Efecto de factores sociodemográficos en la mortalidad del COVID-19 en Costa Rica: un enfoque geográfico

Introducción: La enfermedad por coronavirus (COVID-19) se ha extendido entre la población de todo el país y ha tenido un gran impacto a nivel mundial. Sin embargo, existen diferencias geográficas importantes en la mortalidad de COVID-19 entre las diferentes regiones del mundo y en Costa Rica. Objetivo: Explorar el efecto de algunos de los factores sociodemográficos en la mortalidad de COVID-19 en pequeñas divisiones geográficas o cantones de Costa Rica. Métodos: Usamos registros oficiales y aplicamos un modelo de regresión clásica de Poisson y un modelo de regresión ponderada geográficamente. Resultados: Obtuvimos un criterio de información de Akaike (AIC) más bajo con la regresión ponderada (927.1 en la regresión de Poison versus 358.4 en la regresión ponderada). Los cantones con un mayor riesgo de mortalidad por COVID-19 tuvo una población más densa; bienestar material más alto; menor proporción de cobertura de salud y están ubicadas en el área del Pacífico de Costa Rica. Conclusiones: Una estrategia de intervención de COVID-19 específica debería concentrarse en áreas de la costa pacífica con poblaciones más densas, mayor bienestar material y menor población por unidad de salud.

Introduction: The coronavirus disease (COVID-19) has spread among the population of Costa Rica and has had a great global impact. However, there are important geographic differences in mortality from COVID-19 among world regions and within Costa Rica. Objective: To explore the effect of some sociodemographic factors on COVID-19 mortality in the small geographic divisions or cantons of Costa Rica. Methods: We used official records and applied a classical epidemiological Poisson regression model and a geographically weighted regression model. Results: We obtained a lower Akaike Information Criterion with the weighted regression (927.1 in Poisson regression versus 358.4 in weighted regression). The cantons with higher risk of mortality from COVID-19 had a denser population; higher material well-being; less population by health service units and are located near the Pacific coast. Conclusions: A specific COVID-19 intervention strategy should concentrate on Pacific coast areas with denser population, higher material well-being and less population by health service units.

Spatial Modeling of Leprosy Disease in East Java Province with Spatially Varying Regression Coefficients Models

Indonesia ranks third with the most leprosy cases globally. East Java is the province that has the highest leprosy cases. The Provincial Government socialized the East Java Leprosy Eradication Program, which targets a maximum of one leprosy case per 10,000 residents. We propose spatially varying regression coefficients models to evaluate the effects of risk factors on of leprosy cases in East Java, use Geographically Weighted Generalized Poisson Regression and Geographically Weighted Negative Binomial Regression (GWNBR) models. The best models GWNBR categorize municipalities into six groups based on variables that have a significant impact on leprosy cases. The percentage of households with access to adequate sanitation is a significant factor in determining leprosy cases in all municipalities in East Java. We can conclude that clean and healthy living behavior, health facilities, and health workers significantly affect the number of leprosy cases in East Java.

Scrub typhus in urban areas of Wardha district in central India

Background & objectives: Scrub typhus caused by Orientia tsutsugamushi presents as acute undifferentiated fever and can be confused with other infectious causes of fever. We studied scrub typhus as part of a study on hospital-based surveillance of zoonotic and vector-borne zoonotic diseases at a tertiary care hospital located in the Wardha district, Maharashtra, India. We report here descriptive epidemiology and climatic factors affecting scrub typhus. Methods: Patients of any age and sex with fever of ?5 days were enrolled for this study. Data on sociodemographic variables were collected by personal interviews. Blood samples were tested by IgM ELISA to diagnose scrub typhus. Confirmation of scrub typhus was done by indirect immunofluorescence assay for IgM (IgM IFA). The climatic determinants were determined using time-series Poisson regression analysis. Results: It was found that 15.9 per cent of the study participants were positive for scrub typhus by IgM ELISA and IgM IFA, both. Positivity was maximum (23.0%) in 41-60 yr of age and more females were affected than males (16.6 vs. 15.5%). Farmworkers were affected more (23.6%) than non-farm workers (12.9%). The disease positivity was found to be high in monsoon and post-monsoon seasons (22.9 and 19.4%) than in summer and winter. Interpretation & conclusions: There were three hot spots of scrub typhus in urban areas of Wardha district. Rainfall and relative humidity in the previous month were the significant determinants of the disease

