Multiple imputation to deal with missing objectively-measured physical activity data: findings from two cohorts / Imputação múltipla para lidar com dados faltantes em acelerometria: resultados de duas coortes

The objective of this article was to describe patterns of losses of information regarding accelerometer data and to assess the use of multiple imputation to generate physical activity estimates for individu-als without accelerometry data. Two birth cohort studies from Pelotas (Brazil) with participants aged 22 and 11-years old assessed objectively measured physical activity differences between complete and imputed cases. Mean values of overall physical activity for complete cases (n1993 = 2,985 and n2004 = 3,348) and for complete cases plus imputed cases (n1993 = 760 and n2004 = 79) were described accord-ing to predictors. Male individuals, participants with black skin color, and less schooled individuals presented higher averages of overall physical activity than their counterparts. Almost all imputed estimates were comparable to the complete cases, and the highest difference found was 0.7 mg for the first quintile of socioeconomic status of the 1993 birth cohort. Multiple imputation is a positive technique to deal with missing data from objectively measured physical activity. It provides a set of relevant variables to be used in order to efficiently predict accelerometer data

O objetivo desse artigo foi descrever os padrões de perda de informação em dados de acelerometria, além de avaliar o processo de imputação múltipla para estimar o nível de atividade física para indivíduos sem dados de acelerometria. Participantes de duas coortes de nascimentos de Pelotas (Brasil) com 22 e 11 anos participaram do estudo e diferenças entre casos completos e imputados foram avaliadas. A média geral de atividade física para os casos completos (n1993 = 2.985 e n2004 = 3.348) e para casos completos mais imputados (n1993 = 760 e n2004 = 79) foi descrita de acordo com os preditores. Indivíduos do sexo masculino, de cor da pele preta e com menor escolaridade apresentaram maiores médias de atividade física geral. Quase todas as estimativas imputadas foram comparáveis com os valores de casos completos, e a maior diferença encontrada foi 0,7 mg para o primeiro quintil de renda na coorte de 1993. Imputação múltipla é uma boa técnica para lidar com dados faltantes de atividade física medida por acelerometria. Essa técnica fornece um gama relevante de variáveis para serem usadas a fim de predizer valores de acelerometria eficientemente

Objectively measured physical activity according to the periods of the day in the Pelotas Cohort / Medida objetiva de atividade física de acordo com períodos do dia em uma coorte de Pelotas

This study aims to describe objectively measured physical activity (PA) in different periods of the day in young adults according to sex, socioeconomic position and during weekdays and weekends. This is a cross-sectional analysis carried out with the participants of the 1993 Pelotas Birth Cohort at 22 years. PA was assessed by triaxial accelerometer. Descriptive analyses were performed presenting the time spent on light PA (LPA) and bouted moderate to vigorous PA (MVPA) in different periods of the day (morning - 6am to 11:59 am, afternoon ­ 12pm to 7:59 pm and night ­ 8pm to 11:59pm). The present study included 2,766 individuals (48.2% male and 51.8% female). LPA was higher among women, while bouted MVPA levels were higher among men. The median of PA was higher on weekdays compared to weekends for all intensities. The bouted MVPA medians in the morning and at night were zero minutes for all days and both sexes. The richest group presented a higher percentage of individuals with zero minutes. PA may vary according to different periods of the day and intensity. The absence of PA practice was markedly influenced by sex and socioeconomic position

Este estudo teve o objetivo de mensurar atividade física (AF) objetivamente em diferentes períodos do dia em adultos jovens de acordo com sexo, posição socioeconômica e dia de semana e final de semana. Esta é uma análise transversal conduzida com participantes da Coorte de Nascimentos de 1993 de Pelotas aos 22 anos. AF foi avaliada por um acelerômetro triaxial. Foram realizadas análises descritivas apresentando o tempo em AF leve (AFL) e moderada a vigorosa (AFMV ) em diferentes períodos do dia (manhã ­ 6h às 11:59h, tarde ­ 12h às 19:59h e noite ­ 20h às 0h). O presente estudo incluiu 2.766 individuos (48.2% homens e 51.8% mulheres). AFL foi maior entre as mulheres enquanto AFMV foi maior entre os homens. A mediana de AF foi maior nos dias de semana comparado aos dias de final de semana para qualquer intensidade. As medianas de AFMV pela manhã e noite foram zero minutos para todos os dias nos dois sexos. O grupo econômico mais alto apresentou maior percentual de individuos com zero minutos de AFMV. AF pode variar de acordo com diferentes períodos do dia e intensidades. A ausência de prática de AF foi marcadamente influenciada por sexo e posição socioeconômica

Day care attendance during the first 12 months of life and occurrence of infectious morbidities and symptoms / Frequência em creches durante os primeiros 12 meses de vida e ocorrência de morbidades e sintomas infecciosos

ABSTRACT Objective: To investigate the occurrence of infectious morbidities according to day care attendance during the first year of life. Methods: This was a cross-sectional analysis of data from the 12-month follow-up of a medium-sized city birth cohort from children born in 2015, in the Southern Brazil. Main exposure variables were day care attendance from 0 to 11 months of age, type of day care center (public or private), and age at entering day care. Health outcomes were classified as follows: "non-specific respiratory symptoms," "upper respiratory tract infection," "lower respiratory tract infection," "flu/cold," "diarrhea," or "no health problem," considering the two weeks prior to the interview administered at 12 months of life. Associations were assessed using Poisson regression adjusted by demographic, behavioral, and socioeconomic variables. Results: The sample included 4018 children. Day care attendance was associated with all classifications of health outcomes mentioned above, except for flu/cold. These were stronger among children who entered day care at an age closer to the outcome time-point. An example are the results for lower respiratory tract infection and diarrhea, with adjusted prevalence ratios of 2.79 (95% CI: 1.67-4.64) and 2.04 (95% CI: 1.48-2.82), respectively, for those who entered day care after 8 months of age when compared with those who never attended day care. Conclusions: The present study consistently demonstrated the association between day care attendance and higher occurrence of infectious morbidities and symptoms at 12 months of life. Hence, measures to prevent infectious diseases should give special attention to children attending day care centers.

