Chikungunya virus (CHIKV) is an arthritogenic alphavirus that acutely causes fever as well as severe joint and muscle pain. Chronic musculoskeletal pain persists in a substantial fraction of patients ...for months to years after the initial infection, yet we still have a poor understanding of what promotes chronic disease. While replicating virus has not been detected in joint-associated tissues of patients with persistent arthritis nor in various animal models at convalescent time points, viral RNA is detected months after acute infection. To identify the cells that might contribute to pathogenesis during this chronic phase, we developed a recombinant CHIKV that expresses Cre recombinase (CHIKV-3'-Cre). CHIKV-3'-Cre replicated in myoblasts and fibroblasts, and it induced arthritis during the acute phase in mice. Importantly, it also induced chronic disease, including persistent viral RNA and chronic myositis and synovitis similar to wild-type virus. CHIKV-3'-Cre infection of tdTomato reporter mice resulted in a population of tdTomato+ cells that persisted for at least 112 days. Immunofluorescence and flow cytometric profiling revealed that these tdTomato+ cells predominantly were myofibers and dermal and muscle fibroblasts. Treatment with an antibody against Mxra8, a recently defined host receptor for CHIKV, reduced the number of tdTomato+ cells in the chronic phase and diminished the levels of chronic viral RNA, implicating these tdTomato+ cells as the reservoir of chronic viral RNA. Finally, isolation and flow cytometry-based sorting of the tdTomato+ fibroblasts from the skin and ankle and analysis for viral RNA revealed that the tdTomato+ cells harbor most of the persistent CHIKV RNA at chronic time points. Therefore, this CHIKV-3'-Cre and tdTomato reporter mouse system identifies the cells that survive CHIKV infection in vivo and are enriched for persistent CHIKV RNA. This model represents a useful tool for studying CHIKV pathogenesis in the acute and chronic stages of disease.
Type I interferons (IFNs) are key mediators of the innate immune response. Although members of this family of cytokines signal through a single shared receptor, biochemical and functional variation ...exists in response to different IFN subtypes. While previous work has demonstrated that type I IFNs are essential to control infection by chikungunya virus (CHIKV), a globally emerging alphavirus, the contributions of individual IFN subtypes remain undefined. To address this question, we evaluated CHIKV pathogenesis in mice lacking IFN-β (IFN-β knockout IFN-β-KO mice or mice treated with an IFN-β-blocking antibody) or IFN-α (IFN regulatory factor 7 knockout IRF7-KO mice or mice treated with a pan-IFN-α-blocking antibody). Mice lacking either IFN-α or IFN-β developed severe clinical disease following infection with CHIKV, with a marked increase in foot swelling compared to wild-type mice. Virological analysis revealed that mice lacking IFN-α sustained elevated infection in the infected ankle and in distant tissues. In contrast, IFN-β-KO mice displayed minimal differences in viral burdens within the ankle or at distal sites and instead had an altered cellular immune response. Mice lacking IFN-β had increased neutrophil infiltration into musculoskeletal tissues, and depletion of neutrophils in IFN-β-KO but not IRF7-KO mice mitigated musculoskeletal disease caused by CHIKV. Our findings suggest disparate roles for the IFN subtypes during CHIKV infection, with IFN-α limiting early viral replication and dissemination and IFN-β modulating neutrophil-mediated inflammation.
Type I interferons (IFNs) possess a range of biological activity and protect against a number of viruses, including alphaviruses. Despite signaling through a shared receptor, there are established biochemical and functional differences among the IFN subtypes. The significance of our research is in demonstrating that IFN-α and IFN-β both have protective roles during acute chikungunya virus (CHIKV) infection but do so by distinct mechanisms. IFN-α limits CHIKV replication and dissemination, whereas IFN-β protects from CHIKV pathogenesis by limiting inflammation mediated by neutrophils. Our findings support the premise that the IFN subtypes have distinct biological activities in the antiviral response.
The optimal oxygen saturation (SpO2) target for extremely preterm infants is unknown.
To systematically review evidence evaluating the effect of restricted vs liberal oxygen exposure on morbidity and ...mortality in extremely preterm infants.