A study on impact of oral health on general health among the elderly residing in a slum of Kolkata: A cross-sectional study

Context: Oral health means more than only good teeth. It is a state-of-being-free from mouth and facial pain, oral and throat cancer, oral infections, periodontal diseases, tooth decay or loss, and other diseases/disorders. The age distribution of the world's population is changing. With advances in medicine, the proportion of older people continues to increase worldwide. Aims, Setting, Materials and Methods: A cross-sectional study was carried out among 158 elderly (>60 years) residing in a slum of Kolkata during the period from April 2017 to June 2017 to assess the impact of oral health on general health. Data were collected using a pretested predesigned schedule containing Geriatric Oral Health Assessment Index. Data analysis was performed in R software. Poisson regression was used to find the associates of the impact of oral health. Results: Mean (standard deviation) age was 68.54 (5.9) years. A total of 104 (65.8%) participants reported; foul breath as a problem and 88 (55.7%) reported gum bleeding as a problem. All participants used to clean their teeth daily but only 36.1% used to clean their teeth at least twice daily. More than half the participants reported that they have limited the kind of food they eat due to dental/gum condition and trouble chewing. Conclusion: There is a need to provide sensitive oral health services that are accessible, affordable, appropriate, and acceptable. Knowledge regarding oral health and hygiene should be provided to all elderly, especially diabetics. Further research with the broader conceptual framework, in different age groups and in different settings are warranted.

Risk behaviors contributing to recent serious unintentional injuries among school-going adolescent boys in Kolkata: Application of zero-inflated count model

Background: Unintentional injuries have become a major noncommunicable disease burden, especially among the adolescents. Objective: The current study was conducted to estimate the effect of different aspects of daily activities of adolescence for sustaining serious unintentional injuries in the past 1 year. Methods: A cross-sectional survey with multistage sampling with validated pretested questionnaire was done among the school-going adolescent boys in Kolkata. Poisson regression was used to model the counts of serious injuries. To account for the excess of zero in the outcome, zero-inflated Poisson regression was performed. Results: Among the participants, 73.5% did not report any serious unintentional injury sustained in the past 1 year, 11.9% reported to have sustained serious unintentional injury once in the past 1 year, and rest had more than one count. Statistically significant higher chance of sustaining an episode of injury was found among frequent users of motorbike (incidence rate ratio [IRR]: 1.183), frequently walking on roads (IRR: 1.910), and frequently crossing major roads on bicycle (IRR: 2.181) were observed. A statistically significant protective rate ratio was also obtained for those frequently obeying traffic signals while crossing roads (IRR: 0.493) and frequent users of bicycles (IRR: 0.384). Significantly lower rate ratio for sustaining a serious injury was observed with frequently getting into fight at home (IRR: 0.343) and getting beaten up at school (IRR: 0.595). Conclusions: The study revealed traveling in a car and obeying traffic rules were protective from sustaining serious injury. However, walking and participation in sports appeared to be risky, especially for sustaining another episode of serious injury.

Associação da posição socioeconômica e da depressão materna com a saúde das crianças: avaliação da PNAD 2008, Brasil / Associating socioeconomic position and maternal depression with the health of children: an evaluation of the 2008 Brazilian household survey

Resumo O estudo analisou a associação entre posição socioeconômica (renda), depressão materna e saúde da criança no Brasil, utilizando informações da Pesquisa Nacional por Amostra de Domicílios 2008 (PNAD/IBGE). A análise considerou o delineamento amostral da pesquisa e incluiu 46.874 indivíduos com idade até 9 anos. Modelos Poisson foram estimados para três desfechos de saúde da criança: saúde reportada pelos pais ou responsáveis, restrição das atividades habituais por motivo de saúde e episódios de acamamento nas duas semanas anteriores à entrevista. Os resultados apontaram associação entre a depressão da mãe e os três desfechos, mesmo após o ajuste para posição socioeconômica, características maternas (saúde autorreferida, idade, escolaridade e tabagismo), idade, sexo e cor da pele da criança, além de região geográfica, situação censitária e número de moradores do domicílio. Constatou-se ainda que a associação entre depressão materna e saúde da criança independe da posição socioeconômica. Assim, políticas de saúde pública que objetivem atenuar os efeitos adversos da depressão materna sobre a saúde da criança, precisam considerar também os estratos mais elevados de renda da sociedade.

