Repeated measures

A randomized, controlled clinical trial demonstrates improved owner-assessed cognitive function in senior dogs receiving a senolytic and NAD+ precursor combination

Age-related decline in mobility and cognition are associated with cellular senescence and NAD + depletion in dogs and people. A combination of a novel NAD + precursor and senolytic, LY-D6/2, was examined in this randomized controlled trial. Seventy dogs with mild to moderate cognitive impairment were enrolled and allocated into placebo, low or full dose groups. Primary outcomes were change in cognitive impairment measured with the owner-reported Canine Cognitive Dysfunction Rating (CCDR) scale and change in activity measured with physical activity monitors. Fifty-nine dogs completed evaluations at the 3-month primary endpoint, and 51 reached the 6-month secondary endpoint. There was a significant difference in CCDR score across treatment groups from baseline to the primary endpoint (p = 0.02) with the largest decrease in the full dose group. No difference was detected between groups using in house cognitive testing. There were no significant differences between groups in changes in measured activity. The proportion of dogs that improved in frailty and owner-reported activity levels and happiness was higher in the full dose group than other groups, however this difference was not significant. Adverse events occurred equally across groups. All groups showed improvement in cognition, frailty, and activity suggesting placebo effect and benefits of trial participation. We conclude that LY-D6/2 improves owner-assessed cognitive function over a 3-month period and may have broader, but more subtle effects on frailty, activity and happiness as reported by owners.

Enhancing Cognitive Function in Older Adults through Processing Speed Training: Implications for Cognitive Health Awareness

It may be possible to enhance adults' cognitive health and promote healthy aging through processing speed training using the Useful Field of View (UFOV) related activities and software. This study investigated the impact of utilizing UFOV on processing speed improvement in older adults in response to the growing global attention on cognitive health and aging issues. In this quasi-experimental study, 22 individuals (mean age ± SD = 71.9 ± 4.8) participated in the experimental group, and 20 community-based participants (mean age ± SD = 67.1 ± 4.8) were in the control group. The intervention involved ten sessions of UFOV training, each lasting 60 min, conducted twice a week for the experimental group while the control group engaged in volunteer service activities. Measurements of Counting Back, Fabrica, Double-Decision, and Hawkeye were administered to all participants before and after the intervention. The results showed significant improvements in the experimental group for the four measurements (p ≤ 0.01, 0.05, 0.001, 0.001) and non-significant gains in the control group (p ≥ 0.05) for all. Furthermore, mixed repeated-measures ANOVA analysis, with time 1 pre-test measures as the covariate, revealed significant interaction effects between time and group for all measurement indicators (p = 0.05, 0.01, 0.05) except for Fabrica (p > 0.05). In conclusion, these findings support the effectiveness of UFOV cognitive training interventions in enhancing specific cognitive abilities.

Statistical Detection of Differentially Abundant Proteins in Experiments with Repeated Measures Designs and Isobaric Labeling

Repeated measures experimental designs, which quantify proteins in biological subjects repeatedly over multiple experimental conditions or times, are commonly used in mass spectrometry-based proteomics. Such designs distinguish the biological variation within and between the subjects and increase the statistical power of detecting within-subject changes in protein abundance. Meanwhile, proteomics experiments increasingly incorporate tandem mass tag (TMT) labeling, a multiplexing strategy that gains both relative protein quantification accuracy and sample throughput. However, combining repeated measures and TMT multiplexing in a large-scale investigation presents statistical challenges due to unique interplays of between-mixture, within-mixture, between-subject, and within-subject variation. This manuscript proposes a family of linear mixed-effects models for differential analysis of proteomics experiments with repeated measures and TMT multiplexing. These models decompose the variation in the data into the contributions from its sources as appropriate for the specifics of each experiment, enable statistical inference of differential protein abundance, and recognize a difference in the uncertainty of between-subject versus within-subject comparisons. The proposed family of models is implemented in the R/Bioconductor package MSstatsTMT v2.2.0. Evaluations of four simulated datasets and four investigations answering diverse biological questions demonstrated the value of this approach as compared to the existing general-purpose approaches and implementations.

Longitudinal in vivo monitoring of axonal degeneration after brain injury

Traumatic brain injury (TBI)-induced axonal degeneration leads to acute and chronic neuropsychiatric impairment, neuronal death, and accelerated neurodegenerative diseases of aging, including Alzheimer's and Parkinson's diseases. In laboratory models, axonal degeneration is traditionally studied through comprehensive postmortem histological evaluation of axonal integrity at multiple time points. This requires large numbers of animals to power for statistical significance. Here, we developed a method to longitudinally monitor axonal functional activity before and after injury in vivo in the same animal over an extended period. Specifically, after expressing an axonal-targeting genetically encoded calcium indicator in the mouse dorsolateral geniculate nucleus, we recorded axonal activity patterns in the visual cortex in response to visual stimulation. In vivo aberrant axonal activity patterns after TBI were detectable from 3 days after injury and persisted chronically. This method generates longitudinal same-animal data that substantially reduces the number of required animals for preclinical studies of axonal degeneration.

Simple design and analysis strategies for solving problems in observational orthopaedic clinical research

Randomized controlled trials are the gold standard to establishing causal relationships in clinical research. However, these studies are expensive and time consuming to conduct. This article aims to provide orthopaedic surgeons and clinical researchers with methodology to optimize inference and minimize bias in observational studies that are often much more feasible to undertake. To mitigate the risk of bias arising from their nonexperimental design, researchers must first understand the ways in which measured covariates can influence treatment, outcomes, and missingness of follow-up data. With knowledge of these relationships, researchers can then build causal diagrams to best understand how to control sources of bias. Some common techniques for controlling for bias include matching, regression, stratification, and propensity score analysis. Selection bias may result from loss to follow-up and missing data. Strategies such as multiple imputation and time-to-event analysis can be useful for handling missingness. For longitudinal data, repeated measures allow observational studies to best summarize the impact of the intervention over time. Clinical researchers familiar with fundamental concepts of causal inference and techniques reviewed in this article will have the power to improve the quality of inferences made from clinical research in orthopaedic trauma surgery.

Using Job Analysis for Identifying the Desired Competencies of 21st-Century Surgeons for Improving Trainees Selection

OBJECTIVE

The current selection for surgical training is based on ineffective methods. In order to identify or to develop more valid selection tools to improve the selection, it is necessary to first define what are the competencies that are most important for success in contemporary surgery. Therefore, the current study aims to identify what competencies are required for success as a surgeon in the 21st-century and to evaluate their relative importance for selection for surgical training.

METHODS

Job analysis was conducted using a mixed-methods design. First, 104 senior surgeons from all surgical fields from various hospitals in Israel were interviewed in order to query their perceptions of competencies associated with success as a surgeon. Their answers were coded and analyzed to create a list of important competencies. Next, a larger sample of 1,102 surgeons and residents from all surgical fields completed a questionnaire in which they rated the importance of each competency in the list for success as a surgeon and for selection for surgical training in the 21st-century.

