Coronavirus — Testing Guidance – Rapid COVID-19 Platforms in Outpatient Specialty Care and Primary Care Settings — Clinical Pathway

Testing Guidance – Rapid COVID-19 Platforms in Ambulatory Settings

Current Available Platforms

LumiraDX: Antigen based
CHOP IDDL lab-developed RT-PCR, molecular

Testing Sensitivity and Specificity and Community Disease Prevalence

Real-time PCR tests, such as the lab-developed test created and validated by our Infectious Diseases Diagnostics Laboratory, offer the highest sensitivity and specificity of commercially available platforms.

Antigen based testing have the benefit of being more rapid (15-30 minute testing time) and are available as point-of-care (POC) test.

They have a slightly decreased sensitivity and specificity, which leads to increased rates of false positives, and more importantly, false negatives. With a community prevalence of about 2% in the pediatric age group, a rapid test such as LumiraDx would have a false negative rate of about 2.4% compared to a PCR. This means that for every 100 patients who would be correctly identified as having COVID on PCR, 2-3 patients will receive a negative result on a rapid antigen test. For this reason, use of antigen-based testing platforms needs to be thoughtfully considered.

Recommendations for Office-based Testing

Symptomatic Patients

Patients with clinical syndromes consistent with a diagnosis of COVID-19 should receive a rapid test as a first line when visit to an office is indicated for clinical management. Ambulatory settings who can set up ‘testing only’ visits should do this to utilize in office antigen testing; when not possible refer to drive through for PCR.

Rapid Test Interpretation

POSITIVE Rapid Test
- If this test is positive, the patient should be diagnosed with acute COVID-19 infection.
- Confirmation with a repeat rapid test or a PCR-based test is not necessary.

NEGATIVE Rapid Test
- If this test is negative, a second test with a PCR-based modality may be warranted based on the following exceptions.
- Exceptions For patients where there was
  - A convincing pre-test probability of a diagnosis of COVID-19, such as concerning symptoms (as per our clinical pathway)
  - A symptomatic patient with a documented exposure (per our exposure definitions), utilize a confirmatory PCR if rapid negative
  - A symptomatic patient with presence of a potential high-risk situation, such as an immunocompromised family member at home

Pre-procedural Clearance or Upcoming Planned Admission or AGP

Patients who have a planned upcoming procedures or admissions should receive a PCR-based test only.

Clearance of Quarantine at 7 Days After Exposure

Asymptomatic patients who have been exposed to a known case, and have completed 7 days of quarantine, may receive a test to truncate their quarantine, ideally at or after the 7 days from exposure. If the test is being performed on or after day 7 of quarantine (day 7 after exposure), either PCR or antigen tests may be used.

CDC recommendations do allow for an earlier test, as early as day 5 of quarantine, with the recommendation that quarantine should still continue to day 7, even with a negative result. If a test is performed on day 5 or 6 of quarantine, only a PCR-test should be used. The patient and caregivers should be provided guidance at the time of testing that even with a negative result, quarantine must continue till day 7.

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The clinical pathways are based upon publicly available medical evidence and/or a consensus of medical practitioners at The Children’s Hospital of Philadelphia (“CHOP”) and are current at the time of publication. These clinical pathways are intended to be a guide for practitioners and may need to be adapted for each specific patient based on the practitioner’s professional judgment, consideration of any unique circumstances, the needs of each patient and their family, and/or the availability of various resources at the health care institution where the patient is located.

Accordingly, these clinical pathways are not intended to constitute medical advice or treatment, or to create a doctor-patient relationship between/among The Children’s Hospital of Philadelphia (“CHOP”), its physicians and the individual patients in question. CHOP does not represent or warrant that the clinical pathways are in every respect accurate or complete, or that one or more of them apply to a particular patient or medical condition. CHOP is not responsible for any errors or omissions in the clinical pathways, or for any outcomes a patient might experience where a clinician consulted one or more such pathways in connection with providing care for that patient.