Search PubMed⌕ Search

Biomedical subjects

Emil Kupek

Publications and source records attributed to Emil Kupek.

15 recordsLinked to original sources
PubMed2006

Beyond logistic regression: structural equations modelling for binary variables and its application to investigating unobserved confounders.

BACKGROUND: Structural equation modelling (SEM) has been increasingly used in medical statistics for solving a system of related regression equations. However, a great obstacle for its wider use has been its difficulty in handling categorical variables within the framework of generalised linear models. METHODS: A large data set with a known structure among two related outcomes and three independent variables was generated to investigate the use of Yule's transformation of odds ratio (OR) into Q-metric by (OR-1)/(OR+1) to approximate Pearson's correlation coefficients between binary variables whose covariance structure can be further analysed by SEM. Percent of correctly classified events and non-events was compared with the classification obtained by logistic regression. The performance of SEM based on Q-metric was also checked on a small (N = 100) random sample of the data generated and on a real data set. RESULTS: SEM successfully recovered the generated model structure. SEM of real data suggested a significant influence of a latent confounding variable which would have not been detectable by standard logistic regression. SEM classification performance was broadly similar to that of the logistic regression. CONCLUSION: The analysis of binary data can be greatly enhanced by Yule's transformation of odds ratios into estimated correlation matrix that can be further analysed by SEM. The interpretation of results is aided by expressing them as odds ratios which are the most frequently used measure of effect in medical statistics.

Cesarean Section↗
PubMed2006

Record linkage and capture-recapture estimates for underreporting of human leptospirosis in a Brazilian health district.

Record linkage and capture-recapture models were used to estimate the number of cases of human leptospirosis in the health district of Santa Maria, RS in southern Brazil. Twelve months of laboratory, hospital and epidemiological surveillance data were matched by name, age, residence and the month of diagnosis. Only laboratory-confirmed cases were considered. The record linkage revealed more than 20 times more cases than the official estimate for the health district, indicating a leptospirosis epidemic, with an annual incidence of more than 3 per 1,000 inhabitants and a case fatality of 0.37%. Severe cases were predominantly found through hospital records, overlapping to some extent with the epidemiological surveillance data, whereas less severe cases were found almost exclusively through laboratory logs. Different combinations of data sources influenced the detection rate for low versus high severity cases. Based on log-linear capture-recapture models, stratified by case severity and taking into account possible dependencies between the data sources, an insignificant number of cases were missed by all sources.

Brazil↗
PubMed2006

Social class inequalities in childhood mortality and morbidity in an English population.

The objective of this study was to examine the association between social class of the head of household at the time of birth and mortality and morbidity during the first 10 years of life in a cohort of all 117 212 children born to women who both lived, and delivered in hospital, in Oxfordshire or West Berkshire during the period 1 January 1979 to 31 December 1988. Logistic regression was used to estimate social class gradients, with odds ratios (OR), for mortality during the early neonatal period, late neonatal period, post-neonatal period, post-infancy period and throughout the first 10 years of life. Logistic regression was also used to estimate social class gradients, with ORs, for hospital admission rates for 16 broad groups of diseases during years 0-3, 4-6, 7-10 and throughout the first 10 years of life. Poisson regression was used to estimate social class gradients, with effect sizes, for overall hospital admission rates during years 0-3, 4-6, 7-10 and throughout the first 10 years of life. The study revealed a significant social class gradient in mortality during the first 10 years of life (adjusted OR for each decrement in social class category 1.08; [95% confidence interval 1.03, 1.14]). The study also revealed a significant adjusted social class gradient in hospital admission rates for 14 of the 16 groups of diseases during the first 10 years of life. For the majority of these, the social class gradients had attenuated somewhat by the later childhood years. However, the social class gradient persisted throughout the first 10 years of life for diseases of the respiratory system (1.07 [1.05, 1.08]), diseases of the digestive system (1.06 [1.04, 1.09]), and injury and poisoning (1.07 [1.06, 1.09]). In addition, a significant adjusted social class gradient was found in overall hospital admission rates for each age group studied. This study suggests that there are significant social class inequalities in a wide range of adverse child health outcomes.

Age Factors↗
PubMed2005

Effects of diet energy level and tomato powder consumption on antioxidant status in rats.

