Preoperative SARS-CoV-2 screening: Can it really rule out COVID-19?
- PDF / 305,754 Bytes
- 6 Pages / 595.276 x 790.866 pts Page_size
- 77 Downloads / 131 Views
EDITORIALS
Preoperative SARS-CoV-2 screening: Can it really rule out COVID-19?
Sylvain A. Lother, MD, FRCPC
Received: 26 May 2020 / Revised: 7 June 2020 / Accepted: 8 June 2020 Ó Canadian Anesthesiologists’ Society 2020
Expanded indications for testing the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have been recommended as health systems emerge from pandemic-related slowdowns. Routine preoperative screening prior to elective surgery has been broadly discussed. The putative benefits are intuitive: identify SARS-CoV-2 carriers before surgery to prevent adverse patient events, prevent further transmission, reduce consumption of resources and personal protective equipment, and improve hospital system efficiency. The harm associated with routine testing are less frequently considered. This editorial will address the deficiencies of real-time reverse transcriptase polymerase chain reaction (RT-PCR) as a method for detecting SARS-CoV-2 and provide information required to appropriately interpret test results. The purpose of SARS-CoV-2 screening with RT-PCR is to detect viral genetic material (RNA) in the presymptomatic phase of infection. This incubation period for SARS-CoV-2 is protracted with initial low levels of viral RNA until replication increases in the hours or days leading up to symptom onset.1 On average, logarithmic viral replication and subsequent symptoms only start five to six days after exposure, but in some instances, this can be delayed up to 14 days.2 Before viral RNA reaches detectable thresholds, patients may appear well prior to elective surgery despite being exposed to SARS-CoV-2 in the preceding 14 days. If viral carriage is not detected by testing, patients may proceed with elective
S. A. Lother, MD, FRCPC (&) Sections of Critical Care and Infectious Diseases, Department of Internal Medicine, University of Manitoba, JJ399- 820 Sherbrook St, Winnipeg, MB R3A 1R9, Canada e-mail: [email protected]
surgery whereby signs and symptoms of coronavirus disease (COVID-19) may arise in the postoperative period, leading to adverse outcomes.3 While screening with RT-PCR may detect some presymptomatic preoperative patients, the window of diagnostic utility is small, and careful interpretation of negative and positive test results must be considered prior to altering the course of therapy.
Screening in a low-risk population When evaluating any screening test, one must consider the sensitivity, specificity, and population prevalence of the target condition. Without a reference standard, measuring RT-PCR sensitivity for SARS-CoV-2 in asymptomatic patients remains an unresolved problem.4 As of 7 June 2020, clinical sensitivity has not been reported for any commercial tests in asymptomatic people. In the symptomatic cohort, considerable concern exists over false negative results, ranging from 11% to 40%.5–7 The probability of detecting SARS-CoV-2 also varies based on time from the exposure, being as low as 0% in the immediate days following exposure, 33% one day before symptom ons
Data Loading...
