Smoking exposure trajectories and pulmonary function in early adulthood in a Brazilian cohort.

OBJECTIVES: To investigate smoking trajectories and their association with pulmonary function (PF) and respiratory symptoms at age 22. METHODS: Data from a population-based cohort study of 3350 individuals and their spirometries were analysed. The outcomes were: forced expiratory volume in the first second (FEV1), forced vital capacity (FVC), forced expiratory flow at the mid expiratory phase (FEF25-75 %), FEV1/FVC and FEF25-75/FVC ratio. Smoking data were collected at perinatal follow-up (gestational exposure) and 15, 18 and 22 years. Group-based trajectory model was applied. RESULTS: Four groups were identified: no exposure (NE), gestational (GE), gestational and adulthood (GAE) and continuous (CE) exposure. Both CE and GAE trajectories were associated with lower values of FEV1/FVC (-1.77pp; p = 0.01 and -1.58 pp; p<0.001 respectively) and FEF25-75/FVC ratio (-7.27pp; p = 0.019 and -6.04pp; p<0.001 respectively) compared to the NE trajectory. Lower FEV1 and FEF25-75 % values were also related to the GAE trajectory (-68 ml; p = 0.03 and -253 ml/s;p<0.001 respectively). Compared to those who never smoked, individuals who smoked 10 or more cigarettes daily presented a reduction in the FEV1/FVC ratio by 1.37pp (p<0.001), FEF25-75 % by 126 ml (p = 0.012) and FEF25-75 %/FVC ratio by 3.62pp (p = 0.011). CE trajectory showed higher odds of wheezing (OR 4.14; p<0.001) and cough (OR 2.39; p = 0.002) compared to the non-exposed group. CONCLUSIONS: The in-uterus exposure to maternal smoking reduces PF later in life. However, the perpetuation of smoking behaviour throughout adolescence and early adulthood is determinant for PF main reduction and the emergence of respiratory-related symptoms.

Association of the length of time using computers and mobile devices with low back, neck and mid-back pains: findings from a birth cohort.

OBJECTIVES: Neck and low back pains are the leading causes of years lived with disability, and using computers or mobile devices in excess could be risk factors for back pain. Our aim was to evaluate the association of the length of time using computers and mobile devices with neck, mid-back and low back pains and the number of regions with pain. STUDY DESIGN: Cross-sectional study nested in the 1993 Pelotas birth cohort with young adults aged 22 years. METHODS: Outcomes analyzed were neck, mid-back and low back pains and the number of regions with pain. Exposures were the number of daily hours using computers and mobile devices. Crude and adjusted analyses were performed to estimate prevalence ratios using Poisson regression. RESULTS: Almost half of the sample reported having back pain, the low back pain being the most prevalent. Compared with individuals using mobile devices for less than one hour, the prevalence of neck pain was 1.41 and 1.81 times higher among individuals using mobile devices from three to seven hours and for seven or more hours per day, respectively. Neck pain prevalence was 1.47 times higher among individuals using computers for more than two hours than among those not using computers. Using mobile devices for seven hours or more was associated to 1.19 times higher prevalence of low back pain. CONCLUSION: Using mobile devices in excess was associated to neck and low back pains, while the use of computers in excess was associated only to neck pain. It is important that guidelines are developed to recommend the adequate length of time that computers and mobile devices should be used to prevent back pain.

Differential influences of early growth and social factors on young children's cognitive performance in four low-and-middle-income birth cohorts (Brazil, Guatemala, Philippines, and South Africa).

BACKGROUND: Studies relating childhood cognitive development to poor linear growth seldom take adequate account of social conditions related to both, leading to a focus on nutrition interventions. We aimed to assess the roles of both biological and social conditions in determining early childhood cognition, mediated by birthweight and early linear growth. METHODS: After exploratory structural equation modelling to identify determining factors, we tested direct and indirect paths to cognitive performance through birthweight and child height-for-age at 2 years, assessed between 4 and 8.5 years of age among 2448 children in four birth cohort studies in low-and-middle-income countries (Brazil, Guatemala, Philippines and South Africa). Determinants were compared across the cohorts. FINDINGS: Three factors yielded excellent fit, comprising birth endowment (primarily maternal age and birth order), household resources (crowding, dependency) and parental capacity (parental education). We estimated their strength together with maternal height in determining cognitive performance. Percentage shares of total effects of the four determinants show a marked transition from mainly biological determinants of birth weight (birth endowment 34%) and maternal height (30%) compared to household resources (25%) and parental capacity (11%), through largely economic determinants of height at 2 years (household resources (60%) to cognitive performance being predominantly determined by parental capacity (64%) followed by household resources (29%). The largely biological factor, birth endowment (maternal age and birth order) contributed only 7% to childhood cognitive performance and maternal height was insignificant. In summary, the combined share of social total effects (household resources and parental capacity) rises from 36∙2% on birth weight, to 78∙2% on height for age at 24 m, and 93∙4% on cognitive functioning. INTERPRETATION: Across four low- and middle-income contexts, cognition in childhood is influenced more by the parental capacity of families and their economic resources than by birth weight and early linear growth. Improving children's cognitive functioning requires multi-sectoral interventions to improve parental education and enhance their economic wellbeing, interventions that are known to improve also early childhood growth.

