Sample size estimation in clinical trials using ventilator-free days as the primary outcome: a systematic review.

BACKGROUND: Ventilator-free days (VFDs) are a composite endpoint increasingly used as the primary outcome in critical care trials. However, because of the skewed distribution and competitive risk between components, sample size estimation remains challenging. This systematic review was conducted to systematically assess whether the sample size was congruent, as calculated to evaluate VFDs in trials, with VFDs' distribution and the impact of alternative methods on sample size estimation. METHODS: A systematic literature search was conducted within the PubMed and Embase databases for randomized clinical trials in adults with VFDs as the primary outcome until December 2021. We focused on peer-reviewed journals with 2021 impact factors greater than five. After reviewing definitions of VFDs, we extracted the sample size and methods used for its estimation. The data were collected by two independent investigators and recorded in a standardized, pilot-tested forms tool. Sample sizes were calculated using alternative statistical approaches, and risks of bias were assessed with the Cochrane risk-of-bias tool. RESULTS: Of the 26 clinical trials included, 19 (73%) raised "some concerns" when assessing risks of bias. Twenty-four (92%) trials were two-arm superiority trials, and 23 (89%) were conducted at multiple sites. Almost all the trials (96%) were unable to consider the unique distribution of VFDs and death as a competitive risk. Moreover, significant heterogeneity was found in the definitions of VFDs, especially regarding varying start time and type of respiratory support. Methods for sample size estimation were also heterogeneous, and simple models, such as the Mann-Whitney-Wilcoxon rank-sum test, were used in 14 (54%) trials. Finally, the sample sizes calculated varied by a factor of 1.6 to 17.4. CONCLUSIONS: A standardized definition and methodology for VFDs, including the use of a core outcome set, seems to be required. Indeed, this could facilitate the interpretation of findings in clinical trials, as well as their construction, especially the sample size estimation which is a trade-off between cost, ethics, and statistical power. Systematic review registration PROSPERO ID: CRD42021282304. Registered 15 December 2021 ( https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42021282304 ).

Benefits and adverse effects of ACE inhibitors in patients with heart failure with reduced ejection fraction: a systematic review and meta-analysis.

PURPOSE: Angiotensin-converting enzyme (ACE) inhibitors are part of first-line treatment for reduced ejection fraction heart failure (HFrEF). The aim was to assess the benefits and adverse effects of ACE inhibitors in HFrEF with a focus on important patient outcomes. METHODS: A systematic review of double-blind randomized clinical trials (RCTs) and comparison of ACE inhibitors versus placebo, in HFrEF patients published in French or English. Searches were undertaken of Medline, Cochrane Central, and Embase. The primary outcomes were all-cause mortality and adverse events. RESULTS: From 636 articles analysed, 11 were included (13,882 patients). For all-cause mortality (5 RCTs, 9277 patients), the number needed to treat (NNT) to avoid one death at 6 months was 50 (33-107). The NNT to prevent one death at 12 months (6 RCTs, 13,016 patients) was 63 (35-314). Under the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach, the evidence was of moderate quality. The number needed to harm was 12 (10-15) for cough, 20 (14-31) for hypotension, 23 (17-36) for dizziness, 31 (23-47) for hyperkalaemia, and 49 (30-121) for increased creatinine levels. The quality of evidence was moderate for these criteria except for cough (low quality of evidence). CONCLUSION: This review focuses on clinical elements necessary in a shared decision-making process. In practice, general practitioners will be able to use these data to discuss ACE inhibitor treatment with HFrEF patients. This study was registered in the PROSPERO registry under the reference number CRD42018096930.

Acute respiratory distress syndrome subphenotypes and therapy responsive traits among preclinical models: protocol for a systematic review and meta-analysis.

