Background: Symptom criteria for COVID-19 testing of heath care workers (HCWs) limitations on testing availability have been challenging during the COVID-19 pandemic. An evidence-based symptom criteria for identifying HCWs for testing, based on the probability of positive COVID-19 test results, would allow for a more appropriate use of testing resources. Methods:This was an observational study of outpatient COVID-19 testing of HCWs. Prior to testing, HCWs were asked about the presence of 10 symptoms. Their responses were then compared to their subsequent pharyngeal swab COVID-19 polymerase chain reaction test results. These data were used to derive and evaluate a symptom-based testing criteria.Results: A total of 961 HCWs were included in the analysis, of whom 225 (23%) had positive test results. Loss of taste or smell was the symptom with the largest positive likelihood ratio (3.33). Dry cough, regardless of the presence or absence of other symptoms, was the most sensitive (74%) and the least specific (32%) symptom. The existing testing criteria consisting of any combination of one or more of three symptoms (fever, shortness of breath, dry cough) was 93% sensitive and 9% specific (area unce the curve [AUC] = 0.63, 95% confidence interval [CI] = 0.59 to 0.67). The derived testing criteria consisting of any combination of one or more of two symptoms (fever, loss of taste or smell) was 89% sensitive and 48% specific (AUC = 0.75, 95% CI = 0.71 to 0.78). The hybrid testing criteria consisting of any combination of one or more of four symptoms (fever, shortness of breath, dry cough, loss of taste or smell) was 98% sensitive and 8% specific (AUC = 0.77, 95% CI = 0.73 to 0.80).

Objectives: The primary goal of evaluation for acute-onset headache is to exclude aneurysmal subarachnoid hemorrhage (SAH). Noncontrast cranial computed tomography (CT), followed by lumbar puncture (LP) if the CT is negative, is the current standard of care. Computed tomography angiography (CTA) of the brain has become more available and more sensitive for the detection of cerebral aneurysms. This study addresses the role of CT ⁄ CTA versus CT ⁄ LP in the diagnostic workup of acute-onset headache.Methods: This article reviews the recent literature for the prevalence of SAH in emergency department (ED) headache patients, the sensitivity of CT for diagnosing acute SAH, and the sensitivity and specificity of CTA for cerebral aneurysms. An equivalence study comparing CT ⁄ LP and CT ⁄ CTA would require 3,000 + subjects. As an alternative, the authors constructed a mathematical probability model to determine the posttest probability of excluding aneurysmal or arterial venous malformation (AVM) SAH with a CT ⁄ CTA strategy.Results: SAH prevalence in ED headache patients was conservatively estimated at 15%. Representative studies reported CT sensitivity for SAH to be 91% (95% confidence interval [CI] = 82% to 97%) and sensitivity of CTA for aneurysm to be 97.9% (95% CI = 88.9% to 99.9%). Based on these data, the posttest probability of excluding aneurysmal SAH after a negative CT ⁄ CTA was 99.43% (95% CI = 98.86% to 99.81%).Conclusions: CT followed by CTA can exclude SAH with a greater than 99% posttest probability. In ED patients complaining of acute-onset headache without significant SAH risk factors, CT ⁄ CTA may offer a less invasive and more specific diagnostic paradigm. If one chooses to offer LP after CT ⁄ CTA, informed consent for LP should put the pretest risk of a missed aneurysmal SAH at less than 1%.ACADEMIC EMERGENCY MEDICINE 2010; 17:444-451 ª

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Commentary on: Sensitivity of computed tomography performed within six hours of onset of headache for diagnosis of subarachnoid haemorrhage: prospective cohort study.PerryJJDepartment of Emergency Medicine, Buffalo General Hospital, Buffalo, NY 14203, USAStiellIGDepartment of Emergency Medicine, Buffalo General Hospital, Buffalo, NY 14203, USASivilottiMLDepartment of Emergency Medicine, Buffalo General Hospital, Buffalo, NY 14203, USAet al.BMJ2011343d4277