RESULTS

Twenty-four competencies (five technical skills, six cognitive abilities, 13 personality characteristics) were identified in the interview analysis. Analysis of the questionnaire's data revealed that all 24 competencies were perceived as important for success as a surgeon in the 21st-century as well as for selection for surgical training. The perceived importance of personality characteristics was higher than both cognitive abilities (p < 0.001) and technical skills (p < 0.001). The results did not differ between different surgical fields.

CONCLUSIONS

Twenty-four competencies were identified as important for 21st-century surgeons and for selection for surgical training. Although all competencies were perceived as important, personality characteristics were perceived as more important than technical skills and cognitive abilities. This updated definition of required competencies may aid in developing more valid selection methods of candidates for surgical training.

Within-person decline in pregnancy smoking is observable prior to pregnancy awareness: Evidence across two independent observational cohorts

Decreased consumption of nicotine and other drugs during pregnancy appears to be a cross-species phenomenon from which mechanism(s) capable of interrupting addictive processes could be elucidated. Whether pregnancy influences smoking behaviour independent of women's knowledge of the pregnancy, however, has not been considered. Using repeated measures analysis of variance (ANOVA), we estimated within-person change in mean cigarettes/day smoked across the estimated date of conception but prior to individually reported dates of pregnancy recognition using longitudinal smoking data from two independent observational cohorts, the Growing Up Healthy (GUH, n = 271) and Midwest Infant Development Studies (MIDS, n = 145). Participants smoked an average of half a pack/day in the month immediately before conception (M (SD) = 12(8.1) and 9.5(6.7) cigarettes/day in GUH and MIDS, respectively). We observed within-person declines in smoking after conception, both before (MGUH  = -0.9; 95% CI -1.6, -0.2; p = 0.01; MMIDS  = -1.1; 95% CI -1.9, -0.3; p = 0.01) and after (MGUH  = -4.8; 95% CI -5.5, -4.1; p < 0.001; MMIDS  = -3.3; 95% CI -4.4, -2.5; p < 0.001) women were aware of having conceived, even when women who had quit and women who were planning to conceive were excluded from analyses. Pregnancy may interrupt smoking-related processes via mechanisms not previously considered. Plausible candidates and directions for future research are discussed.

Repeated-Measures Analysis in the Context of Heteroscedastic Error Terms with Factors Having Both Fixed and Random Levels

The design and analysis of experiments which involve factors each consisting of both fixed and random levels fit into linear mixed models. The assumed linear mixed-model design matrix takes either a full-rank or less-than-full-rank form. The complexity of the data structures of such experiments falls in the model-selection and parameter-estimation process. The fundamental consideration in the estimation process of linear models is the special case in which elements of the error vector are assumed equal and uncorrelated. However, different assumptions on the structure of the variance–covariance matrix of error vector in the estimation of parameters of a linear mixed model may be considered. We conceptualise a repeated-measures design with multiple between-subjects factors, in which each of these factors has both fixed and random levels. We focus on the construction of linear mixed-effects models, the estimation of variance components, and hypothesis testing in which the default covariance structure of homoscedastic error terms is not appropriate. We illustrate the proposed approach using longitudinal data fitted to a three-factor linear mixed-effects model. The novelty of this approach lies in the exploration of the fixed and random levels of the same factor and in the subsequent interaction effects of the fixed levels. In addition, we assess the differences between levels of the same factor and determine the proportion of the total variation accounted for by the random levels of the same factor.

The benefit of an ambulant psychiatric rehabilitation program in Vienna, Austria: an uncontrolled repeated measures study

We investigated the benefit of a 6-week ambulant psychiatric rehabilitation program in an ambulant psychiatric rehabilitation clinic in Vienna, Austria, from January 2014 to December 2016 by an uncontrolled repeated measures study. The potential of this intervention program was assessed by effectiveness and cost measures using suitable statistical analyses. We compared the effectiveness and cost measures of this ambulant psychiatric rehabilitation program on patients for the period of up to 12 months after discharge to the period of 12 months before admission to the intervention program based on self-reported catamnesis questionnaires. For the program's effectiveness measures, we accounted for both psychological indices for measuring depression severity, symptom burden, and functioning to document the health improvement of patients and economy-related indices such as the number of sick leave days for patients. For the program's cost measures, both direct tangible treatment and medication costs and indirect tangible costs based on the productivity loss measured in non-working days of the patients were considered. The results significantly demonstrated that all psychological effectiveness measures for the patients highly improved by the 6-weeks rehabilitation program and remained rather stable 12 months after discharge. We found that costs for the 6-week ambulant psychiatric rehabilitation program could be easily covered within 12 months after discharge once a total societal cost perspective was considered. Even additional total cost savings of up to over 5000 Euro could be achieved which were highest for employed patients, followed by unemployed patients receiving rehabilitation allowance due to both their high direct medication and treatment costs as well as high indirect costs for productivity loss. The most important finding was that this treatment program was especially beneficial for rehabilitation patients in earlier stages of psychiatric diseases who were still employed, indicating the need for early intervention in mental disorder.

Prospective analysis of myocardial strain through the evolution of Chagas disease in the hamster animal model

Speckle tracking echocardiography (STE) enables early diagnosis of myocardial damage by evaluating myocardial strain. We aimed to study sequential changes in structural and ventricular functional parameters during Chagas disease (CD) natural history in an animal model. 37 Syrian hamsters were inoculated intraperitoneally with Trypanosoma cruzi (Chagas) and 20 with saline (Control). Echocardiography was performed before the infection (baseline), at 1 month (acute phase), 4, 6, and 8 months (chronic phase) using Vevo 2100 (Fujifilm Inc.) ultrasound system. Left ventricular end-diastolic diameter, Left ventricular end-systolic diameter (LVESD), Left ventricular ejection fraction (LVEF), Global longitudinal (GLS), circumferential (GCS) and radial (GRS) strain were evaluated. Tricuspid annular plane systolic excursion (TAPSE) was used to assess right ventricular function. At 8 months, animals were euthanized and LV myocardial samples were analyzed for quantitation of inflammation and fibrosis. LVEF decreased over time in Chagas group and a difference from Control was detected at 6 months (p-value of groups#time interaction = 0.005). There was a pronounced decrease in GLS, GCS and TAPSE in Chagas group (p-value of groups#time interaction = 0.003 for GLS, < 0.001 for GCS and < 0.009 for TAPSE vs Control) since the first month. LVESD, LVEF and GLS were significantly correlated to the number of inflammatory cells (r = 0.41, p = 0.046; r = − 0.42, p = 0.042; r = 0.41, p = 0.047) but not to fibrosis. In the Syrian hamster model of CD STE parameters (GLS and GCS) showed an early decrease. Changes in LVEF, LVESD, and GLS were correlated to myocardial inflammation but not to fibrosis.

