病例-病例-时间-对照设计

自身病例对照设计(如病例交叉设计、自身对照病例系列研究)虽然能控制不随时间变化的混杂因素(可测量或不可测量的)的影响,但是不能控制暴露时间变化趋势所带来的混杂.双向病例交叉设计可以控制暴露时间变化趋势.但是在药物流行病学的研究中,疾病状态通常影响后续的药物使用,因此这种双向病例交叉设计往往不适用.Suissa 提出的病例-时间-对照设计将病例交叉设计和病例对照设计相结合,很好地控制了暴露的时间变化趋势所带来的偏倚.但是当病例组和对照组不能良好地匹配时,可能会引入新的选择偏倚.本文介绍一种新的研究设计方法“病例-病例-时间-对照设计”,该研究设计是“病例-时间-对照设计”的衍生,即在选择对照组时并不采用外部对照,而是将未来病例作为当前病例的对照,从而避免了暴露的时间趋势所带来的混杂.文后还通过实例分析,对此方法的优点和局限性进行阐释.     

The Effects of Express Lane Eligibility on Medicaid and CHIP Enrollment among Children

Objective

To estimate the impact of Express Lane Eligible (ELE) implementation on Medicaid/CHIP enrollment in eight states.

Data Sources/Study Setting

2007 to 2011 data from the Statistical Enrollment Data System (SEDS) on Medicaid/CHIP enrollment.

Study Design

We estimate difference-in-difference equations, with quarter and state fixed effects. The key independent variable is an indicator for whether the state had ELE in place in the given quarter, allowing the experience of statistically matched non-ELE states to serve as a formal counterfactual against which to assess the changes in the eight ELE states. The model also controls for time-varying economic and policy factors within each state.

Data Collection/Extraction Methods

We obtained SEDS enrollment data from CMS.

Principal Findings

Across model specifications, the ELE effects on Medicaid enrollment among children were consistently positive, ranging between 4.0 and 7.3 percent, with most estimates statistically significant at the 5 percent level. We also find that ELE increased combined Medicaid/CHIP enrollment.

Conclusions

Our results imply that ELE has been an effective way for states to increase enrollment and retention among children eligible for Medicaid/CHIP. These results also imply that ELE-like policies could improve take-up of subsidized coverage under the ACA.     

Placebo use in vaccine trials: Recommendations of a WHO expert panel

Vaccines are among the most cost-effective interventions against infectious diseases. Many candidate vaccines targeting neglected diseases in low- and middle-income countries are now progressing to large-scale clinical testing. However, controversy surrounds the appropriate design of vaccine trials and, in particular, the use of unvaccinated controls (with or without placebo) when an efficacious vaccine already exists. This paper specifies four situations in which placebo use may be acceptable, provided that the study question cannot be answered in an active-controlled trial design; the risks of delaying or foregoing an efficacious vaccine are mitigated; the risks of using a placebo control are justified by the social and public health value of the research; and the research is responsive to local health needs. The four situations are: (1) developing a locally affordable vaccine, (2) evaluating the local safety and efficacy of an existing vaccine, (3) testing a new vaccine when an existing vaccine is considered inappropriate for local use (e.g. based on epidemiologic or demographic factors), and (4) determining the local burden of disease.     

Accuracy of the Modified Somatic Perception Questionnaire and Pain Disability Index in the Detection of Malingered Pain-Related Disability in Chronic Pain

The Modified Somatic Perception Questionnaire (MSPQ) and the Pain Disability Index (PDI) are both popular clinical screening instruments in general orthopedic, rheumatologic, and neurosurgical clinics and are useful for identifying pain patients whose physical symptom presentations and disability may be non-organic. Previous studies found both to accurately detect malingered pain presentations; however, the generalizability of these results is not clear. This study used a criterion groups validation design (retrospective cohort of patients with chronic pain, n = 328) with a simulator group (college students, n = 98) to determine the accuracy of the MSPQ and PDI in detecting Malingered Pain Related Disability. Patients were grouped based on independent psychometric evidence of MPRD. Results showed that MSPQ and PDI scores were not associated with objective medical pathology. However, they accurately differentiated Not-MPRD from MPRD cases. Diagnostic statistics associated with a range of scores are presented for application to individual cases. Data from this study can inform the clinical management of chronic pain patients by screening for psychological overlay and malingering, thus alerting clinicians to the possible presence of psychosocial obstacles to effective treatment and triggering further psychological assessment and/or treatment.     

