Maria Regina Alves Cardoso

Crowding: risk factor or protective factor for lower respiratory disease in young children?

BackgroundTo study the effects of household crowding upon the respiratory health of young children living in the city of São Paulo, Brazil.MethodsCase-control study with children aged from 2 to 59 months living within the boundaries of the city of São Paulo. Cases were children recruited from 5 public hospitals in central São Paulo with an acute episode of lower respiratory disease. Children were classified into the following diagnostic categories: acute bronchitis, acute bronchiolitis, pneumonia, asthma, post-bronchiolitis wheezing and wheezing of uncertain aetiology. One control, crudely matched to each case with regard to age (<2, 2 years old or more), was selected among healthy children living in the neighborhood of the case.All buildings were surveyed for the presence of environmental contaminants, type of construction and building material. Plans of all homes, including measurements of floor area, height of walls, windows and solar orientation, was performed. Data were analysed using conditional logistic regression.ResultsA total of 313 pairs of children were studied. Over 70% of the cases had a primary or an associated diagnosis of a wheezing illness. Compared with controls, cases tended to live in smaller houses with less adequate sewage disposal. Cases and controls were similar with respect to the number of people and the number of children under five living in the household, as well the number of people sharing the childs bedroom.After controlling for potential confounders, no evidence of an association between number of persons sharing the childs bedroom and lower respiratory disease was identified when all cases were compared with their controls. However, when two categories of cases were distinguished (infections, asthma) and each category compared separately with their controls, crowding appeared to be associated with a 60% reduction in the incidence of asthma but with 2 1/2-fold increase in the incidence of lower respiratory tract infections (p = 0.001).ConclusionOur findings suggest that household crowding places young children at risk of acute lower respiratory infection but may protect against asthma. This result is consistent with the hygiene hypothesis.

Análise de séries temporais em epidemiologia: uma introdução sobre os aspectos metodológicos

A time series, also denominated historical series, is a sequence of data obtained in regular intervals of time during a specific period. In the analysis of a time series, one first wants to model the study phenomenon and, from this, to describe the behaviour of the series, to make estimates, and, in the end, to evaluate the factors that may have influenced the behaviour of the series, with the objective of defining cause-effect relationships between two or more series. For this, there is a set of available statistical techniques which depend upon the defined model (or that estimated for the series), the type of the study series, and of the objective of the work. To analyse trends, it is possible to adjust polynomial regression models based on the whole series or on the neighbourhood of a specific point. This can also be done with mathematical functions. A seasonal phenomenon is defined as the one that occurs regularly in fixed periods of time and, if there is seasonality considered as deterministic in the series, one can use regression models which include functions like seno or cosseno to the variable time. In the analysis of the behaviour of a time series without trend and seasonality, the auto-regressive models (AR) or models which incorporate moving averages (ARMA) can be used. When trend is present, one can use auto-regressive models integrated with moving averages (ARIMA) and to incorporate the seasonality component the SARIMA models are used. The generalized linear models constitute another class of models. In this group of statistical models, the response variable is a counting process and the independent variables are those which are candidates to explain the behaviour of the series throughout the time. This class of models is indicated when the study variables do not follow the Normal distribution, mainly because they are counting processes. These models represent a group of probability distributions known as exponential family of distributions that incorporates many additive functions like the linear regression, Poisson, logistic, log-linear, etc. The generalized additive models are an extension of this class of models, in which each independent variable analysed does not enter in the model with its own value, but adopting a non parametric function in a non specific manner, which is estimated from smoothing curves.Este e um artigo introdutorio sobre analise de series temporais, onde se pretende apresentar, de maneira sumaria, alguns modelos estatisticos mais utilizados em analise de series temporais . Uma serie temporal, tambem denominada serie historica, e uma sequencia de dados obtidos em intervalos regulares de tempo durante um periodo especifico. Na analise de uma serie temporal, primeiramente deseja-se modelar o fenomeno estudado para, a partir dai, descrever o comportamento da serie, fazer estimativas e, por ultimo, avaliar quais os fatores que influenciaram o comportamento da serie, buscando definir relacoes de causa e efeito entre duas ou mais series. Para tanto, ha um conjunto de tecnicas estatisticas disponiveis que dependem do modelo definido (ou estimado para a serie), bem como do tipo de serie analisada e do objetivo do trabalho. Para analise de tendencias, podem se ajustar modelos de regressao polinomial baseados na serie inteira ou em vizinhanca de um determinado ponto. Isso tambem pode ser realizado com funcoes matematicas. Define-se como um fenomeno sazonal aquele que ocorre regularmente em periodos fixos de tempo e, se existir sazonalidade dita deterministica na serie, podem-se utilizar modelos de regressao que incorporem funcoes do tipo seno ou cosseno a variavel tempo. Os modelos auto-regressivos formam outra classe de modelos. Na analise do comportamento de uma serie historica livre de tendencia e de sazonalidade podem ser utilizados modelos auto-regressivos (AR) ou que incorporem medias moveis (ARMA). Quando ha tendencia, utilizam-se os modelos auto-regressivos integrados de medias moveis (ARIMA) e, para incorporar o componente de sazonalidade, utilizam-se os modelos SARIMA. Por ultimo ha os modelos lineares generalizados. Neste grupo de modelos estatisticos, a variavel resposta e um processo de contagem e as variaveis independentes sao variaveis candidatas a explicar o comportamento da serie ao longo do tempo. Estes modelos sao indicados quando as variaveis em estudo nao tem aderencia a distribuicao normal, principalmente pelo fato de serem processos de contagem . Estes modelos compoem um grupo de distribuicoes de probabilidades conhecido como familia exponencial de distribuicoes que englobam diversas funcoes aditivas, como a regressao linear, de Poisson, logistica, log-linear etc. Os modelos aditivos generalizados sao uma extensao desta classe de modelos, nos quais cada variavel independente analisada nao entra no modelo com o seu valor, mas sim, adotando uma funcao nao parametrica de forma nao especificada, estimada a partir de curvas de alisamento.