Short-term exposure to air pollution and biomarkers of cardiovascular effect: A repeated measures study

To help understand the pathophysiologic mechanisms linking air pollutants and cardiovascular disease (CVD), we employed a repeated measures design to investigate the associations of four short-term air pollution exposures - particulate matter less than 2.5 μm in diameter (PM_2.5), nitrogen dioxide (NO₂), ozone (O₃) and sulfur dioxide (SO₂), with two blood markers involved in vascular effects of oxidative stress, soluble lectin-like oxidized LDL receptor-1 (sLOX-1) and nitrite, using data from the Multi-Ethnic Study of Atherosclerosis (MESA). Seven hundred and forty participants with plasma sLOX-1 and nitrite measurements at three exams between 2002 and 2007 were included. Daily PM_2.5, NO₂, O₃ and SO₂ zero to seven days prior to blood draw were estimated from central monitors in six MESA regions, pre-adjusted using site-specific splines of meteorology and temporal trends, and an indicator for day of the week. Unconstrained distributed lag generalized estimating equations were used to estimate net effects over eight days with adjustment for sociodemographic and behavioral factors. The results showed that higher short-term concentrations of PM_2.5, but not other pollutants, were associated with increased sLOX-1 analyzed both as a continuous outcome (percent change per interquartile increase: 16.36%, 95%CI: 0.1-35.26%) and dichotomized at the median (odds ratio per interquartile increase: 1.21, 95%CI: 1.01-1.44). The findings were not meaningfully changed after adjustment for additional covariates or in several sensitivity analyses. Pollutant concentrations were not associated with nitrite levels. This study extends earlier experimental findings of increased sLOX-1 levels following PM inhalation to a much larger population and at ambient concentrations. In light of its known mechanistic role in promoting vascular disease, sLOX-1 may be a suitable translational biomarker linking air pollutant exposures and cardiovascular outcomes.

Design, methods, and reporting of impact studies of cardiovascular clinical prediction rules are suboptimal: a systematic review

OBJECTIVES

To evaluate design, methods, and reporting of impact studies of cardiovascular clinical prediction rules (CPRs).

STUDY DESIGN AND SETTING

We conducted a systematic review. Impact studies of cardiovascular CPRs were identified by forward citation and electronic database searches. We categorized the design of impact studies as appropriate for randomized and nonrandomized experiments, excluding uncontrolled before-after study. For impact studies with appropriate study design, we assessed the quality of methods and reporting. We compared the quality of methods and reporting between impact and matched control studies.

RESULTS

We found 110 impact studies of cardiovascular CPRs. Of these, 65 (59.1%) used inappropriate designs. Of 45 impact studies with appropriate design, 31 (68.9%) had substantial risk of bias. Mean number of reporting domains that impact studies with appropriate study design adhered to was 10.2 of 21 domains (95% confidence interval, 9.3 and 11.1). The quality of methods and reporting was not clearly different between impact and matched control studies.

CONCLUSION

We found most impact studies either used inappropriate study design, had substantial risk of bias, or poorly complied with reporting guidelines. This appears to be a common feature of complex interventions. Users of CPRs should critically evaluate evidence showing the effectiveness of CPRs.

Spatially resolved measurement of dynamic glucose uptake in live ex vivo tissues

Highly proliferative cells depend heavily on glycolysis as a source of energy and biological precursor molecules, and glucose uptake is a useful readout of this aspect of metabolic activity. Glucose uptake is commonly quantified by using flow cytometry for cell cultures and positron emission tomography for organs in vivo. However, methods to detect spatiotemporally resolved glucose uptake in intact tissues are far more limited, particularly those that can quantify changes in uptake over time in specific tissue regions and cell types. Using lymph node metabolism as a case study, we developed an optimized method to detect dynamic and spatially resolved glucose uptake in living tissue by combining ex vivo tissue slice culture with a fluorescent glucose analogue. Live slices of murine lymph node were treated with the glucose analogue 2-[N-(7-nitrobenz-2-oxa-1,3-dia-xol-4-yl)amino]-2-deoxyglucose (2-NBDG). Incubation parameters were optimized to differentiate glucose uptake in activated versus naïve lymphocytes. Regional glucose uptake could be imaged at both the tissue level, by widefield microscopy, and at the cellular level, by confocal microscopy. Furthermore, the glucose assay was readily multiplexed with live immunofluorescence labelling to generate maps of 2-NBDG uptake across tissue regions, revealing highest uptake in T cell-dense regions. The signal was predominantly intracellular and localized to lymphocytes rather than stromal cells. Finally, we demonstrated that the assay was repeatable in the same slices, and imaged the dynamic distribution of glucose uptake in response to ex vivo T cell stimulation for the first time. We anticipate that this method will serve as a broadly applicable, user-friendly platform to quantify dynamic metabolic activities in complex tissue microenvironments.

Spatially Resolved Analytical Chemistry in Intact, Living Tissues

Tissues are an exciting frontier for bioanalytical chemistry, one in which spatial distribution is just as important as total content. Intact tissue preserves the native cellular and molecular organization and the cell-cell contacts found in vivo. Live tissue, in particular, offers the potential to analyze dynamic events in a spatially resolved manner, leading to fundamental biological insights and translational discoveries. In this Perspective, we provide a tutorial on the four fundamental challenges for the bioanalytical chemist working in living tissue samples as well as best practices for mitigating them. The challenges include (i) the complexity of the sample matrix, which contributes myriad interfering species and causes nonspecific binding of reagents; (ii) hindered delivery and mixing; (iii) the need to maintain physiological conditions; and (iv) tissue reactivity. This framework is relevant to a variety of methods for spatially resolved chemical analysis, including optical imaging, inserted sensors and probes such as electrodes, and surface analyses such as sensing arrays. The discussion focuses primarily on ex vivo tissues, though many considerations are relevant in vivo as well. Our goal is to convey the exciting potential of analytical chemistry to contribute to understanding the functions of live, intact tissues.

Transplanted Human Neural Progenitor Cells Attenuate Motor Dysfunction and Lengthen Longevity in a Rat Model of Ataxia

The spastic Han Wistar (sHW) rat serves as a model for human ataxia presenting symptoms of motor deterioration, weight loss, shortened lifespan, and Purkinje neuron loss. Past studies revealed that human neural progenitor cells (NPCs) improved ataxic symptoms at 20 d posttransplantation in sHW rats. In this study, we investigated the fate and longer-term effectiveness of these transplanted NPCs. Rats were placed into four treatment groups: an untreated normal control group (n = 10), an untreated mutant rat control (n = 10), a mutant group that received an injection of dead NPCs (n = 9), and a mutant group that received live NPCs (n = 10). Bilateral cerebellar injections containing 500,000 of either live or dead NPCs were performed on mutant sHW rats at 40 d of age. Motor activity for all mutant rats started to decline in open field testing around day 35. However, at day 45, the live NPC-treated mutants exhibited significant improvements in open field activity. Similar improvements were observed during rotarod testing and weight gain through the completion of the experiments (100 d). Immunohistochemistry revealed few surviving human NPCs in the cerebella of 80- and 100-d-old NPC-treated mutants; while cresyl violet staining revealed that live NPC-treated mutants had significantly more surviving Purkinje neurons compared to mutants that were untreated or received dead NPCs. Direct stereotactic implantation of NPCs alleviated the symptoms of ataxia, acting as a neuroprotectant, supporting future clinical applications of these NPCs in the areas of ataxia as well as other neurodegenerative diseases.