Abstract The study analyzed the association between socioeconomic position (income), maternal depression and the health of children in Brazil, using information from the 2008 National Household Survey (PNAD/IBGE). The analysis considered the sampling design for the research and included 46,874 individuals up to the age of nine. The Poisson models were estimated for three health outcomes for children: health as reported by the parents or the responsible person, restrictions on habitual activities for health reasons and periods when they were confined to bed two weeks before the interviews in the study. The results showed an association between the mothers' depression and the three health outcomes, even after taking into account the following: socioeconomic position, maternal characteristics (health self-referral, age, level of education and smoking), age, gender, the child's race, geographical region, the situation as noted in the census and the number of residents in a household. It was found that there still exists an association between maternal depression and children's health irrespective of socioeconomic position. Therefore public policies that aim to reduce the adverse effects of maternal depression on the health of children need to also take into account the higher income segments of society.

Study on the relationship between frequencies of prenatal care and neonatal low birth weight in women of childbearing age from rural areas of Shaanxi province / 中华流行病学杂志

Objective To investigate the relationship between frequencies of prenatal care and neonatal low birth weight (LBW) among women of childbearing age from the rural areas of Shaanxi province.Methods A questionnaire survey was conducted among the childbearing-aged women from the rural areas.Samples were selected through multi stage stratified random sampling method.The childbearing aged women were in pregnancy or having had definite outcomes of pregnancy.Measurement of data was described by median ± standard deviation,and chi square test was used to compare the rates.Neonatal low birth weight and frequencies of prenatal care were dependent variables and independent variables grouped into the generalized Poisson regression model.Confounding factors were under control.Results The overall incidence rate of LBW was 3.75％ among 18 911 rural women of childbearing age during 2010-2013.Frequencies on pregnancy care were up to 15 times (0.70％),with a minimum of 0 (0.70％),an average of 5.65± 2.74 times (including ≥ 10 times accounted for 12.37％;≥7 times accounted for 28.52％;≥5 times accounted for 62.80％ and ＜4 times accounted for 21.49％).After controlling confounding factors,results from the generalized Poisson regression analysis revealed that the difference was statistically significant when compared to the reference group.The incidence of neonatal LBW in the ＜4 group was 1.61 times of the one in the ＞7 group (OR=1.61,95％CI:1.31-2.00) while in the ＜4 group it was 1.23 times of the 4-7 group (OR=1.23,95％ CI:1.04-1.45).Conclusion In the rural areas of Shaanxi province,the incidence of neonatal LBW was gradually reduced through the increasing number of frequencies on prenatal care,among women of childbearing age.

Study on the relationship between frequencies of prenatal care and neonatal low birth weight in women of childbearing age from rural areas of Shaanxi province / 中华流行病学杂志

Objective To investigate the relationship between frequencies of prenatal care and neonatal low birth weight (LBW) among women of childbearing age from the rural areas of Shaanxi province.Methods A questionnaire survey was conducted among the childbearing-aged women from the rural areas.Samples were selected through multi stage stratified random sampling method.The childbearing aged women were in pregnancy or having had definite outcomes of pregnancy.Measurement of data was described by median ± standard deviation,and chi square test was used to compare the rates.Neonatal low birth weight and frequencies of prenatal care were dependent variables and independent variables grouped into the generalized Poisson regression model.Confounding factors were under control.Results The overall incidence rate of LBW was 3.75％ among 18 911 rural women of childbearing age during 2010-2013.Frequencies on pregnancy care were up to 15 times (0.70％),with a minimum of 0 (0.70％),an average of 5.65± 2.74 times (including ≥ 10 times accounted for 12.37％;≥7 times accounted for 28.52％;≥5 times accounted for 62.80％ and ＜4 times accounted for 21.49％).After controlling confounding factors,results from the generalized Poisson regression analysis revealed that the difference was statistically significant when compared to the reference group.The incidence of neonatal LBW in the ＜4 group was 1.61 times of the one in the ＞7 group (OR=1.61,95％CI:1.31-2.00) while in the ＜4 group it was 1.23 times of the 4-7 group (OR=1.23,95％ CI:1.04-1.45).Conclusion In the rural areas of Shaanxi province,the incidence of neonatal LBW was gradually reduced through the increasing number of frequencies on prenatal care,among women of childbearing age.