Poluição atmosférica e atendimentos por pneumonia e gripe em São Paulo, Brasil

OBJECTIVE A time series was developed to investigate the effect of air pollution levels on morbidity due to respiratory diseases such as pneumonia and influenza among elderly people from 1996 to 1998. METHODS Daily data on emergency room visits was collected at the university clinics hospital in São Paulo, Brazil. Daily levels of CO, NO2, O3, SO2 and PM10 were obtained from the State Environmental Agency. Daily measures of temperature and relative humidity were obtained from the Institute of Astronomy and Geophysics of the University of São Paulo. Generalized additive Poisson regression models were used to assess the relationship between pneumonia and influenza and air pollution, using the number of emergency room visits as dependent variable and the average daily levels of each pollutant as independent variables. The models were estimated and adjusted by seasonality (non-parametric function), weather, weekdays, motor vehicle circulation curbs periods and daily numbers of non-respiratory hospital admissions. RESULTS The pollutants O3 and SO2 showed a statistical association with pneumonia and influenza. These associations remained robust when control variables were included. An interquartile range for O3 (38.80 microgram/m3) and SO2 (15.05 microgram/m3) increased in 8.07% and 14.5%, respectively, the number of emergency room visits due to pneumonia and influenza. CONCLUSION The study results suggest that air pollution in the city of São Paulo may promote adverse health effects in elderly people.

Hepatitis C Virus Coinfection in a Cohort of HIV-Infected Individuals from Santos, Brazil: Seroprevalence and Associated Factors

