Sampling Males Who Inject Drugs in Haiphong,Vietnam: Comparison of Time-Location and Respondent-Driven Sampling Methods

Accurate measurements of HIV prevalence and associated risk factors among hidden and high-risk groups are vital for program planning and implementation. However, only two sampling methods are purported to provide representative estimates for populations without sampling frames: time-location sampling (TLS) and respondent-driven sampling (RDS). Each method is subject to potential biases and questionable reliability. In this paper, we evaluate surveys designed to estimate HIV prevalence and associated risk factors among people who inject drugs (PWID) sampled through TLS versus RDS. In 2012, males aged ≥16 years who reported injecting drugs in the previous month and living in Haiphong, Vietnam, were sampled using TLS or RDS. Data from each survey were analyzed to compare HIV prevalence, related risk factors, socio-demographic characteristics, refusal estimates, and time and expenditures for field implementation. TLS (n = 432) and RDS (n = 415) produced similarly high estimates for HIV prevalence. Significantly lower proportions of PWID sampled through RDS received methadone treatment or met an outreach worker. Refusal estimates were lower for TLS than for RDS. Total expenditures per sample collected and number of person-days of staff effort were higher for TLS than for RDS. Both survey methods were successful in recruiting a diverse sample of PWID in Haiphong. In Vietnam, surveys of PWID are conducted throughout the country; although the refusal estimate was calculated to be much higher for RDS than TLS, RDS in Haiphong appeared to sample PWID with less exposure to services and required fewer financial and staff resources compared with TLS.     

Evaluation of Respondent-Driven Sampling in a Study of Urban Young Men Who Have Sex with Men

Evidence suggests that respondent-driven sampling (RDS) is an efficient approach to sampling among varied populations of adult men who have sex with men (MSM) both in the USA and abroad, although no studies have yet evaluated its performance among younger MSM, a population with a steep rise in HIV infection in recent years. Young MSM (YMSM) may differ in terms of their connectedness to other YMSM (e.g., due to evolving sexual identity, internalization of sexual minority stigma, and lack of disclosure to others) and mobility (e.g., due to parental monitoring) which may inhibit the sampling process. The aims of this study were to evaluate the efficiency and effectiveness of RDS-based sampling among young urban MSM and to identify factors associated with recruitment success. We hypothesized that demographic, social, behavioral, and network factors, including racial/ethnic minority status, homelessness (i.e., as an indicator of socioeconomic marginalization), HIV-positive status, substance use problems, gay community connectedness, and network size would be positively related to recruitment productivity, while sexual minority stigmatization, environmental barriers (e.g., parental monitoring), and meeting sex partners on the internet (i.e., virtual venue) would be negatively related to recruitment productivity. Between December 2009 and February 2013, we used RDS to recruit a sample of 450 YMSM, ages 16–20. Findings suggest that the use of RDS for sampling among YMSM is challenging and may not be feasible based on the slow pace of recruitment and low recruitment productivity. A large number of seeds (38 % of the sample, n = 172) had to be added to the sample to maintain a reasonable pace of recruitment, which makes use of the sample for RDS-based population estimates questionable. In addition, the prevalence of short recruitment chains and segmentation in patterns of recruitment by race/ethnicity further hamper the network recruitment process. Thus, RDS was not particularly efficient in terms of the rate of recruitment or effective in generating a representative sample. Hypotheses regarding factors associated with recruitment success were supported for network size and internalized stigma (but not other factors), suggesting that participants with larger network sizes or high levels of internalized stigma may have more and less success recruiting others, respectively.     

