Geographic analysis of vaccine uptake in a cluster-randomized controlled trial in Hue, Vietnam

This paper identifies spatial patterns and predictors of vaccine uptake in a cluster-randomized controlled trial in Hue, Vietnam. Data for this study result from the integration of demographic surveillance, vaccine record, and geographic data of the study area. A multi-level cross-classified (non-hierarchical) model was used for analyzing the non-nested nature of individual's ecological data. Vaccine uptake was unevenly distributed in space and there was spatial variability among predictors of vaccine uptake. Vaccine uptake was higher among students with younger, male, or not literate family heads. Students from households with higher per-capita income were less likely to participate in the trial. Residency south of the river or further from a hospital/polyclinic was associated with higher vaccine uptake. Younger students were more likely to be vaccinated than older students in high- or low-risk areas, but not in the entire study area. The findings are important for the management of vaccine campaigns during a trial and for interpretation of disease patterns during vaccine-efficacy evaluation.     

Differences in child injury hospitalizations in Sweden: the use of time-trend analysis to compare various community injury-prevention approaches

AIM: Sweden's child injury fatality rates are among the lowest in the world. The country has engaged in a number of community injury-prevention programmes. The purpose of this study was to compare child injury hospitalization rates from the Skaraborg District with the rest of Sweden. Our study hypothesis was that municipalities that offered comprehensive child injury-prevention programmes would see significant decreases in their child injury hospitalization rates, compared with other areas. METHODS: The study areas comprised three groups, consisting of municipalities in Skaraborg that had adapted the Safe Communities approach to injury prevention programmes, other municipalities in the District, and the rest of Sweden. The aim of the analysis was twofold: (1) to fit time trends for children's injuries in various areas in an integrated manner; and (2) to compare time trends across locations between community safety-promotion programmes as well as with the control areas. Panel data models and parametric splines were used. RESULTS: There were differences between incidence rates in the study areas and with regard to gender. There was a steep decrease in injury rates in one of the Safe Communities study areas for both genders. CONCLUSIONS: The methods applied in this analysis reveal more detailed and sophisticated time trends than the usual simple linear regression approach. The model provided a clearer view of the interactions of gender, area, and time as they impacted on children's injuries, and allowed for better insight into the impact of safety programmes.     

The pathophysiology, clinical signs and therapy of urate nephropathy

Tumor lysis syndrome is an oncologic emergency that is characterized by severe electrolyte abnormalities. The syndrome occurs in patients with lymphoproliferative malignancies, most often after chemotherapy, but also spontaneously. The pathophysiology involves tumor cell lysis resulting in the release of potassium, phosphate and uric acid. The deposition of uric acid and calcium phosphate crystals in the renal tubules may lead to acute renal failure. The treatment consists in hydration, correction of the acidosis and hyperkalemia, use of allopurinol and recombinant urate oxidase (rasburicase) for preventing urate nephropathy and haemodialysis. The authors report a case of a patient with acute myeloid leukemia, who developed severe tumor lysis syndrome after chemotherapy.     

Association between preventive care provided in public dental services and caries prevalence

OBJECTIVE: To assess the association between preventive care provided in public dental services and young people's oral health. METHODS: Oral health data on 4,033 young people aged 15 to 19 years living in 85 municipalities of the state of Rio Grande do Sul, Southern Brazil, were obtained from the national oral health survey "Saúde Bucal Brasil 2003" for the period 2002-2003. The following variables were studied: age, gender, income, education, time elapsed since last dental visit, reason for dental visit, and water fluoridation. Data on dental care services were obtained from the national database of public health services. Statistical analysis was performed using multilevel logistic regression. RESULTS: Youngsters from the 21 municipalities with the lowest preventive care (scaling + fluoride + sealants) rates per 100 inhabitants were 2.27 (95% CI: 1.45;3.56) more likely to have non-filled dental cavities than those from the 21 municipalities with the highest care rates. After adjustment for a number of individual and contextual factors this likelihood decreased to 1.76 (95% CI: 1.13;2.72). The variance attributable to variables at municipal level was 14.1% for the empty model and decreased to 10.5% for the fully adjusted model. CONCLUSIONS: Rio Grande do Sul public dental services may have contributed for the reduction in the number of non-filled cavities in young people. However, it was not possible to detect the impact of this service on total dental caries experience.     

Case report: three farmworkers who gave birth to infants with birth defects closely grouped in time and place-Florida and North Carolina, 2004-2005

CONTEXT: There is little evidence linking adverse reproductive effects to exposure to specific pesticides during pregnancy. CASE PRESENTATION: In February 2005, three infants with congenital anomalies were identified in Collier County, Florida, who were born within 8 weeks of one another and whose mothers worked for the same tomato grower. The mothers worked on the grower's Florida farms in 2004 before transferring to its North Carolina farms. All three worked during the period of organogenesis in fields recently treated with several pesticides. The Florida and North Carolina farms were inspected by regulatory agencies, and in each state a large number of violations were identified and record fines were levied. DISCUSSION: Despite the suggestive evidence, a causal link could not be established between pesticide exposures and the birth defects in the three infants. Nonetheless, the prenatal pesticide exposures experienced by the mothers of the three infants is cause for concern. Farmworkers need greater protections against pesticides. These include increased efforts to publicize and comply with both the U.S. Environmental Protections Agency's Worker Protection Standard and pesticide label requirements, enhanced procedures to ensure pesticide applicator competency, and recommendations to growers to adopt work practices to reduce pesticide exposures. RELEVANCE TO PROFESSIONAL PRACTICE: The findings from this report reinforce the need to reduce pesticide exposures among farmworkers. In addition, they support the need for epidemiologic studies to examine the role of pesticide exposure in the etiology of congenital anomalies.     