Effect of Stroke Education Pamphlets vs a 12-Minute Culturally Tailored Stroke Film on Stroke Preparedness Among Black and Hispanic Churchgoers: A Cluster Randomized Clinical Trial

Importance

Black individuals and Hispanic individuals are less likely to recognize stroke and call 911 (stroke preparedness), contributing to racial/ethnic disparities in intravenous tissue plasminogen activator use.

Objective

To evaluate the effect of culturally tailored 12-minute stroke films on stroke preparedness vs the usual care practice of distributing stroke education pamphlets.

Design, Setting, and Participants

Cluster randomized clinical trial between July 26, 2013, and August 16, 2018, with randomization of 13 black and Hispanic churches located in urban neighborhoods to intervention or usual care. In total, 883 congregants were approached, 503 expressed interest, 375 completed eligibility screening, and 312 were randomized. Sixty-three individuals were ineligible (younger than 34 years and/or did not have at least 1 traditional stroke risk factor).

Interventions

Two 12-minute stroke films on stroke preparedness for black and Hispanic audiences.

Main Outcomes and Measures

The primary outcome was the Stroke Action Test (STAT), assessed at baseline, 6 months, and 12 months.

Results

In total, 261 of 312 individuals completed the study (83.7% retention rate). Most participants were female (79.1%). The mean (SD) age of participants was 58.57 (11.66) years; 51.1% (n = 159) were non-Hispanic black, 48.9% (n = 152) were Hispanic, and 31.7% (n = 99) had low levels of education. There were no significant end-point differences for the STAT at follow-up periods. The mean (SD) baseline STAT scores were 59.05% (29.12%) correct for intervention and 58.35% (28.83%) correct for usual care. At 12 months, the mean (SD) STAT scores were 64.38% (26.39%) correct for intervention and 61.58% (28.01%) correct for usual care. Adjusted by education, a post hoc subgroup analysis revealed a mean (SE) intervention effect of 1.03% (0.44%) (P = .02) increase per month in the low-education subgroup (about a 10% increase in 12 months). In the high-education subgroup, the mean (SE) intervention effect was -0.05% (0.30%) (P = .86). Regarding percentage correct, the low-education intervention subgroup improved from 52.4% (7 of 21) to 66.7% (14 of 21) compared with the other subgroups.

Conclusions and Relevance

No difference was observed in stroke preparedness at 12 months in response to culturally tailored 12-minute stroke films or conventional stroke education pamphlets. Additional studies are required to confirm findings from a post hoc subgroup analysis that suggested a significant education effect.

Trial Registration

ClinicalTrials.gov identifier: NCT01909271.

Repeated Measures Designs and Analysis of Longitudinal Data: If at First You Do Not Succeed-Try, Try Again

Anesthesia, critical care, perioperative, and pain research often involves study designs in which the same outcome variable is repeatedly measured or observed over time on the same patients. Such repeatedly measured data are referred to as longitudinal data, and longitudinal study designs are commonly used to investigate changes in an outcome over time and to compare these changes among treatment groups. From a statistical perspective, longitudinal studies usually increase the precision of estimated treatment effects, thus increasing the power to detect such effects. Commonly used statistical techniques mostly assume independence of the observations or measurements. However, values repeatedly measured in the same individual will usually be more similar to each other than values of different individuals and ignoring the correlation between repeated measurements may lead to biased estimates as well as invalid P values and confidence intervals. Therefore, appropriate analysis of repeated-measures data requires specific statistical techniques. This tutorial reviews 3 classes of commonly used approaches for the analysis of longitudinal data. The first class uses summary statistics to condense the repeatedly measured information to a single number per subject, thus basically eliminating within-subject repeated measurements and allowing for a straightforward comparison of groups using standard statistical hypothesis tests. The second class is historically popular and comprises the repeated-measures analysis of variance type of analyses. However, strong assumptions that are seldom met in practice and low flexibility limit the usefulness of this approach. The third class comprises modern and flexible regression-based techniques that can be generalized to accommodate a wide range of outcome data including continuous, categorical, and count data. Such methods can be further divided into so-called “population-average statistical models” that focus on the specification of the mean response of the outcome estimated by generalized estimating equations, and “subject-specific models” that allow a full specification of the distribution of the outcome by using random effects to capture within-subject correlations. The choice as to which approach to choose partly depends on the aim of the research and the desired interpretation of the estimated effects (population-average versus subject-specific interpretation). This tutorial discusses aspects of the theoretical background for each technique, and with specific examples of studies published in Anesthesia & Analgesia, demonstrates how these techniques are used in practice.

Reporting and analysis of repeated measurements in preclinical animals experiments

A common feature of preclinical animal experiments is repeated measurement of the outcome, e.g., body weight measured in mice pups weekly for 20 weeks. Separate time point analysis or repeated measures analysis approaches can be used to analyze such data. Each approach requires assumptions about the underlying data and violations of these assumptions have implications for estimation of precision, and type I and type II error rates. Given the ethical responsibilities to maximize valid results obtained from animals used in research, our objective was to evaluate approaches to reporting repeated measures design used by investigators and to assess how assumptions about variation in the outcome over time impact type I and II error rates and precision of estimates. We assessed the reporting of repeated measures designs of 58 studies in preclinical animal experiments. We used simulation modelling to evaluate three approaches to statistical analysis of repeated measurement data. In particular, we assessed the impact of (a) repeated measure analysis assuming that the outcome had non-constant variation at all time points (heterogeneous variance) (b) repeated measure analysis assuming constant variation in the outcome (homogeneous variance), (c) separate ANOVA at individual time point in repeated measures designs. The evaluation of the three model fitting was based on comparing the p-values distributions, the type I and type II error rates and by implication, the shrinkage or inflation of standard error estimates from 1000 simulated dataset. Of 58 studies with repeated measures design, three provided a rationale for repeated measurement and 23 studies reported using a repeated-measures analysis approach. Of the 35 studies that did not use repeated-measures analysis, fourteen studies used only two time points to calculate weight change which potentially means collected data was not fully utilized. Other studies reported only select time points (n = 12) raising the issue of selective reporting. Simulation studies showed that an incorrect assumption about the variance structure resulted in modified error rates and precision estimates. The reporting of the validity of assumptions for repeated measurement data is very poor. The homogeneous variation assumption, which is often invalid for body weight measurements, should be confirmed prior to conducting the repeated-measures analysis using homogeneous covariance structure and adjusting the analysis using corrections or model specifications if this is not met.

