do estado do país. No final de 2020, os casos confirmados representavam 3,1% da população total, enquanto nossa estimativa aponta para quase 15% dos cerca de 212 milhões de brasileiros no mesmo período. O método de Wu et al., que adotamos com pequenas modificações nas especificações, aplica correções de vieses para compensar pela testagem incompleta e pela acurácia imperfeita dos testes. Nossas estimativas, que são comparáveis aos resultados obtidos por Wu et al. para os Estados Unidos, indicam que projeções a partir de modelos compartimentais (tais como modelos SEIR) tendem a superestimar o número de infecções, e que há uma heterogeneidade regional considerável (resultados apresentados por estado).

Resumen: Usando los datos recogidos por la Encuesta Nacional por Muestra de Domicilios - COVID-19 (PNAD-COVID19) y un modelado semibayesiano desarrollado por Wu et al., hemos estimado el efecto del subregistro de casos de COVID-19 en Brasil en diciembre de 2020. El número total de individuos infectados es de entre 3 a 8 veces más el número de casos informados, dependiendo del estado. Los casos confirmados son un 3,1% del total de población y nuestra estimación del total de casos es al menos un 15% de aproximadamente 212 millones de brasileños en 2020. El método que se tomó fue el de Wu et al., con leves modificaciones en las especificaciones previas, es aplicable a las correcciones de sesgo para tener en cuenta los test incompletos y la imprecisión de los tests. Nuestras estimaciones, que son comparables a los resultados obtenidos por Wu et al. para los Estados Unidos, indican las proyecciones de los modelos compartimentales (tales como los modelos SEIR), que tienden a sobreestimar el número de infecciones, así como la considerable heterogeneidad regional (los resultados se presentan por estado).

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ABSTRACT BACKGROUND: The authors of randomized controlled trials will usually claim that they have met the randomization process criterion. However, sequence generation schemes differ and some schemes that are claimed to be randomized are not genuinely randomized. Even less well understood, and often more difficult to ascertain, is whether the allocation was really concealed. OBJECTIVE: To detect the extent of control over selection bias, in a comparison between two Cochrane groups: oral health and otorhinolaryngology; and to describe the methods used to control for this bias. DESIGN AND SETTING: Cross-sectional study conducted in a public university in São Paulo, Brazil. METHODS: The risk of selection bias in 1,714 records indexed in Medline database up to 2018 was assessed, independent of language and access. Two dimensions implicated in the allocation were considered: generation of the allocation sequence; and allocation concealment. RESULTS: We included 420 randomized controlled trials and all of them were evaluated to detect selection bias. In the sample studied, only 28 properly controlled the selection bias. Lack of control over selection bias was present in 80% of the studies evaluated in both groups. CONCLUSION: The two groups were similar regarding control over selection bias. They are also similar to the methods used. The dimension of allocation concealment appears to be a limiting factor with regard to production of randomized controlled trials with low risk of selection bias. The quality of reporting in studies on oral health and otorhinolaryngology is suboptimal and needs to be improved, in line with other fields of healthcare.

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PURPOSE: Cohort participants usually have lower mortality rates than nonparticipants, but it is unclear if this survival advantage decreases or increases as cohort studies age. METHODS: We used a 1975 private census of Washington County, Maryland, to compare mortality among cohort participants to nonparticipants for three cohorts, Campaign Against Cancer and Stroke (CLUE I), Campaign Against Cancer and Heart Disease (CLUE II), and Atherosclerosis Risk In Communities (ARIC) initiated in 1974, 1989, and 1986, respectively. We analyzed mortality risk using time-truncated Cox regression models. RESULTS: Participants had lower mortality risk in the first 10 years of follow-up compared with nonparticipants (fully adjusted average hazard ratio [95% confidence intervals] were 0.72 [0.68, 0.77] in CLUE I, 0.69 [0.65, 0.73] in CLUE II, and 0.74 [0.63, 0.86] in ARIC), which persisted over 20 years of follow-up (0.81 [0.78, 0.84] in CLUE I, 0.87 [0.84, 0.91] in CLUE II, and 0.90 [0.83, 0.97] in ARIC). This lower average hazard for mortality among participants compared with nonparticipants attenuated with longer follow-up (0.99 [0.96, 1.01] after 30+ years in CLUE I, 1.02 [0.99, 1.05] after 30 years in CLUE II, and 0.95 [0.89, 1.00] after 30+ years in ARIC). In ARIC, participants who did not attend visits had higher mortality, but those who did attend visits had similar mortality to the community. CONCLUSIONS: Our results suggest the volunteer selection for mortality in long-standing epidemiologic cohort studies often diminishes as the cohort ages.

