Brazilian Children Research Articles

Effectiveness of an Executive Functions Parental Program in ADHD Children

Attention/Deficit Hyperactivity Disorder (ADHD) is one of the most prevalent disorders in the child population. Evidence suggests that children with this disorder usually present impairments in executive functions (EF). This study aims to evaluate the effects of a home-based intervention applied by parents (Flii, A Space Adventure) on the EF of Brazilian children with ADHD. Sixteen children with ADHD aged 7 to 12 participated in this study. A battery of neuropsychological tests and questionnaires was applied as assessment. Afterwards, children’ received Flii programa applied at home by the parents. A relevant improvement in visuospatial working memory in the Flii group after the intervention (T2) compared to the control group. The results of the intragroup analyzes suggest that the intervention group had gains in processing speed, cognitive flexibility, verbal and visuospatial working memory. These results suggest that Flii was effective in promoting some changes in the children’ executive functioning.

Functioning profile and related impairments of children and adolescents with cerebral palsy - PartiCipa Brazil preliminary results.

Limited information is available about functioning and related impairments of children and adolescents with Cerebral Palsy (CP) in low- and middle-income countries (LMIC) like Brazil. The aim of this study is to describe the characteristics, functioning, and impairments of Brazilian children and adolescents with CP. Cross-sectional preliminary study as part of the PartiCipa Brazil multicentered cohort study. Families of children and adolescents with CP from Brazil, 4 months to 15 years, were enrolled. They responded to an online survey with questions about their child's health condition, impairments, contextual factors, and functioning according to the Gross Motor Function Classification System (GMFCS) and the Manual Ability Classification System (MACS). Data were described as frequencies, percentages, means, and standard deviations, according to age bands. Of the 404 participants (6.5±3.6 years) enrolled in this preliminary analysis, 54.7% are male, 90.4% under 12 years of age, 77.7% have bilateral CP, 49% in GMFCS levels IV and V, and 50.7% in MACS levels II and V. Most participants are from Southeast (63.4%) and Centre-west (19.5%) of Brazil. Regarding the impairments and functioning limitations: 1 in 2 did not talk; 1 in 2 has epilepsy; 2 of 5 reports pain, 1 of 4 has visual impairments, 3 out of 5 did not feed themselves, 1 out of 20 has a hearing impairment and 1 of 4 did not go to school. This first preliminar Brazilian study shows a high prevalence of children at MACS levels II and V and GMFCS levels IV and V, representing almost half of the group, indicating more impairments and limitations than children/adolescents from high-income countries. This study provides a preliminary deeper understanding of the key impairments and limitations in activities among children and adolescents with CP from various Brazilian regions.

Evidence of validity of the Head-Toes-Knees-Shoulders Revised (HTKS-R) for Brazilian children

ABSTRACT This study aims to examine the reliability and validity of the Head-Toes-Knees-Shoulders Revised (HTKS-R) as a measure of self-regulation in Brazilian children aged 3–5. The early childhood period is crucial for laying the foundations for personal, social and cognitive functioning, influencing development throughout life. Self-regulation, a malleable construct, plays a vital role in academic performance and behaviors throughout life. The HTKS-R, a widely used measure, assesses behavioral self-regulation, including cognitive flexibility, working memory and inhibitory control. The study included 379 children between the ages of 3 and 5 from a variety of backgrounds. Data were collected using the HTKS-R, a standardized self-report measure that integrates executive functions into a game to assess self-regulation. Exploratory Graphical Analysis (EGA) and Confirmatory Factor Analysis (CFA) were employed to analyze the data. The results of the EGA and BootEGA indicated a unidimensional structure for the HTKS-R, confirming its internal consistency and stability. The CFA supported the fit of the unidimensional model, demonstrating the test’s construct validity. The HTKS-R showed factorial invariance between genders. The results suggest that the HTKS-R is a reliable and valid measure of self-regulation in Brazilian children aged 3–5. The applicability of the test in different age groups and environments provides valuable information about children’s self-regulation skills. The study contributes to the literature by validating the HTKS-R in the Brazilian context and highlights its potential for assessing self-regulation in diverse populations.