MEDLINE, PubMed, CENTRAL, and CINAHL databases from their inception to March 31, 2014, and abstracts submitted to Pediatric Academic Societies from 2000 to 2014.
All published randomized trials evaluating the effect of restricted (SpO2, 85%-89%) vs liberal (SpO2, 91%-95%) oxygen exposure in preterm infants (<28 weeks' gestation at birth).
All meta-analyses were performed using Review Manager 5.2. The Cochrane risk-of-bias tool was used to assess study quality. The summary of the findings and the level of confidence in the estimate of effect were assessed using GRADEpro. Treatment effect was analyzed using a random-effects model.
Death before hospital discharge, death or severe disability before 24 months, death before 24 months, neurodevelopmental outcomes, hearing loss, bronchopulmonary dysplasia, necrotizing enterocolitis, and severe retinopathy of prematurity.
Five trials were included in the final synthesis. These studies had a similar design with a prespecified composite outcome of death/disability at 18 to 24 months corrected for prematurity; however, this outcome has not been reported for 2 of the 5 trials. There was no difference in the outcome of death/disability before 24 months (risk ratio RR, 1.02 95% CI, 0.92-1.14). Mortality before 24 months was not different (RR, 1.13 95% CI, 0.97-1.33); however, a significant increase in mortality before hospital discharge was found in the restricted oxygen group (RR, 1.18 95% CI, 1.03-1.36). The rates of bronchopulmonary dysplasia, neurodevelopmental outcomes, hearing loss, and retinopathy of prematurity were similar between the 2 groups. Necrotizing enterocolitis occurred more frequently in infants on restricted oxygen (RR, 1.24 95% CI, 1.05-1.47). Using the Grades of Recommendation, Assessment, Development, and Evaluation (GRADE) criteria, we found that the quality of evidence for these outcomes was moderate to low.
Although infants cared for with a liberal oxygen target had significantly lower mortality before hospital discharge than infants cared for with a restricted oxygen target, the quality of evidence for this estimate of effect is low. Necrotizing enterocolitis occurred less frequently in the liberal oxygen group. We found no significant differences in death or disability at 24 months, bronchopulmonary dysplasia, retinopathy of prematurity, neurodevelopmental outcomes, or hearing loss at 24 months.
In clinical trials it is not uncommon to face a multiple testing problem which can have an impact on both type I and type II error rates, leading to inappropriate interpretation of trial results. ...Multiplicity issues may need to be considered at the design, analysis and interpretation stages of a trial. The proportion of trial reports not adequately correcting for multiple testing remains substantial. The purpose of this article is to provide an introduction to multiple testing issues in clinical trials, and to reduce confusion around the need for multiplicity adjustments. We use a tutorial, question-and-answer approach to address the key issues of why, when and how to consider multiplicity adjustments in trials. We summarize the relevant circumstances under which multiplicity adjustments ought to be considered, as well as options for carrying out multiplicity adjustments in terms of trial design factors including Population, Intervention/Comparison, Outcome, Time frame and Analysis (PICOTA). Results are presented in an easy-to-use table and flow diagrams. Confusion about multiplicity issues can be reduced or avoided by considering the potential impact of multiplicity on type I and II errors and, if necessary pre-specifying statistical approaches to either avoid or adjust for multiplicity in the trial protocol or analysis plan.
Systematic reviewer authors intending to include all randomized participants in their meta-analyses need to make assumptions about the outcomes of participants with missing data.
The objective of ...this paper is to provide systematic reviewer authors with a relatively simple guidance for addressing dichotomous data for participants excluded from analyses of randomized trials.
This guide is based on a review of the Cochrane handbook and published methodological research. The guide deals with participants excluded from the analysis who were considered 'non-adherent to the protocol' but for whom data are available, and participants with missing data.
Systematic reviewer authors should include data from 'non-adherent' participants excluded from the primary study authors' analysis but for whom data are available. For missing, unavailable participant data, authors may conduct a complete case analysis (excluding those with missing data) as the primary analysis. Alternatively, they may conduct a primary analysis that makes plausible assumptions about the outcomes of participants with missing data. When the primary analysis suggests important benefit, sensitivity meta-analyses using relatively extreme assumptions that may vary in plausibility can inform the extent to which risk of bias impacts the confidence in the results of the primary analysis. The more plausible assumptions draw on the outcome event rates within the trial or in all trials included in the meta-analysis. The proposed guide does not take into account the uncertainty associated with assumed events.
