Stability and change in fruit and vegetable intake of Brazilian adolescents over a 3-year period: 1993 Pelotas Birth Cohort.

OBJECTIVE: To assess the stability and changes in fruit and vegetable (FV) consumption over a 3-year period during adolescence in a population-based birth cohort. DESIGN: Longitudinal descriptive study. FV consumption was collected in 2008 and 2011/12 using an FFQ. We conducted descriptive analyses of medians to assess the trends in FV intake over time. Stability of FV intake was assessed by percentage of agreement and kappa coefficients. SETTING: Pelotas, Rio Grande do Sul, Brazil. SUBJECTS: Adolescents from 15 to 18 years of age (n 3915). RESULTS: We observed an overall slight decrease in FV consumption during adolescence and also a moderate stability, especially in those with higher socio-economic status (proportion of agreement 38.6% and 40.5% for boys and girls, respectively). About a half of those consuming low levels of FV at 15 years of age still consumed low levels 3 years later. CONCLUSIONS: Our results showed that FV consumption presented a moderate stability across a 3-year period during adolescence, especially in those with higher socio-economic status. Given the great proportions of non-communicable diseases such as CVD, diabetes and obesity, knowledge about the patterns of FV consumption during adolescence has implications for health promotion interventions.

HIV/AIDS transmission knowledge among adolescents aged 11 years from Southern Brazil.

OBJECTIVE: To investigate the effect of demographic, socioeconomic, educational and family variables on HIV/AIDS knowledge among adolescents aged 11 years. METHODS: 3,949 adolescents born in Pelotas (Brazil). HIV/AIDS knowledge was assessed through a self-administered questionnaire and measured through five questions about HIV transmission: heterosexual intercourse, homosexual intercourse, needle sharing, open-mouth kissing and hugging someone with AIDS. All the analyses were adjusted based on a hierarchical model, using Poisson regression with robust adjustment of variance. RESULTS: Prevalence of wrong answers to the examined questions were 17.2% for heterosexual transmission, 44.1% for homosexual intercourse, 34.9% for needle sharing, 25.6% for kiss on the mouth and 16.2% for hugging someone with AIDS. In adjusted analysis, lower knowledge levels were more prevalent among boys, adolescents with lower socioeconomic status and with less maternal education level, among those who had not talked about sex with mother and without sexual education lessons at school. Knowledge was not associated with school type (public or private), skin color or talk about sex with father. CONCLUSION: Providing information to adolescents is essential to improve knowledge about HIV and other sexually transmitted infections, especially among young males, with lower socioeconomic status and with lower maternal education level. Public policies aimed to reducing HIV infection should consider maternal and school relevance to improve knowledge on adolescents.

[Prevalence of grade retention and associated factors among adolescents from the 1993 Pelotas, Brazil, birth cohort]. / Prevalência de retenção escolar e fatores associados em adolescentes da coorte de nascimentos de 1993 em Pelotas, Brasil.

OBJECTIVE: To evaluate the occurrence of grade retention until 11 years of age and the factors associated with retention. METHODS: This prospective study included 4 452 adolescents from the 1993 city of Pelotas birth cohort (state of Rio Grande do Sul, Brazil). This sample represents 87.5% of the original cohort. Grade retention was defined as the repetition of at least one school grade until the date of the interview. The following independent variables were analyzed: sex, skin color, birth weight, ownership of goods, age, maternal schooling, type of school (private, state, or city), age at school entry, and employment. RESULTS: The overall frequency of grade retention was 36.3%, vs. 42.8% for boys and 30.0% for girls. The adjusted analysis showed that the lower the level of maternal schooling, ownership of goods, and birth weight, the higher the risk of grade retention for both boys and girls. Black/brown adolescents, those studying in public schools, and those who were 7 years of age or older at school entry had a higher risk of grade retention. For boys, childhood labor was associated with grade retention. CONCLUSIONS: Low socioeconomic and low maternal schooling levels were the factors most strongly associated with grade retention. Strategies to reduce this situation must take into account demographic and socioeconomic characteristics.

[Self-reported discrimination by adolescents in a Brazilian birth cohort: prevalence and associations]. / Discriminação autorrelatada por adolescentes de uma coorte de nascimentos brasileira: prevalência e associações.