Environmental Attitudes in Children: An Exploratory Study of Their Relationships with Future Perspectives and Values

The present study aims to assess the extent and direction in which future perception and human values are related to environmental attitudes in a sample of children. The participants were 406 Brazilian children, most of them female (56.3 %) with a mean age of 10.23. The results indicated that environmental attitudes of preservation were positively related to all factors of the future perspective scale and the excitement, suprapersonal, existence, interactive, and normative values. The utilization attitudes correlated with the promotion, suprapersonal, existence, interactive, and normative values, but were not significantly correlated with future perspective. The analysis of predictive power showed that optimism towards the future, suprapersonal, normative, and existence values predicted preservation attitudes, while promotion, existence, and interactive values predicted utilization attitudes. The results support the importance of human values and time perspective in environmental attitudes from childhood.

Early developmental insights into the social construction of race.

The way that societies assign people to racial categories has far-reaching social, economic, and political consequences. One framework for establishing racial boundaries is based on ancestry, which historically has been leveraged to create rigid racial categories, particularly with respect to being categorized as white. A second framework is based on skin tone, which can vary within families and across the lifespan, and is thus more likely to blur racial boundaries. The persistence of these distinct cultural beliefs about race requires that they be transmitted to each new generation, but there have been few cross-cultural studies on their development during childhood. Participants (5- to 12-year-old children, N = 123) were from the United States, in which the ancestry model has been more prevalent, or from Brazil, in which the skin tone model has been more prevalent. In both countries, 5- to 7-year-olds endorsed the belief that skin tone determines race, for example, by assigning biological siblings with differing skin tones to different racial categories. However, racial concepts diverged among the 10- to 12-year-olds, with children from the United States shifting toward a classification based on ancestry and children in Brazil endorsing a classification based on skin tone even more strongly with age. These differing conceptions were especially evident with reference to white racial categorization: Older children from Brazil persisted in classifying lighter skinned people as white when they had African ancestry, unlike older children from the United States. These findings provide important insights into the developmental and cultural influences on racial classification systems. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Validating the Child Behavior Checklist 1.5-5 as a screening tool for autism spectrum disorder.

Early identification of Autism Spectrum Disorder is very important, especially in low and middle-income countries, where access to resources is often limited. The Child Behavior Checklist 1.5-5 is a tool that has been used to help identify children with autism spectrum disorder through specific behavior patterns. However, its effectiveness in low- and middle-income country settings has not been thoroughly studied. This research focused on evaluating the Child Behavior Checklist 1.5-5 as a screening tool for autism spectrum disorder among Brazilian children. The study involved 1292 children aged 3-5 years from the general population and 70 children with autism spectrum disorder aged 1-5 years. Using advanced statistical methods, the study tested how well the Child Behavior Checklist identified children with autism spectrum disorder and how reliable it was in this context. The findings showed that the Child Behavior Checklist 1.5-5 performed well in identifying autism spectrum disorder, with high reliability and consistency in the results. Although one item in each of the autism spectrum problems and withdrawn syndrome subscales did not perform as strongly, the overall tool was effective. In summary, the Child Behavior Checklist 1.5-5 proves to be a reliable and valid tool for early autism spectrum disorder screening in Brazilian children. This can help ensure that more children in low- and middle-income country settings are identified early and receive the necessary support and interventions to help them thrive. Future research should continue to test this tool in different contexts to confirm its usefulness across various populations.

Effect of unprocessed and minimally processed foods on blood pressure in children

Abstract Background The poor eating habits of children, including a decrease in the consumption of unprocessed foods and an increase in the consumption of processed foods, have been associated with excess body weight, which is a well-established risk factor for cardiovascular diseases (CVDs), especially high blood pressure (BP). We aimed to investigate whether the consumption of unprocessed and minimally processed foods is associated with high BP in children at nine years of age. Methods Cross-sectional study of 142 Brazilian children participating in a cohort study conducted at the participant’s home. The child’s food consumption markers were evaluated using the Brazilian Food and Nutrition Surveillance System (SISVAN) and were classified by NOVA. Using a standardized procedure for approaching the child, BP was measured by the auscultatory method. Biological, socioeconomical, demographic, and anthropometric data of the mother and child were also collected. Logistic regression analysis adjusting for important predictors was used to evaluate the association between food consumption and BP. Results The prevalence of high BP in children was 20.4%, and the mean systolic and diastolic BP were significantly (p < 0.05) higher in children classified as high BP (110.1 and 71.3 mmHg, respectively). An important proportion (44.8%) of children had excess body weight (>85th percentile) and high BP when compared to eutrophic children. Not consuming healthy foods was associated with high systolic BP, even after adjustment for other important covariates (OR = 3.97; p = 0.028). Conclusions Not consuming healthy foods was associated with increased odds of children having high BP at nine years of age. Interventions promoting a healthy diet and the consumption of fruits and vegetables in childhood may contribute to preventing diseases associated with CVD, a global public health problem. Key messages • Educating parents to avoid processed foods and monitoring children’s BP are essential actions to prevent associated chronic diseases throughout life. • Public policies aimed at educating parents to encourage the consumption of healthy foods may significantly contribute to reducing adverse cardiovascular outcomes.

