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Ecological Study (ecological + study)
Selected AbstractsCesarean Section Rates and Maternal and Neonatal Mortality in Low-, Medium-, and High-Income Countries: An Ecological StudyBIRTH, Issue 4 2006Fernando Althabe MD ABSTRACT: Background: Cesarean section rates show a wide variation among countries in the world, ranging from 0.4 to 40 percent, and a continuous rise in the trend has been observed in the past 30 years. Our aim was to explore the association of cesarean section rates of different countries with their maternal and neonatal mortality and to test the hypothesis that in low-income countries, increasing cesarean section rates were associated with reductions in both outcomes, whereas in high-income countries, such association did not exist. Methods: We performed a cross-sectional multigroup ecological study using data from 119 countries from 1991 to 2003. These countries were classified into 3 categories: low-income (59 countries), medium-income (31 countries), and high-income (29 countries) countries according to an international classification. We assessed the ecological association between national cesarean section rates and maternal and neonatal mortality by fitting multiple linear regression models. Results: Median cesarean section rates were lower in low-income than in medium- and high-income countries. Seventy-six percent of the low-income countries, 16 percent of the medium-income countries, and 3 percent of high-income countries showed cesarean section rates between 0 and 10 percent. Three percent of low-income countries, 36 percent of medium-income countries, and 31 percent of high-income countries showed cesarean section rates above 20 percent. In low-income countries, a negative and statistically significant linear correlation was observed between cesarean section rates and neonatal mortality and between cesarean section rates and maternal mortality. No association was observed in medium- and high-income countries for either neonatal mortality or maternal mortality. Conclusions: No association between cesarean section rates and maternal or neonatal mortality was shown in medium- and high-income countries. Thus, it becomes relevant for future good-quality research to assess the effect of the high figures of cesarean section rates on maternal and neonatal morbidity. For low-income countries, and on confirmation by further research, making cesarean section available for high-risk pregnancies could contribute to improve maternal and neonatal outcomes, whereas a system of care with cesarean section rates below 10 percent would be unlikely to cover their needs. (BIRTH 33:4 December 2006) [source] The impact of a supervised injecting facility on ambulance call-outs in Sydney, AustraliaADDICTION, Issue 4 2010Allison M. Salmon ABSTRACT Aims Supervised injecting facilities (SIFs) are effective in reducing the harms associated with injecting drug use among their clientele, but do SIFs ease the burden on ambulance services of attending to overdoses in the community? This study addresses this question, which is yet to be answered, in the growing body of international evidence supporting SIFs efficacy. Design Ecological study of patterns in ambulance attendances at opioid-related overdoses, before and after the opening of a SIF in Sydney, Australia. Setting A SIF opened as a pilot in Sydney's ,red light' district with the aim of accommodating a high throughput of injecting drug users (IDUs) for supervised injecting episodes, recovery and the management of overdoses. Measurements A total of 20 409 ambulance attendances at opioid-related overdoses before and after the opening of the Sydney SIF. Average monthly ambulance attendances at suspected opioid-related overdoses, before (36 months) and after (60 months) the opening of the Sydney Medically Supervised Injecting Centre (MSIC), in the vicinity of the centre and in the rest of New South Wales (NSW). Results The burden on ambulance services of attending to opioid-related overdoses declined significantly in the vicinity of the Sydney SIF after it opened, compared to the rest of NSW. This effect was greatest during operating hours and in the immediate MSIC area, suggesting that SIFs may be most effective in reducing the impact of opioid-related overdose in their immediate vicinity. Conclusions By providing environments in which IDUs receive supervised injection and overdose management and education SIF can reduce the demand for ambulance services, thereby freeing them to attend other medical emergencies within the community. [source] Hospitalizations for opioid poisoning: a nation-wide population-based study in Denmark, 1998,2004ADDICTION, Issue 1 2009Anne-Mette Bay Bjørn ABSTRACT Aims To assess hospitalization rates (HR) for poisoning with heroin, methadone or strong analgesics and relate them to quantities of prescribed methadone and strong analgesics in Denmark between 1998 and 2004. Design Population-based ecological study. Settings We extracted data on all emergency department visits and hospital admissions registered in the Danish National Patient Registry with a diagnosis of poisoning with heroin (n = 1688), methadone (n = 173) or strong analgesics (n = 