Sonographic follow-up after endoscopic carpal tunnel release for severe carpal tunnel syndrome: a one-year neuroanatomical prospective observational study

BACKGROUND

Endoscopic carpal tunnel release (ECTR) has been gradually adopted for the treatment of severe carpal tunnel syndrome (CTS). However, perioperative assessment of neuroanatomical parameters of median nerve, which are important determinant of median nerve recovery, has rarely been reported. This one-year prospective study aimed to investigate the natural history of the neuroanatomical morphology of the median nerve after ECTR in severe CTS patients by high-frequency ultrasonography and assess the ability of neuroanatomical measures to quantify morphological recovery of the median nerve after ECTR.

METHODS

This study recruited 31 patients (44 wrists) with a definitive diagnosis of severe CTS and underwent ECTR operation. The edema length (EL) of median nerve from the inlet of the carpal tunnel to the proximal wrist was detected on long axis imaging plane and the anteroposterior diameter (D) and cross-sectional area (CSA) at the inlet of the carpal tunnel on short axis imaging plane were detected by high frequency ultrasound. All these metrics were detected at 3 days before surgery and at the 2nd week, 4th week, 3rd month, 6th month and 12th month after surgery separately.

RESULTS

There was no significant difference of each parameter between the 2-week postoperative (1.914 ± 0.598 cm in EL, 0.258 ± 0.039 cm in D and 0.138 ± 0.015 cm2 in CSA) and 3-days preoperative time points (P-EL =0.250; P-D = 0.125; P-CSA =0.712). From the fourth week to the third month after surgery, the parameters quickly improved. The EL (0.715 ± 0.209 cm), D (0.225 ± 0.017 cm) and CSA (0.117 ± 0.012 cm2) at the 3- month postoperative time points were more reduced than at the fourth week after surgery (P-EL < 0.001; P-D = 0.038; P-CSA =0.014). Thereafter, the neurological anatomy parameters recovered slowly. By the 12-month postoperative time points, the three parameters were neuroanatomically close to normal. Compared to the control group in D (0.213 ± 0.005 cm), there was no difference at the 12-month time point (0.214 ± 0.009 cm, P = 0.939). However, the difference in EL (0.098 ± 0.030 cm vs. 0.016 ± 0.011 cm) and CSA (0.103 ± 0.008 cm2 vs. 0.073 ± 0.005 cm2) between patients and healthy volunteers at the 12-month time point still existed (P-EL < 0.001; P-CSA < 0.001).

CONCLUSIONS

Neuroanatomical parameters were gradually improved after ECTR surgery. The best time for US follow up is at 3-month postoperative time point for patients who do not show clinical improvement, since at this time the change is the greatest for most CTS patients. This study has been registered in Chinese Clinical Trial Registry: ChiCTR-ROC-17014068 (retrospectively registered 20-12-2017).

Improving Community Stroke Preparedness in the HHS (Hip-Hop Stroke) Randomized Clinical Trial

BACKGROUND AND PURPOSE

Deficiencies in stroke preparedness cause major delays to stroke thrombolysis, particularly among economically disadvantaged minorities. We evaluated the effectiveness of a stroke preparedness intervention delivered to preadolescent urban public school children on the stroke knowledge/preparedness of their parents.

METHODS

We recruited 3070 fourth through sixth graders and 1144 parents from 22 schools into a cluster randomized trial with schools randomized to the HHS (Hip-Hop Stroke) intervention or attentional control (nutrition classes). HHS is a 3-hour culturally tailored, theory-based, multimedia stroke literacy intervention targeting school children, which systematically empowers children to share stroke information with parents. Our main outcome measures were stroke knowledge/preparedness of children and parents using validated surrogates.

RESULTS

Among children, it was estimated that 1% (95% confidence interval [CI], 0%-1%) of controls and 2% (95% CI, 1%-4%; P=0.09) of the intervention group demonstrated optimal stroke preparedness (perfect scores on the knowledge/preparedness test) at baseline, increasing to 57% (95% CI, 44%-69%) immediately after the program in the intervention group compared with 1% (95% CI, 0%-1%; P<0.001) among controls. At 3-month follow-up, 24% (95% CI, 15%-33%) of the intervention group retained optimal preparedness, compared with 2% (95% CI, 0%-3%; P<0.001) of controls. Only 3% (95% CI, 2%-4%) of parents in the intervention group could identify all 4 letters of the stroke FAST (Facial droop, Arm weakness, Speech disturbance, Time to call 911) acronym at baseline, increasing to 20% at immediate post-test (95% CI, 16%-24%) and 17% at 3-month delayed post-test (95% CI, 13%-21%; P=0.0062), with no significant changes (3% identification) among controls. Four children, all in the intervention group, called 911 for real-life stroke symptoms, in 1 case overruling a parent's wait-and-see approach.

CONCLUSIONS

HHS is an effective, intergenerational model for increasing stroke preparedness among economically disadvantaged minorities.

CLINICAL TRIAL REGISTRATION

URL: https://clinicaltrials.gov. Unique identifier: NCT01497886.

Statistical primer: performing repeated-measures analysis

Longitudinal data arise when repeated measurements are taken on the same individuals over time. Inference about between-group differences of within-subject change is usually of interest. This statistical primer for cardiothoracic and vascular surgeons aims to provide a short and practical introduction of biostatistical methods on how to analyse repeated-measures data. Several methodological approaches for analysing repeated measures will be introduced, ranging from simple approaches to advanced regression modelling. Design considerations of studies involving repeated measures are discussed, and the methods are illustrated with a data set measuring coronary sinus potassium in dogs after occlusion. Cardiothoracic and vascular surgeons should be aware of the myriad approaches available to them for analysing repeated-measures data, including the relative merits and disadvantages of each. It is important to present effective graphical displays of the data and to avoid arbitrary cross-sectional statistical comparisons.

Heart rate variability metrics for fine-grained stress level assessment

BACKGROUND AND OBJECTIVES

In spite of the existence of a multitude of techniques that allow the estimation of stress from physiological indexes, its fine-grained assessment is still a challenge for biomedical engineering. The short-term assessment of stress condition overcomes the limits to stress characterization with long blocks of time and allows to evaluate the behaviour change in real-world settings and also the stress level dynamics. The aim of the present study was to evaluate time and frequency domain and nonlinear heart rate variability (HRV) metrics for stress level assessment using a short-time window.

