BCG revaccination against tuberculosis.
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AIDS-Related Opportunistic Infections↗
Biomedical subjects
L C Rodrigues
Publications and source records attributed to L C Rodrigues.
The lack of selection bias in a snowball sampled case-control study on drug abuse.
BACKGROUND: Friend controls in matched case-control studies can be a potential source of bias based on the assumption that friends are more likely to share exposure factors. This study evaluates the role of selection bias in a case-control study that used the snowball sampling method based on friendship for the selection of cases and controls. METHODS: The cases selected fro the study were drug abusers located in the community. Exposure was defined by the presence of at least one psychiatric diagnosis. Psychiatric and drug abuse/dependence diagnoses were made according to the Diagnostic and Statistical Manual of Mental Disorders (DSM-III-R) criteria. Cases and controls were matched on sex, age and friendship. The measurement of selection bias was made through the comparison of the proportion of exposed controls selected by exposed cases (p1) with the proportion of exposed controls selected by unexposed cases (p2). If p1 = p2 then, selection bias should not occur. RESULTS: The observed distribution of the 185 matched pairs having at least one psychiatric disorder showed a p1 value of 0.52 and a p2 value of 0.51, indicating no selection bias in this study. CONCLUSIONS: Our findings support the idea that the use of friend controls can produce a valid basis for a case-control study.
Adolescent↗
Salivary testing for human immunodeficiency virus type 1 infection in children born to infected mothers in Sao Paulo, Brazil. The Sao Paulo Collaborative Study for Vertical Transmission of HIV-1.
OBJECTIVE: To validate a method for salivary testing for HIV infection in children older than 12 months. METHODS: Oral fluid samples were collected via sponge foam swabs from children born to HIV-positive mothers and were tested for antibodies to HIV-1 and HIV-2 with an IgG antibody capture enzyme-linked immunosorbent assay and a modified Western blot for confirmation. In each child serum antibody status was the standard used to validate the salivary antibody test. RESULTS: We obtained 331 oral fluid samples from children born to HIV-positive mothers. The specificity and sensitivity of salivary testing compared with results on sera were both 100% (297 of 297 (95% confidence interval 98.8 to 100%) and 34 of 34 (95% confidence interval 89.7 to 100%), respectively). Compliance in the study population increased from 91% to 97% when mothers were offered the opportunity to provide oral fluid from their children instead of blood specimens. CONCLUSION: Salivary testing provides an accurate and acceptable noninvasive method for assessing the HIV infection status of children born to infected mothers by using IgG antibody capture enzyme-linked immunosorbent assay alone with a strategy of duplicate retesting of reactive specimens.
Acquired Immunodeficiency Syndrome↗
Coffee consumption and intrauterine growth retardation in Brazil.
OBJECTIVE: To examine the association between coffee consumption in pregnancy and foetal growth. DESIGN: Retrospective unmatched case-control study. SETTING: Maternidade de Campinas, Universidade Estadual de Campinas, Pontificia Universidade Católica de Campinas, Hospital Albert Sabin. SUBJECTS: 356 mother/baby pairs who had interauterine growth retardation (IUGR) and 356 mother/baby pairs who were appropriate for gestational age (AGA). INTERVENTIONS: Newborns were classified as being IUGR according to the Lubchenco classification. Gestational age of the newborns was evaluated by the Capurro method. Coffee consumption in pregnancy was assessed by a food frequency questionnaire. Coffee consumption and a range of risk factors for IUGR were stratified and entered into a logistic regression model. The final results were expressed by the attributable risk percent (AR%). RESULTS: More IUGR mothers (85.4%) than AGA mothers (70.5%) ingested coffee in pregnancy (OR = 2.45; P < 0.001). The proportion of mothers who delivered IUGR babies increased as the average consumption of coffee increased (test for trend = 31.76; P < 0.001). The tendency for heavy coffee drinkers to deliver IUGR babies remained after controlling for alcohol intake and cigarette smoking (P < 0.001). According to the logistic regression model and to the attributable risk percent (AR% = 28.0%), coffee consumption, (independent of average coffee consumption) was an important preventable cause of IUGR in this Brazilian population. CONCLUSIONS: We recommend moderation in the consumption of coffee in pregnancy, since intrauterine growth retardation increases the risk of perinatal and neonatal morbidity and mortality. Further large prospective studies evaluating the content of caffeine in the coffee consumed by this population is advised.