384). To ascertain sale of prescribed medications we used data from the Danish Medicines Agency. Measurements Age- and gender-standardized HR and defined daily doses (DDD) per 1000 people per day. Findings HR for heroin poisoning was 4.4 [95% confidence interval (CI): 3.8,4.9] per 100 000 person-years (p-y) in 1998 and 4.6 (CI: 4.0,5.2) per 100 000 p-y in 2004. HR for methadone poisoning increased from 0.1 (CI: 0.0,0.2) per 100 000 p-y in 1998 to 1.1 (CI: 0.8,1.4) per 100 000 p-y in 2004. HR for poisoning with strong analgesics increased from 0.6 (CI: 0.4,0.9) per 100 000 p-y in 1998 to 2.1 (CI: 1.8,2.6) per 100 000 p-y in 2004. The sale of prescribed strong analgesics (5.0 DDD per 1000 people per day in 1998 to 5.9 DDD in 2004) and methadone (3.0 DDD per 1000 people per day in 1998 to 3.4 DDD in 2004) increased slightly between 1998 and 2004. Conclusion Increasing sale of prescribed methadone and strong analgesics coincided with increasing HRs of poisoning with these drugs, whereas HR of heroin poisoning varied. Further longitudinal studies are important for the guidance of future policy making. [source] Robust principal component analysis and outlier detection with ecological dataENVIRONMETRICS, Issue 2 2004Donald A. Jackson Abstract Ecological studies frequently involve large numbers of variables and observations, and these are often subject to various errors. If some data are not representative of the study population, they tend to bias the interpretation and conclusion of an ecological study. Because of the multivariate nature of ecological data, it is very difficult to identify atypical observations using approaches such as univariate or bivariate plots. This difficulty calls for the application of robust statistical methods in identifying atypical observations. Our study provides a comparison of a standard method, based on the Mahalanobis distance, used in multivariate approaches to a robust method based on the minimum volume ellipsoid as a means of determining whether data sets contain outliers or not. We evaluate both methods using simulations varying conditions of the data, and show that the minimum volume ellipsoid approach is superior in detecting outliers where present. We show that, as the sample size parameter, h, used in the robust approach increases in value, there is a decrease in the accuracy and precision of the associated estimate of the number of outliers present, in particular as the number of outliers increases. Conversely, where no outliers are present, large values for the parameter provide the most accurate results. In addition to the simulation results, we demonstrate the use of the robust principal component analysis with a data set of lake-water chemistry variables to illustrate the additional insight available. We suggest that ecologists consider that their data may contain atypical points. Following checks associated with normality, bivariate linearity and other traditional aspects, we advocate that ecologists examine their data sets using robust multivariate methods. Points identified as being atypical should be carefully evaluated based on background information to determine their suitability for inclusion in further multivariate analyses and whether additional factors explain their unusual characteristics. Copyright © 2004 John Wiley & Sons, Ltd. [source] Comparative fire ecology of tropical savanna and forest treesFUNCTIONAL ECOLOGY, Issue 6 2003William A. Hoffmann Summary 1Fire is important in the dynamics of savanna,forest boundaries, often maintaining a balance between forest advance and retreat. 2We performed a comparative ecological study to understand how savanna and forest species differ in traits related to fire tolerance. We compared bark thickness, root and stem carbohydrates, and height of reproductive individuals within 10 congeneric pairs, each containing one savanna and one forest species. 3Bark thickness of savanna species averaged nearly three times that of forest species, thereby reducing the risk of stem death during fire. The allometric relationship between bark thickness and stem diameter differed between these two tree types, with forest species tending to have a larger allometric coefficient. 4The height of reproductive individuals of forest species averaged twice that of congeneric savanna species. This should increase the time necessary for forest species to reach reproductive size, thereby reducing their capacity to reach maturity in the time between consecutive fires. 