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ABSTRACT We aim to alert the difference between groups while comparing studies of abdominal oncological operations performed either by minimally invasive or laparotomic approaches and potential conflicts of interest in presenting or interpreting the results. Considering the large volume of scientific articles that are published, there is a need to consider the quality of the scientific production that leads to clinical decision making. In this regards, it is important to take into account the choice of the surgical access route. Randomized, controlled clinical trials are the standard for comparing the effectiveness between these interventions. Although some studies indicate advantages in minimally invasive access, caution is needed when interpreting these findings. There is no detailed observation in each of the comparative study about the real limitations and potential indications for minimally invasive procedures, such as the indications for selected and less advanced cases, in less complex cavities, as well as its elective characteristic. Several abdominal oncological operations via laparotomy would not be plausible to be completely performed through a minimally invasive access. These cases should be carefully selected and excluded from the comparative group. The comparison should be carried out, in a balanced way, with a group that could also have undergone a minimally invasive access, avoiding bias in selecting those cases of minor complexity, placed in the minimally invasive group. It is not a question of criticizing the minimally invasive technologies, but of respecting the surgeon's clinical decision regarding the most convenient method, revalidating the well-performed traditional laparotomy route, which has been unfairly criticized or downplayed by many people.

RESUMO Objetivamos alertar a desigualdade entre grupos de pacientes, em estudos comparativos de cirurgias oncológicas abdominais por acessos minimamente invasivos ou laparotômicos, e os possíveis conflitos de interesse na demonstração ou interpretação dos resultados. Diante do grande volume de artigos científicos produzidos, há necessidade de se considerar a qualidade da produção científica de estudos para a tomada da decisão clínica quanto à eleição da via de acesso cirúrgico. Ensaios clínicos randomizados e controlados são o padrão para comparar a eficácia entre estas intervenções em situações diversas. Apesar de alguns estudos indicarem vantagens no acesso minimamente invasivo, é preciso cautela na interpretação desses achados. Não se percebe detalhada discussão que alerte, em cada estudo comparativo, sobre os reais limites e indicações possíveis de cirurgias minimamente invasivas, como indicações para casos selecionados, menos avançados, mais eletivos, e em cavidades menos complexas. Diversas cirurgias oncológicas abdominais via laparotômica não seriam plausíveis de serem, completamente, realizadas por acesso minimamente invasivo. Estas deveriam ser, criteriosamente, selecionadas e excluídas do grupo comparativo. A comparação deve ser, equilibradamente, realizada com grupo que, muito provavelmente, também poderia ter sido submetido ao acesso minimamente invasivo a contento, evitando viés de seleção da concentração de casos de complexidade menor no grupo da cirurgia minimamente invasiva. Não se trata, aqui, de desmerecer as tecnologias minimamente invasivas, mas de respeito à decisão clínica do cirurgião pelo método mais conveniente, revalidando a via laparotômica tradicional bem procedida, a qual tem sido, injustamente, criticada ou inferiorizada por muitos em nosso meio.