Alcohol Drinking↗
Socioeconomic deprivation and notification rates for tuberculosis in London during 1982-91.
OBJECTIVES: To investigate the association between four sociodemographic measures (unemployment, overcrowding, low social class, and the proportion of migrants from areas of high prevalence of tuberculosis) and average level and rate of change of notification rates for tuberculosis. DESIGN: Ecological analysis of both the average and the rate of change of standardised annual notification rates for tuberculosis from 1982-91 and sociodemographic measures from the 1981 and 1991 censuses. SETTING: 32 London boroughs. SUBJECTS AND DATA: Sociodemographic measures from the 1981 and 1991 censuses and tuberculosis notification rates for 1982-91. MAIN OUTCOME MEASURES: A measure of the association between average levels and rate of change in tuberculosis notification rates and four sociodemographic measures in 1981 and between the rate of change in tuberculosis notification rates between 1981 and 1991 and changes in sociodemographic measures between 1981 and 1991. RESULTS: The average level of notifications was correlated with overcrowding and the proportion of migrants but not with unemployment or social class. No significant association was found between the rate of change in notification rates and sociodemographic measures in 1981. An association was found between increases in unemployment and the rate of change in notification rates, but the effect was small. Changes in the levels of unemployment explained 23% of the variation between boroughs in the rate of change in their notification rates. CONCLUSION: The average tuberculosis notification rates were related to overcrowding and the proportion of migrants in 1981. Only increases in unemployment from 1981 to 1991, however, were significantly associated with the rate of change in notifications over the same period.
Crowding↗
Vitamin A, folate, and iron concentrations in cord and maternal blood of intra-uterine growth retarded and appropriate birth weight babies.
OBJECTIVES: (i) To evaluate the relationship between the levels of vitamin A, folate and iron in maternal blood and cord blood from mother-baby pairs who had intra-uterine growth retardation (IUGR) and appropriate birth weight (ABW) for gestational age. (ii) To assess low or marginal levels of vitamin A, folate and iron as risk factors for IUGR. DESIGN: Retrospective unmatched case-control study. SETTING: Maternidade de Campinas, Universidade Estadual de Campinas, Pontificia Universidade Catolica de Campinas, Hospital Albert Sabin. SUBJECTS: 356 mother-baby pairs who had IUGR and 356 mother-baby pairs who had ABW for gestational age. INTERVENTIONS: Newborns were classified as being IUGR according to the Lubchenco classification. Gestational age of the newborns was evaluated by the Capurro method. Vitamin A, folate, ferritin, and haemoglobin were measured respectively by high performance liquid chromatography (HPLC), radioimmunoassay, immunoenzymetric assay and by the cyanmethaemoglobin method. RESULTS: The percentages of IUGR babies with abnormal levels of nutritional indices compared with ABW babies were 33.1 vs 14.6 for vitamin A, 25.7 vs 19.9 for red blood cell (RBC) folate, 37.0 vs 21.4 for haemoglobin, but similar for ferritin. The percentages of IUGR mothers with abnormal levels of nutritional indices compared to ABW mothers were similar (1.1 vs 1.4) for vitamin A, and 36.8 vs 32.1 for RBC folate. IUGR mothers were less often anaemic (43.2 vs 50.8), but tended to have higher levels of ferritin (37.6 vs 23.9) compared to ABW mothers. CONCLUSIONS: These results indicate marked differences in cord blood between IUGR and ABW with small differences in maternal levels. They suggest that micronutrient deficiency is the result of being born small rather than vice versa. The high levels of ferritin in IUGR mothers may reflect subclinical maternal infection contributing to IUGR. Maternal micronutrient deficiency is unlikely to be a causative factor for IUGR in this population. SPONSORSHIP: ODA (Overseas Development Agency), United Kingdom; CNPq (Conselho Nacional de Desenvolvimento Cientifico e Tecnologico), Brazil.
