Challenges in the virtual assessment of COVID-19 infections in the community

Introduction

Pneumonia is a major complication of COVID 19 infection that can lead to respiratory failure, ICU admission, or death. While 80% of COVID-19 cases are considered mild,¹ this figure includes cases of pneumonia that were considered non-severe based on American Thoracic Society (ATS) definitions.² The ATS definition of severe pneumonia is pneumonia with respiratory failure, organ failure or septic shock, or pneumonia with 3 minor criteria ( eg. respiratory rate> 30, hypotension requiring fluid resuscitation).²  Thus, mild pneumonia can still be a serious illness. Of over 1,000 COVID-19 pneumonia cases admitted to Chinese hospitals, 84% met this definition of mild illness.³

Family physicians are being encouraged to provide virtual care for COVID-19.^4,5 How to determine which COVID-19 cases are mild and appropriate for care in the community during virtual assessments is unclear.⁶   This article will review recent findings to highlight challenges family physicians may face in providing virtual assessments for adults with suspected COVID-19 infections.

What is considered a ”mild” COVID-19 infection?

Most studies of COVID-19 patients have been limited to hospitalized cases.^3,7 Information regarding milder infections is limited. A U.S. Centre for Disease Control (CDC) report of 4,226 COVID-19 cases reported 21-31% were hospitalized, 5-12% were admitted to an ICU, and 2-3% died.⁸ While this suggests that 70%-80% of COVID-19 infections are ‘mild’ and not requiring hospitalization, this varied with age. Hospitalization occurred in 14-21% of young adults, 21-30% of adults 45-64 years of age, 29-44% of adults aged 65 -74 years, 31-59% of those 75-84 years, and 31-70% of those 85 years of age and older.⁸ Thus, anywhere from 30%-80% of adults may have mild disease, depending on age.

There is little published information about the clinical characteristics of adults with mild non-pneumonia disease. The National Institutes of Health (NIH) in the United States recently defined mild COVID-19 illness as respiratory symptoms “without shortness of breath or abnormal imaging”.⁹   Moderate illness is considered “evidence of lower respiratory disease by clinical assessment or imaging with SpO2>93% on room air…”. Patients with moderate or severe disease are recommended to be hospitalized,^6,9 and most hospitalized COVID-19 patients will have pneumonia.³ Thus, the absence of pneumonia is key in differentiating mild from moderate disease. Without imaging, family physicians will need to rule out pneumonia clinically during virtual assessments.  

Can the characteristics of pneumonia in adults admitted to hospital help inform virtual assessments?

In 1,099 COVID-19 cases of pneumonia admitted to over 500 Chinese hospitals, 84% were mild and 16% were severe.³ In mild pneumonia cases, 43% did not have a fever, 32% did not have a cough, and 85% did not have shortness of breath. In 46% a chest x ray was normal.³ Of 5700 COVID-19 cases admitted to hospitals in New York city, 70% had a temperature <38C.⁷ The respiratory rate was >24 breaths/minute in only 17% and the heart rate was >100 beats/minute in 43%.⁷ These are typical characteristics that have been proposed for use in virtual assessments,⁵ many of which may be normal in those who require hospitalization.

Even the symptoms of mild and severe pneumonia overlap broadly.  In mild pneumonia, typical symptoms on admission were cough (67%), fever (43%), fatigue (38%), sputum (33%), dyspnea (15%) and myalgias (14%).³ In severe pneumonia, symptoms were cough (71%), fever (48%), fatigue (40%), sputum (35%), dyspnea (38%), and myalgias (17%).³ While chest exam findings were not reported, 84% of mild and 95% of severe cases had abnormal chest CT findings.³ Symptoms assessed during virtual assessments may be absent in patients with radiologic features of mild or even severe COVID-19 pneumonia.  Notably, the absence of dyspnea cannot be relied upon to rule out pneumonia. 

Oxygen saturation measurements have been proposed for inclusion in virtual assessments.⁵ In 50% of patients admitted to New York city hospitals, the oxygen saturation was 95%.⁷ The NIH definition of moderate disease includes an SaO2>93%.⁹  An oxygen saturation <93% is defined as  severe pneumonia⁹ and is associated with increased mortality.¹⁰  This suggests a limited role for oxygen saturation in differentiating mild from moderate disease. By the time oxygen saturation is declining, disease may already be advanced and severe.  Identifying pneumonia early may be critical. Mortality in  mild pneumonia cases admitted to hospital was 0.1% compared to 8.1% in severe pneumonia.³

Are there validated tools that can rule out community-acquired pneumonia without the need for imaging?