OBJECTIVE: To evaluate the prevalence of and factors associated with discrimination self-reported by adolescents. METHODS: Cross-sectional analysis of adolescents belonging to a cohort of live births in 1993 in the city of Pelotas, Brazil. From the 5 249 members of the cohort, information was collected from 4 452 adolescents in 2004 and 2005 regarding self-reported discrimination, sociodemographic variables, physical attributes, and nutritional status. A Poisson regression was utilized in the raw and adjusted analyses to estimate prevalence rates (RP). RESULTS: The global prevalence of self-reported discrimination was 16.4%. In the adjusted analysis, discrimination was reported more by the following groups: girls (RP = 1.27, 95%CI: 1.10-1.48), people identified by others as black (RP = 1.28, 95%CI: 1.04-1.57), poorer adolescents (RP = 1.58, 95%CI: 1.23-2.02), those who perceived themselves to be very thin or very fat (RP = 1.81 and 1.54 respectively), those whose families had financial trouble (RP = 1.76, 95%CI: 1.49-2.08), those who wore glasses (RP = 1.74, 95%CI: 1.45-2.10), those who thought their teeth looked bad (RP = 1.58, 95%CI: 1.21-2.07), those who had been reprimanded in school (RP = 1.23, 95%CI: 1.01- 1.51), and those who had been involved in fights in the past year (RP = 1.62, 95%CI: 1.36-1.94). The association between discrimination and nutritional status varied by sex (interaction P = 0.009). Thin children reported greater discrimination than those who were overweight or obese. Discrimination on the basis of obesity was higher among girls, with this effect more strongly felt among rich girls than among poor ones. CONCLUSIONS: Self-reported discrimination was prevalent and unequally distributed among the population. Actions to reduce experiences of discrimination must be implemented during the initial stages of life.

Quality of DNA extracted from saliva samples collected with the Oragene™ DNA self-collection kit.

BACKGROUND: Large epidemiological studies in DNA biobanks have increasingly used less invasive methods for obtaining DNA samples, such as saliva collection. Although lower amounts of DNA are obtained as compared with blood collection, this method has been widely used because of its more simple logistics and increased response rate. The present study aimed to verify whether a storage time of 8 months decreases the quality of DNA from collected samples. METHODS: Saliva samples were collected with an OrageneTM DNA Self-Collection Kit from 4,110 subjects aged 14-15 years. The samples were processed in two aliquots with an 8-month interval between them. Quantitative and qualitative evaluations were carried out in 20% of the samples by spectrophotometry and genotyping. Descriptive analyses and paired t-tests were performed. RESULTS: The mean volume of saliva collected was 2.2 mL per subject, yielding on average 184.8 µg DNA per kit. Most samples showed a Ratio of OD differences (RAT) between 1.6 and 1.8 in the qualitative evaluation. The evaluation of DNA quality by TaqMan®, High Resolution Melting (HRM), and restriction fragment length polymorphism-PCR (RFLP-PCR) showed a rate of success of up to 98% of the samples. The sample store time did not reduce either the quantity or quality of DNA extracted with the Oragene kit. CONCLUSION: The study results showed that a storage period of 8 months at room temperature did not reduce the quality of the DNA obtained. In addition, the use of the Oragene kit during fieldwork in large population-based studies allows for DNA of high quantity and high quality.

Prevalência de retenção escolar e fatores associados em adolescentes da coorte de nascimentos de 1993 em Pelotas, Brasil / Prevalence of grade retention and associated factors among adolescents from the 1993 Pelotas, Brazil, birth cohort