METHODS

The electrocardiogram (ECG) signal from 14 volunteers was monitored using the Vital Jacket^TM while they performed the Trier Social Stress Test (TSST) which is a standardized stress-inducing protocol. Window lengths from 220 s to 50 s for HRV analysis were tested in order to evaluate which metrics could be used to monitor stress levels in an almost continuous way.

RESULTS

A sub-set of HRV metrics (AVNN, rMSSD, SDNN and pNN20) showed consistent differences between stress and non-stress phases, and showed to be reliable parameters for the assessment of stress levels in short-term analysis.

CONCLUSIONS

The AVNN metric, using 50 s of window length analysis, showed that it is the most reliable metric to recognize stress level across the four phases of TSST and allows a fine-grained analysis of stress effect as an index of psychological stress and provides an insight into the reaction of the autonomic nervous system to stress.

Bayesian hierarchical piecewise regression models: a tool to detect trajectory divergence between groups in long-term observational studies

Background

Bayesian hierarchical piecewise regression (BHPR) modeling has not been previously formulated to detect and characterise the mechanism of trajectory divergence between groups of participants that have longitudinal responses with distinct developmental phases. These models are useful when participants in a prospective cohort study are grouped according to a distal dichotomous health outcome. Indeed, a refined understanding of how deleterious risk factor profiles develop across the life-course may help inform early-life interventions. Previous techniques to determine between-group differences in risk factors at each age may result in biased estimate of the age at divergence.

Methods

We demonstrate the use of Bayesian hierarchical piecewise regression (BHPR) to generate a point estimate and credible interval for the age at which trajectories diverge between groups for continuous outcome measures that exhibit non-linear within-person response profiles over time. We illustrate our approach by modeling the divergence in childhood-to-adulthood body mass index (BMI) trajectories between two groups of adults with/without type 2 diabetes mellitus (T2DM) in the Cardiovascular Risk in Young Finns Study (YFS).

Results

Using the proposed BHPR approach, we estimated the BMI profiles of participants with T2DM diverged from healthy participants at age 16 years for males (95% credible interval (CI):13.5–18 years) and 21 years for females (95% CI: 19.5–23 years). These data suggest that a critical window for weight management intervention in preventing T2DM might exist before the age when BMI growth rate is naturally expected to decrease. Simulation showed that when using pairwise comparison of least-square means from categorical mixed models, smaller sample sizes tended to conclude a later age of divergence. In contrast, the point estimate of the divergence time is not biased by sample size when using the proposed BHPR method.

Conclusions

BHPR is a powerful analytic tool to model long-term non-linear longitudinal outcomes, enabling the identification of the age at which risk factor trajectories diverge between groups of participants. The method is suitable for the analysis of unbalanced longitudinal data, with only a limited number of repeated measures per participants and where the time-related outcome is typically marked by transitional changes or by distinct phases of change over time.

Electronic supplementary material

The online version of this article (doi:10.1186/s12874-017-0358-9) contains supplementary material, which is available to authorized users.

Physical Properties and Effect in a Battery of Safety Pharmacology Models for Three Structurally Distinct Enteric Polymers Employed as Spray-Dried Dispersion Carriers

Establishing a wide therapeutic index (TI) for pre-clinical safety is important during lead optimization (LO) in research, prior to clinical development, although is often limited by a molecules physiochemical characteristics. Recent advances in the application of the innovative vibrating mesh spray-drying technology to prepare amorphous solid dispersions may offer an opportunity to achieve high plasma concentrations of poorly soluble NCEs to enable testing and establishment of a wide TI in safety pharmacology studies. While some of the amorphous solid dispersion carriers are generally recognized as safe for clinical use, whether they are sufficiently benign to enable in vivo pharmacology studies has not been sufficiently demonstrated. Thus, the physical properties, and effect in a battery of in vivo safety pharmacology models, were assessed in three classes of polymers employed as spray-dried dispersion carriers. The polymers (HPMC-AS, Eudragit, PVAP) displayed low affinity with acetone/methanol, suitable for solvent-based spray drying. The water sorption of the polymers was moderate, and the degree of hysteresis of HPMC-AS was smaller than Eudragit and PVAP indicating the intermolecular interaction of water-cellulose molecules is weaker than water-acrylate or water-polyvinyl molecules. The polymer particles were well-suspended without aggregation with a mean particle size less than 3 μm in an aqueous vehicle. When tested in conscious Wistar Han rats in safety pharmacology models (n = 6–8/dose/polymer) investigating effects on CNS, gastrointestinal, and cardiovascular function, no liabilities were identified at any dose tested (30–300 mg/kg PO, suspension). In brief, the polymers had no effect in a modified Irwin test that included observational and evoked endpoints related to stereotypies, excitation, sedation, pain/anesthesia, autonomic balance, reflexes, and others. No effect of the polymers on gastric emptying or intestinal transit was observed when measured using a barium sulfate tracer material. Finally, in telemetry-instrumented rats the polymers had no effect on acute or 24-h mean blood pressure and heart rate values at doses up to 300 mg/kg. Thus, the properties of the three enteric polymers are appropriate as spray-dried dispersion carriers and were benign in a battery of safety pharmacology studies, demonstrating their applicability to enable in vivo safety pharmacology profiling of poorly soluble molecules during LO.

Intervention to Improve Quality of life for African-AmericaN lupus patients (IQAN): study protocol for a randomized controlled trial of a unique a la carte intervention approach to self-management of lupus in African Americans

BACKGROUND

Systemic Lupus Erythematosus (lupus) is a chronic autoimmune disease that can impact any organ system and result in life-threatening complications. African-Americans are at increased risk for morbidity and mortality from lupus. Self-management programs have demonstrated significant improvements in health distress, self-reported global health, and activity limitation among people with lupus. Despite benefits, arthritis self-management education has reached only a limited number of people. Self-selection of program could improve such trends. The aim of the current study is to test a novel intervention to improve quality of life, decrease indicators of depression, and reduce perceived and biological indicators of stress in African-American lupus patients in South Carolina.

METHODS/DESIGN

In a three armed randomized, wait list controlled trial, we will evaluate the effectiveness of a patient-centered 'a-la-carte' approach that offers subjects a variety of modes of interaction from which they can choose as many or few as they wish, compared to a 'set menu' approach and usual care. This unique 'a-la-carte' self-management program will be offered to 50 African-American lupus patients participating in a longitudinal observational web-based SLE Database at the Medical University of South Carolina. Each individualized intervention plan will include 1-4 options, including a mail-delivered arthritis kit, addition and access to an online message board, participation in a support group, and enrollment in a local self-management program. A 'set menu' control group of 50 lupus patients will be offered a standardized chronic disease self-management program only, and a control group of 50 lupus patients will receive usual care. Outcomes will include changes in (a) health behaviors, (b) health status, (c) health care utilization, and (d) biological markers (urinary catecholamines).

