Silvia Emiko Shimakura

Modeling Spatial Variation in Leukemia Survival Data

In this article we combine ideas from spatial statistics with lifetime data analysis techniques to investigate possible spatial variation in survival of adult acute myeloid leukemia patients in northwest England. Exploratory analysis suggests both clinically and statistically significant variation in survival rates across the region. A multivariate gamma frailty model incorporating spatial dependence is proposed and applied, with results confirming the dependence of hazard on location.

Análise de sobrevivência: teoria e aplicações em saúde

O objetivo apoiar o desenvolvimento metodologico em analise de dados longitudinais, atraves da aplicacao, teste e disseminacao de metodos estatisticos inovadores no contexto da saude, particularmente os voltados para a analise de sobrevida

A spatial approach for the epidemiology of antibiotic use and resistance in community-based studies: the emergence of urban clusters of Escherichia coli quinolone resistance in Sao Paulo, Brasil

BackgroundPopulation antimicrobial use may influence resistance emergence. Resistance is an ecological phenomenon due to potential transmissibility. We investigated spatial and temporal patterns of ciprofloxacin (CIP) population consumption related to E. coli resistance emergence and dissemination in a major Brazilian city. A total of 4,372 urinary tract infection E. coli cases, with 723 CIP resistant, were identified in 2002 from two outpatient centres. Cases were address geocoded in a digital map. Raw CIP consumption data was transformed into usage density in DDDs by CIP selling points influence zones determination. A stochastic model coupled with a Geographical Information System was applied for relating resistance and usage density and for detecting city areas of high/low resistance risk.ResultsE. coli CIP resistant cluster emergence was detected and significantly related to usage density at a level of 5 to 9 CIP DDDs. There were clustered hot-spots and a significant global spatial variation in the residual resistance risk after allowing for usage density.ConclusionsThere were clustered hot-spots and a significant global spatial variation in the residual resistance risk after allowing for usage density. The usage density of 5-9 CIP DDDs per 1,000 inhabitants within the same influence zone was the resistance triggering level. This level led to E. coli resistance clustering, proving that individual resistance emergence and dissemination was affected by antimicrobial population consumption.

Spatial risk distribution: modeling infant mortality in Porto Alegre, Rio Grande do Sul State, Brazil

Estimation and mapping of risk profiles are the main concerns of epidemiology. This paper analyzes spatial distribution of infant mortality cases as compared to live-born controls from Porto Alegre, Rio Grande do Sul. The modeling framework adopted in this research work is a spatial point process. Under this structure, a risk measure which continuously varies over the study region is defined and estimated using generalized additive model methods. This approach has the advantage of allowing for risk factors that are simple and easy to interpret. The procedure also allows the construction of tolerance contours which help identify areas of significantly high/low risk and an overall test for the null hypothesis of constant risk over the region. Application of this method to infant mortality data showed a highly significant spatial variation in risk for neonatal mortality data and non-significant results for post-neonatal mortality data.

A geographical population analysis of dental trauma in school-children aged 12 and 15 in the city of Curitiba-Brazil

BackgroundThe study presents a geographical analysis of dental trauma in a population of 12 and 15 year-old school-children, in the city of Curitiba, Brazil (n = 1581), using a database obtained in the period 2005-2006. The main focus is to analyze dental trauma using a geographic information system as a tool for integrating social, environmental and epidemiological data.MethodsGeostatistical analysis of the database and thematic maps were generated showing the distribution of dental trauma cases according to Curitibas Health Districts and other variables of interest. Dental trauma spatial variation was assessed using a generalized additive model in order to identify and control the individual risk-factors and thus determine whether spatial variation is constant or not throughout the Health Districts and the place of residence of individuals. In addition, an analysis was made of the coverage of dental trauma cases taking the spatial distribution of Curitibas primary healthcare centres.ResultsThe overall prevalence of dental trauma was 37.1%, with 53.1% in males and 46.7% in females. The spatial analysis confirms the hypothesis that there is significant variation in the occurrence of dental trauma, considering the place of residence in the population studied (Monte Carlo test, p = 0,006). Furthermore, 28.7% of cases had no coverage by the primary healthcare centres.ConclusionsThe effect of the place of residence was highly significant in relation to the response variable. The delimitation of areas, as a basis for case density, enables the qualification of geographical territories where actions can be planned based on priority criteria. Promotion, control and rehabilitation actions, applied in regions of higher prevalence of dental trauma, can be more effective and efficient, thus providing healthcare refinement.

Invasive aspergillosis in hematopoietic stem cell transplant recipients: a retrospective analysis.

Invasive aspergillosis (IA) currently is an important cause of mortality in subjects undergoing hematopoietic stem cell transplants (HSCT) and is also an important cause of opportunistic respiratory and disseminated infections in other types of immunocompromised patients. We examined the medical records of 24 cases of proven and probable invasive aspergillosis (IA) at the Hospital de Clinicas of the Federal University of Parana, Brazil, from January 1996 to October 2006. During this period occurred a mean of 2.2 cases per year or 3.0 cases per 100 HSTC transplants. There was a significant relationship between structural changes in the bone marrow transplant (BMT) Unit and the occurrence of IA cases (p=0.034, relative risk (RR) = 2.47). Approximately 83% of the patients died due to invasive fungal infection within 60 days of follow up. Some factors tended to be associated with mortality, but these associations were not significant. These included corticosteroid use, neutropenia (<100 cells/mm(3)) at diagnosis, patients that needed to change antifungal therapy because of toxicity of the initial first-line regimen and disseminated disease. These factors should be monitored in BMT units to help prevent IA. Physicians should be aware of the risk factors for developing invasive fungal infections and try to reduce or eliminate them. However, once this invasive disease begins, appropriate diagnostic and treatment measures must be implemented as soon as possible in order to prevent the high mortality rates associated with this condition.

