Nitin Khanna, MD Spine Care Specialists, Munster, IN, U.S.
Testing in Orthopedics & Spine Clinical Settings: The Unknown Category
As COVID-19 infection rates begin to slow, elective surgery is ramping up and facilities are screening patients for COVID-19. However, it is important to understand COVID-19 testing abilities and limitations in this new reality. Simply utilizing a questionnaire and temperature check are inadequate to screen patients, though due to the significant testing limitations, it tends to serve as the absolute minimum acceptable standard. Many different tests are currently performed, but each should be interpreted with care and caution in order to provide the safest possible environment for patients and staff.
Preoperative COVID-19 Screening Tests
A recent report from China described 34 cases of patients who were unknown to be positive for COVID-19 and who had undergone elective surgery. All patients developed postoperative COVID-19 pneumonia, which led to 15 patients being admitted into the intensive care unit, 7 of whom died.1 This report highlights the importance of knowing a patient’s COVID-19 status prior to consideration of a surgical intervention.
Many different tests are currently available, but the turnaround times vary from hours to days. Clearly, tests with faster turnaround times are more efficient. Furthermore, they decrease the likelihood that the patient has had an “interval exposure” between the test and the time of surgery. For example, imagine that a patient gets tested and has surgery 5 days later. Despite instructions to self-quarantine, there is a possibility that the patient may be exposed to COVID-19 during that 5-day period.
The rapid COVID-19 ID NOW test from Abbott, touted as a 5-minute test, was highly anticipated but has recently been heavily criticized. The U.S. Food and Drug Administration (FDA) issued a warning regarding accuracy compared with side-to-side comparisons with the Cepheid polymerase chain reaction (PCR) test.2 A group from New York University reported almost a one-third increase in false negative rates for the rapid COVID-19 ID NOW test compared with standard PCR testing.3
The False Negative Test
A poorly obtained sample, such as from a superficial swab, can be an obvious reason for a false negative. Even in the case of a technically well-procured nasopharyngeal sample, it is important to understand the pathogenesis of the virus as well as the reasons for a false negative. COVID-19 is not a binary disease; rather, it is a spectrum of illness.5 Sicker patients with higher viral loads have higher positive testing rates compared with patients with recent infection and lower viral loads.
There has been recent interest in the FDA-approved at-home saliva test developed at Rutgers.4 However, this test will likely have a significant false negative rate because the virus can be present in the nasopharynx; thus, if this region is not tested, a false negative result is possible. There are no head-to-head data available comparing the saliva test to the Cephiad PCR test. Furthermore, it is unclear whether the at-home saliva test is accurate enough to utilize for preoperative elective surgery.
Of note, all of the aforementioned tests can fail. Once the virus seeds the lung tissue, bronchoscopy lavage has demonstrated positive COVID-19 results despite negative results on an oropharyngeal swab PCR testing.6 Chest computed tomography images with ground glass appearance are a nonspecific finding and have been incorporated into the diagnostic algorithms for COVID-19 treatment. However, at this point, no study has suggested utilizing CT scans to screen patients for elective surgery.
COVID-19 Positive vs COVID-19 Unknown vs COVID-19 Negative
It is universally accepted that a COVID-19–positive patient should postpone a truly elective procedure because the risk to the patient and staff far outweigh the benefit of an early intervention. Furthermore, it is becoming clear that we are unable to classify any patient as COVID-19 negative. The COVID-19–unknown classification has to be the one utilized for all patients who require elective surgery. All the precautions and procedures to decrease risk of transmission are key to managing all elective orthopedic and spine surgery cases.
Antibody testing is a major area of debate and confusion. Many tests flooded the market without FDA clearance. In early May, the FDA revised its position on antibody testing:
We unfortunately see unscrupulous actors marketing fraudulent test kits and using the pandemic as an opportunity to take advantage of Americans’ anxiety. Some test developers have falsely claimed their serological tests are FDA approved or authorized. Others have falsely claimed that their tests can diagnose COVID-19 or that they are for at-home testing, which would fall outside of the policies outlined in our March 16 guidance, as well as the updated guidance. Also, since that time, the FDA has become aware that a concerning number of commercial serology tests are being promoted inappropriately, including for diagnostic use, or are performing poorly based on an independent evaluation by the NIH [National Institutes of Health].7
The FDA recently announced the antibody testing approval for Roche and Abbott, which both have high sensitivity and specificity immunoglobulin G tests.8,9 The goal of antibody testing is to demonstrate previous exposure to COVID-19 and possible immunity. However, the overreliance on the presence of antibodies to COVID-19 has been emphasized.
“Right now, we have no evidence that the use of a serologic test can show that an individual has immunity or is protected from reinfection,” said Maria van Kerkhove, the World Health Organization’s COVID-19 technical lead.10 A positive antibody test result cannot and should not embolden a health care worker to ignore the standard COVID-19 precautions.
As we continue to navigate COVID-19 elective surgery pathways, we must put a primary focus on the safety of patients and health care workers through education. Understanding the benefits and limitations of the various COVID-19 tests will be crucial to optimizing our path forward.
- Lei S, Jiang F, Su W, et al. Clinical characteristics and outcomes of patients undergoing surgeries during the incubation period of COVID-19 infection. April 4, 2020. EClinicalMedicine.
- Coronavirus (COVID-19) update: FDA informs public about possible accuracy concerns with Abbott ID NOW point-of-care test [news release]. U.S. Food & Drug Administration. May 14, 2020.
- Basu A, Zinger T, Inglima K, et al. Performance of the rapid Nucleic Acid Amplification by Abbott ID NOW COVID-19 in nasopharyngeal swabs transported in viral media and dry nasal swabs, in a New York City academic institution [preprint].https://www.biorxiv.org/content/10.1101/2020.05.11.089896
- Coronavirus (COVID-19) update: FDA authorizes first diagnostic test using at-home collection of saliva specimens [news release]. U.S. Food & Drug Administration. May 8, 2020.
- Farkas J. COVID-19. The Internet Book of Critical Care. Posted March 2, 2020. Updated May 6, 2020.
- Wang W, Xu Y, Gao R, et al. Detection of SARS-CoV-2 in different types of clinical specimens [published online ahead of print March 11, 2020]. JAMA.
- Shah A, Shuren J. Insight into FDA’s revised policy on antibody tests: prioritizing acess and accuracy. FDA Voices. May 4, 2020.
- Keown A. Roche wins emergency approval for its COVID-19 antibody test. BioSpace. May 4, 2020.
- Keown A. Abbott earns emergency use authorization for another COVID-19 antibody test. BioSpace. May 11, 2020
- Coronavirus: double warning over antibody tests. BBC News. April 18, 2020.