RESUMO Objetivo: Investigar a ocorrência de morbidades infecciosas de acordo com a frequência em creches durante o primeiro ano de vida. Métodos: Esta foi uma análise transversal dos dados de uma coorte de nascimento, em uma cidade de tamanho médio, na visita aos 12 meses de idade de crianças nascidas em 2015 no Sul do Brasil. As principais variáveis de exposição foram frequência em creches de zero aos 11 meses de idade, tipo de creche (pública ou particular) e idade ao entrar na creche. Os resultados de saúde foram classificados como: "sintomas respiratórios não específicos", "infecção do trato respiratório superior", "infecção do trato respiratório inferior", "gripe/resfriado", "diarreia" ou "nenhum problema de saúde", considerando as duas semanas anteriores à entrevista feita aos 12 meses de vida da criança. As associações foram avaliadas com a regressão de Poisson ajustada pelas variáveis demográficas, comportamentais e socioeconômicas. Resultados: A amostra incluiu 4.018 crianças. O ato de frequentar creches foi associado a todas as classificações de resultados de saúde mencionados, exceto gripe/resfriado. Esses resultados foram mais fortes entre as crianças que começaram a frequentar creches em uma idade mais próxima ao ponto de tempo do resultado. Um exemplo são os resultados para infecção do trato respiratório inferior e diarreia, índice de prevalência ajustado de 2,79 (IC de 95%: 1,67-4,64) e 2,04 (IC de 95%: 1,48-2,82), respectivamente, naqueles que ingressaram nas creches após os oito meses de idade, em comparação com aqueles que nunca frequentaram creche. Conclusões: O presente estudo mostra sistematicamente a associação entre a frequência em creches e a maior ocorrência de morbidades infecciosas e sintomas aos 12 meses de vida da criança. Assim, deve-se dar atenção especial às medidas para prevenir as doenças infecciosas em crianças que frequentes creches.

Day care attendance during the first 12 months of life and occurrence of infectious morbidities and symptoms.

OBJECTIVE: To investigate the occurrence of infectious morbidities according to day care attendance during the first year of life. METHODS: This was a cross-sectional analysis of data from the 12-month follow-up of a medium-sized city birth cohort from children born in 2015, in the Southern Brazil. Main exposure variables were day care attendance from 0 to 11 months of age, type of day care center (public or private), and age at entering day care. Health outcomes were classified as follows: "non-specific respiratory symptoms," "upper respiratory tract infection," "lower respiratory tract infection," "flu/cold," "diarrhea," or "no health problem," considering the two weeks prior to the interview administered at 12 months of life. Associations were assessed using Poisson regression adjusted by demographic, behavioral, and socioeconomic variables. RESULTS: The sample included 4018 children. Day care attendance was associated with all classifications of health outcomes mentioned above, except for flu/cold. These were stronger among children who entered day care at an age closer to the outcome time-point. An example are the results for lower respiratory tract infection and diarrhea, with adjusted prevalence ratios of 2.79 (95% CI: 1.67-4.64) and 2.04 (95% CI: 1.48-2.82), respectively, for those who entered day care after 8 months of age when compared with those who never attended day care. CONCLUSIONS: The present study consistently demonstrated the association between day care attendance and higher occurrence of infectious morbidities and symptoms at 12 months of life. Hence, measures to prevent infectious diseases should give special attention to children attending day care centers.

Associations of physical activity and sedentary time with body composition in Brazilian young adults.

The findings of studies on the association between physical activity and adiposity are not consistent, and most are cross-sectional and used only self-reported measures. The aims of this study were to evaluate: 1) independent and combined cross-sectional associations of objectively-measured physical activity and sedentary time with body composition outcomes at 30 years, and 2) prospective associations of changes in self-reported physical activity from 23 to 30 years with the same outcomes in participants from the 1982 Pelotas (Brazil) Birth Cohort. Body mass index, waist circumference, visceral abdominal fat, fat mass index, and android/gynoid fat ratio were the outcomes. 3,206 participants were analysed. In cross-sectional analyses, higher objectively-measured moderate-to-vigorous physical activity was associated with lower body mass index (ß = 0.017, 95%CI: -0.026; -0.009), waist circumference (ß = -0.043, 95%CI: -0.061; -0.025), visceral abdominal fat (ß = -0.006, 95%CI: -0.009; -0.003), and fat mass index (ß = -0.015, 95%CI: -0.021; -0.009), independent of sedentary time. Sedentary time was independently associated only with higher fat mass index (ß = 0.003, 95%CI: 0.001; 0.005). In longitudinal analyses, using self-reported measure, adiposity was lower among those who were consistently active or who became active. Adiposity was similar among the "became inactive" and "consistently inactive" subjects. Our findings suggest metabolic benefits from engagement in physical activity throughout young adulthood, with stronger associations on concurrent levels.