Distributional (Single) Index Models

A Distributional (Single) Index Model (DIM) is a semi-parametric model for distributional regression, that is, estimation of conditional distributions given covariates. The method is a combination of classical single index models for the estimation of the conditional mean of a response given covariates, and isotonic distributional regression. The model for the index is parametric, whereas the conditional distributions are estimated non-parametrically under a stochastic ordering constraint. We show consistency of our estimators and apply them to a highly challenging data set on the length of stay (LoS) of patients in intensive care units. We use the model to provide skillful and calibrated probabilistic predictions for the LoS of individual patients, that outperform the available methods in the literature

Probabilistic analysis of COVID-19 patients' individual length of stay in Swiss intensive care units

RATIONALE The COVID-19 pandemic induces considerable strain on intensive care unit resources. OBJECTIVES We aim to provide early predictions of individual patients' intensive care unit length of stay, which might improve resource allocation and patient care during the on-going pandemic. METHODS We developed a new semiparametric distributional index model depending on covariates which are available within 24h after intensive care unit admission. The model was trained on a large cohort of acute respiratory distress syndrome patients out of the Minimal Dataset of the Swiss Society of Intensive Care Medicine. Then, we predict individual length of stay of patients in the RISC-19-ICU registry. MEASUREMENTS The RISC-19-ICU Investigators for Switzerland collected data of 557 critically ill patients with COVID-19. MAIN RESULTS The model gives probabilistically and marginally calibrated predictions which are more informative than the empirical length of stay distribution of the training data. However, marginal calibration was worse after approximately 20 days in the whole cohort and in different subgroups. Long staying COVID-19 patients have shorter length of stay than regular acute respiratory distress syndrome patients. We found differences in LoS with respect to age categories and gender but not in regions of Switzerland with different stress of intensive care unit resources. CONCLUSION A new probabilistic model permits calibrated and informative probabilistic prediction of LoS of individual patients with COVID-19. Long staying patients could be discovered early. The model may be the basis to simulate stochastic models for bed occupation in intensive care units under different casemix scenarios

Randomized trial of the effect of antipyresis by metamizol, propacetamol or external cooling on metabolism, hemodynamics and inflammatory response

Objective: We investigated the metabolic, hemodynamic, and inflammatory responses of pharmacological and physical therapies aimed at reducing body temperature in febrile critically ill patients. Design and setting: Open-label, randomized trial in a surgical ICU in a tertiary university hospital. Patients: Thirty analgosedated, mechanically ventilated patients with a temperature of 38.5°C or higher were randomized to receive either intravenous metamizol, intravenous propacetamol, or external cooling. Measurements and results: Body temperature and metabolic and hemodynamic variables were recorded at baseline and during the following 4h. Cytokine concentrations were assessed before and 4 and 12h after the initiation of antipyresis. Body temperature decreased significantly in all treatment groups. For a 1°C temperature decrease, the energy expenditure index increased by 5% with external cooling and decreased by 7% and 8% in the metamizol and propacetamol groups, respectively. Metamizol induced a significant decrease in mean arterial pressure and urine output compared to baseline and to the other two groups. C-reactive protein increased over time, but compared to the other groups it was significantly lower in patients receiving metamizol after 4h. Cytokine concentrations were not different among the three groups or over time, although interleukin 6 tended to decrease over time in the metamizol group. Conclusions: Metamizol, propacetamol, and external cooling equally reduced temperature. Considering the undesirable hemodynamic effects, metamizol should not be considered the first antipyretic choice in unstable patients. Propacetamol or external cooling should be preferred, although the latter should be avoided in patients unlikely to tolerate the increased metabolic demand induced by external coolin

Intravascular Lymphoma Mimicking Cerebral Stroke: Report of Two Cases

Ischemic stroke is a serious disease leading to significant morbidity and mortality. Multifocal and recurrent strokes are usually caused by embolic diseases, i.e. atrial fibrillation, but rare causes like cerebral vasculitis and clotting disorders are also well known. Here we report on two patients suffering from the very rare intravascular large B-cell lymphoma leading to multifocal and recurrent strokes in the brain and spinal cord as the prominent neurological symptom. The difficulties and the need for diagnostic brain biopsy in making an ‘in vivo’ diagnosis in this particular disease are outlined. Furthermore, the prerequisite for an interdisciplinary approach in these patients is strongly emphasized. Delayed diagnosis for several reasons was the most probable cause for cerebral relapse leading to death in one patient a few months after diagnosis. Conversely, early initiation of immunochemotherapy with a classical lymphoma schedule (R-CHOP) led to long-lasting remission of the disease in the other patient. With this report we like to improve alertness to intravascular large B-cell lymphoma as a cause for multifocal and recurrent strokes