An American Thoracic Society and Infectious Diseases Society of America (ATS/IDSA) 2019 guideline for  community-acquired pneumonia (CAP) advised clinical signs and symptoms were inaccurate for diagnosis in the absence of imaging.² A previous American College of Chest Physicians guideline suggested the absence of abnormal vital signs and a clear chest examination could reduce the likelihood of pneumonia sufficiently that chest imaging was not needed.¹¹ Vital signs included a heart rate>100 bpm, a respiratory rate>24 breaths/min, and oral temperature >38 C.¹¹  A more recent systemic review also found that the absence of abnormal vital signs and a normal pulmonary exam could significantly reduce the likelihood of pneumonia being present.¹²  

The negative likelihood ratio (LR-) for the absence of these findings was 0.10.¹² This means in  younger adults (ages 20-64) with a prevalence of COVID-19 pneumonia of 20-30%,⁸ the absence of these findings could reduce the risk that pneumonia is present to 2.4%-4%.  For older adults (65 and older) with a pneumonia prevalence of 30-50%,⁸ the likelihood of pneumonia when all findings are absent would be 4% - 9%. However, these low risks include a normal chest examination, which would not be part of a virtual assessment.    

Where absence of abnormal vital signs alone were used, the LR- was 0.24.¹² Relying on this in virtual assessments would reduce the likelihood of pneumonia in younger adults to 6% - 10%. In older adults with a pneumonia prevalence of 30%-50%, normal vital signs could reduce the chance that pneumonia was present to 10%-19%. Given this risk for pneumonia and the high fatality rates in the elderly,^3,8 imaging would seem warranted even where vital signs are normal.  In younger adults, the absence of these characteristics may reduce the need for a chest xray sufficiently, but would require accurate measurements of vital signs to achieve this level of certainty.

Can validated pneumonia severity ratings be used to identify adults with COVID-19 at low risk for mortality, such that even if pneumonia is missed, there is a low risk of death?

The ATS/IDSA guideline recommends the use of the Pneumonia Severity Index/Patient Outcomes Research Team (PSI/PORT) score to identify adults with low, moderate and high risk pneumonia.¹³ A PSI score < 70 is classed as low risk and appropriate for outpatient management, with a 30-day mortality  <1%.¹⁴ However, even where adults had a PSI score>70 indicating an elevated risk, the 30-day mortality remained <1% if the following were absent: altered mental status, heart rate > 125 bpm, respiratory rate > 30 /min, systolic blood pressure<90mmHg, and an oral temperature <35C or > to 40C.¹⁴ However, these mortality rates reflect what can be expected with outpatient antibiotic treatment. Low risk adults with COVID-19 infections would not receive a specific treatment. Thus, the PSI mortality estimates may not apply in COVID-19 associated CAP.

Are there any COVID-19 specific tools for predicting disease severity or the need for admission?

A recent systematic review examined 10 models for predicting a severe prognosis or the need for admission in COVID-19 patients.¹⁵ They concluded all studies had serious flaws such that their performance under actual clinical conditions was unknown. None were recommended for clinical use currently. Some models relied on information not available in virtual encounters, such as C-reactive protein and CT scoring.  A similar conclusion was reached by an Oxford group after assessing systematic reviews and guidelines.¹⁶ At present, there are no validated COVID-19 specific tools to assist family physicians in deciding if community care is appropriate or not.¹⁷

Conclusions

Assessing the risk for pneumonia in virtual assessments is critical for determining who requires hospital care and who does not.^6,9 The NIH notes “given that pulmonary disease can rapidly progress, patients with moderate COVID-19 should be admitted to a health care facility”.⁹ Given the risks when pneumonia is present, a low threshold for obtaining imaging is needed. This may be particularly important for older individuals where pneumonia symptoms may be atypical or absent, and mortality is high.  However, while mortality is highest in the elderly, CDC data indicates severe COVID-19 complications occur in adults of all ages.⁸  

Family physicians need to be aware of the limitations of virtual assessments for suspected COVID-19 disease. In-person assessments and imaging will be needed in many instances to allow for the early identification of pneumonia and appropriate hospital care.^6,9  Whether these in-persons assessments should be provided by family physicians, in emergency departments or in established COVID Assessment Centres is a further consideration.  Clearly, research is urgently required to improve the evidence base for identifying mild COVID-19 disease in community contexts. Relying on virtual assessments in the absence of valid clinical assessment tools and rigorous evaluations may do more harm than good if patients have severe pneumonia by the time they are referred to hospital.

Dr. McIsaac MD MSc is a staff physician in the Ray D. Wolfe Department of Family Medicine, Sinai Health, Toronto, and an Associate Professor in the Department of Family and Community Medicine of the University of Toronto

Dr. Upshur MD,MA,MSc is Professor in the Department of Family and Community Medicine and the Dalla Lana School of Public Health, University of Toronto and Associate Director, Lunenfeld-Tanenbaum Research Institute, Sinai Health, Toronto

Ms. Kukan MSc is a Research Coordinator working with Dr. McIsaac on grant funded research in the Granovsky-Gluskin Family Medicine Centre, Sinai Health, Toronto.

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