Birth Weight↗
Global challenge of tuberculosis.
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BCG Vaccine↗
Verbal autopsies for adult deaths: issues in their development and validation.
BACKGROUND: The verbal autopsy appears to be an attractive technique for the assessment of causes of adult death in settings where the proportion of people who die while under medical care is low. Verbal autopsies have been used extensively to assess causes of childhood deaths. The existing experience in verbal autopsies for adult deaths is limited mainly to maternal deaths. This paper aims to highlight the critical issues in verbal autopsies to assess causes of adult death which need further research. METHODS: This paper reviews the methods of verbal autopsy used in 35 published studies and discusses issues in the development of verbal autopsies, including mortality classification, design of questionnaires, interviewers, respondents, recall periods, procedures for deriving a diagnosis and the recording of single versus multiple causes of death. It also discusses issues in the validation of verbal autopsies, including the choice of reference diagnosis and the required sample size. RESULTS: The methodological approaches used in verbal autopsy studies have varied widely. Very few studies of the validity of verbal autopsies have been conducted. In these studies, the reported sensitivity and specificity varied widely between different causes of death and between studies. CONCLUSIONS: The information available is inadequate to draw firm conclusions on preferred methodological approaches for verbal autopsies for adult deaths. Before these tools are used more widely for adult deaths, further research is required to compare alternative methods and to evaluate the validity of this tool in a range of settings.
Adolescent↗
Heterosexual transmission of HIV.
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Female↗
Incidence of hospital-acquired infection and length of hospital stay.
Two different measures of hospital-acquired infection (HAI), risk per discharge and incidence rate, were used to analyse the incidence of 225 primary HAIs detected in 3,090 patients in an 11-month survey. Longer hospital stay was associated with a greater risk of developing HAI, but the strength of the association was different for the two measures used. Day-specific incidence rates were found to vary, with a peak between the 14th and 19th days of hospitalisation. Similar patterns were observed when the data were stratified by age, sex and operation. Methods for calculating HAI should control for the length of hospital stay. Further studies are required to clarify the mechanisms that affect the temporal pattern of incidence of HAI observed with length of hospitalisation.
Adolescent↗
Protective effect of BCG against tuberculous meningitis and miliary tuberculosis: a meta-analysis.
The protective effect of BCG against tuberculosis (TB) estimated in randomized controlled trials and observational studies ranges from negative to close to a 100%. One of the many explanations offered for this is that different immunological mechanisms may be associated with protective effect against different forms and sites of disease. In this investigation, we recalculated vaccine protective effect separately for pulmonary disease and for meningeal/miliary disease in randomized controlled trials and case-control studies, tested for heterogeneity in site-specific estimates of protective effect and calculated a summary measure when appropriate. We found protective effect against pulmonary disease to be heterogeneous to a statistically significant degree, and thus we did not calculate a summary measure of protection. Protective effect against meningeal and miliary TB was higher than against pulmonary disease and, except for a single study with two cases only, appeared to be homogenous. Summary BCG protective effect against miliary or meningeal TB in randomized controlled trials was 86% (95% confidence interval [CI] 65, 95) and in case-control studies 75% (95% CI: 61, 84). The fact that protective effect appeared to be homogeneous against meningitis and miliary TB but not against pulmonary disease may result from the fact that patients with meningitis are on average younger and thus less likely to have been exposed to atypical bacteria; to a waning of the protective effect of BCG; or from the diversity of mechanisms of pathogenesis of pulmonary disease, which can originate from reinfection, reactivation or primary progression.
BCG Vaccine↗
Heterosexual transmission of HIV.
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Acquired Immunodeficiency Syndrome↗
Health risks associated with bathing in sea water.