This guide proposes methods for handling participants excluded from analyses of randomized trials. These methods can help in establishing the extent to which risk of bias impacts meta-analysis results.
Fresh red cells may improve outcomes in critically ill patients by enhancing oxygen delivery while minimizing the risks of toxic effects from cellular changes and the accumulation of bioactive ...materials in blood components during prolonged storage.
In this multicenter, randomized, blinded trial, we assigned critically ill adults to receive either red cells that had been stored for less than 8 days or standard-issue red cells (the oldest compatible units available in the blood bank). The primary outcome measure was 90-day mortality.
Between March 2009 and May 2014, at 64 centers in Canada and Europe, 1211 patients were assigned to receive fresh red cells (fresh-blood group) and 1219 patients were assigned to receive standard-issue red cells (standard-blood group). Red cells were stored a mean (±SD) of 6.1±4.9 days in the fresh-blood group as compared with 22.0±8.4 days in the standard-blood group (P<0.001). At 90 days, 448 patients (37.0%) in the fresh-blood group and 430 patients (35.3%) in the standard-blood group had died (absolute risk difference, 1.7 percentage points; 95% confidence interval CI, -2.1 to 5.5). In the survival analysis, the hazard ratio for death in the fresh-blood group, as compared with the standard-blood group, was 1.1 (95% CI, 0.9 to 1.2; P=0.38). There were no significant between-group differences in any of the secondary outcomes (major illnesses; duration of respiratory, hemodynamic, or renal support; length of stay in the hospital; and transfusion reactions) or in the subgroup analyses.
Transfusion of fresh red cells, as compared with standard-issue red cells, did not decrease the 90-day mortality among critically ill adults. (Funded by the Canadian Institutes of Health Research and others; Current Controlled Trials number, ISRCTN44878718.).
Previous trials suggesting that high-frequency oscillatory ventilation (HFOV) reduced mortality among adults with the acute respiratory distress syndrome (ARDS) were limited by the use of outdated ...comparator ventilation strategies and small sample sizes.
In a multicenter, randomized, controlled trial conducted at 39 intensive care units in five countries, we randomly assigned adults with new-onset, moderate-to-severe ARDS to HFOV targeting lung recruitment or to a control ventilation strategy targeting lung recruitment with the use of low tidal volumes and high positive end-expiratory pressure. The primary outcome was the rate of in-hospital death from any cause.
On the recommendation of the data monitoring committee, we stopped the trial after 548 of a planned 1200 patients had undergone randomization. The two study groups were well matched at baseline. The HFOV group underwent HFOV for a median of 3 days (interquartile range, 2 to 8); in addition, 34 of 273 patients (12%) in the control group received HFOV for refractory hypoxemia. In-hospital mortality was 47% in the HFOV group, as compared with 35% in the control group (relative risk of death with HFOV, 1.33; 95% confidence interval, 1.09 to 1.64; P=0.005). This finding was independent of baseline abnormalities in oxygenation or respiratory compliance. Patients in the HFOV group received higher doses of midazolam than did patients in the control group (199 mg per day interquartile range, 100 to 382 vs. 141 mg per day interquartile range, 68 to 240, P<0.001), and more patients in the HFOV group than in the control group received neuromuscular blockers (83% vs. 68%, P<0.001). In addition, more patients in the HFOV group received vasoactive drugs (91% vs. 84%, P=0.01) and received them for a longer period than did patients in the control group (5 days vs. 3 days, P=0.01).
In adults with moderate-to-severe ARDS, early application of HFOV, as compared with a ventilation strategy of low tidal volume and high positive end-expiratory pressure, does not reduce, and may increase, in-hospital mortality. (Funded by the Canadian Institutes of Health Research; Current Controlled Trials numbers, ISRCTN42992782 and ISRCTN87124254, and ClinicalTrials.gov numbers, NCT00474656 and NCT01506401.).
