A Machine-learning Parsimonious Multivariable Predictive Model of Mortality Risk in Patients With Covid-19 (preprint)

BackgroundThe COVID-19 pandemic is impressively challenging the healthcare system. Several prognostic models have been validated but few of them are implemented in daily practice. The objective of the study was to validate a machine-learning risk prediction model using easy-to-obtain parameters, potentially available at home, to help identifying patients with COVID-19 who are at higher risk of death.MethodsThe training cohort included all patients admitted to Fondazione Policlinico Gemelli with COVID-19 from March 5, 2020 to November 5, 2020. Afterwards, the model was tested on all patients admitted to the same hospital with COVID-19 from November 6, 2020 to February 5 2021. The primary outcome was in-hospital mortality.The out-of-sample performance of the model was estimated from the training set in terms of Area under the Receiving Operator Curve (AUROC) and classification matrix statistics by averaging the results of 5-fold cross validation repeated 3-times and comparing the results with those obtained on the test set. An explanation analysis of the model, based on the SHapley Additive exPlanations (SHAP), is also presented. To assess the subsequent time evolution, the change in paO2/FiO2 (P/F) at 48 hours after the baseline measurement was plotted against its baseline value.ResultsAmong the 921 patients included in the training cohort, 120 died (13%). Variables selected for the model were age, platelet count, SpO2, blood urea nitrogen (BUN), hemoglobin, C-reactive protein, neutrophil count, and sodium. The results of the 5-fold cross-validation repeated 3-times gave AUROC of 0.87, and statistics of the classification matrix to the Youden index as follows: sensitivity 0.840, specificity 0.774, negative predictive value 0.971. Then, the model was tested on a new population (n=1463) in which the mortality rate was 22.6 %. The test model showed AUROC 0.818, sensitivity 0.813, specificity 0.650, negative predictive value 0.922. Considering the first quartile of the predicted risk score (low-risk score group), the mortality rate was 1.6%, 17.8% in the second and third quartile (high-risk score group) and 53.5% in the fourth quartile (very high-risk score group). The three risk score groups showed good discrimination for the P/F value at admission, and a positive correlation was found for the low-risk class to P/F at 48 hours after admission (adjusted R-squared= 0.48).ConclusionsWe developed a predictive model of death for people with SARS-CoV-2 infection by including only easy-to-obtain variables (abnormal blood count, BUN, C-reactive protein, sodium and lower SpO2). It demonstrated good accuracy and high power of discrimination. The simplicity of the model makes the risk prediction applicable for patients at home, in the Emergency Department, or during hospitalization.

Nasopharyngeal Microbiota Profiling of SARS-CoV-2 Infected Patients (preprint)

We analyzed the bacterial communities of the nasopharynx in 40 SARS-CoV-2 infected and uninfected patients. All patients had a mild COVID-19 disease. We did not find statistically significant differences in either bacterial richness and diversity or composition. These findings suggest a nasopharyngeal microbiota at least early resilient to SARS-CoV-2 infection.

Confirmed or unconfirmed cases of 2019 novel coronavirus pneumonia in Italian patients: a retrospective analysis of clinical features (preprint)

Background: Since December 2019, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged as a novel etiologic agent of viral pneumonia. We aimed to compare clinical features of 165 Italian patients with laboratory confirmed or unconfirmed 2019-nCoV pneumonia. Methods: On March 31 2020, hospitalized patients who presented with fever and/or respiratory symptoms, exposures, and presence of lung imaging features consistent with 2019-nCoV pneumonia, were included. Before admission to a hospital ward, patients underwent RT-PCR based SARS-CoV-2 RNA detection in their nasopharyngeal swab samples. Results: Of 165 patients studied, 119 had positive RT-PCR results and 46 were RT-PCR negative for two days or longer (i.e., when the last swab sample was obtained). The median age was 70 years (IQR, 58–78), and 123 (74.6%) of 165 patients had at least one comorbidity. The majority of patients (101/165, 61.2%) had a mild pneumonia, and the remaining patients (64/165, 38.8%) a severe/critical pneumonia. We did not find any substantial difference in symptoms, incubation periods, and radiographic/CT abnormalities as well as in many of the biological abnormalities recorded. However, at multivariable analysis, higher concentrations of hemoglobin (OR, 1.34; 95% CI, 1.11‒1.65; P = 0.003) and lower counts of leukocytes (OR, 0.81; 95% CI, 0.72‒0.90; P <0.001) were statistically associated with confirmed COVID-19 diagnosis. While mortality rates were similar, patients with confirmed diagnosis were more likely to receive antivirals (95% vs 19.6%, P <0.001) and to develop ARDS (63% vs 37%, P = 0.003) than those with unconfirmed COVID-19 diagnosis. Conclusions: Our findings suggest that unconfirmed 2019-nCoV pneumonia cases may be actually COVID-19 cases and that clinicians should be cautious when managing patients with presentations compatible with COVID-19.

Sarilumab use in severe SARS-CoV-2 pneumonia (preprint)

Importance: Interleukin-6 signal blockade has shown preliminary beneficial effects in treating aberrant host inflammatory response against SARS-CoV-2 leading to severe respiratory distress. Objective: to describe the effect of off-label intravenous use of Sarilumab in patients with severe SARS-CoV-2-related pneumonia. Design: Observational clinical cohort study. Setting: Fondazione Policlinico Universitario A. Gemelli IRCCS as Italian Covid reference center. Participants: Patients with laboratory-confirmed SARS-CoV-2 infection and respiratory distress with PaO2/FiO2 ratio<300 treated with Sarilumab between March 23rd - April 4th, 2020. Date of final follow-up was April 18, 2020. Main outcomes and measures: We describe the clinical outcomes of 53 patients with SARS-CoV-2 severe pneumonia treated with intravenous Sarilumab in terms of pulmonary function improvement or Intensive Care Unit (ICU) admission rate in medical wards setting and of live discharge rate in ICU treated patients as well as in terms of safety. Each patient received Sarilumab 400 mg administered intravenously on day 1, with eventual additional infusion based on clinical judgement, and was followed for at least 14 days, unless previously discharged or dead. No gluco-corticosteroids were used at baseline. Results: Of the 53 SARS-CoV-2pos patients receiving Sarilumab, 39 (73.6%) were treated in medical wards (66.7% with a single infusion) while 14 (26.4%) in ICU (92.6% with a second infusion). The median PaO2/FiO2 of patients in the Medical Ward was 146(IQR:120-212) while the median PaO2/FiO2 of patients in ICU was 112(IQR:100-141.5), respectively. Within the medical wards, 7(17.9%) required ICU admission, 4 of whom were re-admitted to the ward within 5-8 days. At 19 days median follow-up, 89.7% of medical inpatients significantly improved (46.1% after 24 hours, 61.5% after 3 days), 70.6% were discharged from the hospital and 85.7% no longer needed oxygen therapy. Within patients receiving Sarilumab in ICU, 64.2% were discharged from ICU to the ward and 35.8% were still alive at the last follow-up. Overall mortality rate was 5.7% after Sarilumab administration: 1(2.5%) patient died in the Medical Ward whilst 2(14.2%) patients died in ICU, respectively. Conclusions and relevance: IL6-R inhibition appears to be a potential treatment strategy for severe SARS-CoV-2 pneumonia and intravenous Sarilumab seems a promising treatment approach showing, in the short term, an important clinical benefit and good safety.