Estimating age- and sex-specific mortality rates for small areas with TOPALS regression: an application to Brazil in 2010 / Estimativa de taxas de mortalidade por idade e sexo para pequenas áreas com regressão de TOPALS: uma aplicação para o Brasil em 2010 / Estimación de las tasas de mortalidad por edad y sexo de las pequeñas áreas con regresión de TOPALS: una aplicación a Brasil en 2010

Abstract High variability in recorded vital events creates serious problems for small-area mortality estimation by age and sex. Many existing approaches to fitting local mortality schedules, including those most often used in Brazil, estimate rates by making rigid mathematical assumptions about local age patterns. Such methods assume that all areas within a larger area (for example, microregions within a mesoregion) have identically-shaped log mortality schedules by age. We propose a more flexible statistical estimation method that combines Poisson regression with the TOPALS relational model (DE BEER, 2012). We use the new method to estimate age-specific mortality rates in Brazilian small areas (states, mesoregions, microregions, and municipalities) in 2010. Results for Minas Gerais show notable differences in the age patterns of mortality between adjacent small areas, demonstrating the advantages of using a flexible functional form in regression models.

Resumo A alta variabilidade dos dados nos registros vitais, em razão do baixo número de pessoas expostas, impõe sérios problemas para estimação da mortalidade por idade e sexo em pequenas áreas. Muitas abordagens atuais, incluindo as mais utilizadas no Brasil, estimam as taxas específicas de mortalidade assumindo pressupostos matemáticos rígidos sobre o verdadeiro padrão etário da mortalidade. Padronização indireta, por exemplo, assume que todas as áreas dentro de uma área maior (microrregiões em uma mesorregião, por exemplo) possuem um padrão de mortalidade idêntico, com diferença constante no nível das taxas logarítmicas por idade. Propomos um método estatístico mais flexível que combina regressão Poisson com um modelo relacional denominado TOPALS (DE BEER, 2012). Usamos o novo método para estimar as taxas específicas de mortalidade em pequenas áreas no Brasil (estados, mesorregiões, microrregiões e municípios) em 2010. Resultados para o estado de Minas Gerais mostram diferenças notáveis no padrão de mortalidade por idade entre pequenas áreas adjacentes, demonstrando as vantagens do uso de um método de estimação mais flexível.

Resumen La alta variabilidad de los datos en los registros vitales, debida al bajo número de personas expuestas al riesgo de morir, plantea serios problemas para la estimación de la mortalidad por edad y sexo en pequeñas áreas. Muchos enfoques recientes, incluyendo los más utilizados en Brasil, estiman las tasas de mortalidad por edad con presupuestos matemáticos rígidos acerca del verdadero padrón etario de la mortalidad. La estandarización indirecta, por ejemplo, asume que todas las áreas dentro de una área mayor (microrregiones de una mesorregión) tengan una idéntica estructura de la mortalidad, con diferencia constante en los niveles de las tasas logarítmicas por edad. Proponemos un método estadístico más flexible que combina la regresión de Poisson con un modelo relacional llamado TOPALS. Utilizamos el nuevo método para estimar las tasas de mortalidad específicas en pequeñas áreas en Brasil (estados, mesorregiones, microrregiones y municipios) en 2010. Los resultados para el estado de Minas Gerais muestran diferencias notables en la estructura de mortalidad entre áreas pequeñas adyacentes, lo que demuestra las ventajas de usar un método de estimación más flexible.

Regresiones aplicadas al estudio de eventos discretos en epidemiología / Regressions applied to the study of discrete events in epidemiology

En este manuscrito se revisan algunos aspectos básicos de la utilización de regresiones en los estudios epidemiológicos, haciendo énfasis en aquellas aplicadas al estudio de eventos discretos. De esta manera se hace una introducción a los modelos lineales generalizados, cuya estructura es una extensión de una ecuación lineal para analizar desenlaces discretos. De este modo podemos estimar medidas de asociación como la razón de tasas usando la regresión de Poisson, o bien, el riesgo relativo (o la razón de prevalencias) usando la regresión log-binomial. En cada caso es esencial conocer la naturaleza de la variable dependiente, su distribución y reconocer las limitaciones de cada una de las herramientas de análisis.