BACKGROUND: Subphenotypes were recently reported within clinical acute respiratory distress syndrome (ARDS), with distinct outcomes and therapeutic responses. Experimental models have long been used to mimic features of ARDS pathophysiology, but the presence of distinct subphenotypes among preclinical ARDS remains unknown. This review will investigate whether: 1) subphenotypes can be identified among preclinical ARDS models; 2) such subphenotypes can identify some responsive traits. METHODS: We will include comparative preclinical (in vivo and ex vivo) ARDS studies published between 2009 and 2019 in which pre-specified therapies were assessed (interleukin (IL)-10, IL-2, stem cells, beta-agonists, corticosteroids, fibroblast growth factors, modulators of the receptor for advanced glycation end-products pathway, anticoagulants, and halogenated agents) and outcomes compared to a control condition. The primary outcome will be a composite of the four key features of preclinical ARDS as per the American Thoracic Society consensus conference (histologic evidence of lung injury, altered alveolar-capillary barrier, lung inflammatory response, and physiological dysfunction). Secondary outcomes will include the single components of the primary composite outcome, net alveolar fluid clearance, and death. MEDLINE, Embase, and Cochrane databases will be searched electronically and data from eligible studies will be extracted, pooled, and analyzed using random-effects models. Individual study reporting will be assessed according to the Animal Research: Reporting of In Vivo Experiments guidelines. Meta-regressions will be performed to identify subphenotypes prior to comparing outcomes across subphenotypes and treatment effects. DISCUSSION: This study will inform on the presence and underlying pathophysiological features of subphenotypes among preclinical models of ARDS and should help to determine whether sufficient evidence exists to perform preclinical trials of subphenotype-targeted therapies, prior to potential clinical translation. SYSTEMATIC REVIEW REGISTRATION: PROSPERO (ID: CRD42019157236).

Risk Factors Associated With New-Onset Diabetes After Liver Transplant: A Case Control Study.

BACKGROUND: New-onset diabetes after transplant is a severe complication that can present in liver transplant recipients, negatively impacting quality of life and graft survival. It also contributes to increased risk of infection, cardiovascular disease, and rejection, which are the main causes of death among liver transplant recipients. The aim of the present study was to assess the risk factors associated with new-onset diabetes after transplant. METHOD: This was a case control study based on the data from 146 liver transplant patients at a reference hospital. The data from the charts were collected using a 2-part form: Part I (sociodemographic variables) and Part II (clinical variables). RESULTS: Multiple analysis showed that pre-existing systemic arterial hypertension (odds ratio [OR], 2.65; 95% CI, 1.12-6.28) and the use of sodium mycophenolate associated with tacrolimus (OR, 2.68; 95% CI, 1.02-7.06) increased the risk of new-onset diabetes after transplant. On comparing the anthropometric variables, lipid panel, and blood glucose levels of liver transplant patients with and without diabetes, higher glycemic levels were found in the group with diabetes (P < .001). CONCLUSION: Pre-existing systemic arterial hypertension and the associated use of sodium mycophenolate and tacrolimus increased the risk of new-onset diabetes after transplant.

On the difficulties of predicting the adsorption of volatile organic compounds at low pressures in microporous solid: the example of ethyl benzene.

Adsorption isotherms of toluene and ethyl benzene, at 25 degrees C and 40 degrees C, were determined in two microporous activated carbons and one zeolite. Significant differences were found in the adsorption behavior, at low pressures, between the two vapors on the same adsorbent material. The quantities of adsorbed ethyl benzene at 25 degrees C, in the low-pressure region, were lower than what was observed at 40 degrees C in all the studied adsorbents, contrary to what was found for toluene. This fact was not related to kinetic effects at the two temperatures nor to vapor swelling of the adsorbents structure. Also, there was no molecular sieving since at high pressures the toluene and ethyl benzene occupied the same adsorption space. The differences found in the ethyl benzene adsorption at the two temperatures pose difficulties in the analysis of the adsorption data and, therefore, in the prediction of results. This is discussed in the analysis of the results with the application of the Dubinin-Astakhov equation and in the estimation of the isosteric heats of adsorption. The adsorption potentials of two possible ethyl benzene conformations were estimated for the adsorption in the pores of activated carbon from the Horvath and Kawazoe model, and the values compared with those found experimentally. The results were interpreted in terms of the ethyl benzene conformation effects when the molecule is confined in pores that are about the same size of one of the conformations.