BACKGROUND AND AIMS: Evaluate the influence of tomato powder in diets differing in energy level on antioxidant status in blood and liver of rats. METHODS: Twenty-four adult male Wistar rats weighing 150-180 g were placed four groups (n=6). For 28 days, animals were fed a diet that was either hyper energetic or hypo energetic. Some diets were supplemented with tomato powder. Liver and blood were collected for analysis of antioxidant enzymes, non-enzymatic antioxidants, thiobarbituric acid reactive species, ubiquinol 9, alpha-tocopherol, lycopene and beta-carotene. Data were analysed by two-way ANOVA. RESULTS: Food intake and thiobarbituric acid-reactive substances contents in liver and plasma were significantly decreased by tomato powder at both energy levels. After tomato powder supplementation, the hepatic levels of ubiquinol 9, alpha-tocopherol, lycopene and beta-carotene were significantly enhanced. In plasma, only the contents of lycopene and beta-carotene were enhanced. The erythrocytic and hepatic activities of catalase were lower, while those of glutathione peroxidase were higher after the ingestion of tomato powder. Total and reduced glutathione contents in liver showed lower levels in cafeteria-fed rats compared to the hypo energetic diet. CONCLUSIONS: The data suggest that the lycopene and beta-carotene component in the tomato power supplement might be beneficial for the prevention of oxidative damage in rats fed both types of energetic diets.

Analysis of Variance↗
PubMed2005

[Measles epidemiology in the State of Santa Catarina, Brazil, 1996-2000].

This ecological study, based on an analysis of secondary data from epidemiological surveillance and using the municipality (county) as the unit of analysis, showed that measles vaccine coverage was lower than necessary for eradication (95%) and control (90%) in many municipalities in the State of Santa Catarina, Brazil, both before and during the last epidemic in 1997, particularly regarding the second dose of the vaccine, applied as a component of the MMR vaccine, scheduled at 15 months of age. Low vaccine coverage was associated with higher measles incidence. However, during the 1997 epidemic small-scale measles outbreaks were recorded even in municipalities with first-dose coverage of 95% or higher, particularly among those which also had low second-dose coverage for MMR. Approximately 80% of all measles cases during 1996-2000 occurred among schoolchildren and young adults. Measles virus circulation in the municipality in the previous year and population density increased the risk of measles. Two imported cases of measles in Santa Catarina in 2004 illustrate that it would be premature to describe the current situation as one of eradication.

Adolescent↗
PubMed2005

Socioeconomic differences in childhood hospital inpatient service utilisation and costs: prospective cohort study.

STUDY OBJECTIVE: To examine the association between socioeconomic position at the time of birth and the use and cost of hospital inpatient services during the first 10 years of life. DESIGN: Analysis of a database of linked birth registrations, hospital records, and death certificates. Associations between the social class of the head of household and hospital inpatient service utilisation and costs during the first 10 years of life were analysed using multilevel multiple regression modelling. PARTICIPANTS AND SETTING: All 117 212 children born to women who both lived and delivered in hospital in Oxfordshire or West Berkshire, southern England, during the period 1 January 1979 to 31 December 1988. MAIN RESULTS: The study showed that children born into social classes II, III-NM, III-M, IV, and V were more likely to be admitted to hospital, spend longer in hospital overall, and generate greater hospital costs than children born into social class I. The adjusted effect regarding hospital inpatient admissions, days, and costs was 1.27 (95% CI: 1.26, 1.27), 1.20 (1.19, 1.21), and 1.50 (1.49, 1.53), respectively, for children born into social class V when compared with children born into social class I. The impact of social class on hospital inpatient admissions, days, and costs was most acutely felt during years 3-10 of life as compared with the first two years of life. CONCLUSIONS: Health service decision makers need to be alert to the adverse sequelae that might result from socioeconomic disadvantage when planning health services for children. Particular attention should be paid to targeting deprived populations with prevention interventions that are known to be effective.

Child↗
PubMed2004

Transfusion risk for hepatitis B, hepatitis C and HIV in the state of Santa Catarina, Brazil, 1991-2001.

We examined the time trend of residual risk of transfusing blood contaminated with HIV, hepatitis B and hepatitis C, in the largest blood bank of the state of Santa Catarina, Brazil, 1991-2001. The HIV risk was reduced approximately 10 times during the decade of 1990, to 1:48777, but then increased significantly by the end of 2001. A similar time trend was observed for hepatitis B and hepatitis C, although the increase was not significant in this case. Even during the period of lowest risk, the estimates were considerably higher than in developed countries.

Brazil↗
PubMed2004

Three decades of meningococcal disease in the state of Santa Catarina, Brazil.