5There was no difference in total non-structural carbohydrate content of stems or roots between savanna and forest species, though greater allocation to total root biomass by savanna species probably confers greater capacity to resprout following fire. 6These differences in fire-related traits may largely explain the greater capacity of savanna species to persist in the savanna environment. [source] Length,weight relationships of cryptic reef fishes from the southwestern Gulf of California, MèxicoJOURNAL OF APPLIED ICHTHYOLOGY, Issue 4 2006E. F. Balart Summary Length,weight relationships of 33 cryptic reef fishes from the southwestern Gulf of California were estimated. The most common families were Gobiidae (seven species), Labrisomidae (four), Pomacentridae (three), and Tripterygiidae (three). These are the first length,weight parameters reported for 32 of these species. Specimens were sampled during a comparative ecological study of community structure of fish assemblages associated with coral heads, rocky walls, and artificial reefs in Bahía de La Paz, Baja California Sur. The b values varied between 2.63 and 3.61. New maximum length records for five of the species were established in the study. [source] An ecological study of the relationship between two living fossils in Malawi: the Mulanje Tiger Moth (Callioratis grandis) and the Mulanje Cycad (Encephalartos gratus)AFRICAN JOURNAL OF ECOLOGY, Issue 2 2010Julian Bayliss Abstract The Mulanje tiger moth (Callioratis grandis) has recently been discovered feeding solely on the Mulanje Cycad, Encephalartos gratus. In its type locality Encephalartos gratus is severely threatened through habitat destruction and human population growth. As a result the first detailed demographic survey of Encephalartos gratus on Mount Mulanje was undertaken with particular emphasis on the relationship between E. gratus and Callioratis grandis. What is unusual about C. grandis is that the males exhibit lekking behaviour, for which aposematism may be a prerequisite. Cycads were surveyed in a systematic manner. Both the biotic and abiotic parameters were recorded from 532 wild Encephalartos gratus. Results showed the morphological range of measurements differed from that of previously published literature on this species. Results also showed that the incidence of Callioratis larval damage was related to the maturity of the wild cycads , moth damage was greater on more mature plants. Approximately 50% of surveyed cycads showed evidence of Callioratis moth damage, however, there was no apparent preference from the moth to select either male or female cycads as food plants for the larvae. In some cases there was severe damage to cycad fronds, but this did not seem to affect the production of reproductive cones or even the survival of individual cycads. Résumé On a découvert récemment que le papillon du Mulanje (Callioratis grandis) ne se nourrit que sur le cycadale Mulanje Encephalartos gratus. Dans son milieu type, Encephalartos gratus est gravement menacé dans la nature à cause de la destruction de l'habitat et de la croissance de la population humaine. Par conséquent, la première étude démographique détaillée d'Encephalartos gratus réalisée sur le mont Mulanje fut entreprise en insistant particulièrement sur la relation entre Encephalartos gratus et Callioratis grandis. Ce qui est inhabituel chez C. grandis, c'est que les mâles présentent un comportement territorial (lek). Les cycadales ont été systématiquement surveillées. On a enregistré les paramètres biotiques et abiotiques pour 532 Encephalartos gratus poussant dans la nature. Les résultats ont montré que l'amplitude des mesures morphologiques différait de ce que la littérature existante décrit sur cette espèce. Ils ont aussi montré que l'incidence des dommages causés par les larves de Callioratisétait liée à la maturité des cycadales sauvages , les dégâts causés par les papillons étaient plus graves sur les plants plus matures. Environ 50% des cycadales suivis montraient des traces de dommages causés par ce papillon, mais il n'y avait pas de preuve qui aurait pu montrer que le papillon sélectionnait des cycadales mâles ou femelles pour en nourrir ses larves. Dans certains cas, il y avait des dégâts sérieux dans les feuilles de cycadales; cependant, cela ne semblait pas affecter la production de cônes reproducteurs, pas plus que la survie des individus. [source] A simple method for isolation of microsatellites from the Japanese squirrel, Sciurus lis, without constructing a genomic libraryMOLECULAR ECOLOGY RESOURCES, Issue 4 2003K. Shibata Abstract We developed a simple and easy method to isolate microsatellites without screening genomic libraries by hybridization. The method requires only three basic techniques: polymerase chain reaction, DNA cloning and sequencing. We applied this method to develop microsatellite markers for the Japanese squirrel and isolated 45 clones that contained repetitive sequences. Among the 22 clones that we tested further, we found 11 diagnostic microsatellite loci that are applicable to the molecular ecological study of Japanese squirrels. [source] Sensitivity Analyses for Ecological RegressionBIOMETRICS, Issue 1 2003Jon Wakefield Summary. In many ecological regression studies investigating associations between environmental exposures and health outcomes, the observed relative risks are in the range 1.0,2.0. The interpretation of such small relative risks is difficult due to a variety of biases,some of which are unique to ecological data, since they arise from within-area variability in exposures/confounders. The potential for residual spatial dependence, due to unmeasured confounders and/or data anomalies with spatial structure, must also be considered, though it often will be of secondary importance when compared to the likely effects of unmeasured confounding and within-area variability in exposures/confounders. Methods for addressing sensitivity to these issues are described, along with an