The American Gastroenterological Association (AGA) has issued guidance for pre-endoscopy coronavirus testing based on a review of existing literature and a survey of endoscopist risk tolerance.
While serologic antibody testing is not recommended for any patients, use of nucleic acid amplification testing (NAAT) for viral RNA should be informed by local prevalence of asymptomatic individuals, reported lead guideline panelist Shahnaz Sultan, MD, of the University of Minnesota in Minneapolis and colleagues.
“The two main concerns with a pretesting strategy are the false positives and false negatives,” the panelists wrote in Gastroenterology. When performing endoscopy in a false-negative patient, health care providers who wear a surgical mask instead of an N95/N99 respirator may have an increased risk of infection, and the patient undergoing the procedure may be falsely reassured that they are not contagious, the panelists wrote.
Among false-positive individuals, “implications for the patient include cancellation of the procedure, self-quarantine for 14 days, apprehension, and loss of work.”
Because of these concerns, the panelists concluded that pretesting strategies should be tailored to the local prevalence of asymptomatic infection because this rate is associated with likelihood of encountering false-positive and false-negative patients.
To determine appropriate prevalence thresholds, Dr. Sultan and colleagues first conducted a meta-analysis of 12 studies comparing the accuracy of various NAAT tests. This revealed a pooled sensitivity of 0.941 and a pooled specificity of 0.971. These figures remained consistent when only studies with low risk bias were considered; pooled sensitivity and specificity were 0.929 and 0.968, respectively.
“An important caveat of these studies is that tests were validated in samples from symptomatic individuals and it is likely that in asymptomatic individuals the tests may not perform as well and have lower sensitivity and specificity,” the panelists noted.
Next, Dr. Sultan and colleagues conducted an online survey of U.S. endoscopists to determine their tolerance for risk of coronavirus transmission, with proposed risk thresholds ranging from 1/40,000 to 1/1,000. Out of 74 respondents, 28 (37.8%) said that they would be willing to accept a risk level of 1/40,000, whereas 27 (36.5%) would accept risks between 1/10,000 and 1/2,500, and 19 (25.7%) would accept a risk level of 1/1,000. Among clinicians expressing the highest risk tolerance (1/1,000), almost two-thirds (63.2%) were private practitioners.
Drawing on these findings, the panelists issued three tiered recommendations for pretesting based on local prevalence of asymptomatic infection.
- Low prevalence (less than 0.5%): Pretesting is not recommended.
- Intermediate prevalence (0.5-2%): Pretesting is recommended.
- High prevalence (greater than 2%): Pretesting is not recommended.
The panelists recommended against pretesting in low and high prevalence settings because of the likelihood of false positives and false negatives, respectively. For “hotspot” areas, in which hospital capacity is acutely burdened, the panelists noted that “resumption of outpatient endoscopy may depend on availability of PPE.”
In areas of intermediate prevalence, the pretesting recommendation stands only if “testing is feasible and there is less perceived burden on patients, and when the benefits outweigh the downsides (e.g., false positives do not significantly outnumber the true positives).” According to the guidance, when performing upper and lower endoscopies on negative patients in areas of intermediate prevalence, surgical masks are appropriate for endoscopists and staff, with the caveat that those unwilling to accept any increased risk may still wear an N95/N99 respirator or a powered air-purifying respirator (PAPR).
Finally, the panelists made a recommendation against pretesting for antibodies in all areas, regardless of asymptomatic infection prevalence.
“Evidence supporting the role of seroconversion for return to work or hospital staffing policies is also lacking,” they added.
All recommendations were based on low or very low certainty evidence.
To help endoscopy centers determine an appropriate pretesting strategy, the AGA has created an online interactive tool that allows for input of diagnostic test accuracy and local prevalence rate.The investigators reported no conflicts of interest.
Instructions for using the tool, along with additional COVID-19 guidance, can be found on the AGA website: www.gastro.org/COVID.
This story was updated on 10/13/2020.
SOURCE: Sultan S et al. Gastroenterology. 2020 Jul 28.