Ocular symptoms in nonspecific conjunctival hyperreactivity

BACKGROUND Ocular symptoms can be triggered by nonspecific environmental factors, characterizing conjunctival hyperreactivity (CHR). OBJECTIVE To examine CHR in subjects with ocular symptoms by means of a hyperosmolar conjunctival provocation test (HCPT). METHODS Sixty-three subjects with ocular complaints (itching, redness, or tearing) were tested for allergy to a common panel of inhalant allergens (Alk Abelló-FDA Allergenic, Brazil). They were considered allergic if tests were positive to at least 1 allergen. HCPT with serial diluted glucose concentrations was positive if it produced conjunctival hyperemia up to a 50% solution. Digital images were analyzed by 2 observers who marked redness in the challenged eyes in red (GIMP 2.6.5 software). The number of red dots of the affected eye was compared with the number of blue dots of the control eye. RESULTS HCPT was positive in 6 of 7 grass pollen-sensitive subjects, in 17 of 20 dust mite-sensitive subjects, and in 10 of 11 subjects who were sensitive to both allergens. HCPT was positive in 33 of 38 allergic subjects (87%) and in 4 of 25 (16%) non-allergic subjects; sensitivity was 87%, and specificity was 84%. Significant correlation (r = 0.96 Pearson; P < .0001) was seen between the number of red dots in 23 digitalized images marked by observers. CONCLUSION HCPT indentified CHR in allergic as well as in non-allergic subjects. Allergic subjects exhibited more CHR than did non-allergic subjects. Conjunctival hyperreactivity was present in allergic subjects even when they were asymptomatic. Digital images may be useful for objective evaluation of ocular hyperemia in HCPT.

Análise espacial do risco de leptospirose canina na Vila Pantanal, Curitiba, Paraná

Leptospirosis is a serious zoonotic disease associated to low income areas of urban settings. Although rodents are considered the main reservoir for urban leptospirosis, dogs may also develop the disease and become asymptomatic carriers. The objective of this study was to apply a statistical method based on the spatial point processes theory for canine leptospirosis to identify how seroreagents dogs are spatially distributed and their risk determinants in a village of Curitiba city. The model analysis allowed the identification of over-risk regions, where seropositivity risk for canine leptospirosis was significantly higher, revealing that not just one, but the combination of animal, owner and environment factors influenced the disease risk within areas with greater spatial effect. Analysis of results clearly identified the highest risk areas in the Pantanal Village, allowing the establishment of more specific preventive actions and focused on risk areas as priority for public health surveillance.

Multi-state models for defining degrees of chronicity related to HIV-infected patient therapy adherence

Poucos estudos sobre AIDS que avaliam fatores associados a falha terapeutica consideram sua evolucao lenta, com a passagem por multiplos estados de saude, consequencia do uso de antirretrovirais. Nesse artigo foram estudados fatores associados a progressao entre estados imunes, enfocando adesao, em 722 pacientes HIV+ acompanhados por 3 anos. O desfecho foi a contagem de celulas CD4 classificada em s1 (CD4 ≥ 500), s2 (350 ≤ CD4 < 500) e s3 (CD4 < 350). As transicoes entre estados foram modeladas por modelos multiestado. A adesao a terapia antirretroviral e o tempo de doenca estao associados diferentemente a mudanca do estado imune vivido pelo paciente. Baixa adesao a terapia aumentou o risco de s1→s2 e adesao intermediaria aumentou o de s2→s3. Por outro lado, idades elevadas e tempo de doenca de 2 a 4 anos se apresentam como fatores de protecao na progressao da AIDS. A modelagem multiestado e uma abordagem poderosa no estudo de doencas cronicas, por estimar os fatores associados a cada etapa da evolucao de doencas cronicas, possibilitando a adocao de intervencoes mais individualizadas e eficazes.Few studies on AIDS that evaluate factors associated with treatment failure have considered the slow evolution of the disease and multiple health state transitions following the use of antiretrovirals. In this article we study factors associated with the progression between different stages of the disease, focusing on therapy adherence using a sample of 722 HIV+ patients followed up for 3 years. States were defined using the following classifications of the CD4 cell count: s₁ (CD4 ≥ 500); s₂ (350 ≤ CD4 < 500); and s₃ (CD4 < 350). The transitions between states were modeled using multi-state models. Antiretroviral therapy adherence and disease duration were associated with transitions between immune states during follow-up. Low adherence increased the hazard ratio of a transition between s₁ to s₂ and intermediate adherence increased the hazard ratio of a transition between s₂ to s₃. On the other hand, older age and disease duration between two and four years are protective factors for AIDS progression. Multi-state modeling is a powerful approach for studying chronic diseases and estimating factors associated with transitions between each stage of progression, thus enabling the use of more individualized and effective interventions.

Peritonitis as a risk factor for long‐term cardiovascular mortality in peritoneal dialysis patients: the case of a friendly fire?

Since the impact of peritonitis on long‐term non‐infectious mortality has not been investigated until the present, the aim of this study was to analyze the impact of peritonitis on long‐term cardiovascular (CV) mortality in a large peritoneal dialysis (PD) cohort.