Revisiting ADHD age-of-onset in adults: to what extent should we rely on the recall of childhood symptoms?

BACKGROUND: ADHD diagnosis requires the presence of symptoms before the age of twelve. In clinical assessment of adults, the most frequent strategy to check this criterion is investigating self-report recall of symptoms, despite little evidence on the validity of this approach. We aim to evaluate the recall accuracy and factors associated with its reliability in a large population-based sample of adults. METHODS: Individuals from the 1993 Pelotas Birth Cohort were followed-up from childhood to adulthood. At the age of 22, 3810 individuals were assessed through structured interviews by trained psychologists regarding mental health outcomes, including ADHD diagnosis and ADHD symptoms in childhood. The retrospective recall was compared with available information on ADHD childhood symptoms at the age of eleven. We also assessed factors related to recall accuracy through multiple regression analyses. RESULTS: Self-reported recall of childhood symptoms at 22 years of age had an accuracy of only 55.4%, with sensitivity of 32.8% and positive predictive value of 40.7%. Current inattention symptoms were associated with lower risk and social phobia with higher risk for false-positive endorsement, while higher levels of schooling correlated with lower risk and male gender with higher risk for false-negative endorsement. CONCLUSIONS: Clinicians treating male patients with social phobia and ADHD symptoms should assess even more carefully retrospective recall of ADHD childhood symptoms. Moreover, characteristics associated with recall improvement do not impact accuracy robustly. In this context, the recall of childhood ADHD symptoms seems an unreliable method to characterize the neurodevelopmental trajectory in adults with currently-impairing ADHD symptomatology.

A risk calculator to predict adult attention-deficit/hyperactivity disorder: generation and external validation in three birth cohorts and one clinical sample.

AIM: Few personalised medicine investigations have been conducted for mental health. We aimed to generate and validate a risk tool that predicts adult attention-deficit/hyperactivity disorder (ADHD). METHODS: Using logistic regression models, we generated a risk tool in a representative population cohort (ALSPAC - UK, 5113 participants, followed from birth to age 17) using childhood clinical and sociodemographic data with internal validation. Predictors included sex, socioeconomic status, single-parent family, ADHD symptoms, comorbid disruptive disorders, childhood maltreatment, ADHD symptoms, depressive symptoms, mother's depression and intelligence quotient. The outcome was defined as a categorical diagnosis of ADHD in young adulthood without requiring age at onset criteria. We also tested Machine Learning approaches for developing the risk models: Random Forest, Stochastic Gradient Boosting and Artificial Neural Network. The risk tool was externally validated in the E-Risk cohort (UK, 2040 participants, birth to age 18), the 1993 Pelotas Birth Cohort (Brazil, 3911 participants, birth to age 18) and the MTA clinical sample (USA, 476 children with ADHD and 241 controls followed for 16 years from a minimum of 8 and a maximum of 26 years old). RESULTS: The overall prevalence of adult ADHD ranged from 8.1 to 12% in the population-based samples, and was 28.6% in the clinical sample. The internal performance of the model in the generating sample was good, with an area under the curve (AUC) for predicting adult ADHD of 0.82 (95% confidence interval (CI) 0.79-0.83). Calibration plots showed good agreement between predicted and observed event frequencies from 0 to 60% probability. In the UK birth cohort test sample, the AUC was 0.75 (95% CI 0.71-0.78). In the Brazilian birth cohort test sample, the AUC was significantly lower -0.57 (95% CI 0.54-0.60). In the clinical trial test sample, the AUC was 0.76 (95% CI 0.73-0.80). The risk model did not predict adult anxiety or major depressive disorder. Machine Learning approaches did not outperform logistic regression models. An open-source and free risk calculator was generated for clinical use and is available online at https://ufrgs.br/prodah/adhd-calculator/. CONCLUSIONS: The risk tool based on childhood characteristics specifically predicts adult ADHD in European and North-American population-based and clinical samples with comparable discrimination to commonly used clinical tools in internal medicine and higher than most previous attempts for mental and neurological disorders. However, its use in middle-income settings requires caution.

