A signed-rank test for clustered data

Summary .   We consider the problem of comparing two outcome measures when the pairs are clustered. Using the general principle of within-cluster resampling, we obtain a novel signed-rank test for clustered paired data. We show by a simple informative cluster size simulation model that only our test maintains the correct size under a null hypothesis of marginal symmetry compared to four other existing signed rank tests; further, our test has adequate power when cluster size is noninformative. In general, cluster size is informative if the distribution of pair-wise differences within a cluster depends on the cluster size. An application of our method to testing radiation toxicity trend is presented.     

Matrix-based concordance correlation coefficient for repeated measures

Summary In many clinical studies, Lin's concordance correlation coefficient (CCC) is a common tool to assess the agreement of a continuous response measured by two raters or methods. However, the need for measures of agreement may arise for more complex situations, such as when the responses are measured on more than one occasion by each rater or method. In this work, we propose a new CCC in the presence of repeated measurements, called the matrix‐based concordance correlation coefficient (MCCC) based on a matrix norm that possesses the properties needed to characterize the level of agreement between two p× 1 vectors of random variables. It can be shown that the MCCC reduces to Lin's CCC when p= 1. For inference, we propose an estimator for the MCCC based on U‐statistics. Furthermore, we derive the asymptotic distribution of the estimator of the MCCC, which is proven to be normal. The simulation studies confirm that overall in terms of accuracy, precision, and coverage probability, the estimator of the MCCC works very well in general cases especially when n is greater than 40. Finally, we use real data from an Asthma Clinical Research Network (ACRN) study and the Penn State Young Women's Health Study for demonstration.     

Epidemiological evaluations of the efficacy of slow-released praziquantel-medicated bars for dogs in the prevention and control of cystic echinococcosis in man and animals

To assess the epidemiological efficacy of type SRP III slow-released praziquantel-medicated bars for dogs in the prevention and control of cystic echinococcosis in man and livestock, praziquantel-medicated bars were implanted subcutaneously in over 90% of dogs in villages in north Xinjiang, China, where cystic echinococcosis is highly endemic. After implantation, infection rate of Echinococcus granulosus in dogs, specific antibodies in children and prevalence of echinococcosis in one-year-old lambs were observed for 3 years. Coproantigen of E. granulosus was positive in 41.2% of the dogs at the start of experiment. In the second and third year after medicated-bar implantation, coproantigen was undetectable in any dogs examined, while 3.0% of dogs were positive at the end of the fourth year. The antibody positive rate in 7-year-old pupils, that was 41.2% before the experiment, declined gradually and it was 5.4% in the fourth year, while children in the non-intervention control area showed 30.6% seropositivity. The prevalence of hydatid disease in children aged 7–16 years also declined significantly. The prevalence of hydatidosis in lambs one year of age was 44.8% in the first year, dropping to 10.7% in the fourth year, while in the non-intervention control area the level of infection was 46.4%. These results demonstrated not only that the slow released praziquantel-medicated bars efficiently blocked reinfection in dogs at least for 2 years, but also the measure was effective in preventing transmission of cystic echinococcosis to both man and livestock.     

WHO health risk assessment process for static fields

The World Health Organization (WHO) has a commitment to helping Member States achieve safe, sustainable and health-enhancing human environments, protected from biological, chemical and physical agents. The latter includes advising on the health impact of electromagnetic fields (EMFs) and radiation.

The results of the WHO/ICNIRP/NRPB workshop on static magnetic fields, published in this volume, provide a valuable and much needed contribution to the health risk assessment of exposure to static electric and magnetic fields, which is currently being coordinated by the WHO's International EMF Project. This WHO health risk assessment will be published as an environmental health criteria (EHC) monograph in early 2005.

This paper briefly gives an overview of the process of developing the WHO static fields EHC monograph, the criteria applied to studies that could contribute to the EHC, along with the ‘weight-of-evidence’ approach to health risk assessment. In addition, there is an increasing awareness of the need to account for uncertainty in the science database. This is traditionally addressed by further research, and the EMF project addresses these needs through the development of a ‘research agenda’. However, research programmes may take several years to complete, and the long latency associated with diseases such as cancer in people may also preclude a rapid outcome in some studies. The issue of current uncertainty is being addressed by the WHO EMF project through the development of a ‘precautionary framework’ in which precautionary measures will be applied to policy recommendations.     