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PURPOSE: Migration is often a stressful process that can have deleterious effects on health. We study the potential mental health consequences of migration by comparing Mexican migrants to the United States who have since returned to Mexico with Mexicans who have never migrated. METHODS: Data from the Mexican Migration Project were used to compare returned migrants and non-migrants in Mexico for the years 2007-2016 (N = 7716). Random intercept logistic regression models were used to estimate the associations between characteristics of migration and psychiatric problems. Coarsened exact matching was implemented to account for the selection bias inherent to migration. RESULTS: Relatively healthier Mexicans were more likely to migrate to the United States, regardless of their documentation status. Returned migrants in Mexico who traveled to the United States while undocumented were significantly more likely to report that they experienced psychiatric problems when compared with non-migrant Mexicans, even after adjusting for demographic, socioeconomic, pre-migration health, and community-level factors. CONCLUSIONS: Undocumented return migrants in Mexico are at-risk of developing psychiatric problems, despite evidence that suggests migrants tend to be healthier than non-migrants before they travel to the United States. Mental health services should encompass strategies for migrants on both sides of the border.

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Abstract Quantitative monographic studies systematically use inferential statistical procedures to test hypotheses. For this purpose, sampling procedures and sample sizes need to be adequate for the proposed procedures. The aim of this study was to identify the sample selection methods, as well as the performance and types of calculation to determine the sample size adopted in theses and dissertations developed in a graduate program in the field of Physical Education. Theses and dissertations defended between 2003 and 2013 were obtained through digital repository. Only quantitative studies were included, in which the following issues were analyzed: (1) sample selection criteria; (2) presence of sample calculation; (3) calculation type to estimate sample size. A total of 199 studies were included. Of these, 6% (n=11) used probabilistic methods for sample selection and 3% (n=6) used animal models. As for the accomplishment of sample calculations, 36% (n=72) studies reported having adopted this procedure. Of studies that performed sample calculations, 25% (n=18) used predictive equations, 67% (n=48) considered methods with statistical power as their base, 3% (n=2) used confidence interval, 4% (n=3) did not mention the method and 1% (n=1) was based on the type of statistical test to be used later. Non-probabilistic sampling methods predominate for the selection of subjects; most studies do not report adopting calculations to estimate sample size and, among those that reported the use, the models that consider statistical power as the main criterion are predominant.

Resumo Trabalhos monográficos quantitativos utilizam, sistematicamente, procedimentos estatísticos inferenciais para testar hipóteses. Para tanto, é necessário que os procedimentos de amostragem e os tamanhos amostrais estejam adequados aos procedimentos propostos. Objetivou-se identificar os métodos de seleção amostral, bem como a realização e os tipos de cálculo para determinação do tamanho amostral adotados em teses e dissertações desenvolvidas em um programa de pós-graduação no campo da Educação Física. As teses e dissertações, defendidas entre 2003 e 2013, foram obtidas via repositório digital. Foram incluídos apenas estudos de caráter quantitativo, nos quais analisou-se: (1) critério para seleção amostral; (2) presença de cálculo amostral; (3) tipo de cálculo para estimativa do tamanho amostral. Foram incluídos 199 trabalhos. Dentre estes, 6% (n=11) usaram métodos probabilísticos para seleção amostral e 3% (n=6) usaram amostra animal. Quanto à realização de cálculo amostral 36% (n=72) dos trabalhos relatam ter adotado. Dos estudos que citam ter realizado cálculos, 25% (n=18) usaram equações preditivas, 67% (n=48) consideraram métodos com o poder estatístico como base, 3% (n=2) usaram o intervalo de confiança, 4% (n=3) não citam o método e 1% (n=1) baseou-se no tipo de teste estatístico a ser usado posteriormente. Os métodos de amostragem não-probabilísticos predominam para a seleção dos sujeitos; grande parte dos estudos não relata adotar cálculos para a estimativa do tamanho amostral e dentre aqueles que citam utilizar, os modelos que consideram o poder estatístico como principal critério são predominantes.