Objetivo. Avaliar a ocorrência de retenção escolar até os 11 anos de idade e os fatores associadosà retenção. Métodos. Estudo prospectivo, incluindo 4 452 adolescentes da coorte de nascidos emPelotas, Estado do Rio Grande do Sul, Brasil, em 1993. A amostra representa 87,5% da coorte original. A retenção escolar foi definida como a repetição de pelo menos uma série escolar atéa data da entrevista. As variáveis independentes analisadas foram: sexo, cor da pele, peso ao nascer, índice de bens, idade e escolaridade materna, tipo de escola (privada, estadual oumunicipal), idade de ingresso na escola e trabalho. Resultados. A frequência de retenção escolar foi de 36,3%, sendo de 42,8% entre os meninos e 30,0% entre as meninas. Na análise ajustada, quanto menor a escolaridade da mãe,o índice de bens e o peso ao nascer, maior foi o risco de retenção escolar em ambos os sexos. Adolescentes cuja cor da pele era parda/preta, aqueles que frequentavam escolas públicas e aquelesque ingressaram na escola com 7 anos ou mais apresentaram maior risco de retenção escolar. Apenas entre os meninos, o trabalho infantil esteve associado com a ocorrência de retenção.Conclusões. O baixo nível socioeconômico e a baixa escolaridade materna foram os fatores mais fortemente associados com a retenção escolar. Estratégias para a redução desse evento devem levar em consideração características demográficas e socioeconômicas.

Objective. To evaluate the occurrence of grade retention until 11 years of age and the factors associated with retention. Methods. This prospective study included 4 452 adolescents from the 1993 city of Pelotas birth cohort (state of Rio Grande do Sul, Brazil). This sample represents 87.5% of the original cohort. Grade retention was defined as the repetition of at least oneschool grade until the date of the interview. The following independent variables were analyzed: sex, skin color, birth weight, ownership of goods, age, maternal schooling, type of school (private, state, or city), age at school entry, and employment. Results. The overall frequency of grade retention was 36.3%, vs. 42.8% for boysand 30.0% for girls. The adjusted analysis showed that the lower the level of maternal schooling, ownership of goods, and birth weight, the higher the risk of grade retention for both boys and girls. Black/brown adolescents, those studying in public schools, and those who were 7 years of age or older at school entry had a higher risk of grade retention. For boys, childhood labor was associated with grade retention.Conclusions. Low socioeconomic and low maternal schooling levels were the factors most strongly associated with grade retention. Strategies to reduce this situation must take into account demographic and socioeconomic characteristics.

Discriminação autorrelatada por adolescentes de uma coorte de nascimentos brasileira: prevalência e associações / Self-reported discrimination by adolescents in a Brazilian birth cohort: prevalence and associations

OBJETIVO: Avaliar a prevalência e os fatores associados à discriminação autorrelatada por adolescentes. MÉTODOS: Análise transversal dos adolescentes pertencentes à coorte de nascidos vivos em 1993 na cidade de Pelotas, Rio Grande do Sul, Brasil. Dos 5 249 membros da coorte, foram coletadas informações em 2004 e 2005 sobre discriminação autorrelatada, variáveis sociodemográficas, atributos físicos e estado nutricional em 4 452 adolescentes. Regressão de Poisson foi utilizada nas análises bruta e ajustada para estimar as razões de prevalência (RP). RESULTADOS: A prevalência global de discriminação autorrelatada foi de 16,4 por cento. Na análise ajustada, a discriminação foi mais relatada por meninas (RP = 1,27, IC95 por cento: 1,10 a 1,48); heteroclassificados pretos (RP = 1,28, IC95 por cento: 1,04 a 1,57); pelos mais pobres (RP = 1,58, IC95 por cento: 1,23 a 2,02); os que se perceberam como muito magros ou muito gordos (RP = 1,81 e 1,54, respectivamente), com dificuldades financeiras familiares (RP = 1,76, IC95 por cento: 1,49 a 2,08); que usavam óculos (RP = 1,74, IC95 por cento: 1,45 a 2,10), com autopercepção negativa da aparência dental (RP = 1,58, IC95 por cento: 1,21 a 2,07), com reprovação escolar (RP = 1,23, IC95 por cento: 1,01 a 1,51) ou que participaram em brigas no último ano (RP = 1,62, IC95 por cento: 1,36 a 1,94). A associação entre discriminação e estado nutricional foi diferente conforme o sexo (P de interação = 0,009). Meninos magros relataram maior discriminação, enquanto aqueles com sobrepeso e obesidade apresentaram menor prevalência. Em meninas, a prevalência de discriminação foi maior entre as obesas, sendo esse efeito mais forte entre as ricas do que nas pobres. CONCLUSÕES: A discriminação autorrelatada foi prevalente e desigualmente distribuída na população. Intervenções para reduzir experiências discriminatórias devem ser implementadas em fases iniciais da vida.