Elevated Cardiac Troponin I in Sepsis and Septic Shock: No Evidence for Thrombus Associated Myocardial Necrosis

Elevated cardiac troponin I (cTnI) is frequently observed in patients with severe sepsis and septic shock. However, the mechanisms underlying cTnI release in these patients are still unknown. To date no data regarding coagulation disturbances as a possible mechanism for cTnI release during sepsis are available.Consecutive patients with systemic inflammatory response syndrome (SIRS), sepsis or septic shock without evidence of an acute coronary syndrome were analyzed. Coagulation parameters (clotting time (CT), clot formation time (CFT), maximum clot firmness (MCF), alpha-angle) were assessed in native whole blood samples, and using specific activators to evaluate the extrinsic and intrinsic as well as the fibrin component of the coagulation pathway with the use of rotational thrombelastometry (ROTEM). Thirty-eight patients were included and 22 (58%) were cTnI-positive. Baseline characteristics between TnI-positive and -negative patients were similar. The CT, CFT, MCF and the alpha-angle were similar between the groups with trends towards shorter CT in the extrinsic and fibrin activation.We found no differences in coagulation parameters analyzed with rotational thrombelastometry between cTnI-positive and -negative patients with SIRS, severe sepsis, and septic shock. These findings suggest that pathophysiological mechanisms other than thrombus-associated myocardial damage might play a major role, including reversible myocardial membrane leakage and/or cytokine mediated apoptosis in these patients

Higher risk for influenza-associated pulmonary aspergillosis (IAPA) in asthmatic patients: A Swiss multicenter cohort study on IAPA in critically ill influenza patients.

BACKGROUND Influenza-associated pulmonary aspergillosis (IAPA) is an important complication of severe influenza with high morbidity and mortality. METHODS We conducted a retrospective multicenter study in tertiary hospitals in Switzerland during 2017/2018 and 2019/2020 influenza seasons. All adults with PCR-confirmed influenza infection and treatment on intensive-care unit (ICU) for >24 h were included. IAPA was diagnosed according to previously published clinical, radiological, and microbiological criteria. We assessed risk factors for IAPA and predictors for poor outcome, which was a composite of in-hospital mortality, ICU length of stay ≥7 days, mechanical ventilation ≥7 days, or extracorporeal membrane oxygenation. RESULTS One hundred fifty-eight patients (median age 64 years, 45% females) with influenza were included, of which 17 (10.8%) had IAPA. Asthma was more common in IAPA patients (17% vs. 4% in non-IAPA, P = 0.05). Asthma (OR 12.0 [95% CI 2.1-67.2]) and days of mechanical ventilation (OR 1.1 [1.1-1.2]) were associated with IAPA. IAPA patients frequently required organ supportive therapies including mechanical ventilation (88% in IAPA vs. 53% in non-IAPA, P = 0.001) and vasoactive support (75% vs. 45%, P = 0.03) and had more complications including ARDS (53% vs. 26%, P = 0.04), respiratory bacterial infections (65% vs. 37%, P = 0.04), and higher ICU-mortality (35% vs. 16.4%, P = 0.05). IAPA (OR 28.8 [3.3-253.4]), influenza A (OR 3.3 [1.4-7.8]), and higher SAPS II score (OR 1.07 [1.05-1.10]) were independent predictors of poor outcome. INTERPRETATION High clinical suspicion, early diagnostics, and therapy are indicated in IAPA because of high morbidity and mortality. Asthma is likely an underappreciated risk factor for IAPA

A high-risk gut microbiota configuration associates with fatal hyperinflammatory immune and metabolic responses to SARS-CoV-2.

