A heart patient who recently came from Europe messaged us, complaining of sinat (low-grade fever), sore throat, occasional dry cough and loose bowel movement. Otherwise, he felt okay and had good appetite.
We prescribed symptomatic treatment for the fever and sore throat, and oral hydration for the diarrhea. We advised him to go on isolation at home.
His symptoms, though mild, persisted after three days, so we requested to have him tested for the new coronavirus disease (COVID-19). It took another three days to get the result.
Meanwhile, his fever had completely subsided, he had no more diarrhea, but he still had mild sore throat.
His COVID-19 test result was negative. Our patient was ecstatic upon hearing the news and asked if he could mingle already with his family.
We advised him to continue his isolation and do the test again after another week. A single lab test does not rule out COVID-19, particularly in a high-risk patient like him—with a travel history preceding the development of classic COVID-19 symptoms.
There is a probability that the result might have been a false negative. That means the test failed to detect the presence of the disease.
No single perfect test
We don’t have any single perfect laboratory test for any disease. That’s why lab tests are assessed based on their sensitivity and specificity.
In a certain percentage, lab tests could miss diagnosing the disease; they overdiagnose and turn out positive when it’s supposed to be negative (false positive), or they give negative results when, in fact, the person has the disease (false negative), like what we suspect happened to our patient.
So, sensitivity is the ability of a test to correctly diagnose cases with the disease (true positive), whereas specificity is the ability of the test to correctly identify patients without the disease (true negative rate).
This is expressed as percentage. When we say a test is 80-percent sensitive and 90-percent specific, it means it can diagnose those with active disease in eight out of 10 cases; if it’s negative, it will be correct in nine out of 10 cases.
Such errors or failure to properly diagnose can be in as many as two to four out of 10 testings, again depending on the sensitivity and specificity of the test.
There are several types of test kits now approved for COVID-19 testing. Their sensitivity rate ranges from 30 percent to at best, 71 percent, depending on what the specimen used for the test was.
If just one specimen was taken, the sensitivity can be: 32 percent only for throat swabs (in two out of three cases, the virus will be missed), 53 percent for nasal swabs (one out of two), and 62 percent for sputum or phlegm (one out of three).
If multiple sites are used, it can raise sensitivity to 71 percent, but that means in 29 of 100, the virus can still be missed.
What are the causes of false positive tests? Quite a number, including cross-reaction with another infection one might have had in the past, specimen contamination, unintended laboratory technique error, etc.
Since the lab tests are really not 100-percent accurate (a good number are either false positive or false negative), usually the physician correlates it with other factors in the patient: travel history, degree of exposure, and most importantly the presence of clinical symptoms (fever, cough, colds, diarrhea, muscle pains, etc). The clinical progression of the symptoms is also important.
If one has symptoms but a negative COVID-19 test result, he or she should still be managed as a suspected case.
In short, clinical symptoms carry a heavier weight than the lab test result. As we always tell medical students and trainees: “Treat the patient and not the laboratory test result.”
Should everyone exposed to a COVID-positive individual undergo testing?
The experts don’t recommend it as routine test, especially if we have a limited supply of test kits. The exposed individuals are considered PUMs (persons under monitoring) and they should be quarantined at home for 14 days. The moment they develop any of the COVID symptoms, they’re upgraded to PUIs (persons under investigation) and testing may be done.
Even if the first test turns out to be negative, isolation should be continued, and the test is repeated after another week. Only after two consecutive negative test results can one be considered COVID-free.
Should all COVID-positive individuals be confined in a hospital? If we do that, we’ll not have enough hospital rooms and beds for everyone.
The far bigger majority, around 80 percent, will just have mild symptoms—just like ordinary flu. They can just recover at home, but under isolation.
Around 15 to 20 percent may experience shortness of breath or difficulty of breathing. These are the cases who need to be worked up further and admitted in the hospital.
When chest X-rays are done, they could show pneumonia on both lung fields. Radiologists describe the findings as a “ground-glass” appearance. This can rapidly progress because the coronavirus literally ravages the lung tissues. Most of these cases could worsen, and this advanced lung complication is called acute respiratory distress syndrome (ARDS).
With advanced modern breathing-support devices, many of these cases still survive. Worldwide, the death rate is three to four out of a hundred COVID-positive cases.
In the Philippines, the fatality rate is relatively higher, at eight to nine out of 100. It’s probably because we’re only testing the symptomatic and more severe cases.
How are we doing so far in the war against COVID-19?
We’re doing just fine, says Dr. Tony Leachon, a well-known health advocate. “Our government responses are agile and leaders of various sectors help out to save lives.”
Indeed, I can attest to that. A colleague is critically ill with severe COVID-19 pneumonia at the Philippine Heart Center (PHC) and needed medicine, which was not available locally.
Just one text to Health Undersecretary Eric Domingo, and he promptly responded that he would assist in having a compassionate-use registration for the drug.
Also one text to Dr. Joel Abanilla, the PHC director, and he immediately convened his Infectious Disease Committee to approve sourcing of the product abroad.
Just like the gallant health care front-liners, government officials are putting in long hours and exposing themselves to harm. One Department of Health director is reported to be COVID-positive, and Health Secretary Francisco Duque III is now a PUM and under self-quarantine. He’s asymptomatic, though, and we pray he remains well to lead us in this war.
“It’s amazing how people inside and outside of government are silently working on the sidelines to help save lives and curb this virus,” says Dr. Leachon.
Before the lockdown, experts forecast that we’d have close to a thousand confirmed cases by March 19. As of the same date, there were 217 confirmed cases and 17 deaths.
The numbers are still increasing daily, but the steep curve has somewhat been flattened. Though we have not stemmed the tide yet, it’s no longer as overwhelming as it was at the start of this crisis.
After the initial anxiety and paranoia, many now have the reassuring feeling that this pestilent virus could be vanquished in the end, and that God would wake us up soon from this nightmare to a beautiful, COVID-free morning. INQ