Intrauterine exposure to smoking and wheezing in adolescence: the 1993 Pelotas Birth Cohort.

Previous studies have suggested an association between maternal smoking during pregnancy and asthma symptoms such as wheezing during childhood. However, few have evaluated this association in adolescence, especially in populations with high prevalence of wheezing as in Brazil. Using the 1993 Pelotas birth cohort, a longitudinal study set in southern Brazil of 5249 urban live births, we aimed to evaluate the association between maternal and the partner's smoking during pregnancy and wheezing at 11 and 15 years of age. We evaluated smoking during pregnancy using number of cigarettes/day, and our main outcomes were as follows: wheezing in the last year and number of wheezing crises, at both 11 and 15 years of age, as well as persistent wheezing (having crises at 11 and 15 years of age) and medical asthma diagnosis at age 15. In addition, other socio-demographic variables were included as possible confounders and mediators of this association. We used Poisson regression models to evaluate crude and adjusted associations. Of the 5249 live births in 1993, 87.5% and 85.7% were followed-up to 11 and 15 years of age, respectively. Maternal smoking during pregnancy showed a dose-response association with number of wheezing crises at age 15 (P = 0.023), presence of persistent wheezing (P = 0.034) and asthma diagnosis (P = 0.023). Partner's smoking was not associated with any wheezing variables. Maternal smoking during pregnancy appears to exert an effect on respiratory morbidity of adolescents, evaluated by wheezing symptoms.

Physical activity throughout adolescence and bone mineral density in early adulthood: the 1993 Pelotas (Brazil) Birth Cohort Study.

UNLABELLED: Association between three physical activity (PA) measurements throughout adolescence and bone density at 18 years of age was investigated. PA was associated with both lumbar spine and femoral neck bone mineral density (BMD) in early adulthood independent of type of PA used in the analysis. The results were more consistent in boys. INTRODUCTION: This study amis to evaluate if PA during adolescence could influence BMD later in life. METHODS: A population-based birth cohort study was carried out. PA was assessed at 11 and 15 years of age by questionnaire and included sports performed while BMD (lumbar spine and femoral neck) was measured by dual-energy X-ray absorptiometry at 18 years. A peak strain score was generated based on ground reaction forces of different PA. PA was measured as peak strain score, peak strain score multiplied by minutes/week and minutes/week. Unadjusted and adjusted analyses were performed using linear regression. RESULTS: Overall, 3,811 adolescents were studied (1,866 boys and 1,945 girls). The peak strain score at 11 and 15 years was associated with lumbar and femoral neck BMD at 18 years in boys. Among girls, high-impact PA at 11 years was positively associated with lumbar and femoral BMD (p = 0.01; p < 0.001). After adjusted analysis, weekly minutes of PA at 11 years were not associated with lumbar spine but were associated with femoral neck BMD (p < 0.001); at 15 years, weekly minutes of PA were positively associated with BMD at both sites. Regardless of PA status at 11 years of age, attaining the recommendations of PA (300 min/week) at 15 years appears to be important for BMD at 18 years in both sites in boys and girls. The results Appeared to be more consistent in boys. CONCLUSIONS: PA during adolescence was positively associated with both lumbar spine and femoral neck BMD in early adulthood independent of type of PA used in the analysis.

Life-course evidence of birth weight effects on bone mass: systematic review and meta-analysis.