approach for assessing the implications of spatial dependence. An ecological study of the association between myocardial infarction and magnesium is critically reevaluated to determine potential sources of bias. It is argued that the sophistication of the statistical analysis should not outweigh the quality of the data, and that finessing models for spatial dependence will often not be merited in the context of ecological regression. [source] Cesarean Section Rates and Maternal and Neonatal Mortality in Low-, Medium-, and High-Income Countries: An Ecological StudyBIRTH, Issue 4 2006Fernando Althabe MD ABSTRACT: Background: Cesarean section rates show a wide variation among countries in the world, ranging from 0.4 to 40 percent, and a continuous rise in the trend has been observed in the past 30 years. Our aim was to explore the association of cesarean section rates of different countries with their maternal and neonatal mortality and to test the hypothesis that in low-income countries, increasing cesarean section rates were associated with reductions in both outcomes, whereas in high-income countries, such association did not exist. Methods: We performed a cross-sectional multigroup ecological study using data from 119 countries from 1991 to 2003. These countries were classified into 3 categories: low-income (59 countries), medium-income (31 countries), and high-income (29 countries) countries according to an international classification. We assessed the ecological association between national cesarean section rates and maternal and neonatal mortality by fitting multiple linear regression models. Results: Median cesarean section rates were lower in low-income than in medium- and high-income countries. Seventy-six percent of the low-income countries, 16 percent of the medium-income countries, and 3 percent of high-income countries showed cesarean section rates between 0 and 10 percent. Three percent of low-income countries, 36 percent of medium-income countries, and 31 percent of high-income countries showed cesarean section rates above 20 percent. In low-income countries, a negative and statistically significant linear correlation was observed between cesarean section rates and neonatal mortality and between cesarean section rates and maternal mortality. No association was observed in medium- and high-income countries for either neonatal mortality or maternal mortality. Conclusions: No association between cesarean section rates and maternal or neonatal mortality was shown in medium- and high-income countries. Thus, it becomes relevant for future good-quality research to assess the effect of the high figures of cesarean section rates on maternal and neonatal morbidity. For low-income countries, and on confirmation by further research, making cesarean section available for high-risk pregnancies could contribute to improve maternal and neonatal outcomes, whereas a system of care with cesarean section rates below 10 percent would be unlikely to cover their needs. (BIRTH 33:4 December 2006) [source] Millennium development goals and oral health in cities in southern BrazilCOMMUNITY DENTISTRY AND ORAL EPIDEMIOLOGY, Issue 3 2010Roberto Eduardo Bueno Bueno RE, Moysés SJ, Moysés ST. Millennium development goals and oral health in cities in southern Brazil. Community Dent Oral Epidemiol 2010; 38: 197,205. © 2010 John Wiley & Sons A/S Abstract,,, Objectives:, To investigate social determinants of oral health, analysing the occurrence of associations between millennium development goals (MDG) indicators and oral health (OH) indicators. Methods:, An ecological study was performed in two distinct phases. In Phase 1, MDG indicators and related covariates were obtained from the demographic census of the Brazilian Institute of Geography and Statistics, the Ministry of Health database and the 2000 Human Development Atlas, making up the whole set of independent variables. Principal component analysis was carried out for the independent variables showing the correlations among the variables comprising the main components, and generating a synthetic index allowing the performance of the cities to be known with regard to the MDG (MDG index). In Phase 2, the DMFT index (mean number of decay, missing or filled permanent teeth) and the CF index (prevalence of caries-free individuals), in 12 years old were obtained from the epidemiological survey undertaken in 2002,2003, in 49 cities in southern Brazil, and were analysed in relation to the MDG index using Spearman's correlation. Results:, A statistically significant correlation was found for the DMFT and CF indices, respectively, with: the MDG index (R2 = 0.49 and 0.48; P = 0.00); the socioeconomic status of the population (R2 = 0.12 and 0.12; P = 0.02); the socioenvironmental characteristics (R2 = 0.41 and 0.46; P = 0.00). Conclusions:, The MDG synthetic index of the cities analysed and the respective components relating to their socioeconomic and socioenvironmental status demonstrated a positive correlation with OH indicators. As such, intersectoral public policies based on population strategies that act on social determinants of general and oral health need to be integrated so as to impact on the MDG and OH outcomes. [source] | ||||||||||||||||