The accuracy of the signs and tests that clinicians use to diagnose ventilator-associated pneumonia (VAP) and initiate antibiotic treatment has not been well characterized. We sought to characterize ...and compare the accuracy of physical examination, chest radiography, endotracheal aspirate (ETA), bronchoscopic sampling cultures (protected specimen brush PSB and bronchoalveolar lavage BAL), and CPIS > 6 to diagnose VAP. We searched six databases from inception through September 2019 and selected English-language studies investigating accuracy of any of the above tests for VAP diagnosis. Reference standard was histopathological analysis. Two reviewers independently extracted data and assessed study quality. We included 25 studies (1639 patients). The pooled sensitivity and specificity of physical examination findings for VAP were poor: fever (66.4% 95% confidence interval CI: 40.7–85.0, 53.9% 95% CI 34.5–72.2) and purulent secretions (77.0% 95% CI 64.7–85.9, 39.0% 95% CI 25.8–54.0). Any infiltrate on chest radiography had a sensitivity of 88.9% (95% CI 73.9–95.8) and specificity of 26.1% (95% CI 15.1–41.4). ETA had a sensitivity of 75.7% (95% CI 51.5–90.1) and specificity of 67.9% (95% CI 40.5–86.8). Among bronchoscopic sampling methods, PSB had a sensitivity of 61.4% 95% CI 43.7–76.5 and specificity of 76.5% 95% CI 64.2–85.6; while BAL had a sensitivity of 71.1% 95% CI 49.9–85.9 and specificity of 79.6% 95% CI 66.2–85.9. CPIS > 6 had a sensitivity of 73.8% (95% CI 50.6–88.5) and specificity of 66.4% (95% CI 43.9–83.3). Classic clinical indicators had poor accuracy for diagnosis of VAP. Reliance upon these indicators in isolation may result in misdiagnosis and potentially unnecessary antimicrobial use.
Critically ill patients may develop bleeding caused by stress ulceration. Acid suppression is commonly prescribed for patients at risk of stress ulcer bleeding. Whether proton pump inhibitors are ...more effective than histamine 2 receptor antagonists is unclear.
To determine the efficacy and safety of proton pump inhibitors vs. histamine 2 receptor antagonists for the prevention of upper gastrointestinal bleeding in the ICU.
We searched Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, ACPJC, CINHAL, online trials registries (clinicaltrials.gov, ISRCTN Register, WHO ICTRP), conference proceedings databases, and reference lists of relevant articles.
Randomized controlled parallel group trials comparing proton pump inhibitors to histamine 2 receptor antagonists for the prevention of upper gastrointestinal bleeding in critically ill patients, published before March 2012.
Two reviewers independently applied eligibility criteria, assessed quality, and extracted data. The primary outcomes were clinically important upper gastrointestinal bleeding and overt upper gastrointestinal bleeding; secondary outcomes were nosocomial pneumonia, ICU mortality, ICU length of stay, and Clostridium difficile infection. Trial authors were contacted for additional or clarifying information.
Fourteen trials enrolling a total of 1,720 patients were included. Proton pump inhibitors were more effective than histamine 2 receptor antagonists at reducing clinically important upper gastrointestinal bleeding (relative risk 0.36; 95% confidence interval 0.19-0.68; p = 0.002; I = 0%) and overt upper gastrointestinal bleeding (relative risk 0.35; 95% confidence interval 0.21-0.59; p < 0.0001; I = 15%). There were no differences between proton pump inhibitors and histamine 2 receptor antagonists in the risk of nosocomial pneumonia (relative risk 1.06; 95% confidence interval 0.73-1.52; p = 0.76; I = 0%), ICU mortality (relative risk 1.01; 95% confidence interval 0.83-1.24; p = 0.91; I = 0%), or ICU length of stay (mean difference -0.54 days; 95% confidence interval -2.20 to 1.13; p = 0.53; I = 39%). No trials reported on C. difficile infection.
In critically ill patients, proton pump inhibitors seem to be more effective than histamine 2 receptor antagonists in preventing clinically important and overt upper gastrointestinal bleeding. The robustness of this conclusion is limited by the trial methodology, differences between lower and higher quality trials, sparse data, and possible publication bias. We observed no differences between drugs in the risk of pneumonia, death, or ICU length of stay.
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