Characterizing the Patients, Hospitals, and Data Quality of the eICU Collaborative Research Database.

OBJECTIVES: The eICU Collaborative Research Database is a publicly available repository of granular data from more than 200,000 ICU admissions. The quantity and variety of its entries hold promise for observational critical care research. We sought to understand better the data available within this resource to guide its future use. DESIGN: We conducted a descriptive analysis of the eICU Collaborative Research Database, including patient, practitioner, and hospital characteristics. We investigated the completeness of demographic and hospital data, as well as those values required to calculate an Acute Physiology and Chronic Health Evaluation score. We also assessed the rates of ventilation, intubation, and dialysis, and looked for potential errors in the vital sign data. SETTING: American ICUs that participated in the Philips Healthcare eICU program between 2014 and 2015. PATIENTS: A total of 139,367 individuals who were admitted to one of the 335 participating ICUs between 2014 and 2015. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Most encounters were from small- and medium-sized hospitals, and managed by nonintensivists. The median ICU length of stay was 1.57 days (interquartile range, 0.82-2.97 d). The median Acute Physiology and Chronic Health Evaluation IV-predicted ICU mortality was 2.2%, with an observed mortality of 5.4%. Rates of ventilation (20-33%), intubation (15-24%), and dialysis (3-5%) varied according to the query method used. Most vital sign readings fell into realistic ranges, with manually curated data less likely to contain implausible results than automatically entered data. CONCLUSIONS: Data in the eICU Collaborative Research Database are for the most part complete and plausible. Some ambiguity exists in determining which encounters are associated with various interventions, most notably mechanical ventilation. Caution is warranted in extrapolating findings from the eICU Collaborative Research Database to larger ICUs with higher acuity.

Is Mortality a Useful Primary End Point for Critical Care Trials?

Mortality has long been used as a primary end point for randomized controlled trials in critical care. Recently, a plurality of trials targeting mortality end points as their primary outcome has failed to detect a difference between study arms. While there are a number of reasons for the preponderance of such neutral trials, the use of mortality as an outcome is one important consideration. We explore some of the reasons why such trials may be biased toward a neutral result, as well as reasons to consider alternative end points that are better coupled to the expected therapeutic effect. We also discuss to what extent mortality as a binary outcome is patient-important in the ICU.

Insights Into a "Negative" ICU Trial Derived From Gene Expression Profiling.

OBJECTIVES: Randomized controlled trials in the ICU often fail to show differences in endpoints between groups. We sought to explore reasons for this at a molecular level by analyzing transcriptomic data from a recent negative trial. Our objectives were to determine if randomization successfully balanced transcriptomic features between groups, to assess transcriptomic heterogeneity among the study subjects included, and to determine if the study drug had any effect at the gene expression level. DESIGN: Bioinformatics analysis of transcriptomic and clinical data collected in the course of a randomized controlled trial. SETTING: Tertiary academic mixed medical-surgical ICU. PATIENTS: Adult, critically ill patients expected to require invasive mechanical ventilation more than 48 hours. INTERVENTIONS: Lactoferrin or placebo delivered enterally and via an oral swab for up to 28 days. MEASUREMENTS AND MAIN RESULTS: We found no major imbalances in transcriptomic features between groups. Unsupervised analysis did not reveal distinct clusters among patients at the time of enrollment. There were marked differences in gene expression between early and later time points. Patients in the lactoferrin group showed changes in the expression of genes associated with immune pathways known to be associated with lactoferrin. CONCLUSIONS: In this clinical trial, transcriptomic data provided a useful complement to clinical data, suggesting that the reasons for the negative result were less likely related to the biological efficacy of the study drug, and may instead have been related to poor sensitivity of the clinical outcomes. In larger studies, transcriptomics may also prove useful in predicting response to treatment.

Traumatic Pulmonary Hypertension Secondary to Arteriovenous Fistula and Remote Gunshot Wound.

Pulmonary hypertension is a known complication of high-flow arteriovenous fistulas (AVFs). We present a case of a 58-year-old man who sustained a gunshot wound 6.5 years before presentation for worsening pulmonary hypertension (PH). After diagnostic workup, the PH was attributed to a gunshot-related AVF. Exercise capacity and echocardiographic parameters improved after successful ligation of the AVF. This case highlights a rare and correctable cause of PH that requires careful investigation and multidisciplinary expertise for treatment.

