Usefulness of the epidemiological survey and RT-PCR test in pre-surgical patients for assessing the risk of COVID-19

Determining coronavirus disease 2019 (COVID-19) community incidence threshold for preoperative testing

Preprocedural testing for severe acute respiratory coronavirus virus 2 (SARS-CoV-2) is frequently used to reduce perioperative morbidity and mortality during the pandemic. Such testing is resource intensive, and the relative benefits depend on local epidemiology. We propose a threshold of 20 per 100,000 unlinked cases to activate such testing to optimize the yield and positive predictive value.

Diagnostic yield and costs associated with a routine pre-operative COVID-19 testing algorithm for asymptomatic patients prior to elective surgery

OBJECTIVES

Infection with COVID-19 presents known and unknown perioperative risks to the patient and operative staff. Pre-operative testing protocols have become widespread, yet little is known about the utility of this practice in asymptomatic patients undergoing elective surgery. We describe the impact and cost of a routine testing protocol on elective surgical procedures in a retrospective series at a single institution.

METHODS

Standardized pre-operative COVID-19 testing in all surgical patients was implemented in May 2020. Health system protocol required testing 3 to 5 days before all elective surgery. Data stratified by surgical specialty were collected over the initial 90-day period and disposition over a period of 6-months was assessed for all positive and indeterminate results.

RESULTS

Thirty-one (0.41%) positive results amongst 7579 pre-procedural tests, including 3 of 792 (0.38%) for urologic procedures, were noted in asymptomatic patients. Following a positive test, 20 procedures (62.5%) were delayed an average of 49 days, 8 were not performed and 3 proceeded without delay. All 3 urologic procedures were delayed a mean of 59 days. Institutional cost per test ranged from $34-$54. The number needed to test for one positive result was 244 with a cost of $11,573 for each positive result.

CONCLUSIONS

Institution of a universal pre-operative COVID-19 screening protocol for asymptomatic, unvaccinated patients undergoing elective surgery identified clinically silent infection in 0.4% of cases with a significant associated cost. Risk and symptom-based testing is likely a better strategy for triaging resources.

AGA Rapid Review and Guideline for SARS-CoV2 Testing and Endoscopy Post-Vaccination: 2021 Update

This guideline provides updated recommendations on the role of preprocedure testing for severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) in individuals undergoing endoscopy in the post-vaccination period and replaces the prior guideline from the American Gastroenterological Association (AGA) (released July 29, 2020). Since the start of the pandemic, our increased understanding of transmission has facilitated the implementation of practices to promote patient and health care worker (HCW) safety. Simultaneously, there has been increasing recognition of the potential harm associated with delays in patient care, as well as inefficiency of endoscopy units. With widespread vaccination of HCWs and the general population, a re-evaluation of AGA's prior recommendations was warranted. In order to update the role of preprocedure testing for SARS-CoV2, the AGA guideline panel reviewed the evidence on prevalence of asymptomatic SARS-CoV2 infections in individuals undergoing endoscopy; patient and HCW risk of infections that may be acquired immediately before, during, or after endoscopy; effectiveness of COVID-19 vaccine in reducing risk of infections and transmission; patient and HCW anxiety; patient delays in care and potential impact on cancer burden; and endoscopy volumes. The panel considered the certainty of the evidence, weighed the benefits and harms of routine preprocedure testing, and considered burden, equity, and cost using the Grading of Recommendations Assessment, Development and Evaluation framework. Based on very low certainty evidence, the panel made a conditional recommendation against routine preprocedure testing for SARS-CoV2 in patients scheduled to undergo endoscopy. The panel placed a high value on minimizing additional delays in patient care, acknowledging the reduced endoscopy volumes, downstream impact on delayed cancer diagnoses, and burden of testing on patients.