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Gastrointestinal Diseases↗
Space time clustering of births in SIDS: do perinatal infections play a role?
The aetiology of sudden infant death syndrome (SIDS) remains uncertain; many causal pathways have been proposed. In this paper we have examined firstly the variation in the risk of SIDS with age, month of death and month of birth; and secondly the space time clustering of SIDS deaths, and, separately, space time clustering of their births. Data were obtained from the Office of Populations, Censuses and Surveys on all certified SIDS deaths in the period; children were assigned grid references for the address of birth and of death. Data on number of births were abstracted from published material. A log-linear modelling technique was used to investigate the separate effects of age, month of death and month of birth on the risk of SIDS. The Knox method was used to investigate space time clustering of deaths and of births of children who died of SIDS. Separate, statistically significant effects were found for age, month of death and month of birth. There was minor space time clustering of SIDS births and deaths at large time and space intervals, and a marked space time clustering of births in short space time intervals in the first quarter of the year. The finding of an effect of month of birth on the risk of SIDS, and of space time clustering of births suggest that a perinatal hazard--possibly of infectious origin--may play a role in the aetiology of SIDS.
Birth Intervals↗
Factors influencing childhood immunisation in an urban area of Brazil.
STUDY OBJECTIVE: The aim was to examine the factors associated with incomplete vaccination in an urban area in Sao Paulo, Brazil; and to explore whether differences in vaccine coverage in the catchment area of health centres remain after the demographic constitution of the population in these areas is controlled for. DESIGN: The children were selected as controls for a case-control study. 455 children were selected at random (but age matched) from the health centre registries. Data was collected from the health centre records and from home interviews. SETTING: All children were registered in FAISA, a municipal health service comprising a large network of health centres and hospitals. FAISA's services are free at the point of delivery, and over 85% of the city's children are registered. PARTICIPANTS: Participants were selected to represent, except in their age distribution, all children registered in the municipal health service. MEASUREMENTS AND MAIN RESULTS: Information was collected on subjects' vaccine history, year of birth, sex, birth order and birth weight, and health centre of registration; their mothers' age, education, and marital status; and the family's income per capita and history of migration. Analysis was undertaken to identify risk factors for vaccination and whether the differential coverage in health centres' catchment areas remained after demographic characteristics of the population were controlled for. The high coverage for DPT and polio vaccines suggests that low overall coverage was not simply a result of mothers failing to bring children for vaccination. The variable that best predicted vaccine coverage was year of birth. Children born to immigrant mothers or into large families had lower vaccine uptake. The characteristics of children and their mothers did not account for the variation in vaccination coverage in catchment areas of different health centres. CONCLUSIONS: It is likely that in this area vaccination completeness was associated mainly with the health centre's ability to deliver vaccination to the target population.
Brazil↗
Sudden infant death syndrome: does winter affect poor and rich babies equally?
STUDY OBJECTIVE: The aim was to investigate whether the winter increase in risk of sudden infant death was similar across social classes. DESIGN: This was an unmatched case-control study using routine data. SETTING: Cases and controls were selected from files holding routine birth and death certificate data for England and Wales for 1986. SUBJECTS: Cases were deaths in the first year of life occurring in the summer or the winter of 1986 with mention of sudden infant death or SIDS in the death certificate. Controls were a 1% random sample of all children born in the same year. Only children whose parents were married or living together at the time of birth registration were included. MAIN RESULTS: Data on age and season of death for cases, and on date of birth, social class of father, and birth weight were abstracted from the file. Season of birth and birth weight were treated as confounding variables. The increase in risk of SIDS in winter was calculated for each age group and social class. The winter increase in SIDS was more marked among the higher social classes for all ages, but not to a statistically significant degree: the p values for heterogeneity were 0.26 for age 0-3 months, 0.42 for 4-7 months, and 0.41 for 8-12 months. CONCLUSIONS: There is no direct association between seasonal variation in sudden infant death and social class.
Birth Weight↗
Cot deaths and single parents.
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Alberta↗