Discrepant serological findings in SARS-CoV-2 PCR-negative hospitalized patients with fever and acute respiratory symptoms during the pandemic.

Coronavirus Disease 2019 (COVID-19) serology has an evolving role in the diagnosis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. However, its use in hospitalized patients with acute respiratory symptoms remains unclear. Hospitalized patients with acute respiratory illness admitted to an isolation ward were recruited. All patients had negative nasopharyngeal swab polymerase chain reaction (PCR) for SARS-CoV-2. Serological studies using four separate assays (cPass: surrogate neutralizing enzyme-linked immunosorbent assay [ELISA]; Elecsys: N-antigen based chemiluminescent assay; SFB: S protein flow-based; epitope peptide-based ELISA) were performed on stored plasma collected from patients during the initial hospital stay, and a convalescent visit 4-12 weeks later. Of the 51 patients studied (aged 54, interquartile range 21-84; 62.7% male), no patients tested positive on the Elecsys or cPass assays. Out of 51 patients, 5 had antibodies detected on B-cell Epitope Assay and 3/51 had antibodies detected on SFB assay. These 8 patients with positive serological test to COVID-19 were more likely to have a high-risk occupation (p = 0.039), bacterial infection (p = 0.028), and neutrophilia (p = 0.013) during their initial hospital admission. Discrepant COVID-19 serological findings were observed among those with recent hospital admissions and bacterial infections. The positive serological findings within our cohort raise important questions about the interpretation of sero-epidemiology during the current pandemic.

Comparison between lung ultrasonography and current methods for volume assessment in Asian chronic hemodialysis patients.

INTRODUCTION: Volume assessment in end-stage kidney disease patients on hemodialysis (HD) remains inadequate by existing methods: clinical examination, bioimpedance spectroscopy, measurement of inferior vena cava diameter by ultrasound (IVCD), and plasma B-type natriuretic peptide (NT-pro BNP). This study aims to compare the performance of lung ultrasound against existing methods for volume assessment in a HD cohort. METHODS: Two nephrologists independently performed 28-point lung ultrasound immediately before and after midweek HD in 50 patients. Lung congestion was classified into mild, moderate, and severe categories based on lung ultrasound findings. Clinical examination for crepitations and oedema, change in hydration status (∆HS) measured by bioimpedance spectroscopy, NT-pro BNP, IVCD during inspiration (IVCDimin), expiration (IVCDimax), and inferior vena cava collapsibility index were also assessed before and after midweek HD. FINDINGS: In all, 61% of patients with normohydration status by bioimpedance spectroscopy had moderate or severe lung congestion on lung ultrasound. There were significant correlations between predialysis lung ultrasound, and NT-pro BNP (r = 0.432, P = 0.004), ∆HS (r = 0.447, P < 0.001), and IVCD parameters (P < 0.05). Some correlations weakened postdialysis (∆HS [r = 0.322, P = 0.01] and IVCDimax [r = 0.307, P = 0.03]), whereas NT-pro BNP and ∆HS paradoxically increased in 28% and 30% of the cohort, respectively. On receiver operator curve analysis, most methods of volume assessment had limited discriminatory power to detect mild lung congestion. DISCUSSION: Lung ultrasound demonstrates some comparability with existing volume assessment methods in Asian dialysis patients. However, it appears more effective at detecting subclinical pulmonary congestion, and tracking fluid changes real-time compared to bioimpedance spectroscopy and NT-pro BNP.