OBJECTIVE: To evaluate the prevalence of and factors associated with discrimination self-reported by adolescents. METHODS: Cross-sectional analysis of adolescents belonging to a cohort of live births in 1993 in the city of Pelotas, Brazil. From the 5 249 members of the cohort, information was collected from 4 452 adolescents in 2004 and 2005 regarding self-reported discrimination, sociodemographic variables, physical attributes, and nutritional status. A Poisson regression was utilized in the raw and adjusted analyses to estimate prevalence rates (RP). RESULTS: The global prevalence of self-reported discrimination was 16.4 percent. In the adjusted analysis, discrimination was reported more by the following groups: girls (RP = 1.27, 95 percentCI: 1.10-1.48), people identified by others as black (RP = 1.28, 95 percentCI: 1.04-1.57), poorer adolescents (RP = 1.58, 95 percentCI: 1.23-2.02), those who perceived themselves to be very thin or very fat (RP = 1.81 and 1.54 respectively), those whose families had financial trouble (RP = 1.76, 95 percentCI: 1.49-2.08), those who wore glasses (RP = 1.74, 95 percentCI: 1.45-2.10), those who thought their teeth looked bad (RP = 1.58, 95 percentCI: 1.21-2.07), those who had been reprimanded in school (RP = 1.23, 95 percentCI: 1.01- 1.51), and those who had been involved in fights in the past year (RP = 1.62, 95 percentCI: 1.36-1.94). The association between discrimination and nutritional status varied by sex (interaction P = 0.009). Thin children reported greater discrimination than those who were overweight or obese. Discrimination on the basis of obesity was higher among girls, with this effect more strongly felt among rich girls than among poor ones. CONCLUSIONS: Self-reported discrimination was prevalent and unequally distributed among the population. Actions to reduce experiences of discrimination must be implemented during the initial stages of life.

Incidence of school failure according to baseline leisure-time physical activity practice: prospective study.

PURPOSE: To evaluate the prospective association between leisure-time physical activity practice at 11 years of age and incidence of school failure from 11 to 15 years of age. METHODS: The sample comprised >4,300 adolescents followed up from birth to 15 years of age participating in a birth cohort study in Pelotas, Brazil. The incidence of school failure from age 11 to 15 years was calculated by first excluding from the analyses all subjects who experienced a school failure before 11 years of age, and then categorizing as "positive" all those who reported repeating a grade at school from 11 to 15 years of age. Leisure-time physical activity was measured using a validated questionnaire. RESULTS: The incidence of school failure was 47.9% among boys and 38.2% among girls. Adolescents in the top quartile of leisure-time physical activity practice at 11 years of age had a higher likelihood of school failure (OR: 1.36; 95% CI: 1.06, 1.75) compared with the least active adolescents. In adjusted analyses stratified by sex, boys in the top quartile of leisure-time physical activity practice at 11 years of age were also more likely to have failed at school from age 11 to 15 years (OR: 1.60; 95% CI: 1.09, 2.33). CONCLUSIONS: Adolescents allocating >1,000 min/wk to leisure-time physical activity were more likely to experience a school failure from 11 to 15 years of age. Although this finding does not advocate against physical activity promotion, it indicates that excess time allocated to physical activity may jeopardize school performance among adolescents.

Socioeconomic trajectories from birth to adolescence and risk factors for noncommunicable disease: prospective analyses.