Some basic aspects about using regressions in epidemiological studies are reviewed. Particularly, this manuscript focused on those applied to the study of discrete events. Generalized lineal models, such as Poisson and log-binomial, have a structure that is an extension of a lineal equation to analyze discrete outcomes. Thus, we can estimate association measures as the incidence rate ratio, using the Poisson regression, or the relative risk (or prevalence ratio), using log-binomial regression. In each case it is essential to know the nature of the dependent variable, as well as, its distribution and recognize the limitations of each analysis tool.

The Characteristic Analysis of Researches Network for Journal of Korean Neuropsychiatric Association / 신경정신의학

OBJECTIVES: This study evaluated the structural characteristics of a scientific network of psychiatry and the effect of social networks on the performance of scholars. METHODS: The data were extracted from 261 articles published from 1996 to 2013 in the Journal of the Korean Neuropsychiatric Association, and were transformed into a co-author and their affiliation matrix. We used measures from network analysis (i.e., degree centrality, weighted degree centrality, eigenvector centrality, betweenness centrality) for evaluating the effect of co-authorship network on the performance of scholars (h-index). Netminer 4.1 was used for the network analysis. RESULTS: Both co-authorship and affiliation network demonstrated power law distribution. Coauthor's centralities were correlated with research achievements. Results from poisson regression analysis showed that the eigenvector centrality has a significant positive influence on the h-index and the weighted degree centrality has a significant negative influence on the h-index. CONCLUSION: This study shows that the small world phenomenon exists in the psychiatric coauthorship network, and finds collaboration patterns and effects on scientific performance. The results suggest that in order to achieve better research performance it would be helpful for scholars to work with other well-performing scholars and avoid other scholars who previously worked together.

A simulation/case study under the use of robust Poisson and log-binomial model with generalized estimating equation models regarding non-independent data / 中华流行病学杂志

To explore the appropriate method in estimating relative risk (RR)/prevalence ratio (PR) related to non-independent datasets.The simulation datasets generated by computer and case study were analyzed by two generalized estimating equation (GEE) models to investigate and compare the related applicability.Both convergence effects of log-binomial-GEE model and Robust Poisson-GEE model were almost 100％.The estimation results of the two GEE models were both closer to the true value.95％CI coverage of the two GEE models increased along with the reduction of class aggregation or the increase of the number of categories.Robust-Poisson-GEE model seemed to be more stable and steady than the log-binomial-GEE.The two GEE models could correctly evaluate the effects of exposure on the outcome in the case study.Rarely,there appeared problems on convergence of Robust Poisson or log-binomial-GEE model,and the accuracy was high.Both models could be used to estimate the RR/PR on non-independent epidemiological data.

Evolução temporal da mortalidade por suicídio em pessoas com 60 anos ou mais nos estados brasileiros, 1980 a 2009 / Suicide mortality temporal trends in people aged 60 years or more in the Brazilian states: 1980 to 2009

Este artigo objetiva verificar a evolução temporal da mortalidade por suicídio em pessoas com 60 anos ou mais segundo a unidade da federação no período de 1980 a 2009. Na construção das séries históricas empregaram-se dados da mortalidade por suicídio (CID-9 códigos E950 a E959 e CID-10 códigos X60 a X84 e Y87.0) obtidos do Sistema de Informação sobre Mortalidade (SIM/MS). Dados referentes à contagem populacional foram obtidos do Instituto Brasileiro de Geografia e Estatística. Na avaliação da tendência temporal empregou-se o modelo de regressão de Poisson, no qual a variável resposta foi o número de óbitos e a variável explanatória o ano calendário centralizado. Foram consideradas tendências estatisticamente significativas aquelas cujo p-valor < 0,05. Os resultados mostram a presença de tendência estatisticamente significativa de aumento para quatro estados e de queda para dois (população geral; 60 anos ou mais). Na população masculina houve aumento em cinco e redução em dois. As taxas femininas exibiram aumento em um estado e queda em três. Verificou-se tendência de aumento no Piauí, Ceará e Rio Grande do Norte e de redução no Amazonas, São Paulo e Roraima para aqueles com idades entre 60 e 69 anos. Observaram-se taxas crescentes na população de 70 a 79 anos do Piauí e decrescentes em Roraima.