Tips for a reduction of false positives in manual RT-PCR diagnostics of SARS-CoV-2

RT-PCR is the standard gold technique for testing the presence of RNA of the coronavirus causing Severe Acute Respiratory Syndrome (SARS-CoV-2) due to its high specificity and sensitivity. Despite its general use and reliability, no lab in the world is immune to the generation of false positives. These errors cause a loss of confidence in the technique's power and damage the image of laboratories. More importantly, they can take a toll on tested individuals and have economic, psychological, and health-associated effects. Most false positives are caused during a manual operation inside the laboratory. However, not much has been published about the errors associated with particular laboratory techniques used to detect the virus since the beginning of the actual pandemic. This work precisely reflects on events that occur during manual RT-PCR diagnostics in a COVID-19 laboratory, providing tips for reducing false-positive results.

Effectiveness of a SARS-CoV-2 infection prevention model in elective surgery patients - a prospective study: does universal screening make sense?

This observational study included patients who underwent pre-operative coronavirus disease 2019 (COVID-19) screening in order to preserve patient safety. Reverse transcriptase polymerase chain reaction (PCR) for severe acute respiratory syndrome coronavirus-2 was performed in 2292 of 8740 surgical procedures, and the incidence of a positive PCR result was 0.0022%. No healthcare-associated infections were detected. There was no difference in overall mortality or length of hospital stay compared with the same period from the previous year. A selective screening strategy to identify patients for PCR testing, based on isolation measures, presurgical clinical-epidemiological assessment and selected major surgeries susceptible to a poor COVID-19-related outcome, is effective and safe for patients and healthcare workers.

Error rates in SARS-CoV-2 testing examined with Bayes' theorem

The SARS-CoV-2 pandemic has created a demand for large scale testing, as part of the effort to understand and control transmission. It is important to quantify the error rates of test equipment under field conditions, which might differ significantly from those obtained in the laboratory. A literature review on SARS-CoV-2 reverse-transcription polymerase chain reaction (RT-PCR) is used to construct a clinical test confusion matrix. A simple correction method for bulk test results is then demonstrated with examples. The required sensitivity and specificity of a test are explored for societal needs and use cases, before a sequential analysis of common example scenarios is explored. The analysis suggests that many of the people with mild symptoms and positive test results are unlikely to be infected with SARS-CoV-2 in some regions. It is concluded that current and foreseen alternative tests can not be used to "clear" people as being non-infected. Recommendations are given that regional authorities must establish a programme to monitor operational test characteristics before launching large scale testing; and that large scale testing for tracing infection networks in some regions is not viable, but may be possible in a focused way that does not exceed the working capacity of the laboratories staffed by competent experts. RT-PCR tests can not be solely relied upon as the gold standard for SARS-CoV-2 diagnosis at scale, instead clinical assessment supported by a range of expert diagnostic tests should be used.

Modeling the effect of exposure notification and non-pharmaceutical interventions on COVID-19 transmission in Washington state

Contact tracing is increasingly used to combat COVID-19, and digital implementations are now being deployed, many based on Apple and Google's Exposure Notification System. These systems utilize non-traditional smartphone-based technology, presenting challenges in understanding possible outcomes. In this work, we create individual-based models of three Washington state counties to explore how digital exposure notifications combined with other non-pharmaceutical interventions influence COVID-19 disease spread under various adoption, compliance, and mobility scenarios. In a model with 15% participation, we found that exposure notification could reduce infections and deaths by approximately 8% and 6% and could effectively complement traditional contact tracing. We believe this can provide health authorities in Washington state and beyond with guidance on how exposure notification can complement traditional interventions to suppress the spread of COVID-19.

Physicians' Dilemma of False-Positive RT-PCR for COVID-19: a Case Report

Coronavirus disease 2019 (COVID-19) has played havoc on this world's health and economics since its outbreak in December 2019. Reverse transcription-polymerase chain reaction (RT-PCR) has been the gold standard to diagnose severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Still, few false-positive reports are emerging up that add to the physicians' dilemma and maintenance of health statistics.