PURPOSE: To evaluate the associations between family socioeconomic trajectories from 0 to 11 years of age and risk factors for noncommunicable disease at 15 years. METHODS: Individuals born in the city of Pelotas, Brazil, in 1993 are part of a birth cohort study. Socioeconomic position, collected at birth and at 11 years of age, was our main exposure. Risk factors for chronic disease were collected at 15 years. Body mass index was transformed into Z score using the World Health Organization standard. Transport and leisure-time physical activity, smoking, and alcohol consumption were assessed by self-report. Blood pressure was measured using a digital sphygmomanometer. RESULTS: Of 5,249 cohort members, 85.7% were located at the 15-year follow-up visit. Rich adolescents were more likely to be overweight, be obese, and not use active modes of transport to school. Poor adolescents were more likely to smoke. In relation to socioeconomic trajectories, the odds of obesity were 46% higher among those who were "always rich" compared with those who were "always poor"; the odds of use of an inactive mode of transportation were 326% greater among the "always rich" than the "always poor," whereas the reverse was observed for smoking (odds of 200%). The "always rich" had one-half the odds of walking or cycling to school compared with those who became wealthy in the studied period. CONCLUSIONS: Adolescent socioeconomic position is a stronger determinant of risk factors for noncommunicable diseases than socioeconomic trajectories. However, trajectories do matter, particularly in terms of use of active transportation to school.

Is obesity a risk factor for wheezing among adolescents? A prospective study in southern Brazil.

PURPOSE: To investigate the effect of obesity at the start of adolescence on the prevalence, incidence and maintenance of chest wheezing among individuals aged 11-15 years in a birth cohort in a developing country. METHODS: The seventh follow-up of the 1993 Pelotas birth cohort occurred in 2004 (individuals aged 10-11 years). Between January and August 2008, the eighth follow-up of the cohort was conducted. All the individuals of the original cohort who were alive (who were then adolescents aged between 14 and 15 years) were targets for the study. The International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire was used to define wheezing. In addition to the body mass index (BMI), used to define obesity by the World Health Organization (WHO) criteria, we assessed skinfold thickness. RESULTS: From the original cohort, 4,349 individuals were located (85.7% follow-up rate). The prevalence of chest wheezing at 11 and 15 years were 13.5% (95% CI: 12.5%-14.5%) and 12.1% (95% CI: 11.1%-13.1%), respectively. The prevalence of wheezing at both times was 4.5% (95% CI: 3.9%-5.1%) and the incidence of wheezing was 7.5% (95% CI: 6.7%-8.3%). Independent of the effect of various confounding variables, the prevalence of wheezing at 15 years was 50% greater among obese individuals than among eutrophic individuals at 11 years (RR 1.53; 95% CI: 1.14-2.05). The greater the skinfold tertile at 11 years, the higher the prevalence of wheezing at 15 years was (p = .011). Weight status and skinfolds did not present any association with incident wheezing. After controlling for confounding factors, the risk of persistent wheezing among obese individuals at 11 years was 1.82 (95% CI: 1.30-2.54). CONCLUSIONS: Since obesity at the start of adolescence is associated with asthma symptom persistence, prevention and treatment of obesity may reduce avoidable healthcare costs and disease burden.

Predictors of body mass index change from 11 to 15 years of age: the 1993 Pelotas (Brazil) birth cohort study.

PURPOSE: We explored predictors of nutritional status change from 11 to 15 years of age by analyzing prospective data. METHODS: We collected data at 11 and 15 years of age from individuals born in 1993 in Pelotas, Brazil. We assessed nutritional status using body mass index (BMI) for age in z-score according to the World Health Organization 2007 standards. Independent variables collected at 11 years of age were socioeconomic position, adolescent's perception of own weight, body dissatisfaction, and weight loss dieting. RESULTS: Of the 4,032 adolescents whose nutritional status could be evaluated in the two follow-ups, 93% maintained their nutritional status classification from 11 to 15 years. A total of 102 (2.8%) became obese and 181 (4.5%) ceased to be obese in the 4-year period. The prevalence of obesity decreased from 11 to 15 years of age in both boys and girls. Low-income girls were more likely to become obese from 11 to 15 years of age compared with high-income ones. Among boys, those with high income were more likely to cease being obese compared those with low income. Those who perceived themselves to be obese, who wished to have a smaller silhouette, and who were on diets to lose weight were more likely to become obese or to achieve a normal BMI category at 15 years of age. CONCLUSIONS: BMI tracks strongly in early adolescence. This finding suggests that interventions to more effectively change nutritional status should be implemented in childhood and should consider emotional aspects as well as social and biological ones.

Adolescent blood pressure, body mass index and skin folds: sorting out the effects of early weight and length gains.