The scope of this paper is to determine the temporal evolution of mortality by suicide in people aged 60 or more per State in Brazil between 1980 and 2009. Historical mortality by suicide data (ICD-9 codes E950 to E959 and ICD-10 codes X60 to X84 and Y87.0) were obtained from the Mortality Information System (SIM / MS). Data regarding population counts were obtained from the Brazilian Institute of Geography and Statistics. In the assessment of temporal trends the Poisson regression model was used, in which the dependent variable was the number of deaths and the centralized calendar year was the explanatory variable. Statistically significant trends were considered those whose p-value was d" 0.05. The results revealed the presence of a statistically significant increasing trend in four states and a decrease in two (general population; 60 years or more). In the male population there was an increase in five states and a reduction in two. The female rate showed an increase in one state and a decrease in three. There was an increasing trend in Piauí, Ceará and Rio Grande do Norte and a reduction in Amazonas, Roraima, and São Paulo for people aged between 60 and 69. Increasing rates were observed in the population aged 70-79 in Piauí and decreasing trends in Roraima.

Prevalência e características de mulheres com aborto provocado - Favela México 70, São Vicente - São Paulo / Prevalence and characteristics of women with induced abortion - Favela México 70, São Vicente - São Paulo

No Brasil, o aborto está entre as principais causas de mortalidade materna. Pesquisas mostram que o aborto é praticado clandestinamente por mulheres de todas as classes sociais; no entanto, tem consequências desiguais, dependendo da inserção social, produzindo riscos à vida de mulheres pobres. Embora o tema venha sendo amplamente explorado nos últimos 20 anos, observou-se escassez de dados sobre mulheres de baixa renda. Desta forma, o presente estudo tem por objetivo estimar a prevalência de mulheres com aborto provocado. Arrolaram-se mulheres por inquérito domiciliar de base populacional em setores de baixa renda de São Vicente, São Paulo. Eram elegíveis as mulheres em idade fértil de 15 a 49 anos. A avaliação das razões de prevalência de mulheres com aborto provocado foi realizada por meio de modelos lineares generalizados, usando-se a regressão de Poisson com função de ligação logarítmica e variância robusta para aproximar a binomial. As variáveis que demonstraram ter maior influência no relato de aborto foram: "aceitar sempre esta prática" (IC95 por cento 2,98 - 11,02), seguida de "não ter filho nascido vivo" (IC95 por cento 1,35 - 19,78), ter de "dois a cinco nascidos vivos" (IC95 por cento 1,42 - 14,40) e ter de "seis ou mais nascidos vivos" (IC 95 por cento 1,35 - 19,78), "idade no momento da entrevista" (IC 95 por cento 1,01 - 1,07) e "renda" < R$ 484,97 (IC 95 por cento 1,04 - 2,96). É necessário campanha de grande abrangência sobre a prática do aborto, que consiga sensibilizar para esta causa todas as mulheres, sobretudo as de baixa renda, evitando assim mortes desnecessárias.

In Brazil, abortion is among the leading causes of maternal mortality. Research has shown that abortion is practiced clandestinely by women of all social classes, but has unequal consequences depending on social inclusion, producing risks to poor women. Although the issue has been widely explored in the past 20 years, there is a lack of data about low-income women. Thus, the present study aims to estimate the prevalence of women with induced abortion. Women from a population-based household survey in low-income sectors of São Vicente, São Paulo were recruited. Women of childbearing age from 15 to 49 years were eligible. The evaluation of the prevalence ratios for women with induced abortion was performed by using generalized linear models, with Poisson log-link function and robust variance to approximate the binomial. The most frequent variables that influenced reporting of abortion were: "always accept this practice" (95 percent CI 2.98 - 11.02), followed by "not having a child born alive" (95 percent CI 1.35 - 19.78), having "two to five live births" (95 percent CI 1.42 - 14.40 ), "having 'six or more live births" (95 percent CI 1.35 - 19.78), "age at interview" (95 percent CI 1.01 - 1.07) and "income" < R$ 484.97' (95 percent CI 1.04 - 2.96). A widespread campaign about the practice of abortion, which can raise awareness among women in favor of the cause, especially among those in low-income strata is necessary to prevent unnecessary deaths.

