Srinagar: Doctors Association Kashmir (DAK) on Monday said chest CT scan detects more Covid-19 cases than swab tests.
“Chest CT is better at diagnosing Covid-19 than swab tests,” said DAK President and influenza expert Dr Nisar ul Hassan.
“RT-PCR, which uses swab for the detection of Covid-19 infection has a sensitivity of 60%-70%. That means more than 30% of positive cases may be missed by the test.
Another swab test which is now widely used is rapid antigen test. It has a sensitivity of around 50 percent, which raises the possibility of missing more than half of the positive cases,” he said.
“Studies have shown that CT has a greater sensitivity ranging from 86% and 98% for detecting positive cases, while having a lower false negative rate than the lab tests,” Dr Nisar said.
“In a study of 1,014 patients published in the Journal Radiology, researchers in china found that 88% of the patients showed chest CT findings indicative of Covid-19, while RT-PCR test detected only 59 percent of cases. Among those with negative swab test results, 75 percent had positive chest CT findings.”
He said not only is CT an effective tool for the diagnosis of Covid-19, it can also tell us about the severity of the disease. That will guide treatment and save lives. “At SMHS hospital, we see many patients who test negative on lab tests, but show CT features consistent with Covid-19 disease,” Dr Nisar said.
“Many infected patients go unreported as only RT-PCR positive cases are reported. We have a large number of patients who test positive through CT, but are not reported.”
“Low sensitivity of swab tests implies that many patients with Covid-19 infection may not be identified and consequently may not be isolated from healthy population. And these individuals will continue to spread the disease in the community,” he said.