COVID 19 Other investigations

By Dr Deepu Changappa Cheriamane

Laboratory tests

The most common ancillary laboratory findings in a study of 138 hospitalized patients were the following.

lymphopenia

increased prothrombin time (PT)

increased lactate dehydrogenase

Other commonly identified abnormalities include:

mild elevated inflammatory markers (CRP 89 and ESR)

elevated D-dimer

mildly elevated serum amylase: 17% patients (study of 52 cases)

frank acute pancreatitis has not been reported

mildly deranged liver function tests are common, primarily elevated alanine aminotransferase (ALT) and aspartate aminotransferase (AST)

bilirubin rise is generally mild

alkaline phosphatase (AKP) and gamma‐glutamyl transferase (GGT) levels remain normal

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Complications

COVID Radiology investigation

By Dr Deepu Changappa Cheriamane

Chest X ray 

 It doesn't have any sensitivity or specificity in diagnosing COVID, but can lead to diagnosis with strong suspicion and further referral for PCR.

HRCT Thorax

Multiple radiological organizations and learned societies have stated that CT should not be relied upon as a diagnostic/screening tool for COVID-19. On 16 March 2020, an American-Singaporean panel published that CT findings were not part of the diagnostic criteria for COVID-19. However, CT findings have been used controversially as a surrogate diagnostic test by some.

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Other investigations

COVID19 Diagnostic tests

By Dr Deepu Changappa Cheriamane

RT-PCR

The definitive test for SARS-CoV-2 is the real-time reverse transcriptase-polymerase chain reaction (RT-PCR) test. It is believed to be highly specific, but with sensitivity reported as low as 60-70% and as high as 95-97%. Meta-analysis has reported the pooled sensitivity of RT-PCR to be 89%. Thus, false negatives are a real clinical problem, and several negative tests might be required in a single case to be confident about excluding the disease.

Its sensitivity is predicated on time since exposure to SARS-CoV-2, with a false negative rate of 100% on the first day after exposure, dropping to 67% on the fourth day. On the day of symptom onset (~4 days after exposure) the false negative rate remains at 38%, and it reaches its nadir of 20% three days after symptoms begin (8 days post exposure). From this point on, the false negative rate starts to climb again reaching 66% on day 21 after exposure.

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Radiology investigations

COVID clinical presentation

By Dr Deepu Changappa Cheriamane

Clinical presentation

COVID-19 typically presents with systemic and/or respiratory manifestations. Some individuals infected with SARS-CoV-2 are asymptomatic and can act as carriers. Some also experience mild gastrointestinal or cardiovascular symptoms, although these are much less common. 

The full spectrum of clinical manifestation of COVID-19 remains to be determined. Symptoms and signs are non-specific:

Common

fever (85-90%)

cough (65-70%)

disturbed taste and smell (40-50%) 

fatigue (35-40%)

sputum production (30-35%)

shortness of breath (15-20%)

Less common

myalgia/arthralgia (10-15%)

headaches (10-36%)

sore throat (10-15%)

chills (10-12%)

pleuritic pain

Rare

nausea, vomiting, nasal congestion (<10%), diarrhea (<5%)

palpitations, chest tightness

hemoptysis (<5%)

confusion, seizures, paraesthesia, altered consciousness

stroke(most commonly cryptogenic)

COVID-19 sufferers have reported high rates of disturbances of smell and taste, including anosmia, hyposmia, ageusia, and dysgeusia. The numbers of patients affected vary and current evidence points more towards a neurological than a conductive cause of the olfactory dysfunction. 

Various reports suggest patients with the disease may have symptoms of conjunctivitis, and those affected, may have positive viral PCR in their conjunctival fluid. However a meta-analysis of over 1,100 patients found that conjunctivitis was only present in 1.1% cases. A small case series found conjunctivitis to be the only clinical manifestation in some patients with COVID-19.

Cutaneous lesions may also be seen, similar to many other viral infections. In a cohort of 88 patients, 20% developed skin disease, most commonly an erythematous rash. Most of the skin abnormalities were self-limited, resolving in a few days.

Pediatric

In the main, the clinical presentation in children with COVID-19 is milder than in adults. Symptoms are similar to any acute chest infection, encompassing most commonly pyrexia, dry cough, sore throat, sneezing, myalgia and lethargy. Wheezing has also been noted. Other less common (<10%) symptoms in children included diarrhea, lethargy, rhinorrhea and vomiting.

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Diagnostic tests

COVID - Epidemiology

By Dr Deepu Changappa Cheriamane

Epidemiology

As of July 2020, the number of cases of confirmed COVID-19 globally is over 11 million affecting virtually every territory, other than isolated South Pacific island states and Antarctica, according to an online virus tracker created by the medical journal, The Lancet, and hosted by Johns Hopkins University. As of June 2020, the United States had more than two million cases, Brazil more than one million, with Russia and India with >500,000 cases. 

The R0 (basic reproduction number) of SARS-CoV-2 has been estimated between 2.2 and 3.28 in a non-lockdown population, that is each infected individual, on average, causes between 2-3 new infections. 

The incubation period for COVID-19 was initially calculated to be about five days, which was based on 10 patients only. An American group performed an epidemiological analysis of 181 cases, for which days of exposure and symptom onset could be estimated accurately. They calculated a median incubation period of 5.1 days, that 97.5% became symptomatic within 11.5 days (CI 8.2 to 15.6 days) of being infected, and that extending the cohort to the 99th percentile results in almost all cases developing symptoms in 14 days after exposure to SARS-CoV-2.

As of June 2020 the number of deaths from COVID-19 passed half a million globally. The case fatality rate is ~2-3%. It is speculated that the true case fatality rate is lower than this because many mild/asymptomatic cases are not being tested, which thus skews the apparent death rate upwards.

A paper published by the Chinese Center for Disease Control and Prevention (CCDC) analyzed all 44,672 cases diagnosed up to 11 February 2020. Of these, ~1% were asymptomatic, and ~80% were classed as "mild". 

Another study looked at clinical characteristics in COVID-19 positively tested close contacts of COVID-19 patients. Approximately 30% of those COVID-19 positive close contacts never developed any symptoms or changes on chest CT scans. The remainder showed changes in CT, but ~20% reportedly developed symptoms during their hospital course, none of them developed severe disease. This suggests that a high percentage of COVID-19 carriers are asymptomatic.

In the Chinese population, 55-60%% of COVID-19 patients were male; the median age has been reported between 47 and 59 years.

Pediatric

Children seem to be relatively unaffected by this virus, or indeed other closely-related coronaviruses.with large cohort studies reporting that 1-2% of COVID-19 patients are children. However, there have been cases of critically-ill children with infants under 12 months likely to be more seriously affected. A very low number of pediatric deaths has been reported . In children, male gender does not seem to be a risk factor. The incubation period has been reported to be shorter than in adults, at about two days.

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Clinical presentation