Phonological skills and executive functions: their effects on reading and arithmetic abilities across varied performance levels using quantile regression

ABSTRACT We aimed to investigate the effects of phonological awareness – PA, rapid automatised naming – RAN, visuospatial and verbal working memory – WM and executive functions – EF on the reading and arithmetic skills of children with low- to medium-performance levels. Participants were 472 Brazilian children from 3rd to 5th grades. Quantile Regression Analysis was employed. The PA, RAN and EF were shared main predictors of both reading and math. Verbal WM emerged as a unique main predictor for reading, while visuospatial WM and visuospatial short-term memory were the main predictors for arithmetic. Among children with very low reading proficiency, the effects of cognitive predictors were more pronounced, a trend not observed in arithmetic. The results suggest varying magnitudes of cognitive predictors for reading when considering different levels of performance/difficulties. We also corroborate unique and shared main predictors of reading and math that have implications for research, clinical and educational settings.

Metabolic and Inflammatory Profiles in Children and Adolescents with Autism Spectrum Disorder: A Cross-Sectional Study

Background/Objectives: Autism spectrum disorder (ASD) is associated with several coexisting diseases or comorbidities, including inflammatory and metabolic disorders. In fact, ASD symptoms may be associated with immune system dysfunction. However, studies investigating the peripheral blood levels of immune cells are lacking and have provided mixed findings. In this study, we evaluated the relationship between the intensity level of ASD symptoms and the inflammatory and metabolic profiles in 154 children and adolescents (2–17 years). Methods: Bayesian multilevel models were used to examine the relationship between their symptom intensities and inflammatory/metabolic profiles. Results: Heavier children had higher values for triglyceride and insulin levels. Children with a level 3 of ASD intensity had higher free fatty acids levels. However, when adjusting for ASD intensity, gender, medication use, or weight status, older children appeared to have higher values of triglycerides, insulin levels, and free fatty acids. Conclusions: We concluded that as Brazilian children with ASD became older, they had a higher risk for insulin resistance.

Association between molar incisor hypomineralisation and tooth agenesis: a cross-sectional study in Brazilian children and adolescents.

The aim of the present was to assess the association between MIH and tooth agenesis (TA) in orthodontic patients from the Federal University of Rio Grande do Norte, Natal, Brazil. A cross-sectional study was performed to evaluate the presence of MIH and TA in a sample of 371 pretreatment orthodontic records from patients aged 9-18years. Statistical analyses were performed using the Chi-square and Fisher's exact tests, and logistic regressions. There was a statistically significant association between the prevalence of tooth agenesis and MIH. A higher percentage of third molar agenesis, maxillary premolar agenesis, and mandibular second premolar agenesis was observed among children with MIH-affected teeth. Patients with MIH had a 2.43 times greater chance of third molar agenesis, and a 5.88 times higher likelihood of mandibular premolar agenesis. There is a weak association between MIH and TA. Furthermore, the presence of hypomineralised molars increases the risk of tooth agenesis.

Exposure of elementary school-aged Brazilian children to bisphenol A: association with demographic, social, and behavioral factors, and a worldwide comparison

Bisphenol A (BPA) is a plasticizer used to synthesize polycarbonate plastics and epoxy resins and is well-known for its endocrine-disrupting action. BPA occurrence in the environment is widespread, and there is a growing concern regarding exposure to this chemical during childhood, given the findings indicating the long-lasting hazards associated with exposure during early life compared to adulthood. We examined urinary BPA concentrations from 319 elementary school-aged Brazilian children, using high-performance liquid chromatography coupled to high-resolution mass spectrometry. We found that urinary BPA was detectable in the majority of children, and that urinary BPA levels were higher among children with lower family income and lower maternal educational levels. BPA levels found herein were compared with those from countries with different regulation policies concerning exposure to BPA. They were similar to those reported from studies conducted in Egypt and Australia. Despite more protective regulatory policies in the European Union, they were similar or lower than those reported in European studies. Our findings indicate that exposure of Brazilian children to BPA is widespread and comparable to or even lower than that of countries with stricter regulatory policies.