Countering Countermeasures in the Concealed Information Test Using Covert Respiration Measures

The effects of physical and mental countermeasures on the accuracy of the concealed information test (CIT) were examined in a mock crime experiment with 64 participants. To combat countermeasures, two covert respiration measures, hidden in the seat and back of the examination chair, were used in addition to the standard physiological measures (SCR, FPWL, RLL). Some guilty participants were trained to use either physical or mental countermeasures and apply them to distort the outcomes of the CIT. In the second phase of the experiment participants were detached from the standard polygraph devices and examined solely with the two covert measures. Results indicated that physical countermeasures lowered SCR accuracy but had a relatively small effect on the other standard measures. On the other hand, SCR was relatively resistant to mental countermeasures. Both covert measures were resistant to physical countermeasures in the polygraph phase. When the standard devices were removed, the covert seat measure was effective in the no countermeasure and in the mental countermeasure conditions but not when physical countermeasures were applied. The back measure was entirely ineffective.

Focus: Preventive Medicine: 2020 Evaluation of Portable Vision Screening Instruments

Amblyopia is the most common cause of preventable visual impairment in children and occurs as a result of unilateral or bilateral impairment in best-corrected visual acuity. Early diagnosis and proper treatment are crucial to prevent poor visual outcomes in adulthood. Advances in technology have provided more objective diagnostic tools, which can now be used by a wide range of healthcare providers. Here, we highlight tools that have gained popularity in the past two decades and compare clinically relevant parameters to guide primary care providers seeking to incorporate instrumental vision screening in pediatric patient care.     

Focus: Preventive Medicine: Leveraging Organizational Health Literacy to Enhance Health Promotion and Risk Prevention: A Narrative and Interpretive Literature Review

Organizational health literacy involves the health care organizations’ ability to establish an empowering and co-creating relationship with patients, engaging them in the design and delivery of health services in collaboration with health professionals. Although scholars agree that organizational health literacy contributes to health promotion and risk prevention via patient empowerment, literature is not consistent in depicting the interplay between organizational health literacy and preventive medicine. The article intends to shed light into this issue, summarizing current knowledge about this topic and advancing avenues for further development. A narrative literature review was performed through a systematic search on PubMed^®, Scopus^®, and Web of Science^™. The review focused on 50 relevant contributions. Organizational health literacy triggers the transition towards a patient-centered approach to care. It complements individual health literacy, enabling patients to actively participate in health promotion and risk prevention as co-producers of health services and co-creators of value. However, many obstacles – including lack of time and limited resources available – prevent the transition towards health literate health care organizations. Two initiatives are required to overcome extant barriers. On the one hand, a health literate workforce should be prepared to increase the institutional ability of health care organizations to empower and engage patients in health co-creation. On the other hand, increased efforts should be made to assess organizational health literacy and to make its contribution to preventive medicine explicit.     

Repeated measures random forests (RMRF): Identifying factors associated with nocturnal hypoglycemia

Nocturnal hypoglycemia is a common phenomenon among patients with diabetes and can lead to a broad range of adverse events and complications. Identifying factors associated with hypoglycemia can improve glucose control and patient care. We propose a repeated measures random forest (RMRF) algorithm that can handle nonlinear relationships and interactions and the correlated responses from patients evaluated over several nights. Simulation results show that our proposed algorithm captures the informative variable more often than naïvely assuming independence. RMRF also outperforms standard random forest and extremely randomized trees algorithms. We demonstrate scenarios where RMRF attains greater prediction accuracy than generalized linear models. We apply the RMRF algorithm to analyze a diabetes study with 2524 nights from 127 patients with type 1 diabetes. We find that nocturnal hypoglycemia is associated with HbA1c, bedtime blood glucose (BG), insulin on board, time system activated, exercise intensity, and daytime hypoglycemia. The RMRF can accurately classify nights at high risk of nocturnal hypoglycemia.     

喀斯特槽谷区土地石漠化与综合治理技术研发

深入揭示流域尺度水-土-生资源格局和研发因地制宜的水-土-生治理技术是"十三五"石漠化治理工程的主要瓶颈。国家重点研发计划——"喀斯特槽谷区土地石漠化过程及综合治理技术研发与示范"项目(2016YFC0502300)针对槽谷区特点,锁定两个关键科学问题和五个关键技术,从过程机理研究-技术研发-应用示范3个层面解剖区域水/土/生物资源分布格局与地质地貌之间的关系,阐明石漠化过程中的相关生态变化机理,因地制宜地研发水土资源高效利用、土壤地上/下流/漏失阻控与生态恢复技术;研发野生砧木及经济树种互作效应与优化配套技术,构建槽谷区可持续的生态系统和生态产业模式并示范推广,为区域生态改善和贫困问题解决提供科技支撑。