BACKGROUND: Although there is longstanding evidence of the short-term benefits of promoting rapid growth for young children in low-income settings, more recent studies suggest that early weight gain can also increase the risk of chronic diseases in adults. This paper attempts to separate the effects of early life weight and length/height gains on blood pressure, body mass index (BMI), sum of skin folds and subscapular/triceps skin fold ratio at 14-15 years of age. METHODS: The sample comprised 833 members of a prospective population-based birth cohort from Brazil. Conditional size (weight or height) analyses were used to express the difference between observed size at a given age and expected size based on a regression, including all previous measures of the same anthropometric index. A positive conditional weight or height indicates growing faster than expected given prior size. RESULTS: Conditional weights at all age ranges were positively associated with most outcomes; each z-score of conditional weight at 4 years was associated with an increase of 6.1 mm in the sum of skin folds (95% CI 4.5 to 7.6) in adolescence after adjustment for conditional length/height. Associations of the outcomes with conditional length/height were mostly negative or non-significant-each z-score was associated with a reduction of 2.4 mm (95% CI -3.8 to -1.1) in the sum of skin folds after adjustment for conditional weight. No associations were found with the skin fold ratio. CONCLUSION: The promotion of rapid length/height gain without excessive weight gain seems to be beneficial for long-term outcomes, but this requires confirmation from other studies.

Problemas de saúde mental e tabagismo em adolescentes do sul do Brasil / Mental health problems and smoking among adolescents from Southern Brazil / Problemas de salud mental y tabaquismo en adolescentes del sur de Brasil

OBJETIVO: Analisar a associação entre problemas de saúde mental e uso de tabaco em adolescentes. MÉTODOS: Foram analisados 4.325 adolescentes de 15 anos da coorte de nascimentos de 1993 da cidade de Pelotas, RS. Tabagismo foi definido como fumar um ou mais cigarros nos últimos 30 dias. Saúde mental foi avaliada de acordo com o escore total do questionário Strengths and Difficulties Questionnaire e escore maior ou igual a 20 pontos foi considerado como positivo. Os dados foram analisados por regressão de Poisson, com ajuste robusto para variância. RESULTADOS: A prevalência de tabagismo foi 6,0 por cento e cerca de 30 por cento dos adolescentes apresentaram algum tipo de problema de saúde mental. Na análise bruta, a razão de prevalências para tabagismo foi de 3,3 (IC95 por cento 2,5; 4,2). Após ajuste (para sexo, idade, cor da pele, renda familiar, escolaridade da mãe, grupo de amigos fumantes, trabalho no último ano, repetência escolar, atividade física de lazer e uso experimental de bebida alcoólica), diminuiu para 1,7 (IC95 por cento 1,2; 2,3) entre aqueles com problemas de saúde mental. CONCLUSÕES: Problemas de saúde mental na adolescência podem ter relação com o consumo de tabaco.

OBJECTIVE: To analyze the association between mental health problems and smoking in adolescents. METHODS: A total of 4,325 adolescents aged 15 from the 1993 birth cohort of the city of Pelotas, Southern Brazil, was studied. Smoking was defined as having smoked one or more cigarettes in the previous 30 days. Mental health was assessed according to the total score of the Strengths and Difficulties Questionnaire. Score > 20 points was considered positive. Data were analyzed using Poisson regression with adjustment for robust variance. RESULTS: Smoking prevalence was 6.0 percent and about 30 percent of the adolescents presented some mental health problem. In the crude analysis, the prevalence ratio for smoking was 3.3 (95 percentCI 2.5; 4.2). After the adjusted analysis (for sex, age, skin color, family income, mother's level of schooling, group of friends who smoke, employment in the previous year, school failure, physical activity during leisure time and experimental use of alcohol), it decreased to 1.7 (95 percentCI 1.2; 2.3) among those with mental health problem. CONCLUSIONS: Mental health problems in adolescence may be related to tobacco consumption.