Association of parental eating styles and markers of food intake and nutritional status of Brazilian children

We analysed the relationships between maternal feeding styles and children’s eating and nutritional factors. A cross-sectional study was developed with 416 mothers linked to 130 public higher education institutions in all Brazilian states and their children aged 18 months to six years. A semi-structured online questionnaire was applied using the Google Forms tool, with questions about sociodemographic conditions, food consumption and anthropometry of the children. The children’s food consumption was assessed based on the Food Consumption Markers Form (SISVAN) for the age groups up to 24 months (n = 84) and over 24 months (n = 332), and the parental style in feeding, based on the Parental Feeding Styles Questionnaire (QEPA). The assessment of the child’s nutritional status was based on the weight and height data reported by the mother. The body mass index/age (BMI/Age) was calculated and classified into age-specific WHO curves. Descriptive analysis and univariate analyses were performed, in the Statistical Package for the Social Sciences (SPSS, version 26.0) programs (SPSS Inc., Chicago, IL). To test the association between categorical variables, the Chi-square test or Fisher’s exact test was used, and multiple logistic regression was used to estimate the independent association between the variables of interest, with an estimated odds ratio and 95% confidence interval. Statistical significance was adopted at 5%. Children under 24 months of age with authoritative mothers were 8.7 times more likely to consume ultra-processed foods and 5.3 times less likely to consume foods rich in vitamin A than those with indulgent mothers. Children over 24 months old with authoritative mothers were 2.5 times more likely to eat meals while watching television, 2.0 times more likely to consume sandwich cookies, candies and sweets, and 2.3 times less likely to have at least the three main meals of a day, compared to those with indulgent mothers. The chances of overweight children being born to authoritative mothers were two times greater compared to underweight children. Higher scores in the demandingness domain among responsive mothers increased the odds ratios of children eating unhealthy foods, using screens during meals, and proved to be a protective factor against low child weight.

Problematic behaviors at mealtimes and the nutritional status of Brazilian children with Autism Spectrum Disorder.

The aim of this study was to explore problematic behaviors and their association with the food consumption and nutritional status of children with Autism Spectrum Disorder (ASD). This is a cross-sectional study which enrolled 90 Brazilian children (aged 2-10 years) with ASD. A sociodemographic questionnaire, the ASD Eating Behavior Assessment Scale, and the 24-h recall were used. Age, height, total body weight, and Body Mass Index (BMI) were accessed to estimate nutritional status (BMI/Age). Consumption of fruits, vegetables, total calories, macro and micronutrients (calcium, iron, zinc, omega 3 and omega 6), and Body Mass Index (BMI) were assessed. The regression models were adjusted for covariates (prevalence ratio - PR, α = 0.05). All studied children presented problematic behaviors at mealtimes, with a predominance of food selectivity (57.8%), followed by changes in mealtime skills (34.4%), changes in masticatory motor skills (25.6%), oppositional eating behaviors (20.4%), and rigid eating behaviors (20.0%). Food selectivity was associated with excess body weight (PR: 1.94; 95% CI: 1.08-3.51) and absence of vegetable consumption (PR: 0.61; 95% CI: 0.46-0.81). Rigid eating behaviors was associated with low consumption of fiber (PR: 1.42; 95% CI: 1.15-1.75) and zinc (PR: 2.15; 95% CI: 1.33-3.45), and with excessive caloric (PR: 1.14; 95% CI: 1.02-1.29) and lower calcium intake (PR: 0.52; 95% CI: 0.29-0.91). Selectivity and rigidity behaviors have different relationships with food consumption and are associated with a higher prevalence of inadequacies, which may lead to nutritional risks for children. Further studies may investigate the influence of problematic behaviors and excess body weight in ASD.

Systematic review and meta-analysis of myopia prevalence in Brazilian school children

Systematic review and meta-analysis of myopia prevalence in Brazilian school children

Effect of the COVID-19 pandemic on malnutrition in socially vulnerable children in Brazil.