Consolidation of data on meningococcal disease surveillance for the state of Santa Catarina, Brazil, has provided new insight about the evolution of this disease during the period of 1971-2000. A descriptive epidemiological study, based on retrospective analysis of all cases of meningococcal disease notified in the state of Santa Catarina, linked the surveillance data from the Secretary of the State of Health, magnetic tape records and the data from the national surveillance of diseases of obligatory notification. Following World Health Organization guidelines, cumulative incidence exceeding five cases per 100,000 inhabitants was considered indicative of an epidemic. Official population data from the Fundação Instituto Brasileiro de Geografia e Estatística were used for the incidence denominator. During the 1971-2000 period, 7,893 cases and 1,354 deaths caused by meningococcal disease were reported. This corresponds to a mean of 263 cases and 45 deaths per year, with a mean incidence of 6.4 cases per 100,000 inhabitants and a fatality rate of 17.2%. Three distinct epidemiological periods were identified, two of which can be considered epidemic. Two of three distinct epidemiological periods were characterized by an epidemic of meningococcal disease, covering 20 of the 30 years analyzed. Identification of the epidemics and preventive actions, such as vaccination and health education, contributed to the reduction of morbidity and mortality due to this disease.

Adolescent↗
PubMed2004

[Control of a community outbreak of group C meningococcal meningitis in Corupá, Santa Catarina State, Brazil, based on rapid and effective epidemiological surveillance and immunization].

In 2001, an outbreak of eight cases of meningococcal disease within seven days occurred in a small municipality in northern Santa Catarina State, Brazil. All cases occurred in adolescents and young adults, corresponding to an attack rate of 367.5 cases per 100,000 inhabitants in this population group. Laboratory tests identified serogroup C meningococcus in three out of eight cases. This led to vaccination of all inhabitants in the municipality over two years of age against serogroup C meningococcus -- an outbreak control strategy recommended by the Brazilian Ministry of Health. The absence of new cases during a 12-month period after vaccination indicates the importance of this type of intervention in disease control.

Adolescent↗
PubMed2003

Antenatal visits and adverse perinatal outcomes: results from a British population-based study.

OBJECTIVE: The objective of this study was to explore the relationship between the number of antenatal visits made by a representative sample of British women and adverse perinatal outcomes. STUDY DESIGN: A total of 20,771 women with a singleton pregnancy were recruited from nine representative maternity units in Northern England and North Wales. A record of each woman's antenatal care and the adverse perinatal outcomes of interest were extracted retrospectively from their case notes. Multivariate binomial regression was used to model the probability of adverse outcomes with respect to the absolute number of antenatal visits, after controlling for potentially confounding factors. Separate analyses were performed for primiparae and multiparae, and for low- and high-risk women within each parous group. RESULTS: The study revealed an inverse association between the number of antenatal visits and delivery of a low birthweight infant, infant admission to a special care baby unit and perinatal mortality over the 4-14 antenatal visit range, which dissipated at higher levels of antenatal visits. The study also revealed a significant positive association between the number of antenatal visits and delivery by caesarean section (P<0.01). Similar trends in the probabilities of adverse outcomes were observed for low- and high-risk women within each parous group. CONCLUSION: Further experimental research is required to ascertain whether a causal relationship exists between antenatal visiting schedules and adverse perinatal outcomes.

Adolescent↗
PubMed2003

Food intake and circadian rhythms in shift workers with a high workload.

Shift work is associated with nutritional and health problems. In the present study, the food intake of garbage collectors of the city of Florianopolis (Brazil) was investigated using a dietary survey method based on meal recording during 24 h and adapted for the Brazilian food context. Three different shifts (morning, afternoon, and night) were compared (n=22 per shift). Age, body weight and body mass index (BMI) were similar for all groups. Daily energy expenditure was high in all three shifts, especially in morning shift workers. No difference in daily energy intake was found, in spite of differences in food choices and circadian ingestion rhythms. Energy intake was high and close to levels previously reported in athletes. Several factors not associated with shifts had significant impact on ingestion: hour of the day, time since the last meal, age, and BMI. Ingested foods were analyzed in groups based on nutrient content. Shifts significantly influenced intake of starches, alcoholic drinks, and sweets. In different periods of the day, food and nutrient intake were considerably affected by shifts. The analysis of circadian distribution of food choices and nutrient intake is important in shift workers, because total daily intake may not reveal shift-associated differences.

