Use of an algorithm based on routine blood laboratory tests to exclude COVID-19 in a screening-setting of healthcare workers.

BACKGROUND: COVID-19 is an ongoing pandemic leading to exhaustion of the hospital care system. Our health care system has to deal with a high level of sick leave of health care workers (HCWs) with COVID-19 related complaints, in whom an infection with SARS-CoV-2 has to be ruled out before they can return back to work. The aim of the present study is to investigate if the recently described CoLab-algorithm can be used to exclude COVID-19 in a screening setting of HCWs. METHODS: In the period from January 2021 till March 2021, HCWs with COVID-19-related complaints were prospectively collected and included in this study. Next to the routinely performed SARS-CoV-2 RT-PCR, using a set of naso- and oropharyngeal swab samples, two blood tubes (one EDTA- and one heparin-tube) were drawn for analysing the 10 laboratory parameters required for running the CoLab-algorithm. RESULTS: In total, 726 HCWs with a complete CoLab-laboratory panel were included in this study. In this group, 684 HCWs were tested SARS-CoV-2 RT-PCR negative and 42 cases RT-PCR positive. ROC curve analysis showed an area under the curve (AUC) of 0.853 (95% CI: 0.801-0.904). At a safe cut-off value for excluding COVID-19 of -6.525, the sensitivity was 100% with a specificity of 34% (95% CI: 21 to 49%). No SARS-CoV-2 RT-PCR cases were missed with this cut-off and COVID-19 could be safely ruled out in more than one third of HCWs. CONCLUSION: The CoLab-score is an easy and reliable algorithm that can be used for screening HCWs with COVID-19 related complaints. A major advantage of this approach is that the results of the score are available within 1 hour after collecting the samples. This results in a faster return to labour process of a large part of the COVID-19 negative HCWs (34%), next to a reduction in RT-PCR tests (reagents and labour costs) that can be saved.

[Laboratory input. General practitioners positive about reflective testing]. / Eigen inbreng van het laboratorium. Huisartsen positief over 'reflecterend testen'.

OBJECTIVE: To investigate the opinion of general practitioners on reflective testing, i.e. the practice of additional tests being performed and comments added to the results by laboratory staff when appropriate. DESIGN: Descriptive. METHOD: In the eastern South Limburg region 155 general practitioners received a list of 10 fictitious patient cases, each involving the possible addition of a specific test. The general practitioners could choose what they preferred the laboratory to do: add tests, phone the general practitioner, add a written comment or do nothing. In addition the general practitioners were asked to judge the effect of additional tests and comments on patient management with respect to diagnosis, treatment and referral, using 200 laboratory reports from their own patients. RESULTS: The response to the fictitious cases was 45%. Most general practitioners favoured the laboratory taking the initiative by adding on tests and commenting on the results in the given clinical scenarios. 78% of the questionnaires accompanying the lab reports were returned by 87% of the general practitioners. In nearly all cases (99%) the service was marked as useful. In more than half of the cases (53%) reflective testing affected the measures taken by the general practitioners. CONCLUSION: Reflective testing was in general welcomed by the general practitioners. In the majority of cases this led to an improvement in the diagnosis or adjustment of treatment.

Differentiating transudative from exudative pleural effusion: should we measure effusion cholesterol dehydrogenase?

INTRODUCTION: Pleural effusions are often classified into transudates and exudates based on Light's criteria. In this study, the diagnostic properties of Light's criteria were compared to those of several other analytes for the classification of pleural fluids into transudative and exudative. METHODS: A total of 471 patients with pleural effusions were evaluated. In pleural effusions and simultaneously drawn blood samples, lactate dehydrogenase (LDH), total protein, albumin, cholesterol, amylase, glucose, pH and the cell number were measured. Retrospectively, the clinical records were used to establish a clinical diagnosis. The diagnostic properties of the biochemical tests were calculated using the clinical diagnoses as gold standard. RESULTS: By clinical diagnosis, 108 patients had transudative and 300 patients had exudative pleural effusions. In addition to pleural LDH activity (accuracy 89%, sensitivity 86%, specificity 97%) and fluid to serum LDH ratio (accuracy 89%, sensitivity 91%, specificity 85%), pleural cholesterol concentration readily identified exudates (accuracy 82%, sensitivity 76%, specificity 98%). Combination of these three parameters achieved a higher overall accuracy (accuracy 95%, sensitivity 93%, specificity 100%) than the Light's criteria (accuracy 93%, sensitivity 100%, specificity 73%). Combination of effusion cholesterol concentration and effusion LDH activity had the highest discriminatory potential (accuracy 98%, sensitivity 98%, specificity 95%). CONCLUSIONS: Including effusion cholesterol, concentration in the routine biochemical work-up of pleural fluid allows for correct classification of more pleural effusions than achieved by use of Light's criteria. Combination of cholesterol and LDH had the highest discriminatory potential and the added advantage that no patient plasma is needed for correct classification.