COVID-19: Diagnosis and pathology

Publishing date: 14th October 2020

Disclaimer: The materials provided are for educational purposes only. The following advice is based on the presentations of Dr Ian Scott and Professor Dominic Dwyer of 14 Oct 2020. Whilst all reasonable care has been taken in preparing these materials, including the accuracy of the information supplied, MIPS and the presenters do not accept any liability whatsoever arising out of the use or reliance of the information provided.

Behind the diagnostic process of COVID-19

The COVID-19 pandemic has triggered unrivalled efforts to develop rapid, affordable and accurate essays to diagnose COVID-19 infection. Key to guiding public health interventions of contact tracing and patient isolation to prevent further spread of the virus is laboratory confirmation of infection¹. It remains crucial that healthcare practitioners comprehend the relationships between test results from virologic and serologic testing and the performance of these diagnostic assays in order to diagnose and manage COVID-19 affected patients adequately^2,3.

Covid-19 diagnostic challenges

Early symptoms of COVID-19 (fever, cough, dyspnoea) are non-specific
There is an evolving knowledge of multiple non-respiratory conditions
- De novo COVID-19 caused
- Exacerbations of underlying non-COVID chronic conditions
Presence of secondary infections
Multifaceted phenotype
Delayed diagnoses related to COVID transmission risk:
- Patients not presenting for evaluation because of infection risk
- Impaired access to diagnostic modalities
- Decreased productivity from infection control measures

Covid-19 laboratory testing considerations

When could you suspect a ‘false positive’ nucleic acid test (NAT)?
- Persons not meeting the CDNA case definition for testing or with no epidemiological links to COVID-19 cases
- Indeterminate or discordant laboratory results
- RT-PCR with high cycle threshold
- When a batch of samples test positive on the same run

Serology indications:
- Use retrospective diagnosis
- Identify false negative nucleic acid testing (NATs)
- Confirm unexpected positive NAT: especially important in settings of low incidence
- Monitor asymptomatic infections (close contacts of cases or healthcare workers)
- Use of serosurveys

Key advice for healthcare practitioners

Strategies for reducing diagnostic error

Ask yourself “what else could this be?”
- Develop greater situational awareness
- Avoiding base rate neglect
- Be mindful of pre-existing co-morbidities
- Be aware of distinctive features of COVID-19 syndromes
Engage in peer discussions and interdisciplinary case reviews
Utilise rapid, accurate, point of care diagnostic tests
Repeat PCR testing in cases with high index of suspicion

Good medical practice Code of Conduct

3.2 Good patient care

Ensuring you have adequate knowledge and skills to provide safe clinical care
Maintaining adequate records
Only recommending treatments when there is an identified therapeutic need and/or a clinically recognised treatment, and a reasonable expectation of clinical efficacy and benefit for the patient
Taking steps to alleviate patient symptoms and distress, whether or not a cure is possible.

4.3 Effective communication

Listening to patients, asking for and respecting their views about their health, and responding to their concerns and preferences
Encouraging patients to tell you about their condition and how they are currently managing it
Informing patients of the nature of, and need for, all aspects of their clinical management.
Discussing with patients their condition and the available management options
Confirming that patients understands what you have said and responding their questions, keeping them informed about their clinical progress
Taking all practical steps to ensure that arrangements are made to meet patients’ specific language.

References

¹Gulholm T, Basile K, Kok J, Chen SA, Rawlinson W. Laboratory diagnosis of severe acute respiratory syndrome coronavirus 2. Pathology. 2020 Oct 8.

²Chau CH, Strope JD, Figg WD. COVID‐19 Clinical Diagnostics and Testing Technology. Pharmacotherapy: The Journal of Human Pharmacology and Drug Therapy. 2020 Aug;40(8):857-68.

³Scott IA. COVID‐19 pandemic and the tension between the need to act and the need to know. Internal Medicine Journal. 2020 Aug;50(8):904.

Useful resources

Coronavirus (COVID-19) Information for the public, health professionals and media

Coronavirus (COVID-19) daily update

AHPRA Responding to COVID-19

Coronavirus (COVID-19) information for GPs - RACGP

COVID-19 Support - ACRRM

Resources for dental practitioners - ADA

ADA Dental service restrictions in COVID-19

MIPS relevant resources

COVID-19 resources

How we're assisting members during the COVID-19 pandemic