DISCUSSION

Such a culturally sensitive educational intervention which includes self-selection of program components has the potential to improve disparate trends in quality of life, disease activity, depression, and stress among African-American lupus patients, as better outcomes have been documented when participants are able to choose/dictate the content and/or pace of the respective treatment/intervention program. Since there is currently no "gold standard" self-management program specifically for lupus, this project may have a considerable impact on future research and policy decisions.

TRIAL REGISTRATION

NCT01837875 ; April 18, 2013.

Statistical and data reporting guidelines for the European Journal of Cardio-Thoracic Surgery and the Interactive CardioVascular and Thoracic Surgery

As part of the peer review process for the European Journal of Cardio-Thoracic Surgery (EJCTS) and the Interactive CardioVascular and Thoracic Surgery (ICVTS), a statistician reviews any manuscript that includes a statistical analysis. To facilitate authors considering submitting a manuscript and to make it clearer about the expectations of the statistical reviewers, we present up-to-date guidelines for authors on statistical and data reporting specifically in these journals. The number of statistical methods used in the cardiothoracic literature is vast, as are the ways in which data are presented. Therefore, we narrow the scope of these guidelines to cover the most common applications submitted to the EJCTS and ICVTS, focusing in particular on those that the statistical reviewers most frequently comment on.

A genetically-encoded YFP sensor with enhanced chloride sensitivity, photostability and reduced ph interference demonstrates augmented transmembrane chloride movement by gerbil prestin (SLC26a5)

BACKGROUND

Chloride is the major anion in cells, with many diseases arising from disordered Cl- regulation. For the non-invasive investigation of Cl- flux, YFP-H148Q and its derivatives chameleon and Cl-Sensor previously were introduced as genetically encoded chloride indicators. Neither the Cl- sensitivity nor the pH-susceptibility of these modifications to YFP is optimal for precise measurements of Cl- under physiological conditions. Furthermore, the relatively poor photostability of YFP derivatives hinders their application for dynamic and quantitative Cl- measurements. Dynamic and accurate measurement of physiological concentrations of chloride would significantly affect our ability to study effects of chloride on cellular events.

METHODOLOGY/PRINCIPAL FINDINGS

In this study, we developed a series of YFP derivatives to remove pH interference, increase photostability and enhance chloride sensitivity. The final product, EYFP-F46L/Q69K/H148Q/I152L/V163S/S175G/S205V/A206K (monomeric Cl-YFP), has a chloride Kd of 14 mM and pKa of 5.9. The bleach time constant of 175 seconds is over 15-fold greater than wild-type EYFP. We have used the sensor fused to the transmembrane protein prestin (gerbil prestin, SLC26a5), and shown for the first time physiological (mM) chloride flux in HEK cells expressing this protein. This modified fluorescent protein will facilitate investigations of dynamics of chloride ions and their mediation of cell function.

CONCLUSIONS

Modifications to YFP (EYFP-F46L/Q69K/H148Q/I152L/V163S/S175G/S205V/A206K (monomeric Cl-YFP) results in a photostable fluorescent protein that allows measurement of physiological changes in chloride concentration while remaining minimally affected by changes in pH.

Comparison of Non-invasive and Invasive Arterial Blood Pressure Measurement for Assessment of Dynamic Cerebral Autoregulation

BACKGROUND

There is a growing interest in measuring cerebral autoregulation in patients with acute brain injury. Non-invasive finger photo-plethysmography (Finapres) is the method of choice to relate arterial blood pressure to changes in cerebral blood flow. Among acutely ill patients, however, peripheral vasoconstriction often limits the use of Finapres requiring direct intravascular blood pressure measurement. We evaluated how these two different forms of blood pressure monitoring affect the parameters of dynamic cerebral autoregulation (DCA).

METHODS

We performed 37 simultaneous recordings of BP and cerebral blood flow velocity in 15 patients with acute brain injury. DCA was estimated in the frequency domain using transfer function analysis to calculate phase shift, gain, and coherence. In addition the mean velocity index (Mx) was calculated for assessment of DCA in the time domain.

RESULTS

The mean patient age was 58.1 ± 15.9 years, 80 % (n = 12) were women. We found good inter-method agreement between Finapres and direct intravascular measurement using Bland-Altman and correlation analyses. Finapres gives higher values for the efficiency of dynamic CA compared with values derived from radial artery catheter, as indicated by biases in the phase (26.3 ± 11.6° vs. 21.7 ± 10.5°, p = 0.001) and Mx (0.571 ± 0.137 vs. 0.649 ± 0.128, p < 0.001). Gain in the low frequency range did not significantly differ between the two arterial blood pressure methods. The average coherence between CBFV and ABP was higher when BP was measured with arterial catheter for frequencies above 0.05 Hz (0.8 vs. 0.73, p < 0.001).

CONCLUSION

Overall, both methods yield similar results and can be used for the assessment of DCA. However, there was a small but significant difference for both mean Mx and phase shift, which would need to be adjusted for during monitoring of patients when using both methods. When available, invasive arterial blood pressure monitoring may improve accuracy and thus should be the preferred method for DCA assessment in the ICU.

Hypertrophy signaling pathways in experimental chronic aortic regurgitation

The development of left ventricular hypertrophy and dysfunction in aortic regurgitation (AR) has only been sparsely studied experimentally. In a new model of chronic AR in rats, we examined activation of molecular pathways involved in myocardial hypertrophy. Chronic AR was produced by damaging one or two valve cusps, resulting in eccentric remodeling and left ventricular dysfunction, with no increase in overall fibrosis. Western blotting showed increased activation of Akt and p38 at 12 weeks and of c-Jun amino-terminal kinase at 2 weeks, decreased activation of extracellular regulated kinase 5 at both 2 and 12 weeks, while activation of calcium/calmodulin-dependent protein kinase II and extracellular regulated kinase 1/2 was unchanged. Expression of calcineurin and ANF was also unchanged. Eccentric hypertrophy and early cardiac dysfunction in experimental AR are associated with a pattern of activation of intracellular pathways different from that seen with pathological hypertrophy in pressure overload, and more similar to that associated with benign physiological hypertrophy.

Sample size requirements in trials using repeated measurements and the impact of trial design

OBJECTIVE

Sample size calculations for clinical trials generally use expected changes between groups, and variances obtained from the literature. However, this approach neglects the impact of differences in trial design. We studied the effects of variations in trial design on the required sample size.

METHODS

Data were used from the METEOR (Measuring Effects on Intima-Media Thickness: an Evaluation of Rosuvastatin) trial in which carotid intima-media thickness (CIMT) measurements were performed twice at baseline, at 6, 12 and 18 months, and twice at the end of 2-year study treatment. A sample size formula for continuous outcome measures that incorporates between- and within-individual variance components was used to evaluate the impact of differences in the length of follow-up, and the number of CIMT examinations.

