Diagnosis of COVID-19 in Patients with Negative Nasopharyngeal Swabs: Reliability of Radiological and Clinical Diagnosis and Accuracy Versus Serology.

BACKGROUND: The diagnosis of Coronavirus disease 2019 (COVID-19) relies on the positivity of nasopharyngeal swab. However, a significant percentage of symptomatic patients may test negative. We evaluated the reliability of COVID-19 diagnosis made by radiologists and clinicians and its accuracy versus serology in a sample of patients hospitalized for suspected COVID-19 with multiple negative swabs. METHODS: Admission chest CT-scans and clinical records of swab-negative patients, treated according to the COVID-19 protocol or deceased during hospitalization, were retrospectively evaluated by two radiologists and two clinicians, respectively. RESULTS: Of 254 patients, 169 swab-confirmed cases and one patient without chest CT-scan were excluded. A total of 84 patients were eligible for the reliability study. Of these, 21 patients died during hospitalization; the remaining 63 underwent serological testing and were eligible for the accuracy evaluation. Of the 63, 26 patients showed anti-Sars-Cov-2 antibodies, while 37 did not. The inter-rater agreement was "substantial" (kappa 0.683) between radiologists, "moderate" (kappa 0.454) between clinicians, and only "fair" (kappa 0.341) between radiologists and clinicians. Both radiologic and clinical evaluations showed good accuracy compared to serology. CONCLUSIONS: The radiologic and clinical diagnosis of COVID-19 for swab-negative patients proved to be sufficiently reliable and accurate to allow a diagnosis of COVID-19, which needs to be confirmed by serology and follow-up.

Levels of circulating endothelial cells are low in idiopathic pulmonary fibrosis and are further reduced by anti-fibrotic treatments.

BACKGROUND: It has been suggested that circulating fibrocytes and endothelial cells actively participate in the intense remodelling of the pulmonary vasculature in patients with idiopathic pulmonary fibrosis (IPF). Indeed, fibrotic areas exist that have fewer blood vessels, whereas adjacent non-fibrotic tissue is highly vascularized. The number of circulating endothelial cells (CEC) and endothelial progenitor cells (EPC) might reflect the balance between vascular injury and repair. Thus, fibrocytes as well as endothelial cells could potentially be used as biomarkers of disease progression and treatment outcome. METHODS: Peripheral blood samples were collected from 67 patients with a multidisciplinary diagnosis of IPF and from 45 age-matched and sex-matched healthy volunteers. Buffy coat was isolated according to standard procedures and at least 20 million cells were stained with different monoclonal antibodies for the detection of CEC, EPC and circulating fibrocytes. For the detection of CEC and EPC, cells were stained with anti-CD45, anti-CD34, anti-CD133, anti-CD14, anti-CD309 and with the viability probe Far-Red LIVE/DEAD. For the detection of circulating fibrocytes, cells were first stained with LIVE/DEAD and the following monoclonal antibodies: anti-CD3, anti-CD19, anti-CD45, anti-CD34 and anti-CD14, then cells were fixed, permeabilized and stained with fluorochrome-conjugated anti-collagen I monoclonal antibodies. RESULTS: Patients with IPF displayed almost undetectable levels of circulating fibrocytes, low levels of CEC, and normal levels of EPC. Patients treated with nintedanib displayed higher levels of CEC, but lower levels of endothelial cells expressing CD309 (the type II receptor for vascular endothelial growth factor). Treatment with both nintedanib and pirfenidone reduced the percentage of CEC and circulating fibrocytes. CONCLUSIONS: Levels of CEC were reduced in patients with IPF as compared to healthy individuals. The anti-fibrotic treatments nintedanib and pirfenidone further reduced CEC levels. These findings might help explain the mechanism of action of these drugs and should be explored as predictive biomarkers in IPF.