OBJETIVO: Analizar la asociación entre problemas de salud mental y uso de cigarro en adolescentes. MÉTODOS: Se analizaron 4.325 adolescentes de 15 años de la cohorte de nacimientos de 1993 de la ciudad de Pelotas, Sur de Brasil. Tabaquismo fue definido como fumar uno o más cigarros en los últimos 30 días. Salud mental fue evaluada de acuerdo con el escore total del cuestionario Strengths and Difficulties Questionnaire y escore mayor o igual a 20 puntos fue considerado como positivo. Los datos fueron analizados por regresión de Poisson, con ajuste robusto para varianza. RESULTADOS: La prevalencia de tabaquismo fue 6,0 por ciento y cerca de 30 por ciento de los adolescentes presentaron algún tipo de problema de salud mental. En el análisis bruto, la tasa de prevalencias de problema de tabaquismo de 3,3 (IC95 por ciento 2,5;4,2). Posterior al ajuste para sexo, edad, color de la piel, renta familiar, escolaridad de la madre, grupo de amigos fumadores, trabajo en el último año, repitencia escolar, actividad física de ocio y uso experimental de bebida alcohólica, disminuyó a 1,7 (IC95 por ciento 1,2;2,3) entre aquellos con problemas de salud mental. CONCLUSIONES: Problemas de salud mental en la adolescencia pueden tener relación con el consumo de tabaco.

Socioeconomic trajectory from birth to adolescence and lung function: prospective birth cohort study.

BACKGROUND: Socioeconomic status (SES) has been shown to be an important contributor to lung function. The aim of this study was to evaluate the association between lung function in adolescence and (a) SES at birth; (b) SES in adolescence; (c) SES trajectory from birth to adolescence ('never poor', 'non poor-poor', 'poor-non poor' and 'always poor'). Additionally, we investigate the role of adolescent and parental variables at mediating these associations. METHODS: Prospective birth cohort study in Pelotas, Brazil, including 4,005 adolescents (mean age: 14.7 years) followed up from birth. Lung function was measured by spirometry. Outcome variables were forced expiratory volume in one second in liters (FEV1) and forced vital capacity also in liters (FVC). RESULTS: Mean FEV1 was 3.46 L (95%CI 3.43-3.49) among boys and 2.93 L (95%CI 2.91-2.95) among girls. Mean FVC was 4.00 L (95%CI 3.97; 4.04) among boys and 3.30 L (95%CI 3.27; 3.32) among girls. SES at birth, in adolescence and its trajectory from birth to adolescence were inversely associated with lung function in both adolescent boys and girls. After adjustment for mediating variables, coefficients were largely reduced, particularly among boys, and the main predictor of change in coefficients was the inclusion of height in the models. CONCLUSION: Low income adolescents from Brazil present impaired lung function as compared to the better off, and this is largely explained by height.

Mental health problems and smoking among adolescents from Southern Brazil.

OBJECTIVE: To analyze the association between mental health problems and smoking in adolescents. METHODS: A total of 4,325 adolescents aged 15 from the 1993 birth cohort of the city of Pelotas, Southern Brazil, was studied. Smoking was defined as having smoked one or more cigarettes in the previous 30 days. Mental health was assessed according to the total score of the Strengths and Difficulties Questionnaire. Score > 20 points was considered positive. Data were analyzed using Poisson regression with adjustment for robust variance. RESULTS: Smoking prevalence was 6.0% and about 30% of the adolescents presented some mental health problem. In the crude analysis, the prevalence ratio for smoking was 3.3 (95%CI 2.5; 4.2). After the adjusted analysis (for sex, age, skin color, family income, mother's level of schooling, group of friends who smoke, employment in the previous year, school failure, physical activity during leisure time and experimental use of alcohol), it decreased to 1.7 (95%CI 1.2; 2.3) among those with mental health problem. CONCLUSIONS: Mental health problems in adolescence may be related to tobacco consumption.

Cross-sectional and longitudinal associations between physical activity and blood pressure in adolescence: birth cohort study.

