Yield of Screening for COVID-19 in Asymptomatic Patients Before Elective or Emergency Surgery Using Chest CT and RT-PCR (SCOUT): Multicenter Study

Abstract

Objective: To determine the yield of preoperative screening for COVID-19 with chest CT and RT-PCR in patients without COVID-19 symptoms.

Summary of background data: Many centers are currently screening surgical patients for COVID-19 using either chest CT, RT-PCR or both, due to the risk for worsened surgical outcomes and nosocomial spread. The optimal design and yield of such a strategy are currently unknown.

Methods: This multicenter study included consecutive adult patients without COVID-19 symptoms who underwent preoperative screening using chest CT and RT-PCR before elective or emergency surgery under general anesthesia.

Results: A total of 2093 patients without COVID-19 symptoms were included in 14 participating centers; 1224 were screened by CT and RT-PCR and 869 by chest CT only. The positive yield of screening using a combination of chest CT and RT-PCR was 1.5% [95% confidence interval (CI): 0.8-2.1]. Individual yields were 0.7% (95% CI: 0.2-1.1) for chest CT and 1.1% (95% CI: 0.6-1.7) for RT-PCR; the incremental yield of chest CT was 0.4%. In relation to COVID-19 community prevalence, up to ∼6% positive RT-PCR was found for a daily hospital admission rate >1.5 per 100,000 inhabitants, and around 1.0% for lower prevalence.

Conclusions: One in every 100 patients without COVID-19 symptoms tested positive for SARS-CoV-2 with RT-PCR; this yield increased in conjunction with community prevalence. The added value of chest CT was limited. Preoperative screening allowed us to take adequate precautions for SARS-CoV-2 positive patients in a surgical population, whereas negative patients needed only routine procedures.

FIGURE 1

Flow-chart for patients undergoing preoperative screening for both cohorts. ^aThese patients all had negative RT-PCR and CO-RADS 1–3. ^bSome patients underwent multiple screenings during the study period. In case patients were initially screened using chest CT, and followingly using chest CT and RT-PCR, the combined screening was included. For patients with multiple screenings using 1 strategy, the first screening was included. CT indicates computed tomography; RT-PCR, reverse-transcriptase polymerase chain reaction.

FIGURE 2

Association of positive yield for chest CT and SARS-CoV-2 RT-PCR of asymptomatic patients with regional and temporal variations in community prevalence, measured by the mean daily COVID-19 related hospital admissions per 100.000 inhabitants. Left panel: no discernable pattern of association between positive chest CT results and regional and temporal variations of COVID-19 prevalence. Right panel: positive yield by RT-PCR markedly increases above mean of 1.5 daily COVID-19 related hospital admissions per 100.000 inhabitants. CT indicates computed tomography; RT-PCR, reverse-transcriptase polymerase chain reaction.