A systematic review of the literature was performed in July 2011. Original papers based on longitudinal studies measuring spine, femoral neck, or total body bone mass by DXA were included (n = 17). Birth weight was positively associated with bone mass among children. The association was unclear among adolescents and weak among adults. This study aims to evaluate the association between birth weight and bone mass in future ages through a systematic review of literature and meta-analysis. A systematic review of the literature was performed in July 2011 in Medline, Web of Science and LILACS bases using key terms: ("birth size" OR "birth weight" OR birthweight OR prematurity OR premature OR "gestational age") AND (osteoporosis OR "bone mass" OR "bone density" OR "bone mineral density" OR "bone mineral content" OR "bone area") AND (longitudinal OR cohort). Original papers based on longitudinal studies measuring lumbar spine, femoral neck or total body bone mass by dual-emission X-ray absorptiometry (DXA) were included. A meta-analysis was performed using birth weight and bone mass density and/or content as continuous variables and adjusted for current height and/or weight. A total of 218 articles were retrieved from which 17 were selected and grouped into three categories according to age: studies with children; with adolescents and young adults, and studies with adults (older than 25). Five papers were included in the meta-analysis. Positive association between birth weight and bone mass was clear among children, unclear among adolescents, and weak among adults. The effect on bone mass content was stronger than those on body mass density regardless of age. Birth weight influences positively bone health in later life. Preventive health policies dealing with early-life modifiable risk factors, as birth weight, should be encouraged to attain an optimal peak bone mass as an strategy to decrease osteoporosis in the elderly.

Association of socioeconomic position with maternal pregnancy and infant health outcomes in birth cohort studies from Brazil and the UK.

BACKGROUND: Socioeconomic inequalities in health outcomes are dynamic and vary over time. Differences between countries can provide useful insights into the causes of health inequalities. The study aims to compare the associations between two measures of socioeconomic position (SEP)-maternal education and family income-and maternal and infant health outcomes between ALSPAC and Pelotas cohorts. METHODS: Birth cohort studies were started in Avon, UK, in 1991 (ALSPAC) and in the city of Pelotas, Brazil, in 1982, 1993 and 2004. Maternal outcomes included smoking during pregnancy, caesarean section and delivery not attended by a doctor. Infant outcomes were preterm birth, intra-uterine growth restriction (IUGR) and breast feeding for <3 months. The relative index of inequality was used for each measure of SEP so that results were comparable between cohorts. RESULTS: An inverse association (higher prevalence among the poorest and less educated) was observed for almost all outcomes, with the exception of caesarean sections where a positive association was found. Stronger income-related inequalities for smoking and education-related inequalities for breast feeding were found in the ALSPAC study. However, greater inequalities in caesarean section and education-related inequalities in preterm birth were observed in the Pelotas cohorts. CONCLUSIONS: Mothers and infants have more adverse health outcomes if they are from poorer and less well-educated socioeconomic backgrounds in both Brazil and the UK. However, our findings demonstrate the dynamic nature of the association between SEP and health outcomes. Examining differential socioeconomic patterning of maternal and infant health outcomes might help understanding of mechanisms underlying such inequalities.

Paid employment in subjects with and without chronic obstructive pulmonary disease in five Latin American cities: the PLATINO study.

BACKGROUND: Chronic obstructive pulmonary disease (COPD) is a costly condition that frequently causes permanent work disabilities. Little information exists regarding the impact of COPD on work force participation and the indirect costs of the disease in developing countries. OBJECTIVE: To examine the frequency of paid employment and factors influencing it in a Latin-American population-based study. METHODS: Post-bronchodilator FEV(1)/FVC < 0.70 (forced expiratory volume in 1 s/forced vital capacity) was used to define COPD. Information regarding paid work was assessed by the question 'At any time in the past year, have you worked for payment?' RESULTS: Interviews were conducted with 5571 subjects; 5314 (759 COPD and 4554 non-COPD) subjects underwent spirometry. Among the COPD subjects, 41.8% reported having paid work vs. 57.1% of non-COPD (P < 0.0001). The number of months with paid work was reduced in COPD patients (10.5 ± 0.17 vs. 10.9 ± 0.06, P < 0.05). The main factors associated with having paid work in COPD patients were male sex (OR 0.33, 95%CI 0.23-0.47), higher education level (OR 1.05, 95%CI 1.01-1.09) and younger age (OR 0.90, 95%CI 0.88-0.92). COPD was not a significant contributor to employment (OR 0.83, 95%CI 0.69-1.00, P = 0.054) in the entire population. CONCLUSIONS: Although the proportion of persons with paid work is lower in COPD, having COPD appears not to have a significant impact on obtaining paid employment in the overall population of developing countries.

Caesarean sections and risk of wheezing in childhood and adolescence: data from two birth cohort studies in Brazil.