丙型肝炎病毒抗体诊断试剂盒专项抽验情况分析及建议

目的：了解丙型肝炎病毒抗体诊断试剂盒（酶联免疫方法）的总体质量状况,为丙型肝炎病毒抗体诊断试剂盒（酶联免疫方法）的质量监测及监督管理提供参考。方法：根据《中国药典》2010年版三部丙型肝炎病毒抗体诊断试剂盒（酶联免疫法）质量标准,对抽取的丙型肝炎病毒抗体诊断试剂盒（酶联免疫方法）进行法定检验;并进行了与同品种进口试剂盒的质量比较等探讨性研究。结果：按《中国药典》2010年版三部标准检验,抽取的96批样品检验结果全部符合规定,从不同厂家、不同环节抽取的样品质量无显著性差异;国产试剂盒和进口试剂盒对不同基因型系列转换血清PHV901（基因型1a）﹑ PHV912（2b/3）的检测结果一致。结论：丙型肝炎病毒抗体诊断试剂盒（酶联免疫法）总体质量良好。     

长尾黄鼠体外寄生蚤空间分布格局、变量转换及理论抽样量研究

研究结果表明,长尾黄鼠方形黄鼠蚤与总蚤的空间分布格局是邻接的,而不是随机的或一致的。它们的概率分布服从负二项分布,X_(max)~2X_(0.05)~2。据此,本文给出了用于统计分析的变量转换式与理论抽样量。变量经转换后具有好的正态性,X_(max)~2相似文献   

Haematological parameters of parvovirus B19 infection in 13 fetuses with hydrops foetalis

Thirteen cases of fetal parvovirus B19 infection with hydrops foetalis are reported. Viral DNA was identified by polymerase chain reaction (PCR) of amniotic fluid sampled between the 19th and the 29th week of gestation. Haematological examination revealed severe anaemia in all cases and thrombocytopenia in 11/13 cases, which was severe in two cases. Six fetuses died in utero; two after intrauterine transfusion. Complete recovery was observed in seven fetuses; five cases were treated by intrauterine transfusions, and in two cases spontaneous recovery occurred. Upon follow-up, no case of congenital anaemia was observed.     

Surfactant protein-A in bronchoalveolar lavage fluid from neonates with RDS on conventional and high-frequency oscillatory ventilation

Surfactant protein-A (SP-A) was measured in bronchoalveolar lavage (BAL) samples from ventilated neonates in order to study the concentration of SP-A with regard to: 1) high-frequency oscillatory ventilation (HFOV) vs. conventional mechanical ventilation (CMV); 2) the postnatal course and ontogeny of SP-A; and 3) the correlation with measurements of pulmonary function. Patients on HFOV had markedly lower BAL SP-A concentrations on days 1 and 2 compared to those on CMV, which may indicate influence of mode of ventilation on surfactant metabolism. The SP-A concentrations increased postnatally concurrent with resolution of acute respiratory distress syndrome. Finally, there were only weak correlations between BAL SP-A concentration and dynamic lung compliance and oxygen requirement.     

Analyzing the time and value of housestaff inpatient work

OBJECTIVE: To determine time allocation and the perceived value to education and patient care of the weekday activities of internal medicine housestaff on inpatient rotations and to compare the work activities of interns and residents. DESIGN: An observational study. We classified activities along five dimensions (association, location, activity, time, and value), developed a computer-assisted self-interview survey, and demonstrated its face and content validity, internal consistency, and interrater reliability. Subjects were assigned survey computers for 5 consecutive weekdays over a 24-week period, into which they entered data when prompted several times a day. SETTING: The medical service of a university-affiliated Veterans Administration Medical Center. PARTICIPANTS: Sixty housestaff (36 interns, 24 residents) rotating on the inpatient wards. MEASUREMENTS AND MAIN RESULTS: We analyzed activities according to content (direct patient care, indirect patient care, education), association, and location. Likert-scale ratings of perceived value to education and patient care were also obtained. Housestaff provided complete responses to 3,812 (95%) of 3,992 prompts by a median of 11 seconds; 93% of responses were logically consistent across the measured dimensions. Housestaff spent more time in indirect patient care (56%) than in direct patient care (14%) or educational activities (45%). Formal educational activities had the highest educational value (66 on 0–100 scale), and direct care had the highest value to patient care (81). Over 30% of time was spent in administrative activities, which had low educational value (40). Compared with residents, interns allocated significantly less time to educational activities (38% vs 57%) and more time to lower-value activities such as documentation (19% vs 12%). CONCLUSIONS: Improved data collection methods demonstrate that housestaff in our program, particularly interns, spend much of their workday in activities that are low in educational and patient care value. Selective elimination or delegation of such activities would preserve higher-value experiences during reductions in overall inpatient training time. Planners can use automated random sampling to guide the rational redesign of housestaff work. Support for this work was provided by the Western Region of the Veterans Administration (Ambulatory Care and Education Initiative, 94–04), the Veterans Administration Center for the Study of Provider Behavior, and the RAND Graduate School. Dr. Bozzette is a Senior Research Associate of the HSR&D Service, Department of Veterans Affairs.     