Adult↗
PubMed2002

Bias and heteroscedastic memory error in self-reported health behavior: an investigation using covariance structure analysis.

BACKGROUND: Frequent use of self-reports for investigating recent and past behavior in medical research requires statistical techniques capable of analyzing complex sources of bias associated with this methodology. In particular, although decreasing accuracy of recalling more distant past events is commonplace, the bias due to differential in memory errors resulting from it has rarely been modeled statistically. METHODS: Covariance structure analysis was used to estimate the recall error of self-reported number of sexual partners for past periods of varying duration and its implication for the bias. RESULTS: Results indicated increasing levels of inaccuracy for reports about more distant past. Considerable positive bias was found for a small fraction of respondents who reported ten or more partners in the last year, last two years and last five years. This is consistent with the effect of heteroscedastic random error where the majority of partners had been acquired in the more distant past and therefore were recalled less accurately than the partners acquired more recently to the time of interviewing. CONCLUSIONS: Memory errors of this type depend on the salience of the events recalled and are likely to be present in many areas of health research based on self-reported behavior.

Adult↗
PubMed2002

Clinical, provider and sociodemographic predictors of late initiation of antenatal care in England and Wales.

OBJECTIVE: To identify factors that are predictive of late initiation of antenatal care in England and Wales. DESIGN: A multivariate binomial regression model was constructed to examine the association between clinical, provider and sociodemographic characteristics and late initiation of antenatal care. SETTING: Nine maternity units in Northern England and North Wales. POPULATION: A total of 20,771 women with a singleton pregnancy who delivered a liveborn or stillborn baby between 1 August 1994 and 31 July 1995. All analyses were based on the 17,765 (85.5%) women for whom information on gestational age at initial presentation for antenatal care and other variables incorporated into the regression model was retrievable from the case records. RESULTS: Primiparous women of high obstetric risk were 13.4% more likely to initiate antenatal care after 10 weeks of gestation than a low risk reference group (adjusted OR 1.134, 95% CI 1.011, 1.272; P = 0.0312), and 34.3% more likely to initiate antenatal care after 18 weeks of gestation (adjusted OR 1.343, 95% CI 1.046, 1.724; P = 0.0208). This association between high obstetric risk status and late initiation of antenatal care was not replicated among multiparous women. When the effects of other independent variables on gestational age at booking were examined, the following characteristics were associated with failure to initiate antenatal care by 10 weeks of gestation (P < or = 0.05): maternal age at booking, smoking status, ethnicity, type of hospital at booking, the planned pattern of antenatal care and the planned place of delivery. Adopting a criterion of 18 weeks of gestation exacerbated the association between clinical and sociodemographic characteristics and late initiation of antenatal care, but appeared to dilute the association between provider characteristics and late initiation of antenatal care. CONCLUSIONS: There is a pressing need for further research to identify the specific concerns of late bookers, to identify areas where new interventions might encourage the uptake of services and to gauge the likely impact of increased dissemination of information about the availability of antenatal care services.

Adolescent↗
PubMed2002

[Prevalence and risk factors associated with drug use among school students, Brazil].

OBJECTIVE: To assess prevalence and risk factors associated with drug abuse among public elementary and high school students in the southern city of Florianópolis, Brazil. METHODS: A descriptive cross-sectional study was carried out using a standardized questionnaire created during the 4th National Survey on Drug Abuse. Four hundred and seventy-eight students were interviewed by trained college students. Of the interviewees, 43% aged 13 - 15 years and 32% aged 16 - 18 years and they had a higher socioeconomic status than the national average. RESULTS: Ever use prevalence for alcohol, marijuana, solvent drugs and amphetamines was 86.8%, 19.9%, 18.2% and 8.4%, respectively. Regular use (6 or more times per month) of alcohol, marijuana, solvent drugs and amphetamines was found in 24.2%, 4.9%, 2.5% and 2.3% of students, respectively, a higher percentage when compared to other southern states' capitals and the national average. Age, sex, social status and living with both parents were significantly associated with drug abuse. Girls were twice as likely to consume weight loss drugs and stimulants, and almost three times more likely to use tranquilizers without medical prescription. Boys were almost twice as likely to use solvent drugs. Higher social students were twice as likely to consume alcohol than those of lower social status. Cigarette and marijuana smoking, respectively, were 84% and 67% more likely among students whose parents were separated. CONCLUSIONS: There is a high prevalence of drug use among elementary and high school students in Florianópolis.

Adolescent↗