BACKGROUND: There is evidence from two meta-analyses that children born through caesarean section (C-section) may have an increased risk of developing asthma compared with those born through vaginal delivery. Objective To evaluate the association between mode of delivery and wheezing (current and persistent) in childhood and adolescence, in two birth cohort studies in Brazil. METHODS: The outcome variable was based on the International Study of Allergy and Asthma questionnaire, which collects information about wheezing within the 12 months before the interview. Persistent wheezing was defined when it was present in more than one follow-up at different ages, in the 1993 cohort. The questions were asked to mothers when children were aged 4 years (1993 and 2004 cohorts) and directly to cohort participants at 11 and 15 years (1993 cohort). Mode of delivery was collected by the research team of each cohort when children were born. RESULTS: Response rates in the last follow-up visit of the 1993 and 2004 cohorts were 85% and 92%, respectively. The prevalence of current wheezing increased from 20% to 28% at 4 years from 1993 to 2004; at 11 and 15 years, the prevalence was around 14% and 12%, in the 1993 cohort. The proportion of C-sections increased from 30.5% to 45% between 1993 and 2004. In each cohort, the prevalence of current wheezing was similar among children born through vaginal and C-section. The risk for persistent wheezing in the 1993 cohort was higher among girls born through C-section than boys. CONCLUSION: Despite the increase in the proportion of C-section in two cohorts in Southern Brazil, we found no evidence of an association between mode of delivery and the subsequent risk of wheezing. Among girls, although there was no statistical significance, the risk was higher for those born by C-section, especially regarding persistent wheezing.

Childhood body mass index and risk of asthma in adolescence: a systematic review.

Asthma and obesity, both of which are considered global health issues, affect approximately 300 million individuals worldwide. The observation that asthma and obesity tend to increase in parallel may indicate a potential link between these two conditions. The aim of this systematic review of the literature was to investigate the relationship between childhood nutritional status and incidence or persistence of asthma during adolescence. The principal eligibility criteria for selection of articles were including longitudinal analysis, and which measured of exposure during childhood or adolescence and outcome during adolescence. The systematic search initially returned 1563 unique articles. After inspection of titles and reading the abstracts of these articles, we chose 27 for full reading. Of these, 10 were selected to be included in the present review. Of the 10 selected studies, eight showed positive associations between overweight/obesity and asthma. Of these, two were independent of sex, three were found only among men and another three only among women. The present study shows strong evidence that, although the role of sex is not clear, obesity precedes, and is associated with, the persistence and intensity of symptoms of asthma.

Sex-related differences in COPD in five Latin American cities: the PLATINO study.

There is evidence to suggest sex differences exists in chronic obstructive pulmonary disease (COPD) clinical expression. We investigated sex differences in health status perception, dyspnoea and physical activity, and factors that explain these differences using an epidemiological sample of subjects with and without COPD. PLATINO is a cross-sectional, population-based study. We defined COPD as post-bronchodilator forced expiratory volume in 1 s/forced vital capacity ratio <0.70, and evaluated health status perception (Short Form (SF)-12 questionnaire) and dyspnoea (Medical Research Council scale). Among 5,314 subjects, 759 (362 females) had COPD and 4,555 (2,850 females) did not. In general, females reported more dyspnoea and physical limitation than males. 54% of females without COPD reported a dyspnoea score ≥ 2 versus 35% of males. A similar trend was observed in females with COPD (63% versus 44%). In the entire study population, female sex was a factor explaining dyspnoea (OR 1.60, 95%CI 1.40-1.84) and SF-12 physical score (OR -1.13, 95%CI -1.56- -0.71). 40% of females versus 28% of males without COPD reported their general health status as fair-to-poor. Females with COPD showed a similar trend (41% versus 34%). Distribution of COPD severity was similar between sexes, but currently smoking females had more severe COPD than currently smoking males. There are important sex differences in the impact that COPD has on the perception of dyspnoea, health status and physical activity limitation.

The role of early life variables on the risk of fractures from birth to early adolescence: a prospective birth cohort study.

