CMAAO IMA CORONA FACTS and MYTH BUSTER 96: IDSA Guidelines Diagnosis
Dr K K Aggarwal
President Confederation of Medical Associations of Asia and Oceania, HCFI, Past National President IMA, Chief Editor Medtalks
With inputs from Dr Monica Vasudev
867: Summary of the IDSA guidelines on the diagnosis of COVID-19 [Infectious Diseases Society of America]
SARS-CoV-2 nucleic acid amplification test in symptomatic individuals in the community suspected of having COVID-19, even when the clinical suspicion is low (strong recommendation, very low certainty of evidence).
The panel placed a high value on accurate assessment of COVID-19 with the intent of minimizing overdiagnosis of COVID-19 using clinical diagnosis alone.
Without testing, the rate of overdiagnosis ranges from 62% to 98%. If patients are misdiagnosed as having COVID-19, they may spend unnecessary time in quarantine and then may stop taking appropriate safety precautions to protect themselves from infection.
The IDSA panel suggests collecting nasopharyngeal, or mid-turbinate or nasal swabs, rather than oropharyngeal swabs or saliva alone for SARS-CoV-2 RNA testing in symptomatic individuals with upper respiratory tract infection or influenza-like illness suspected of having COVID-19 (conditional recommendation, very low certainty of evidence).
The rationale for this recommendation is that comparative data showed a much lower sensitivity for oral sampling, compared with nasopharyngeal, mid-turbinate, or nasal sampling.
The average sensitivity of oral swabs is 56%, compared with nasopharyngeal at 97%, mid-turbinate at 100%, and nasal sampling at 95%. Given these test characteristics, there are far less false-negative tests with nasopharyngeal, mid-turbinate, and nasal swabs.
Fewer false negatives means fewer instances of incorrectly telling COVID-19–positive patients that they do not have the illness. An exciting new area of testing that is being evaluated is saliva, which appears to have a sensitivity of 85%.
The IDSA panel suggests that nasal and mid-turbinate swab specimens may be collected for SARS-CoV-2 RNA testing by either patients or health care providers in symptomatic individuals with upper respiratory tract infection or influenza-like illness suspected of having COVID-19 (conditional recommendation, low certainty of evidence).
This recommendation is particularly exciting because patient self-collection provides the potential for health care personnel to avoid exposure to infection, as can occur when health care personnel are swabbing a patient; this is ow testing has been done at most testing centers.
While the data are limited, it appears that patient self-collection of nasal or mid-turbinate swabs results in similar detection rates as occurs with health care personnel–collected nasopharyngeal swabs.
The IDSA panel suggests a strategy of initially obtaining an upper respiratory tract sample (e.g., nasopharyngeal swab) rather than a lower respiratory sample for SARS-CoV-2 RNA testing in hospitalized patients with suspected COVID-19 lower respiratory tract infection. If the initial upper respiratory sample result is negative, and the suspicion for disease remains high, the IDSA panel suggests collecting a lower respiratory tract sample (e.g., sputum, bronchoalveolar lavage fluid, tracheal aspirate) rather than collecting another upper respiratory sample (conditional recommendations, very low certainty of evidence). Remark: • The panel considered timeliness of SARS-CoV-2 NAAT results essential to impact individual care and isolation decisions. In the hospital setting, results within 24 hours of collection is preferable.
The IDSA panel suggests performing a single viral RNA test and not repeating testing in symptomatic individuals with a low clinical suspicion of COVID-19 (conditional recommendation, low certainty of evidence). Remarks: • A low clinical suspicion should be informed by epidemiological information available for the region coupled with clinical judgment. • The panel considered symptomatic patients to have at least one of the most common symptoms compatible with COVID-19
The IDSA panel suggests repeating viral RNA testing when the initial test is negative (versus performing a single test) in symptomatic individuals with an intermediate or high clinical suspicion of COVID-19 (conditional recommendation, low certainty of evidence).