This article aims to evaluate the effect of the COVID-19 pandemic on malnutrition among children under two years of age enrolled in the Bolsa Família Program (BFP). Ecological study of interrupted time series (ITS), with low weight for age, stunting, and overweight as time-dependent variables of malnutrition, extracted monthly (Jan/2008 to June/2021) from the Food and Nutrition Surveillance System. The COVID-19 pandemic was the exposure, dichotomized into pre-pandemic and pandemic. In RStudio, the trend was obtained by Prais-Winsten regression, and the effect of the pandemic on the time-dependent variables was determined by SARIMA modeling, estimating the regression coefficients (RC) adjusted for trend and seasonality (α = 5%). The pandemic was associated with an increase in: i) low weight for age in the South (RC = 0.94; p < 0.001) and Southeast (RC = 1.97; p < 0.001); ii) height deficit in the Midwest (RC = 2.4; p = 0.01), South (RC = 2.15; p < 0.001) and Southeast (RC = 2.96; p < 0.001); and iii) and overweight in the North (RC = 1.51; p = 0.04), Midwest (RC = 2.29; p = 0.01), South (RC = 2.83; p < 0.001), and Southeast (RC = 0.72; p = 0.04). The pandemic increased underweight in the South and Southeast, and the double burden of malnutrition in the Midwest, South, and Southeast. In the Northeast and North, higher rates of malnutrition still persist.

Pediatrics ACES and related life event screener (PEARLS): translation, transcultural adaptation, and validation to Brazilian Portuguese

ObjectiveAdverse Childhood Experiences (ACEs) have been associated with negative health outcomes. Screening for ACEs is crucial for improving health results, however, there is a shortage of standardized tools designed for children in Brazilian Portuguese. This study aimed to translate, culturally adapt, and validate the Pediatrics ACES and Related Life Event Screener (PEARLS) for use in Brazil. MethodThe study followed a methodological design for cross-cultural adaptation and psychometric evaluation. The PEARLS was translated and culturally adapted following a methodology that includes translation, synthesis, expert committee evaluation, target audience evaluation, and back-translation. After adaptation, a pilot cross-sectional study was conducted at a Multidisciplinary Health Care Clinical Center and a General Hospital-Reference Center for Child and Adolescent Care to assess the instrument's internal consistency, convergent validity, content validity and test-retest reliability. ResultsThe PEARLS-Br versions for Children, Teens, and Teen Self-Report were developed and subjected to pilot testing with 202 subjects. Participants demonstrated excellent comprehension, with Verbal Rating Scale median scores of 4 (IQR 4–5). Internal consistency was high, with Cronbach's alpha coefficients ranging from 0.78 to 0.81. Content validity, assessed by Kappa, indicated slight to almost perfect agreement across constructs. Test-retest reliability, assessed by Spearman's correlation coefficient, ranged from 0.89 to 0.94. ConclusionsPEARLS-BR (Child, teen, and teen self-report versions) were successfully translated, culturally adapted, and validated for assessing ACEs in Brazilian children and adolescents. This tool fills a crucial gap in ACE assessment in the Brazilian context, aligning with global recommendations for screening ACEs to improve overall health outcomes.

Functional classification systems in Brazilian children with cerebral palsy: Reliability and associations between functional levels

ABSTRACT Children with Cerebral palsy (CP) present movement and posture disorders. The Gross Motor Function Classification System (GMFCS), Manual Ability Classification System (MACS), Communication Function Classification System (CFCS), Eating and Drinking Ability Classification System (EDACS), and Visual Function Classification System (VFCS) enhance the understanding of their performance. We verified inter-rater reliability and associations between the classification levels. Physical therapists classified 100 Brazilian children with CP (3–17 years) according to GMFCS, MACS, CFCS, EDACS, and VFCS. To evaluate inter-rater reliability (Intraclass Correlation Coefficient-ICC) two independent examiners concurrently assessed a subset of 60 participants. According to Spearman’s correlation coefficients, there were associations between GMFCS/MACS (r = 0.81), GMFCS/CFCS (r = 0.70), MACS/CFCS (r = 0.73), GMFCS/VFCS (r = 0.61), MACS/VFCS (r = 0.61), CFCS/EDACS (r = 0.58), CFCS/VFCS (r = 0.50), and EDACS/VFCS (r = 0.45) (p < .05). The inter-rater reliability ranged from excellent (ICC = 0.93-0.99) to good (ICC = 0.89), p < .05. The classification systems are reliable, and the levels associated with each other in Brazilian children, especially the GMFCS, MACS, and CFCS.

