Spatial accessibility of drug treatment facilities and the effects on locus of control,drug use,and service use among heroin-injecting Mexican American men

BackgroundThis study explores the spatial accessibility of outpatient drug treatment facilities and the potential relationship with drug use-related outcomes among Mexican American heroin users.MethodsSecondary data on 219 current and former heroin-injecting Mexican American men aged 45 and older were drawn from a research study in Houston, Texas. We used geographic information systems (GIS) to derive two spatial accessibility measures: distance from one's place of residence to the closest drug treatment facility (in minutes); and the number of facilities within a 10-minute driving distance from one's place of residence. Exploratory logistic regression analyses examined the association between the spatial accessibility of drug treatment facilities and several drug use-related outcomes: internal locus of control (LOC); perceived chances and worries of injecting in the next six months; treatment utilization; and location of last heroin purchase.ResultsParticipants with greater spatial access to treatment programs were more likely to report a higher chance of injecting in the near future. However, while current heroin users were more worried about injecting in the next six months, greater spatial access to treatment programs seemed to have a buffering effect. Finally, those who lived closer to a treatment programs were more likely to have last purchased heroin inside the neighborhood versus outside the neighborhood. Spatial accessibility was not associated with internal LOC or treatment utilization.ConclusionThe findings showed that the presence of outpatient treatment facilities—particularly services in Spanish—may influence perceived risk of future heroin use and purchasing behaviors among Mexican American men. Implications for future spatially-informed drug use research and the planning of culturally and linguistically responsive drug treatment programs are discussed.     

A flow-based statistical model integrating spatial and nonspatial dimensions to measure healthcare access

Assessing access to healthcare for an entire healthcare system involves accounting for demand, supply, and geographic variation. In order to capture the interaction between healthcare services and populations, various measures of healthcare access have been utilized, including the popular two-step floating catchment area (2SFCA) method. However, despite the many advantages of 2SFCA, the problems, such as inappropriate assumption of healthcare demand and failure to capture cascading effects across the system have not been satisfactorily addressed. In this paper, a statistical model for evaluating flows of individuals was added to the 2SFCA method (hereafter we refer to it as F2SFCA) in order to overcome limitations associated with its current restriction. The proposed F2SFCA model can incorporate both spatial and nonspatial dimensions and thus synthesizes them into one framework. Moreover, the proposed F2SFCA model can be easily adapted to measure access for different types of individuals, over different service provider types, or with capacity constraints in a healthcare system. We implemented the proposed model in a case study assessing access to healthcare for the elderly in Taipei City, Taiwan, and compared the weaknesses and strengths to the 2SFCA method and its variations.     

Local Ecological Factors,Ultrafine Particulate Concentrations,and Asthma Prevalence Rates in Buffalo,New York,Neighborhoods

Previous to this study various healthcare utilization studies and house-to-house surveys had shown that Buffalo's west side had a high utilization rate for asthma and high asthma prevalence in comparison with neighboring communities. The relative contributions of traffic-related pollution and personal and local ecological factors to the high asthma rates were still unknown. To investigate the potential roles of personal home environmental factors and local ecological factors in variations of asthma prevalence in Buffalo neighborhoods, we conducted a cross-sectional survey of a systematic random sample of 2000 households in the city of Buffalo, New York, with a response rate of 80.4%. We found that the odds of having at least one person with asthma per household on Buffalo's west side was 2.57 times [95% confidence interval (CI) = 1.85–3.57] that of Buffalo's east side. There were no statistically significant differences in the odds of finding at least one person with asthma in households of other Buffalo neighborhoods. We further found no difference in the odds of having asthma on Buffalo's west side even after correcting for race/ethnicity, household triggers of asthma, and socioeconomic factors. Monitoring ultrafine particulates showed increased levels in communities downwind of the Peace Bridge Complex and major roadways supplying it. A multiple-regression model showed that asthma prevalence may be influenced by humidity and ultrafine particulate concentrations. These results suggest that increased asthma risk may be influenced by chronic exposure to personal and local ecological factors.     

Neonatal alcohol impairs the context preexposure facilitation effect in juvenile rats: Dose-response and post-training consolidation effects