UNLABELLED: In a prospective cohort from Brazil, we evaluated the incidence of fractures from birth to early adolescence and examined risk factors for fractures. The incidence was 14.2% (95%CI 13.2, 15.2). Male sex, birth length, and maternal age at delivery were positively associated with the risk of fractures. INTRODUCTION: This study aims to evaluate the incidence of fractures from birth to 11 years of age and to explore the effect of early life variables on the risk of fractures. METHODS: All children (N = 5,249) born in 1993 in the city of Pelotas, Brazil were enrolled in a prospective birth cohort study. In 2004-2005, 87.5% of the cohort members were sought for a follow-up visit. History of fractures, including anatomic site and age of the fracture were asked to mothers. RESULTS: The incidence of fractures from birth to 11 years of age was 14.2% (95%CI 13.2, 15.2). Out of the 628 subjects who experienced a fracture, 91 reported two and only 20 reported three or more fractures. Male sex, birth length, and maternal age at delivery were positively associated with the risk of fractures. No consistent associations were found for family income, maternal body mass index, smoking during pregnancy, and birth weight. CONCLUSIONS: Birth length seems to have long-term effect on musculoskeletal health. The higher risk of fractures among children of older mothers needs to be confirmed by other studies. In accordance to the developmental origins of diseases, fractures seem to be, at least in part, programmed in early life.

Can a normal peak expiratory flow exclude severe chronic obstructive pulmonary disease?

BACKGROUND: Chronic obstructive pulmonary disease (COPD) is underdiagnosed. One barrier to diagnosis is the limited availability of spirometry testing, but in adults at risk for COPD, a normal pre-bronchodilator (pre-BD) peak expiratory flow (PEF) may rule out clinically significant COPD. OBJECTIVE: To identify post-BD airway obstruction using data from 13 708 individuals aged >or=40 years from the PLATINO and BOLD studies. METHODS: We evaluated different cut-off points of pre-BD. The PEF was obtained from a diagnostic-quality spirometer (not a mechanical PEF meter). At least one of the following COPD risk factors was present in 77% of the subjects: chronic respiratory symptoms; exposure to tobacco smoke, biomass smoke or dust in the workplace; or a previous diagnosis of asthma, COPD, emphysema or chronic bronchitis. RESULTS: Although the positive predictive value was low as expected, a pre-BD PEF of >or=70% predicted effectively ruled out Stages III and IV COPD of the Global Initiative for Chronic Obstructive Lung Disease. Among those with at least one risk factor, only 12% would require confirmatory spirometry using this criterion. CONCLUSIONS: Adding PEF measurement to a screening questionnaire may rule out severe to very severe COPD without the need for pre- and post-BD spirometry testing. Confirmation is needed from a study using inexpensive PEF meters or pocket spirometers with a staged screening protocol.

Effect of birth size and proportionality on BMI and skinfold thickness in early adolescence: prospective birth cohort study.

OBJECTIVES: To assess the effect of birth weight, length and ponderal index at birth on body mass index (BMI) and skinfold thickness in early adolescence. SUBJECTS/METHODS: Population-based, prospective birth cohort study in Pelotas, Brazil. Out of 5249 cohort members, 87.5% were traced at 11 years of age. Birth weight, length and ponderal index (birth weight/birth length(3) x 100) -- treated as continuous variable and divided into fourths -- were the exposure variables. BMI at 11 years, triceps and subscapular skinfolds were the outcomes. Confounders included sex, gestational age, parity, maternal schooling, family income, maternal smoking during pregnancy and maternal BMI. RESULTS: All three exposure variables were significantly associated with BMI in early adolescence, but the strongest effect was observed for birth weight. Each unit (Z-score) increase in birth weight was associated with 0.46 kg m(-2) increase in BMI at 11 years. The equivalent coefficients for ponderal index and birth length were 0.22 and 0.21 kg m(-2), respectively. High birth weight, length and ponderal index were also associated with increased values for triceps and subscapular skinfolds at 11 years, and with increased prevalence of obesity. CONCLUSIONS: Of the three birth exposures studied, birth weight presented the strongest effect on anthropometry in early adolescence. Ponderal index, a proportionality indicator associated with infant mortality, hospitalizations and anthropometry in infancy, was also associated with anthropometry in early adolescence, but its predictive value for the latter is lower than that of birthweight alone. All three birth size indicators studied presented poor predictability of the later risk of obesity.

Occupational exposures and COPD: an ecological analysis of international data.