Since none of the tests are perfect and any can have false negatives, the panel places a high value on detecting infection when present. If there is a low clinical likelihood of disease, the panel recommends not retesting. When the clinical likelihood of COVID-19 is moderate to high, in the event that the initial test is negative, the panel recommends retesting for COVID-19 1-2 days after the initial test.
The IDSA panel makes no recommendations for or against using rapid (i.e., test time ≤ 1hour) versus standard RNA testing in symptomatic individuals suspected of having COVID-19 (knowledge gap).
The IDSA panel suggests SARS-CoV-2 RNA testing in asymptomatic individuals who are either known or suspected to have been exposed to COVID-19 (conditional recommendation, very low certainty of evidence).
For this recommendation, a known contact is defined as someone who has had direct contact with a confirmed case.
A suspected exposure occurs when someone is working or living in a congregate setting such as long-term care, a correctional facility, or a cruise ship in which there is an outbreak. The time frame during which to do post-exposure testing is five to seven days after the exposure.
The IDSA panel suggests against SARS-CoV-2 RNA testing in asymptomatic individuals with no known contact with COVID-19 who are being hospitalized in areas with a low prevalence of COVID-19 in the community (conditional recommendation, very low certainty of evidence). Remarks: • Asymptomatic individuals are defined as those with no symptoms or signs of COVID-19. • A low prevalence of COVID-19 in the community was considered communities with a prevalence of
The IDSA panel recommends direct SARS-CoV-2 RNA testing in asymptomatic individuals with no known contact with COVID-19 who are being hospitalized in areas with a high prevalence of COVID-19 in the community (conditional recommendation, very low certainty of evidence).
The idea is to do rapid testing to identify individuals entering the hospital either for other illnesses or for procedures, in order to be able to institute appropriate precautions and decrease the likelihood of nosocomial transmission and/or transmission to health care personnel. It is worth noting that the recommendations do not address testing in areas with a low or intermediate prevalence of COVID-19. In the absence of an official guideline-based-recommendation, the decision about testing needs to made by the local hospital system.
Recommendations 11, 12, and 13
The IDSA panel recommends SARS-CoV-2 RNA testing in immunocompromised asymptomatic individuals who are being admitted to the hospital and in asymptomatic individuals prior to receiving immunosuppressive therapy regardless of exposure to COVID-19. It is also recommended to test asymptomatic individuals planning to undergo major surgery.
The rationale for this recommendation is that patients who are to receive chemotherapy, other immunosuppressive procedures, or surgery are at high risk if they have COVID-19 and may be better off delaying the procedure.
Some additional issues were addressed, though not in the form of additional recommendations. It was clarified that some individuals remain nucleic acid positive after their symptoms resolve, and sometimes even after seroconversion. It is not clear if those individuals remain infectious to others. The recommendations did not address serologic testing for public health surveillance.
The IDSA panel suggests against SARS-CoV-2 RNA testing in asymptomatic individuals without a known exposure to COVID-19 who are undergoing a time-sensitive aerosol generating procedure (e.g., bronchoscopy) when PPE is available (conditional recommendation, very low certainty of evidence). Last updated May 6, 2020 and posted online at www.idsociety.org/COVID19guidelines/dx. Please check website for most updated version of these guidelines. Supplementary materials are available here. Version 1.0.1 Remarks: • The panel defined time-sensitive procedures as medically necessary procedures that need to be done within three months
The IDSA panel suggests SARS-CoV-2 RNA testing in asymptomatic individuals without a known exposure to COVID-19 who are undergoing a time-sensitive aerosol generating procedure (e.g., bronchoscopy) when PPE is limited, and testing is available (conditional recommendation, very low certainty of evidence).
• The panel defined time-sensitive procedures as medically necessary procedures that need to be done within three months.
• Testing should be performed as close to the planned procedure as possible (e.g. within 48- 72 hours).
• Decisions about PPE will be dependent on test results because of limited availability of PPE. However, there is a risk for false negative test results, so caution should be exercised for those who will be in close contact with/exposed to the patient’s airways.
The decision to test asymptomatic patients will be dependent on the availability of testing resources.
This recommendation does not address the need for repeat testing if patients are required to undergo multiple procedures over time.