Alcohol exposure on postnatal days (PND) 4-9 in the rat adversely affects hippocampal anatomy and function and impairs performance on a variety of hippocampus-dependent tasks. Exposure during this developmental window reveals a linear relationship between alcohol dose and spatial learning impairment in the context preexposure facilitation effect (CPFE), a hippocampus-dependent variant of contextual fear conditioning. The purpose of the current report was to examine the effect of a range of alcohol doses administered during a narrower window, PND7-9, than previously reported (Experiment 1) and to begin to determine which memory processes involved in this task are impaired by developmental alcohol exposure (Experiment 2). In Experiment 1, rats pups received a single day binge alcohol dose of either 2.75, 4.00, 5.25 g/kg/day or were sham-intubated (SI) from PND7-9. Conditioned freezing during the test day was evident in all dosing groups, except for Group 5.25 g, indicating no graded dose-related behavioral deficits with alcohol exposure limited to PND7-9. In Experiment 2, rat pups were exposed to the highest effective dose from Experiment 1 (5.25 g/kg/day) or were sham intubated over PND7-9. During training, rats remained in the conditioning context for 5-min following immediate shock delivery. During this test of post-shock freezing, both SI and alcohol-exposed rats given prior exposure to the conditioning context showed comparable freezing levels. Since alcohol-exposed rats showed normal post-shock freezing, deficits by these rats on the test day likely reflect a failure to consolidate or retrieve a context-shock association, rather than a deficit in hippocampal conjunctive processes (consolidation, pattern completion) that occur prior to shock on the training day. These findings illustrate the value of the CPFE for characterizing the separable memory processes that are impaired by neonatal alcohol exposure in this task.     

A multivariate hypothesis testing framework for tissue clustering and classification of DTI data

The primary aim of this work is to propose and investigate the effectiveness of a novel unsupervised tissue clustering and classification algorithm for diffusion tensor MRI (DTI) data. The proposed algorithm utilizes information about the degree of homogeneity of the distribution of diffusion tensors within voxels. We adapt frameworks proposed by Hext and Snedecor, where the null hypothesis of diffusion tensors belonging to the same distribution is assessed by an F‐test. Tissue type is classified according to one of the four possible diffusion models, the assignment of which is determined by a parsimonious model selection framework based on Schwarz Criterion. Both numerical phantoms and diffusion‐weighted imaging (DWI) data obtained from excised rat and pig spinal cords are used to test and validate these tissue clustering and classification approaches. The unsupervised clustering method effectively identifies distinct regions of interest (ROIs) in phantoms and real experimental DTI data. Copyright © 2009 John Wiley & Sons, Ltd.     

某养老机构新型冠状病毒肺炎聚集性疫情流行病学特征分析

目的对某养老机构发生一起新型冠状病毒肺炎(COVID-19)聚集性疫情进行回顾性流行病学调查和分析。方法采用"新型冠状病毒肺炎防控方案(第三版)"推荐的个案调查表和依照"新型冠状病毒肺炎聚集性疫情流行病学调查指南(试行第一版)"进行。结果某养老机构有8名护理人员和住院老人感染新冠肺炎,年龄中位为59岁,男、女比例1∶7。于末次暴露后4~15 d确诊。排查出225名密切接触者,无三代院内续发传播;不排除无症状感染存在传染的可能性;病亡1例。结论本次聚集性疫情的感染来源于新冠肺炎确诊病例。建议防控策略应关注养老机构、监管场所等重点部门、重点人群的管控与监测。     

基于地理信息系统的医疗设施空间分布研究

如何优化医疗设施空间分布,最大限度利用医疗卫生资源、保障医疗服务公平性和可及性是政府卫生管理部门经常遇到的难题。地理信息系统技术在医疗设施空间布局研究中得到广泛的应用。基于地理信息系统的医疗设施空间分布研究方法主要包括基于地理学空间相互作用理论的区位分析模型方法、基于运筹学规划技术的区位——配置模型方法和优势度模型方法。     

Stepped‐wedge cluster randomised controlled trials: a generic framework including parallel and multiple‐level designs

Stepped‐wedge cluster randomised trials (SW‐CRTs) are being used with increasing frequency in health service evaluation. Conventionally, these studies are cross‐sectional in design with equally spaced steps, with an equal number of clusters randomised at each step and data collected at each and every step. Here we introduce several variations on this design and consider implications for power. One modification we consider is the incomplete cross‐sectional SW‐CRT, where the number of clusters varies at each step or where at some steps, for example, implementation or transition periods, data are not collected. We show that the parallel CRT with staggered but balanced randomisation can be considered a special case of the incomplete SW‐CRT. As too can the parallel CRT with baseline measures. And we extend these designs to allow for multiple layers of clustering, for example, wards within a hospital. Building on results for complete designs, power and detectable difference are derived using a Wald test and obtaining the variance–covariance matrix of the treatment effect assuming a generalised linear mixed model. These variations are illustrated by several real examples. We recommend that whilst the impact of transition periods on power is likely to be small, where they are a feature of the design they should be incorporated. We also show examples in which the power of a SW‐CRT increases as the intra‐cluster correlation (ICC) increases and demonstrate that the impact of the ICC is likely to be smaller in a SW‐CRT compared with a parallel CRT, especially where there are multiple levels of clustering. Finally, through this unified framework, the efficiency of the SW‐CRT and the parallel CRT can be compared. © 2014 The Authors. Statistics in Medicine Published by John Wiley & Sons Ltd.