The effect of drama-based group therapy on aspects of mental illness stigma

This study examined the effect of drama-based group therapy on the self-esteem and self-stigma of five participants with mental illness and on the public stigma of seven university students without mental illness who participated in the same group. ABA single-case experimental design was utilized to systematically assess change across 14 time points. We used visual analysis to inspect change as well as hierarchical linear modeling that allows the aggregation of single-case results to the population level. To study the effect of the treatment, contrasts were examined, comparing scores at baseline, treatment, and follow-up. The findings for all measures indicated a significant difference between scores in the baseline phase compared with scores in both the intervention and the follow-up phases. Significant differences were not detected between scores in the intervention phase and the follow-up phase. Interpretations of findings are provided, followed by a discussion of possible change processes, limitations, and future directions.     

Molecular genetic studies of ADHD and its candidate genes: A review

Attention-deficit/hyperactivity disorder (ADHD) is a common childhood-onset psychiatric disorder with high heritability. In recent years, numerous molecular genetic studies have been published to investigate susceptibility loci for ADHD. These results brought valuable candidates for further research, but they also presented great challenge for profound understanding of genetic data and general patterns of current molecular genetic studies of ADHD since they are scattered and heterogeneous. In this review, we presented a retrospective review of more than 300 molecular genetic studies for ADHD from two aspects: (1) the main achievements of various studies were summarized, including linkage studies, candidate-gene association studies, genome-wide association studies and genome-wide copy number variation studies, with a special focus on general patterns of study design and common sample features; (2) candidate genes for ADHD have been systematically evaluated in three ways for better utilization. The thorough summary of the achievements from various studies will provide an overview of the research status of molecular genetics studies for ADHD. Meanwhile, the analysis of general patterns and sample characteristics on the basis of these studies, as well as the integrative review of candidate ADHD genes, will propose new clues and directions for future experiment design.     

Problem-based learning (PBL) and speech-language pathology: A tutorial

The aim of this tutorial is to provide an introduction to problem-based learning (PBL), particularly as applied to speech-language pathology (SLP) programs. The tutorial is aimed at the reader who is less familiar with this learning approach. Additionally, it serves as a framework for the articles that follow in this special issue on PBL programs in SLP and other clinical education programs. A brief history of PBL is provided and the rationale and context for this approach are identified. PBL is defined and differentiated from related educational approaches. Different models and variations of PBL are outlined. The key components of PBL are further illustrated using the tutorial cycle. Finally, we present one specific case of a PBL-based SLP program in detail. This tutorial will provide a deeper understanding of PBL for many higher educators in SLP. The strengths of this approach are outlined and the challenges are identified, particularly for those contemplating converting an existing “traditional” course or curriculum.     

对SPSS统计软件中Mcnemar检验结果的讨论

目的：比较手工计算与SPSS软件计算Mcnemar检验的结果,分析结果不一样的原因。方法选取相关书籍上配对设计资料的应用实例,用两种方法计算：一是利用Mcnemar检验公式进行手工计算,二是用SPSS统计软件计算,比较两种计算方法的结果有何不同。结果手工计算的结果为P=0.001,SPSS软件计算的结果为P=0.002,两种方法的结果有出入。结论SPSS统计软件对配对设计四格表资料进行计算时采用的是一种精确检验,运用的是二项分布原理,虽然与手工计算的结果有些出入,但无论用哪种方法都不会影响到最终的统计推断。