Protection against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and associated clinical sequelae requires well-coordinated metabolic and immune responses that limit viral spread and promote recovery of damaged systems. However, the role of the gut microbiota in regulating these responses has not been thoroughly investigated. In order to identify mechanisms underpinning microbiota interactions with host immune and metabolic systems that influence coronavirus disease 2019 (COVID-19) outcomes, we performed a multi-omics analysis on hospitalized COVID-19 patients and compared those with the most severe outcome (i.e. death, n = 41) to those with severe non-fatal disease (n = 89), or mild/moderate disease (n = 42), that recovered. A distinct subset of 8 cytokines (e.g. TSLP) and 140 metabolites (e.g. quinolinate) in sera identified those with a fatal outcome to infection. In addition, elevated levels of multiple pathobionts and lower levels of protective or anti-inflammatory microbes were observed in the fecal microbiome of those with the poorest clinical outcomes. Weighted gene correlation network analysis (WGCNA) identified modules that associated severity-associated cytokines with tryptophan metabolism, coagulation-linked fibrinopeptides, and bile acids with multiple pathobionts, such as Enterococcus. In contrast, less severe clinical outcomes are associated with clusters of anti-inflammatory microbes such as Bifidobacterium or Ruminococcus, short chain fatty acids (SCFAs) and IL-17A. Our study uncovered distinct mechanistic modules that link host and microbiome processes with fatal outcomes to SARS-CoV-2 infection. These features may be useful to identify at risk individuals, but also highlight a role for the microbiome in modifying hyperinflammatory responses to SARS-CoV-2 and other infectious agents

Dynamics of disease characteristics and clinical management of critically ill COVID-19 patients over the time course of the pandemic: an analysis of the prospective, international, multicentre RISC-19-ICU registry.

BACKGROUND It remains elusive how the characteristics, the course of disease, the clinical management and the outcomes of critically ill COVID-19 patients admitted to intensive care units (ICU) worldwide have changed over the course of the pandemic. METHODS Prospective, observational registry constituted by 90 ICUs across 22 countries worldwide including patients with a laboratory-confirmed, critical presentation of COVID-19 requiring advanced organ support. Hierarchical, generalized linear mixed-effect models accounting for hospital and country variability were employed to analyse the continuous evolution of the studied variables over the pandemic. RESULTS Four thousand forty-one patients were included from March 2020 to September 2021. Over this period, the age of the admitted patients (62 [95% CI 60-63] years vs 64 [62-66] years, p < 0.001) and the severity of organ dysfunction at ICU admission decreased (Sequential Organ Failure Assessment 8.2 [7.6-9.0] vs 5.8 [5.3-6.4], p < 0.001) and increased, while more female patients (26 [23-29]% vs 41 [35-48]%, p < 0.001) were admitted. The time span between symptom onset and hospitalization as well as ICU admission became longer later in the pandemic (6.7 [6.2-7.2| days vs 9.7 [8.9-10.5] days, p < 0.001). The PaO2/FiO2 at admission was lower (132 [123-141] mmHg vs 101 [91-113] mmHg, p < 0.001) but showed faster improvements over the initial 5 days of ICU stay in late 2021 compared to early 2020 (34 [20-48] mmHg vs 70 [41-100] mmHg, p = 0.05). The number of patients treated with steroids and tocilizumab increased, while the use of therapeutic anticoagulation presented an inverse U-shaped behaviour over the course of the pandemic. The proportion of patients treated with high-flow oxygen (5 [4-7]% vs 20 [14-29], p < 0.001) and non-invasive mechanical ventilation (14 [11-18]% vs 24 [17-33]%, p < 0.001) throughout the pandemic increased concomitant to a decrease in invasive mechanical ventilation (82 [76-86]% vs 74 [64-82]%, p < 0.001). The ICU mortality (23 [19-26]% vs 17 [12-25]%, p < 0.001) and length of stay (14 [13-16] days vs 11 [10-13] days, p < 0.001) decreased over 19 months of the pandemic. CONCLUSION Characteristics and disease course of critically ill COVID-19 patients have continuously evolved, concomitant to the clinical management, throughout the pandemic leading to a younger, less severely ill ICU population with distinctly different clinical, pulmonary and inflammatory presentations than at the onset of the pandemic