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A retrospective cohort study of neonates born extremely preterm with persistent patent ductus arteriosus after unsuccessful pharmacologic closure compared outcomes between 166 surgically ligated and 142 nonligated neonates. After adjustment for confounders, ligation was not associated with the composite outcome of death or neurodevelopmental impairment, neurodevelopmental impairment alone, chronic lung disease, or retinopathy of prematurity among survivors.

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Abstract The proportion of non-participation in cohort studies, if associated with both the exposure and the probability of occurrence of the event, can introduce bias in the estimates of interest. The aim of this study is to evaluate the impact of participation and its characteristics in longitudinal studies. A systematic review (MEDLINE, Scopus and Web of Science) for articles describing the proportion of participation in the baseline of cohort studies was performed. Among the 2,964 initially identified, 50 were selected. The average proportion of participation was 64.7%. Using a meta-regression model with mixed effects, only age, year of baseline contact and study region (borderline) were associated with participation. Considering the decrease in participation in recent years, and the cost of cohort studies, it is essential to gather information to assess the potential for non-participation, before committing resources. Finally, journals should require the presentation of this information in the papers.

Resumo A proporção de não-participação em estudos de coorte está associada também à exposição e à probabilidade de ocorrência do evento poder gerar viés nas estimativas de interesse. O objetivo do presente trabalho é realizar uma revisão sistemática e metanálise de artigos que descrevem a participação em estudos de coorte e avaliar as características associadas à participação. Foi realizada uma revisão sistemática (MEDLINE, Scopus e Web of Science), buscando-se artigos que descrevessem a proporção de participação na linha de base de estudos de coorte. De 2.964 artigos inicialmente identificados, foram selecionados 50. Entre esses, a proporção média de participação foi de 64,7%. Utilizando-se o modelo de metarregressão com efeitos mistos, somente a idade, ano da linha de base e a região do estudo (limítrofe) estiveram associados à participação. Considerando a diminuição na participação em anos mais recentes e o custo dos estudos de coorte, é essencial buscar informações que permitam avaliar o potencial de não-participação antes de comprometer os recursos.

Resumen La proporción de no participación en estudios de cohorte se asocia también con la exposición y probabilidad de ocurrencia de hechos que pueden generar sesgos en las estimaciones de interés. El objetivo de este estudio es realizar una revisión sistemática y un metaanálisis de artículos que describen la participación en estudios de cohortes y evaluar las características asociadas con la participación. Una revisión sistemática fue realizada (MEDLINE, Scopus y Web of Science), en busca de artículos que describen la relación de participación basada en estudios de cohortes. Se seleccionaron 2964 artículos, de los cuales se identificaron preliminarmente 50. Entre estos, la proporción promedio de participación fue de un 64,7%. Utilizando la metarregresión, sólo la edad, años de referencia y la región de estudio (borderline) se asociaron con la participación. Teniendo en cuenta la disminución de la participación en los últimos años, y el coste de los estudios de cohortes, es esencial buscar información para evaluar el potencial de la no participación antes de comprometer recursos.

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Uno de los mayores dilemas en investigación es la ocurrencia de errores, los que pueden darse por efecto del azar o de forma sistemática. Es así como, se puede considerar que existe sesgo cuando en el curso de una investigación se comete un error de forma sistemática, es decir no aparece como un hecho aleatorio o por efecto del azar. Los sesgos pueden ocurrir por un sinnúmero de causales; pero en términos generales, se acepta que los más frecuentes y quizás los de mayor relevancia son aquellos debidos al observador, a lo que se observa y a aquello con lo que se observa. Dicho de otra forma, el que mide, lo que se mide y con que se mide. Otro considerando a tener en cuenta es que un sesgo puede ocurrir en cualquier etapa del curso de una investigación, desde la planificación a la presentación de resultados y la publicación ulterior de estos. Por todo ello, el objetivo de este artículo es describir los conceptos que permitan comprender la importancia de los sesgos, conocer los más frecuentes en investigación clínica, su asociación con los distintos tipos de diseños de investigación y las estrategias que permiten minimizarlos y controlarlos.