The occupational contribution to chronic obstructive pulmonary disease (COPD) has yet to be put in a global perspective. In the present study, an ecological approach to this question was used, analysing group-level data from 90 sex-specific strata from 45 sites of the Burden of Obstructive Lung Disease study, the Latin American Project for the Investigation of Obstructive Lung Disease and the European Community Respiratory Health Survey follow-up. These data were used to study the association between occupational exposures and COPD Global Initiative for Chronic Obstructive Lung Disease (GOLD) stage II or above. Regression analysis of the sex-specific group-level prevalence rates of COPD at each site against the prevalence of occupational exposure and ever-smoking was performed, taking into account mean smoking pack-yrs and mean age by site, sex, study cohort and sample size. For the entire data set, the prevalence of exposures predicted COPD prevalence (0.8% increase in COPD prevalence per 10% increase in exposure prevalence). By comparison, for every 10% increase in the proportion of the ever-smoking population, the prevalence of COPD GOLD stage II or above increased by 1.3%. Given the observed median population COPD prevalence of 3.4%, the model predicted that a 20% relative reduction in the disease burden (i.e. to a COPD prevalence of 2.7%) could be achieved by a 5.4% reduction in overall smoking rates or an 8.8% reduction in the prevalence of occupational exposures. When the data set was analysed by sex-specific site data, among males, the occupational effect was a 0.8% COPD prevalence increase per 10% change in exposure prevalence; among females, a 1.0% increase in COPD per 10% change in exposure prevalence was observed. Within the limitations of an ecological analysis, these findings support a worldwide association between dusty trades and chronic obstructive pulmonary disease for both females and males, placing this within the context of the dominant role of cigarette smoking in chronic obstructive pulmonary disease causation.

Worldwide burden of COPD in high- and low-income countries. Part II. Burden of chronic obstructive lung disease in Latin America: the PLATINO study.

SETTING: Five Latin American cities: São Paulo, Brazil; Mexico City, Mexico; Montevideo, Uruguay; Santiago, Chile; Caracas, Venezuela. OBJECTIVE: To describe the burden of chronic obstructive pulmonary disease (COPD) in Latin America. DESIGN: This is a multicentre study. Post-bronchodilator spirometry was used and the main outcome measure was FEV(1)/FVC < 0.7 (fixed ratio criterion). Global Obstructive Lung Disease (GOLD) stages were also analysed. RESULTS: The combined population aged > or =40 years in the five countries included in the study was approximately 85.3 million. Of these, it was estimated that 12.2 million have airflow obstruction, which corresponds to our prevalence estimate of 14.3%. The proportion of subjects in Stages II-IV of the GOLD classification was 5.6%. Risk factors presenting the highest aetiological fractions for COPD were age, current smoking, indoor exposure to coal and exposure to dust in the workplace. Smoking, the modifiable factor with the strongest aetiological fraction for COPD, affects 29.2% of adults aged > or =40 years in these cities, corresponding to approximately 25 million smokers in this age group. CONCLUSION: Prevention of smoking and exposure to pollutants, such as coal and dust, are the interventions most likely to succeed against COPD in Latin America. The information obtained by a collaborative study has been vast and encouraging for other similar studies.

Sleep patterns and television viewing in relation to obesity and blood pressure: evidence from an adolescent Brazilian birth cohort.

BACKGROUND: Disruption of circadian rhythms has been associated with obesity in children and adolescents, and with hypertension in adults, in industrialized populations. OBJECTIVE: We examined cross-sectional associations between sleep duration or television viewing and obesity and blood pressure in Brazilian adolescents. DESIGN: The sample consisted of 4452 adolescents aged 10-12 years participating in a prospective birth cohort study in Pelotas, Brazil. Sleep duration and television viewing were determined through questionnaires. Obesity was assessed using international cut-offs for body mass index (BMI), and body fatness by skinfold thicknesses. Blood pressure was measured using a validated monitor. RESULTS: Short sleep duration was associated with increased BMI, skinfolds, systolic blood pressure, activity levels and television viewing. Each hour of sleep reduced BMI by 0.16 kg/m(2) (s.e. 0.04), and was associated with odds ratio for obesity of 0.86 (s.e. 0.04), both P<0.001. Television viewing was associated with increased BMI and skinfolds, and increased blood pressure. The effects of sleep duration and television viewing on obesity were independent of one another. Their associations with blood pressure were mediated by body fatness. CONCLUSIONS: Both short sleep duration and increased television viewing were associated with greater body fatness, obesity and higher blood pressure, independently of physical activity level. These associations were independent of maternal BMI, identified in other studies as the strongest predictor of childhood obesity. Our study shows that behavioural factors associated with metabolic risk in industrialized populations exert similar deleterious effects in a population undergoing nutritional transition and suggest options for public health interventions.