OBJECTIVES: To explore cross-sectional and longitudinal associations between self-reported and accelerometry-based physical activity (PA) and blood pressure (BP) between 11 and 14 years of age. METHODS: Prospective birth cohort study in Pelotas, Brazil. Participants were 427 cohort members who were followed up with at 11, 12, and 14 years of age, and had questionnaire data on PA and BP at 11 and 14 years, as well as accelerometry and questionnaire data on PA at 12 years. Outcome measures were continuous systolic and diastolic BP at 14 years, and change in BP from 11 to 14 years. RESULTS: PA was unrelated to systolic BP in any analyses. PA measured by accelerometry at 12 years, but not questionnaire-derived PA, was inversely associated with diastolic BP at 14 years of age in fully adjusted models. Those who exceeded the 300-minutes PA threshold at all 3 visits had a 2.6 mmHg lower mean increase in DBP from 11 to 14 years compared with those classified below the threshold in all visits. CONCLUSIONS: Accelerometry-based PA was longitudinally inversely associated with diastolic BP. This finding was not evident when analyzing self-reported PA at a given age, suggesting a possible underestimation of the association when using subjective data.

What are the causal effects of breastfeeding on IQ, obesity and blood pressure? Evidence from comparing high-income with middle-income cohorts.

BACKGROUND: A novel approach is explored for improving causal inference in observational studies by comparing cohorts from high-income with low- or middle-income countries (LMIC), where confounding structures differ. This is applied to assessing causal effects of breastfeeding on child blood pressure (BP), body mass index (BMI) and intelligence quotient (IQ). METHODS: Standardized approaches for assessing the confounding structure of breastfeeding by socio-economic position were applied to the British Avon Longitudinal Study of Parents and Children (ALSPAC) (N ≃ 5000) and Brazilian Pelotas 1993 cohorts (N ≃ 1000). This was used to improve causal inference regarding associations of breastfeeding with child BP, BMI and IQ. Analyses were extended to include results from a meta-analysis of five LMICs (N ≃ 10 000) and compared with a randomized trial of breastfeeding promotion. Findings Although higher socio-economic position was strongly associated with breastfeeding in ALSPAC, there was little such patterning in Pelotas. In ALSPAC, breastfeeding was associated with lower BP, lower BMI and higher IQ, adjusted for confounders, but in the directions expected if due to socioeconomic patterning. In contrast, in Pelotas, breastfeeding was not strongly associated with BP or BMI but was associated with higher IQ. Differences in associations observed between ALSPAC and the LMIC meta-analysis were in line with those observed between ALSPAC and Pelotas, but with robust evidence of heterogeneity detected between ALSPAC and the LMIC meta-analysis associations. Trial data supported the conclusions inferred by the cross-cohort comparisons, which provided evidence for causal effects on IQ but not for BP or BMI. CONCLUSION: While reported associations of breastfeeding with child BP and BMI are likely to reflect residual confounding, breastfeeding may have causal effects on IQ. Comparing associations between populations with differing confounding structures can be used to improve causal inference in observational studies.

Validity of a wrist digital monitor for blood pressure measurement in comparison to a mercury sphygmomanometer.

BACKGROUND: Valid measurements of blood pressure, both at clinical and community settings, are essential for monitoring this variable at the population level. OBJECTIVE: To evaluate the validity of a wrist digital monitor for measuring blood pressure among adolescents in comparison to a mercury sphygmomanometer. METHODS: A validation study was carried out in the city of Pelotas, Southern Brazil. Blood pressure was measured twice using two different sphygmomanometers; an OMRON wrist digital and a desktop BD mercury one. Half of the sample was measured first with the digital manometer and subsequently with the mercury one, whereas the remaining half was evaluated in the opposite order. Agreement between both measures was evaluated using the Bland and Altman method. RESULTS: 120 adolescents aged 14 to 15 years were included (50% of each sex). Mean systolic blood pressure among boys was 113.7 mmHg (SD 14.2) when using the mercury manometer and 115.5 mmHg (SD 15.2) when using the digital one. Equivalent values for diastolic blood pressure were 61.5 mmHg (SD 9.9) and 69.6 mmHg (10.2), respectively. Among girls, the mean systolic blood pressure was 104.7 mmHg (SD 10.1) when using the mercury manometer and 102.4 mmHg (SD 11.9) when using the digital device. Values for diastolic blood pressure were 60.0 mmHg (SD 10.4) and 65.7 mmHg (SD 7.7), respectively. CONCLUSIONS: The digital device showed a high level of agreement with the mercury manometer when measuring systolic blood pressure. The level of agreement was lower for diastolic blood pressure. The use of correction equations may be an alternative for studies using this wrist digital monitor in adolescent patients.