One of the biggest dilemmas in clinical research is the occurrence of errors, which can occur by chance or systematic practice. Thus, we can consider that there is bias when in the course of an investigation a systematical error occurs and it is not listed as a random occurrence or by chance. Biases can occur for different causes, but it is generally accepted that the most common and perhaps the most important are those due to the observer, what is observed, and that with which it is observed. In other words, who measured, what is measured, and the instrument that is being used to measure. Another consideration to keep in mind refers to the concept that bias can occur at any stage of the course of an investigation, from the initial planning through the analysis and the results presentation and it subsequent publication. Therefore, the purpose of this paper is to describe the concepts for understanding the importance of the biases, knowing the most common biases in clinical research and its association with different types of research designs as well as the strategies to prevent and control it.

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Estimativas de medidas epidemiológicas podem ser enviesadas devido ao mecanismo de seleção da amostra, quando essa não representa a população-alvo. Além disso, as diferenças entre participantes e não participantes, se associadas à probabilidade futura de ocorrência do agravo pode enviesar também as estimativas das medidas de associação. Esta tese pretende estudar os fatores associados à participação em estudos de coorte e impacto potencial de introdução de viés.Inicialmente foi realizada revisão sistemática. Dos 2.964 artigos inicialmente identificados,foram selecionados 50. Entre estes, a proporção média de participação foi de 64,7 por cento. A grande heterogeneidade dos estudos foi analisada por meio de modelo de metarregressão com efeitos mistos, no qual somente a idade, ano da linha de base e a região do estudo (limítrofe) estiveram associados à participação.Em seguida foi avaliado o potencial de introdução de viés no Estudo Longitudinal de Saúde do Adulto (ELSA-Brasil) por meio da comparação dos 1.784 participantes ELSA do Rio de Janeiro/Fiocruz (ELSA-RJ) com 704 não participantes da mesma instituição. Foram estudadas características relacionadas a comportamentos, histórico familiar de doenças cardiovasculares e diabetes, além de avaliar a frequência dessas mesmas caraterísticas ao longo dos 28 meses de recrutamento. Também se analisou as características dos servidores que não compareceram ao segundo contato presencial. O modelo logístico mostrou que os participantes do ELSA-RJ apresentaram menor chance de serem hipertensos e maior chance de serem obesos. Analisando separadamente cada grupo conforme combinação das variáveis que compuseram as metas de participação (sexo, idade e categoria funcional), variaram significativamente ao longo do tempo:autoavaliação de saúde, tabagismo, inatividade física e histórico familiar de doença cardiovasculares...

Estimates of epidemiological measures may be biased due to sample selection mechanism,when the sample does not represent the target population. Furthermore, the differences between participants and non-participants, if associated with future probability of occurrence of this disease,can also introduce biased estimates of association measures. This thesis aims to study the factors associated with participation in cohort studies and potential impact of introducing bias.We first carried out a systematic review. Of the 2,964 articles initially identified, 50 were selected. Among these, the average proportion of participation was 64.7 percent. The great heterogeneity of the studies was analyzed using metarregression model with mixed effects, in which only the age,year of the baseline and the study region (borderline) were associated with participation. Then we evaluated the potential bias introduction in the Brazilian Longitudinal Study ofAdult Health (ELSA-Brazil) by comparing the 1784 ELSA participants in the Rio deJaneiro/Fiocruz (ELSA-RJ) with 704 non-participants from the same institution that answered aquick survey. Characteristics related to behavior, family history of cardiovascular disease anddiabetes were evaluated, as well as the time pattern along the 28 months of recruitment. We also analyzed the characteristics of the functionaries who did not attend the second personal contact. The logistic model showed that the participants of the ELSA-RJ were less likely to be hypertensive and more likely to be obese. The analysis of each group as combination of variables that comprised the participation goals (gender, age, and employment category) varied significantly over time: healthself-assessment to, smoking, physical inactivity and the family history of cardiovascular disease...

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