Although HIV/hepatitis C virus (HCV) coinfection has been recognized worldwide in individuals exposed to blood-borne and sexually transmitted diseases (STD), limited data are available on the epidemiology of this coinfection in Brazil. A cross-sectional study was carried out to estimate the prevalence of HCV seropositivity in a cohort of people living with HIV/AIDS in Santos, Brazil, and to investigate potential risk factors for HCV infection. Anti-HCV antibodies were sought by using two immunoenzymatic assays. Overall HCV seroprevalence was 36.2% (95% confidence interval [CI] 31.9-40.4%). However, it was significantly higher (84.8%, 95% CI 78.2-91.3%) among intravenous drug users (IDU) as compared to non-IDU (20.9%, 95% CI 16.8-25.1%) (p < 0.001). Multiple logistic regression analysis revealed that HCV seropositivity among IDU was independently associated with needle sharing (adjusted odds ratio [adjOR] = 4.28, p = 0.07) and with serologic evidence of exposure to other bloodborne agents: HBV (adjOR = 4.39, p = 0.01) and HTLV-I/II (adjOR = 6.43, p = 0.02). In contrast, no association with lifetime number of sexual partners, history of STD, or of sex with commercial sex workers (CSW) could be demonstrated. Among non-IDU, HCV seropositivity was independently associated with sexual partnership with IDU (adjOR = 2.15, p = 0.08) and with HBV seropositivity (adjOR = 1.71, p = 0.05), but not with engaging in oral or anal receptive intercourse or having sex with CSW. Results indicate that exposure to blood and sexual partnership with IDU constitute the main risk factors for HCV acquisition among HIV-positive patients in Santos, Brazil. Prevention of HCV spread in this population should thus include harm reduction measures and information on safer sex practices for both IDU and their sexual partners.

The role of respiratory viral infections among children hospitalized for community-acquired pneumonia in a developing country.

We report an investigation for 16 bacteria and viruses among 184 children hospitalized with pneumonia in Salvador, Brazil. Etiology was established in 144 (78%) cases. Viral, bacterial, and mixed infections were found in 110 (60%), 77 (42%), and 52 (28%) patients, respectively. Rhinovirus (21%) and Streptococcus pneumoniae (21%) were the most common pathogens. Our results demonstrate the importance of viral and pneumococcal infections among those patients.

Air pollution and children's health in São Paulo (1986-1998)

Air pollution in the conurbation of São Paulo, Brazil, with 17 million inhabitants, has been measured from air quality monitoring stations. In three contrasted sample areas, childrens respiratory health parameters were collected to assess the role of air pollution in 1986. Twelve years later, in 1998, a similar study was undertaken to evaluate the impact of pollution control programs on the respiratory symptoms of children living in the same neighborhoods previously studied. Results indicated that pollution control programs were in part neutralized by increased number of cars and that the control of a single pollutant was not enough to protect childrens health. In the area where both particulate matter and sulfur dioxide levels decreased, there was a reduction in the prevalence of respiratory symptoms.

Penicillin resistant pneumococcus and risk of treatment failure in pneumonia

Objective: To determine whether the presence of in vitro penicillin-resistant Streptococcus pneumoniae increases the risk of clinical failure in children hospitalised with severe pneumonia and treated with penicillin/ampicillin. Design: Multicentre, prospective, observational study. Setting: 12 tertiary-care centres in three countries in Latin America. Patients: 240 children aged 3–59 months, hospitalised with severe pneumonia and known in vitro susceptibility of S pneumoniae. Intervention: Patients were treated with intravenous penicillin/ampicillin after collection of blood and, when possible, pleural fluid for culture. The minimal inhibitory concentration (MIC) test was used to determine penicillin susceptibility of the pneumococcal strains isolated. Children were continuously monitored until discharge. Main outcome measures: The primary outcome was treatment failure (using clinical criteria). Results: Overall treatment failure was 21%. After allowing for different potential confounders, there was no evidence of association between treatment failure and in vitro resistance of S pneumoniae to penicillin according to the Clinical Laboratory Standards Institute (CLSI)/National Committee for Clinical Laboratory Standards (NCCLS) interpretative standards (adjRR = 1.03; 95%CI: 0.49–1.90 for resistant S pneumoniae). Conclusions: Intravenous penicillin/ampicillin remains the drug of choice for treating penicillin-resistant pneumococcal pneumonia in areas where the MIC does not exceed 2 μg/ml.