Estimation of the Frequency of Intravenous Drug Users in Hamadan City, Iran, Using the Capture-recapture Method / 한국역학회지

OBJECTIVES: The number of illicit drug users is prone to underestimation. This study aimed to use the capture-recapture method as a statistical procedure for measuring the prevalence of intravenous drug users (IDUs) by estimating the number of unknown IDUs not registered by any of the registry centers. METHODS: This study was conducted in Hamadan City, the west of Iran, in 2012. Three incomplete data sources of IDUs, with partial overlapping data, were assessed including: (a) Volunteer Counseling and Testing Centers (VCTCs); (b) Drop in Centers (DICs); and (c) Outreach Teams (ORTs). A log-linear model was applied for the analysis of three-sample capture-recapture results. Two information criteria were used for model selection including Akaike's Information Criterion and the Bayesian Information Criterion. RESULTS: Out of 1,478 IDUs registered by three centers, 48% were identified by VCTCs, 32% by DICs, and 20% by ORTs. After exclusion of duplicates, 1,369 IDUs remained. According to our findings, there were 9,964 (95% CI, 6,088 to 17,636) IDUs not identified by any of the centers. Hence, the real number of IDUs is expected to be 11,333. Based on these findings, the overall completeness of the three data sources was around 12% (95% CI, 7% to 18%). CONCLUSION: There was a considerable number of IDUs not identified by any of the centers. Although the capture-recapture method is a useful and practical approach for estimating unknown populations, due to the assumptions and limitations of the method, the results must be interpreted with caution.

Application of zero-inflated models on regression analysis of count data: a study of sub-health symptoms / 中华流行病学杂志

To explore the goodness of fit about the zero-inflated (ZI) models in analyzing data related to sub-health symptoms in which the counts are non-negative integers. ZI models are conducted with Stata 11.0. The coefficient of a, Vuong test, O test and likelihood test are used to compare the goodness of fit for ZI models with the common used models such as passion model,negative binomial model. When a is 0.939, and the Z statistic of Vuong test is 32.08, P＜0.0001,which shows that there are too many zeros. The mean number of sub-health symptoms is 2.90, s=3.85, 0=308.011, P＜0.001, s2＞(-x), indicating that the data are over-dispersed. In addition, the optimum goodness of fit is found in zero-inflated negative binomial (ZINB) model with the largest log likelihood and the smallest AIC. ZINB seems the optimal model to study those over-dispersed count data with too many zeros.

Handling Overdispersion in Mortality Data in Time-Series Epidemiologic Research Using SAS Software

Analysis of count event data such as mortality cases, were often modelled using Poisson regression model. Maximum likelihood procedures were used by using SAS software to estimate the model parameters of a Poisson regression model. However, the Negative Binomial distribution has been widely suggested as the alternative to the Poisson when there is proof of overdispersion phenomenon. We modelled the mortality cases as the dependent variable using Poisson and Negative Binomial regression and compare both of the models. The procedures were done in SAS by using the function PROC GENMOD. The results showed that the mortality data in Poisson regression exhibit large ratio values between deviance to degree of freedom which indicate model misspecification or overdispersion. This large ratio was found to be reduced in Negative Binomial regression. The Normal probability plot of Pearson residual confirmed that the Negative Binomial regression is a better model than Poisson regression in modelling the mortality data. The objective of this study is to compare the goodness of fit of Poisson regression model and Negative Binomial regression model in the application of air pollution epidemiologic time series study by using SAS software.

Effect of Ambient Air SO_2 on Mortality of Respiratory Diseases in Shenyang / 环境与健康杂志

Objective To assess the effect of ambient air SO2 on mortality of respiratory diseases. Methods Based on the ecological theory, after the adjustment of seasons, temperature, humidity and air pressure, the observed individuals were divided into eight groups. The association between SO2 exposure and mortality rate of respiratory diseases was analyzed using Poisson regression and local auto-regression method. Results SO2 concentration increased by 0.05 mg/m3, the mortality of respiratory diseases increased by 5.90% (95%CI: 2.26%-9.68%) in all groups, in children by 10.23% (95%CI: 2.07%-19.04%), in young-middle-male group by 1.10% (95%CI: -9.51%-12.96%), in young female group by 9.58% (95%CI: -2.57%-23.23%), in young group by 10.23% (95%CI: 2.07%-19.04%), in aged male group by 5.26%(95%CI: 0.01%-10.78%), in aged female group by 8.07% (95%CI: 3.45%-12.89%) and in aged group by 4.66% (95%CI: 1.44%-7.99%) respectively. Conclusion SO2 exposure is found to be associated with the increase of mortality of respiratory diseases, especially in children, aged people and elderly females.