Validation of diagnostic gene sets to identify critically ill patients with sepsis.

PURPOSE: Gene expression diagnostics have been proposed to identify critically ill patients with sepsis. Three expression-based scores have been developed, but have not been compared in a prospective validation. We sought to validate these scores using an independent dataset and analysis. METHODS: We generated gene expression profiles from 61 critically ill patients. We validated the performance of 3 expression-based sepsis scores including 1) the Sepsis MetaScore (SMS); 2) the SeptiCyte™ Lab; and 3) the FAIM3:PLAC8 ratio. Sepsis was identified as the presence of definite, probable, or possible infection in the setting of organ dysfunction (SOFA score ≥ 2). RESULTS: For all 3 models, scores were significantly different between patients with and without sepsis. Discrimination was highest for the SMS (area under the receiver operating characteristics curve [AUROC 0.80 [95% CI 0.67-0.92]), with greater confidence in the presence of infection resulting in better model performance (max AUROC 0.93 [0.87-1.0]). CONCLUSIONS: All three scores distinguished septic from non-septic ICU patients, with the SMS showing the best performance overall in our cohort. Our results suggest that models developed from the co-analysis of multiple cohorts are more generalizable. Further work is needed to identify expression-based biomarkers of response to specific therapies.

Tandem reporter assay for myristoylated proteins post-translationally (TRAMPP) identifies novel substrates for post-translational myristoylation: PKCε, a case study.

Myristoylation, the addition of a 14-carbon fatty acid to the N-terminal glycine of a protein, is key to protein-membrane and protein-protein interactions. Typically, myristoylation occurs cotranslationally; however, post-translational myristoylation of caspase-cleaved proteins is now emerging as a well-established protein modification and as a novel regulator of apoptosis. To identify additional post-translationally myristoylated proteins, we engineered a plasmid vector encoding for a caspase-cleavable reporter protein named tandem reporter assay for myristoylation of proteins post-translationally (TRAMPP). pTRAMPP consists of tdTomato-DEVD-"test myristoylation sequence"-enhanced green fluorescent protein (EGFP). After induction of apoptosis, the reporter protein is cleaved by caspases, which frees a new N-terminal glycine residue attached to EGFP that can be myristoylated. We used pTRAMPP in appropriately transfected cells to identify 7 post-translationally myristoylated proteins. First, we confirmed the post-translational myristoylation of two previously identified putative substrates, cytoplasmic dynein intermediate chain 2A and PKCε (ctPKCε), and identified 5 more caspase-cleaved potential substrates for myristoylation that include the antiapoptotic regulator of apoptosis, Mcl-1, and the causative agent of Huntington's disease, huntingtin protein. Further investigation revealed that post-translationally myristoylated ctPKCε localized to membranes and increased Erk signaling and degradation of the proapoptotic protein Bim, which prevented a significant loss of mitochondrial potential of 17% over nonmyristoylated ctPKCε in HeLa cells in the presence of apoptotic stimuli. Taken together, these findings suggest a possible antiapoptotic role for post-translationally myristoylated caspase-cleaved ctPKCε.

Role of pri-miRNA tertiary structure in miR-17~92 miRNA biogenesis.

MicroRNAs (miRNAs) regulate gene expression in a variety of biological pathways such as development and tumourigenesis. miRNAs are initially expressed as long primary transcripts (pri-miRNAs) that undergo sequential processing by Drosha and then Dicer to yield mature miRNAs. miR-17~92 is a miRNA cluster that encodes 6 miRNAs and while it is essential for development it also has reported oncogenic activity. To date, the role of RNA structure in miRNA biogenesis has only been considered in terms of the secondary structural elements required for processing of pri-miRNAs by Drosha. Here we report that the miR-17~92 cluster has a compact globular tertiary structure where miRNAs internalized within the core of the folded structure are processed less efficiently than miRNAs on the surface of the structure. Increased miR-92 expression resulting from disruption of the compact miR-17~92 structure results in increased repression of integrin α5 mRNA, a known target of miR-92a. In summary, we describe the first example of pri-miRNA structure modulating differential expression of constituent miRNAs.