Associations between neighborhood characteristics, mental health, and parenting among mothers with young children in Brazil: A cross-sectional study of women living in communities of social disadvantage and ethnic diversity

Associations between neighborhood characteristics, mental health, and parenting among mothers with young children in Brazil: A cross-sectional study of women living in communities of social disadvantage and ethnic diversity

Venezuelan migration to Brazil: teachers and students co-constructing multicultural education inside classrooms

PurposeThis study aims to show the complexities of engagement between students - Venezuelan and Brazilian - and their teachers. This qualitative ethnographic study documents the everyday pedagogies and practices that take place in elementary schools with high levels of refugee and immigrant children. While Brazilian law ensures the basic right to public education, forbidding discrimination based on nationality or immigration status (Lei de Diretrizes e Bases da Educação, 1996), the barriers remain. Through the frameworks of multicultural (USA) and intercultural (Brazil) education, this paper shows how Brazilian teachers and students of Venezuelan and Brazilian backgrounds engage, learn from one another and build welcoming spaces, but also how stereotypes are reinforced inside classrooms and schools.Design/methodology/approachThis qualitative study uses ethnography to understand how recent Venezuelan migratory flow influences Brazilian and Venezuelan children’s educational experiences in elementary education. Participants were Venezuelan (N = 57) and Brazilian (N = 76) children in two elementary schools in the city of Boa Vista. Data sources for the study are school observations in four elementary classrooms (1st and 2nd grade) and semi-structured interviews with caregivers, teachers, administrators and other educators. This paper also collected children’s drawings and writings and documents like curricula, strategic planning, guidelines, policies, grades, reports and any other textual or photographic material made available at the city level.FindingsIn the field of education, there is a critical need for understanding children’s education experiences. This paper focuses on the experiences of teachers and students in two elementary schools in Brazil. This paper focus on two findings: first that teachers promote the learning of Portuguese to show care toward their Venezuelan students. Second, children in the classroom show solidarity with one another and resist some of the more rigid Portuguese-only practices enacted by teachers. This work uses the frameworks of intercultural (more commonly used in Brazil) and multicultural education to inform the analysis.Research limitations/implicationsIn this study, this paper puts these frameworks of interculturalism, multiculturalism, language use and solidarity into conversation to understand the dynamics of two elementary classrooms in the city of Boa Vista, Brazil. While this paper shows the shortcomings of a seemingly multicultural and multilanguage classroom, it also shows how children actively resist the rigidity of teaching and learning in elementary schooling.Originality/valueThis study is a response both to the increasing South–South migration trend in Latin America and its consequences on public education systems. Through multicultural and intercultural lenses, this research highlighted the complexity of interactions within multicultural classrooms by delving into a two-year ethnographic study conducted in Boa Vista, Brazil, focusing on Venezuelan and Brazilian children in two local elementary schools. This paper focused on two main observations this paper refers to as “Teaching Portuguese as a Way of Caring” and “Children's Solidarity Work.” Teachers primarily centered their instruction on teaching Portuguese to migrant children, believing it to lead to quicker integration in the classroom and beyond – thus as a way of caring for their migrant students.

Anticipating Leucovorin Rescue Therapy in Patients with Osteosarcoma through Methotrexate Population Pharmacokinetic Model.

Methotrexate (MTX), which presents high inter-individual variability, is part of the Brazilian Osteosarcoma Treatment Group (BOTG) protocol. This work aimed to develop a MTX population pharmacokinetic model (POPPK) for Brazilian children with osteosarcoma (OS) following the BOTG protocol to guide rescue therapy and avoid toxicity. The model was developed in NONMEM 7.4 (Icon®) using retrospective sparse data from MTX therapeutic drug monitoring of children attending a southern Brazilian public reference hospital. Data were described by a two-compartment model using 216 MTX cycles from 32 patients (5-18 y.o.) with OS who received 12 g/m2 dose/cycle. To explain inter-individual and inter-occasion variability in clearance and peripheral volume, covariates from demographic and biochemical data were evaluated. Serum creatinine was a significant covariate of MTX clearance (14.8 L/h), and the body surface area (BSA) was significant for central compartment volume (82.5 L). Inter-compartmental clearance and volume of peripheral compartment were 0.178 L/h and 5.72 L, respectively. The model adequately describes MTX exposure in Brazilian children with OS. Successful simulations were performed to predict MTX concentrations in pediatric patients above five years old with acute kidney injury and anticipate rescue therapy adjustments.