Multilevel analysis of hepatitis A infection in children and adolescents: a household survey in the Northeast and Central-west regions of Brazil

Background The objectives were to estimate the prevalence of hepatitis A among children and adolescents from the Northeast and Midwest regions and the Federal District of Brazil and to identify individual-, household- and area-levels factors associated with hepatitis A infection. Methods This population-based survey was conducted in 2004–2005 and covered individuals aged between 5 and 19 years. A stratified multistage cluster sampling technique with probability proportional to size was used to select 1937 individuals aged between 5 and 19 years living in the Federal capital and in the State capitals of 12 states in the study regions. The sample was stratified according to age (5–9 and 10- to 19-years-old) and capital within each region. Individual- and household-level data were collected by interview at the home of the individual. Variables related to the area were retrieved from census tract data. The outcome was total antibodies to hepatitis A virus detected using commercial EIA. The age distribution of the susceptible population was estimated using a simple catalytic model. The associations between HAV infection and independent variables were assessed using the odds ratio and corrected for the random design effect and sampling weight. Multilevel analysis was performed by GLLAMM using Stata 9.2. Results The prevalence of hepatitis A infection in the 5–9 and 10–19 age-group was 41.5 and 57.4%, respectively for the Northeast, 32.3 and 56.0%, respectively for the Midwest and 33.8 and 65.1% for the Federal District. A trend for the prevalence of HAV infection to increase according to age was detected in all sites. By the age of 5, 31.5% of the children had already been infected with HAV in the Northeast region compared with 20.0% in the other sites. By the age of 19 years, seropositivity was ∼70% in all areas. The curves of susceptible populations differed from one area to another. Multilevel modeling showed that variables relating to different levels of education were associated with HAV infection in all sites. Conclusion The study sites were classified as areas with intermediate endemicity area for hepatitis A infection. Differences in age trends of infection were detected among settings. This multilevel model allowed for quantification of contextual predictors of hepatitis A infection in urban areas.

Estado nutricional e fatores associados ao déficit de crescimento de crianças freqüentadoras de creches públicas do Município de São Paulo, Brasil

This study reports the nutritional status of children attending daycare centers in the Municipality of Sao Paulo, Brazil. A representative sample of 827 children under 84 months of age was evaluated. Anthropometric measurements and information on socioeconomic characteristics and morbidity were collected. The most prevalent nutritional deficit was stunting (7.0%; 95%CI: 3.60-10.40). Univariate analysis showed a significant association between stunting and age ( 7), OR = 3.02(95%CI: 1.46-6.22); and number of siblings (> 2) OR = 4.81 (95%CI: 1.72-13.44). In the multivariate analysis, only diarrhea one month prior to the data collection, OR = 2.54 (95%CI: 1.20-5.38) and > 2 siblings, OR = 7.40 (95%CI: 2.20-24.93), remained associated with stunting.

Wheezing conditions in early childhood: prevalence and risk factors in the city of São Paulo, Brazil

OBJECTIVE To investigate the prevalence and risk factors for wheezing disorders in early childhood in São Paulo, Brazil, the largest metropolitan area of South America. METHODS A population-based cross-sectional survey of 1132 children aged 6-59 months was carried out between 1995 and 1996 to obtain information on recent wheezing and on independent variables such as demographic, socioeconomic, environmental, maternal and nutritional variables and immunization status. Intestinal parasitic infections were diagnosed using standard techniques. Multiple unconditional logistic regression was used to describe associations between outcome and independent variables. FINDINGS The prevalence of recent wheezing (one or more reported episodes in the past 12 months) was 12.5%; 93% of children with wheezing were also reported to have a medical diagnosis of asthma. Recent wheezing was associated with low per capita income, poor quality of housing, day-care attendance, low birth weight and infection with intestinal helminths. CONCLUSION Wheezing in early childhood in São Paulo, although more common than in most developing countries, remains less prevalent than in urban areas of industrialized countries. Low income and conditions associated with poverty (poor housing, low birth weight and parasitic infections) are some of the main risk factors for wheezing disorders among young children in this city.