Mortalidad por leucemias en menores de 20 años: México 1998-2002 / Leukemia mortality on people under 20 years old: Mexico 1988-2002

Introducción. Las leucemias son el cáncer más frecuente durante la infancia. El estudio pretende describir la mortalidad por leucemias en menores de 20 años en México. Material y métodos. A partir del Sistema Estadístico y Epidemiológico de las Defunciones se calcularon tasas específicas por edad, género y entidad federativa. Se estimó la tasa media de mortalidad anual (TMMA) por estado, y la tasa truncada estandarizada por edad de mortalidad. La estandarización fue por el método directo y el error estándar por la aproximación de Poisson, los intervalos de confianza (IC) fueron de 95%. En la elaboración de la razón estandarizada de mortalidad (REM) se utilizó la tasa nacional como referencia. Se calculó la proporción de cambio anual estatal y nacional con IC al 95%, además se estimaron las tendencias nacionales y estatales de 1998 a 2002 por medio de la regresión de Poisson. Resultados. La mortalidad por leucemias representó 51.1%. La razón hombre/mujer fue de 1.3. Los grupos de edad más afectados fueron los de 5-9 y 10-14 años, ambas con TMMA de 27.7 por 10(6) habitantes. La REM para Quintana Roo y Puebla fueron significativas. En cuanto a la tendencia Tlaxcala presentó un incremento y Baja California Sur un decremento, ambos fueron estadísticamente significativos. Conclusiones. La mortalidad por leucemias en menores de 20 años representa un problema de salud pública nacional, por lo que el diagnóstico temprano y tratamiento específico deben ser de alta prioridad.

Introduction. Leukemias are the most frequent form of cancer in childhood and adolescence. This study describes the mortality rate for individuals under 20 years of age with a primary diagnosis of leukemia in Mexico over a 15 year period, from 1988-2002. Material and methods. Specific mortality rates were calculated according to age, gender and state of origin based on data provided by a National Epidemiological Mortality Reporting System (SEED). The median annual mortality rate and age adjusted mortality rate were estimated for each state in Mexico. The direct method was used for standardization and standard error with 95% confidence intervals were also calculated. The national mortality rate was used as a reference to estimate the standardized mortality rate. State annual change and trends were calculated from 1988 to 2002 by Poisson regression. Results. The leukemia mortality rate during the study period was 51.1%; the male/female ratio was 1.3 and the predominant age group ranged from 10 to 14 years of age. The median annual mortality rate of 27.7 per 10(6) inhabitants. Conclusions. Leukemia mortality in children and adolescents under 20 years of age represents a major public health problem in Mexico, early diagnosis and specific treatment must be considered high priority.

Prediction of HIV and AIDS Incidence Using a Back-calculation Model in Korea / 예방의학회지

OBJECTIVE: To estimate the status of HIV infection and AIDS incidence using a back-calculation model in Korea. METHODS: Back-calculation is a method for estimating the past infection rate using AIDS incidence data. The method has been useful for obtaining short-term projections of AIDS incidence and estimating previous HIV prevalence. If the density of the incubation periods is known, together with the AIDS incidence, we can estimate historical HIV infections and forecast AIDS incidence in any time period up to time t. In this paper, we estimated the number of HIV infections and AIDS incidence according to the distribution of various incubation periods RESULTS: The cumulative numbers of HIV infection from 1991 to 1996 were 708~1,426 in Weibull distribution and 918~1,980 in Gamma distribution. The projected AIDS incidence in 1997 was 16~25 in Weibull distribution and 13~26 in Gamma distribution. CONCLUSIONS: The estimated cumulative HIV infections from 1991 to 1996 were 1.4~4.0 times more than notified cumulative HIV infections. Additionally, the projected AIDS incidence in 1997 was less than the notified AIDS cases. The reason for this underestimation derives from the very low level of HIV prevalence in Korea. Further research is required for the distribution of the incubation period of HIV infection in Korea, particularly for the effects of combination treatments.