RESULTS

Trial designs with a shorter duration of follow-up have increased within-individual variance and require larger sample sizes to detect the same treatment effect. Reduction in the number of examinations within a trial with a given duration, i.e. by using single rather than duplicate baseline and end-of-study scans or by not performing intermediate scans, also increased the required sample size to maintain the same power.

CONCLUSION

A longer trial duration and/or more frequent examinations within a trial which has repeated measures of an outcome variable substantially increase study power and reduce the required sample size. In situations where the costs of recruiting, retaining and examining individual participants are known, the sample size, study length and number of examinations can be balanced to optimize the trial design relative to costs or other study objectives.

Longitudinal myocardial contribution to peak systolic flow and stroke volume in the neonatal heart

Systolic longitudinal myocardial function is important for cardiac ejection. Data describing hemodynamic determinants and the time course of myocardial longitudinal contraction as measured by tissue Doppler are lacking. Ten newborn pigs were used for invasive hemodynamic investigation. Tissue Doppler assessment of the lateral part of the mitral valve annulus during systole was performed during pharmacological modulation of inotropy, cardiac pacing, and modulations of loading conditions. The strongest association was found between peak systolic velocity (S') and peak systolic flow (PSF) and end-systolic pressure (ESP), respectively (β = 0.09 cm/mL, p < 0.001 and β = -0.07 cm/mL, p = 0.003). Displacement (D) was mostly influenced by stroke volume (SV) (β = 0.05 cm/mL, p < 0.001). Ejection time, SV, ESP, maximum first derivative of pressure (dP/dtmax), and PSF were all associated with S' and D under different states of hemodynamic modulation; however, the ratio between PSF and S', SV, and D were stable during hemodynamic modulations. Normalized cross correlations indicate that S' and D follow the same trajectory as flow and SV, respectively. In conclusion, this study provides validity of accounting systolic D in the long axis as the longitudinal contribution to SV and peak systolic tissue velocity as the longitudinal contribution to PSF.

Simvastatin as a treatment for pulmonary hypertension trial

RATIONALE

In animal models of pulmonary hypertension, simvastatin has been shown to reduce pulmonary artery pressure and induce regression of associated right ventricular (RV) hypertrophy.

OBJECTIVES

To assess the therapeutic value of simvastatin in patients with pulmonary arterial hypertension (PAH).

METHODS

Forty-two patients with PAH were randomized to receive either simvastatin (80 mg/d) or placebo in addition to current care for 6 months, and thereafter offered open-label simvastatin. The primary outcome was change in RV mass, assessed by cardiac magnetic resonance (CMR).

MEASUREMENTS AND MAIN RESULTS

At 6 months, RV mass decreased by 5.2 +/- 11 g in the statin group (P = 0.045) and increased 3.9 +/- 14 g in the placebo group. The treatment effect was -9.1 g (P = 0.028). N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels decreased significantly in the statin group (-75 +/- 167 fmol/ml; P = 0.02) but not the placebo group (49 +/- 224 fmol/ml; P = 0.43; overall treatment effect -124 fmol/ml; P = 0.041). There were no significant changes in other outcome measures (including 6-minute walk test, cardiac index, and circulating cytokines). From 6 to 12 months, both RV mass and NT-proBNP increased toward baseline values in 16 patients on active treatment who continued with simvastatin but remained stable in 18 patients who switched from placebo to simvastatin. Two patients required a reduction in dose but not cessation of simvastatin.

CONCLUSIONS

Simvastatin added to conventional therapy produces a small and transient early reduction in RV mass and NT-proBNP levels in patients with PAH, but this is not sustained over 12 months.

A randomized trial comparing telemedicine case management with usual care in older, ethnically diverse, medically underserved patients with diabetes mellitus: 5 year results of the IDEATel study

CONTEXT Telemedicine is a promising but largely unproven technology for providing case management services to patients with chronic conditions and lower access to care. OBJECTIVES To examine the effectiveness of a telemedicine intervention to achieve clinical management goals in older, ethnically diverse, medically underserved patients with diabetes. DESIGN, Setting, and Patients A randomized controlled trial was conducted, comparing telemedicine case management to usual care, with blinded outcome evaluation, in 1,665 Medicare recipients with diabetes, aged >/= 55 years, residing in federally designated medically underserved areas of New York State. Interventions Home telemedicine unit with nurse case management versus usual care. Main Outcome Measures The primary endpoints assessed over 5 years of follow-up were hemoglobin A1c (HgbA1c), low density lipoprotein (LDL) cholesterol, and blood pressure levels. RESULTS Intention-to-treat mixed models showed that telemedicine achieved net overall reductions over five years of follow-up in the primary endpoints (HgbA1c, p = 0.001; LDL, p < 0.001; systolic and diastolic blood pressure, p = 0.024; p < 0.001). Estimated differences (95% CI) in year 5 were 0.29 (0.12, 0.46)% for HgbA1c, 3.84 (-0.08, 7.77) mg/dL for LDL cholesterol, and 4.32 (1.93, 6.72) mm Hg for systolic and 2.64 (1.53, 3.74) mm Hg for diastolic blood pressure. There were 176 deaths in the intervention group and 169 in the usual care group (hazard ratio 1.01 [0.82, 1.24]). CONCLUSIONS Telemedicine case management resulted in net improvements in HgbA1c, LDL-cholesterol and blood pressure levels over 5 years in medically underserved Medicare beneficiaries. Mortality was not different between the groups, although power was limited. Trial Registration http://clinicaltrials.gov Identifier: NCT00271739.

Burst Stimulation Improves Hemodynamics During Resuscitation After Prolonged Ventricular Fibrillation

Background— Although return of spontaneous circulation is frequently achieved during resuscitation for sudden cardiac arrest, systolic blood pressure can then decrease, requiring additional myocardial support. Previous studies have shown that a series of 1-ms electric pulses delivered through the defibrillation patches during ventricular fibrillation can stimulate the autonomic nervous system to increase myocardial function after defibrillation. We hypothesized that a similar series of electric pulses could increase myocardial function and blood pressure during the early postresuscitation period.

Methods and Results— Six swine were studied that underwent 6 to 7 minutes of fibrillation. Each animal received 5, 10, 15, or 20 pulse packets consisting of six 10-A, 1-ms pulses every 3 to 4 s in random order whenever systolic blood pressure became <50 mm Hg. All 4 sets of pulse packets were delivered to each animal. Systolic blood pressure and cardiac function (left ventricular+dP/dt) were increased to above prestimulation levels or above by all 4 sets of pulse packets. The increases were significantly greater for the longer than the shorter number of pulse packets. The mean�SD duration of the time that the systolic pressure remained above 50 mm Hg after pulse delivery was 4.2�2.5 minutes.

Conclusions— Electric stimulation during regular rhythm after prolonged ventricular fibrillation and resuscitation can increase blood pressure and cardiac function to above prestimulation levels.