湖北省血吸虫病不同亚型流行区抽样调查病情对比分析

目的 掌握全省血吸虫病不同亚型流行区病情动态，评价防治效果，为制定防治规划提供科学依据。方法 以行政村为单位．采用分层整群随机抽样法，于1989、1995、2001三个年度分别对人、畜进行血吸虫粪检查病，用EXCELL建立数据库，SAS统计分析。结果 3次抽样调查中，不同亚型流行区人群和耕牛感染率总体呈下降趋势，但病人和人群感染度(EPG)均呈上升趋势。洲滩、垸内地区居民感染率和EPG男性高于女性，但丘陵地区女性高于男性；各亚型流行区30-岁以上的年龄组人群感染率和EPG较高。2001年洲滩、丘陵地区人群感染率和EPG最高的职业是农民，垸内地区是渔民。结论 3次抽样调查结果显示，虽然全省人群和耕牛感染率总体呈下降趋势，但不同亚型流行区的病人和人群EPG均呈上升趋势。因此，防治工作需针对不同亚型地区的流行特点，因地制宜，加大力度。巩固血防成果。     

批质量保证二次抽样法在抗疟药治疗恶性疟疗效监测中的适用性研究

目的　探索批质量保证二次抽样法 (DLQAS)在抗疟药对恶性疟疗效监测中应用的可能性。　方法　在现场按WHO推荐的 2 8d体内法氯喹疗效评估方案收集病例 ,给予氯喹治疗 ,判定治疗失败与否 ,比较传统的流行病学方法与DLQAS法对疗效判定的结果 ,评估和比较对样本量的需求。　结果　传统方法调查到治疗失败率为 40 .7% ,DLQAS法第一阶段和第二阶段调查到治疗失败率均大于WHO推荐换用药物治疗失败率上限 2 5 % ;DLQAS法的样本量比传统的流行病学横断面抽样方法少。　结论　DLQAS的现场调查治疗失败判定结果同传统流行病学方法 ,且样本量小、快速 ,适用于对抗疟药治疗恶性疟疗效监测的现场评估。     

Analysis of temporal requirements for myocardial tissue velocity imaging.

AIMS: Movements of myocardial walls include components of high velocity and short duration calling for a high sampling rate in the acquisition of tissue velocity imaging data. This study aims at establishing the optimal sampling requirements for tissue velocity imaging measurements. METHODS AND RESULTS: In 16 healthy individuals, tissue velocity imaging data were acquired at a frame rate of 141-203 frames/s for a subsequent off-line analysis using software enabling a reduction of the sampling rate to 50%, 25% and 12.5% of the initial frame rate. Different components of the myocardial velocity profile were measured at each of these frame rates. The deviation of the results from the initial values increased markedly at decreasing frame rates, producing an underestimation of peak systolic and diastolic velocities, most other measured parameters being overestimated. A cut-off point for an acceptable < or =10% deviation of the results corresponded to at least 70 frames/s for peak systolic and early diastolic velocity, and to at least 100 frames/s for other systolic and diastolic parameters. CONCLUSION: A high sampling rate is essential for a proper rendering of tissue velocity imaging signals, too low frame rates resulting in inferior accuracy of the results. This should be kept in mind while viewing reported tissue velocity imaging data.