Early and accurate detection is essential to prevent the spread of neo-crown and to provide appropriate care for patients. The gold standard for diagnostic use is the nasopharyngeal swab, which requires insertion of a long shaft into the nasal cavity to collect samples from the back of the nose and throat. But the procedure is technically challenging, often uncomfortable for the patient, and requires a shortage of personal protective equipment.
Other methods of collecting specimens - including from oropharyngeal swabs and sputum - have also been tested in small studies, but it is uncertain which method is best for detecting the virus.
In a new study published in EBioMedicine, researchers at Brigham and Women's Hospital conducted a systematic review and meta-analysis, analyzing data from more than 3,000 specimens to compare the three methods mentioned above. The team found that sputum testing was more sensitive for detecting viral RNA that causes new crowns, while oropharyngeal swab testing was less sensitive. Regardless of the collection method used, the earlier the sample was collected after the onset of symptoms, the higher the detection rate.
Jonathan Li, PhD, corresponding author in the Department of Infectious Diseases at Brigham, said, " Accurate diagnosis of neo-crown has implications for health care, return to work, infection control and public health. The gold standard in our hospital is the nasopharyngeal swab, but there is still a lot of uncertainty about which sampling method is the most effective and sensitive. Our study shows that testing sputum significantly improves the detection rate of SARS-CoV-2, thus supporting the use of this type of test as a valuable method for diagnosing and monitoring newly crowned patients."
The authors identified 11 studies that met the criteria from more than 1,000 studies. These studies included results from a total of 3,442 respiratory specimens.
The team examined the frequency with which each collection method produced positive results.
For nasopharyngeal swabs, the detection rate was 54 percent. For oropharyngeal swabs, it was 43 percent; for sputum, it was 71 percent. The rate of virus detection was significantly higher in sputum than in oropharyngeal swabs or nasopharyngeal swabs.
All three tests had the highest detection rates within a week of symptom onset.
Lee said, "The earlier the better in testing, because the accuracy of diagnosis increases after the onset of symptoms, independent of the site of sampling." "Unlike antibody tests, false-positive qPCR tests rarely occur when using these methods to diagnose new crowns early in the disease."