Air pollution and low birth weight in the city of Rio de Janeiro, Brazil, 2002

The objective of this study was to evaluate the effect of air pollution on low birth weight in full term singleton newborns in the city of Rio de Janeiro, Brazil. The study adopted a cross-sectional design based on the year 2002. Data on live births were obtained from the Live Birth Information System of the Brazilian Ministry of Health. Low birth weight was defined as less than 2,500 g. Maternal exposure to air pollution was defined as the mean for a given pollutant over each trimester of pregnancy and was assessed taking birth date into account. Adjusted odds ratios (OR) were estimated for each potential risk factor. For PM(10), CO, and NO(2), no significant increases were detected. For SO(2), the OR of the fourth interquartile range of exposure in the third trimester of pregnancy was 1.149 (95%CI: 1.016-1.301). For O(3), the estimated OR was 0.830 (95%CI: 0.750-0.987). When exposure variable was regarded as a continuous measure, the OR for PM(10), CO, and SO2 in the third trimester were not statistically significant and were 1.089, 2.223, and 1.259, respectively.     

Predicting metal uptake by wetland plants under aerobic and anaerobic conditions

Metal pollution can be a serious threat to ecosystems at a global scale. Although the bioavailability of potentially toxic metals is determined by many biotic and abiotic factors, including pH and redox potential, total metal concentrations in the soil are used widely to assess or predict toxicity. In the present study we tested the effect of desiccation of soils differing in acidification potential and total heavy metal contamination on the growth and metal uptake of three typical, common wetland species: Caltha palustris, Juncus effusus, and Rumex hydrolapathum. We found that plant growth in wet soils mainly was determined by nutrient availability, though in dry soils the combined effects of acidification and increased metal availability prevailed. Metal uptake under anaerobic conditions was best predicted by the acidification potential (sediment S/[Ca + Mg] ratio), not by total metal concentrations. We propose that this is related to radial oxygen loss by wetland plant roots, which leads to acidification of the rhizosphere. Under aerobic conditions, plant metal uptake was best predicted by the amount of CaCl2-extractable metals. We conclude that total metal concentrations are not suitable for predicting bioavailability and that the above diagnostic parameters will provide insight into biogeochemical processes involved in toxicity assessment and soil policy.     

Individualizing drug dosage by using a random intercept linear model

An algorithm for drug dosage individualization is proposed. The algorithm assumes a random intercept linear model for the log of trough-plasma-concentration-to-dosage ratio of the drug at steady-state, and aims at determining an optimum dosage for producing a trough steady-state plasma concentration within a target concentration range. The minimum number of algorithm steps necessary to find the optimum dosage is computed. Computations are illustrated for clozapine, an antipsychotic drug used to treat patients with severe schizophrenia.     

Bias reduction in effectiveness analyses of longitudinal ordinal doses with a mixed-effects propensity adjustment

A mixed-effects propensity adjustment is described that can reduce bias in longitudinal studies involving non-equivalent comparison groups. There are two stages in this data analytic strategy. First, a model of propensity for treatment intensity examines variables that distinguish among subjects who receive various ordered doses of treatment across time using mixed-effects ordinal logistic regression. Second, the effectiveness model examines multiple times until recurrence to compare the ordered doses using a mixed-effects grouped-time survival model. Effectiveness analyses are initially stratified by propensity quintile. Then the quintile-specific results are pooled, assuming that there is not a propensity x treatment interaction. A Monte Carlo simulation study compares bias reduction in fully specified propensity model relative to misspecified models. In addition, type I error rate and statistical power are examined. The approach is illustrated by applying it to a longitudinal, observational study of maintenance treatment of major depression.     

Comparing health inequalities across time and place--rate ratios and rate differences lead to different conclusions: analysis of cross-sectional data from 22 countries 1991-2001

BACKGROUND: Socio-economic inequalities in health within countries are a key public health issue. It is important that we can effectively make international comparisons of the level of inequalities and assess trends over time. We investigate how the results of such comparisons can differ depending on whether inequality is quantified using the rate ratio or rate difference. METHODS: We examine levels and trends in inequality in under-five mortality using data from 22 low/lower-middle income countries [Africa (11), Latin America/Caribbean (5), Asia (6)], each with two Demographic and Health Surveys between 1991 and 2001. Within-country inequalities are quantified using the rate ratio and rate difference. RESULTS: Ranking countries by their level of inequality at one point in time differed, sometimes substantially, according to whether the rate ratio or difference was used (Spearman's rank correlation = 0.49). Similarly, ranking countries according to the magnitude and direction of change in inequality over time depended on the measure used. Importantly from a policy perspective, in five countries the direction of change was in the opposite direction (increase vs decline in inequality) when using the ratio compared with the difference measure. CONCLUSIONS: The results of comparisons of the magnitude of health inequalities between countries and over time depend upon whether the rate ratio or rate difference is used. When statements are made comparing the size of inequalities it should be made completely clear whether these are measured on an absolute or relative scale. If the substantive conclusions differ according to the measure used this should be clearly stated. In this situation emphasis should only be given to results based on one summary measure if this can be clearly and explicitly justified in the context.