An Examination of Measurement Procedures and Characteristics of Baseline Outcome Data in Single-Case Research.

There has been growing interest in using statistical methods to analyze data and estimate effect size indices from studies that use single-case designs (SCDs), as a complement to traditional visual inspection methods. The validity of a statistical method rests on whether its assumptions are plausible representations of the process by which the data were collected, yet there is evidence that some assumptions-particularly regarding normality of error distributions-may be inappropriate for single-case data. To develop more appropriate modeling assumptions and statistical methods, researchers must attend to the features of real SCD data. In this study, we examine several features of SCDs with behavioral outcome measures in order to inform development of statistical methods. Drawing on a corpus of over 300 studies, including approximately 1,800 cases, from seven systematic reviews that cover a range of interventions and outcome constructs, we report the distribution of study designs, distribution of outcome measurement procedures, and features of baseline outcome data distributions for the most common types of measurements used in single-case research. We discuss implications for the development of more realistic assumptions regarding outcome distributions in SCD studies, as well as the design of Monte Carlo simulation studies evaluating the performance of statistical analysis techniques for SCD data.

Computer Adaptive Test Stopping Rules Applied to The Flexilevel Shoulder Functioning Test.

Computerized adaptive testing (CAT) is an attractive alternative to traditional paper-and-pencil testing because it can provide accurate trait estimates while administering fewer items than a linear test form. A stopping rule is an important factor in determining an assessments efficiency. This simulation compares three variable-length stopping rules-standard error (SE) of .3, minimum information (MI) of .7 and change in trait (CT) of .02 - with and without a maximum number of items (20) imposed. We use fixed-length criteria of 10 and 20 items as a comparison for two versions of a linear assessment. The MI rules resulted in longer assessments with more biased trait estimates in comparison to other rules. The CT rule resulted in more biased estimates at the higher end of the trait scale and larger standard errors. The SE rules performed well across the trait scale in terms of both measurement precision and efficiency.

Successful airtraq use in an air medical transport system.

INTRODUCTION: There is a large body of literature that shows that the AirTraq device achieves equal or superior rates of successful intubation in all classes of user. A recent prospective human trial of the device questioned the first pass success rate and whether effective training could occur outside the Operating Room (OR). The purpose of this study was to investigate the first pass success rate for intubation with the AirTraq (AT) device utilizing only mannequin training in an air ambulance setting from Aug. 1 2009 to Aug. 1 2012 and compare it to direct laryngoscopy (DL). HYPOTHESIS: We hypothesize that the AirTraq device will be as effective overall as direct laryngoscopy, and that this requires no OR training to achieve. METHODS: A retrospective chart review of 161 intubations by air ambulance flight nurses from Aug. 1, 2009 to Aug. 1, 2012 was conducted. Data regarding date of service, devices used, number of attempts, rescue device use, and complications was gathered and analyzed. The generalized estimating equation and the chi-squared test were used to evaluate the data. RESULTS: 161 intubations were reviewed. 135 met inclusion criteria. Overall first pass success rate for AT was 82% (68/83) and DL was 74% (35/47). Overall first use success rate for AT was 79% (71/90) and DL was 70% (43/61). The overall success rate of intubation for any patient in which either AT or DL was attempted is 96% (130/135). CONCLUSION: AirTraq was shown to be as effective as direct laryngoscopy. All air crew training for the AirTraq device was performed on mannequins. The successof the device compared to DL shows that mannequin training is sufficient to implement the AirTraq device for pre-hospital intubation.

Enhanced functional response to CXCL12/SDF-1 through retroviral overexpression of CXCR4 on M07e cells: implications for hematopoietic stem cell transplantation.

The chemokine CXCL12 (stromal cell derived factor-1/SDF-1) stimulates hematopoietic stem and progenitor cells (HSCs/HPCs) through the corresponding chemokine receptor CXCR4. CXCL12 is thought to be important for both proper HSC homing, retention, and engraftment into the bone marrow (BM) and mobilization out of the BM. Previous studies suggest that breaking the CXCL12-CXCR4 interaction mobilizes HPCs, blocking CXCR4 inhibits HSC homing, and overexpression increases HSC/HPC repopulation. The efficiency of mobilization and engraftment therefore appears to be dependent on the response of HSCs/HPCs to CXCL12, which is in turn dependent upon levels of CXCR4 expressed on HSCs/HPCs. However, expression of CXCR4 on the surface of HSCs/HPCs appears to be variable. To study the function of CXCR4 on HSCs/HPCs, we used the MSCV-based bicistronic (EGFP) retroviral vector MIEG3 to overexpress CXCR4 on M07e cells, an established model of human HPC. CXCR4 overexpression resulted in significant increases in CXCL12-induced chemotaxis and cell survival. Most importantly, cells overexpressing CXCR4 responded to CXCL12 at levels typically too low induce a response. These data suggest that an increased transplant efficiency resulting from CXCR4 overexpression is likely a function of increased HSC/HPC homing and increased HSC/HPC survival in the recipient's BM. These experiments also validate the ability of the MIEG3-CXCR4 retroviral construct to overexpress CXCR4 efficiently and the use of MIEG3-CXCR4 M07e cells for further study. Finally, this information may have future potential therapeutic implications for improvements in transplant efficiency.