Utility of repeat testing for COVID-19: Laboratory stewardship when the stakes are high

Rearigh, Lindsey; Hewlett, Angela; Fey, Paul D.; Broadhurst, M. Jana; Brett-Major, David M.; Rupp, Mark E.; Schooneveld, Trevor Van

doi:10.1017/ice.2020.397

Cited by 3 publications

(3 citation statements)

References 9 publications

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“…A more recent study by Rearigh et al (11) conducted at an academic medical centre in Omaha, Nebraska also found similar results on a smaller cohort. Of the 275 patients tested, only 2 patients tested positive on serial testing after an initial negative result, for a yield of less than 1.0%.…”

Section: Discussionsupporting

confidence: 58%

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Diagnostic yield of serial SARS-CoV-2 testing in hospitalized patients

Frenette

Loo

2022

Official Journal of the Association of Medical Microbiology and

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BACKGROUND: The detection rate of SARS-CoV-2 by polymerase chain reaction (PCR) varies depending on the time since exposure and is highest around the time of symptom onset. It is conceivable that patients who are incubating SARS-CoV-2 may screen negative at admission and develop transmissible but undetected asymptomatic or pre-symptomatic disease while in hospital. The incidence of COVID-19 in Montreal, Canada started to increase in December 2020. In anticipation of a much larger rise after the holiday period, the McGill University Health Centre implemented serial SARS-CoV-2 testing for all admitted patients on day 5 and 10 after admission, to evaluate the clinical utility of serial SARS-CoV-2 testing among patients who test negative on admission screening. METHODS: We retrospectively analyzed the diagnostic yield of SARS-CoV-2 serial testing for patients admitted between January 4, 2021 and April 30, 2021. RESULTS: 1,505 patients underwent serial testing at day 5 and 841 patients underwent serial testing at day 10. Only 10 patients were positive on serial testing at day 5 and only 12 patients were positive on serial testing at day 10, for a yield at day 5 and day 10 of 0.7% and 1.4% respectively. CONCLUSIONS: The yield of serial SARS-CoV-2 testing was 0.7% at day 5 and 1.4% at day 10. We found that the yield of serial testing was higher when the community incidence was higher and could be considered in this situation. Policies which target repeat testing towards symptomatic or exposed individuals appear to be effective in identifying those with a positive test while admitted but testing negative upon admission.

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Section: Discussionsupporting

confidence: 58%

“…Therefore, some clinicians recommend serial SARS-CoV-2 testing (testing at multiple points in time) for admitted patients with a high pre-test probability of infection (6). Some authors report that universal serial testing increases diagnostic yield considerably (10), while others have reported that universal serial testing is of very limited yield (11,12).…”

mentioning

confidence: 99%

Diagnostic yield of serial SARS-CoV-2 testing in hospitalized patients

Frenette

Loo

2022

Official Journal of the Association of Medical Microbiology and

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“…Thus, repeat testing should be performed despite the fact that it increases the turnaround time and adds cost to the healthcare system. Diagnostic stewardship (correct time and method to collect samples) can be applied to decrease the number of inconclusive results, which in turn will conserve laboratory supplies [ 21 ].…”

Section: Discussionmentioning

confidence: 99%

Incidence of COVID-19 infection and its variation with demographic and clinical profile: lessons learned at a COVID-19 RT-PCR laboratory in Nagpur, India

Gade

Nag

Mishra

et al. 2022

Access Microbiology

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Introduction. The coronavirus disease 2019 (COVID-19) pandemic emerged as a global health crisis in 2020. The first case in India was reported on 30 January 2020 and the disease spread throughout the country within months. Old persons, immunocompromised patients and persons with co-morbidities, especially of the respiratory system, have a more severe and often fatal outcome to the disease. In this study we have analysed the socio-demographic trend of the COVID-19 outbreak in Nagpur and adjoining districts. Methods. The study was conducted from April to December 2020. Nasopharyngeal and oropharyngeal swabs collected from suspected cases of COVID-19 were tested using reverse-transcription polymerase chain reaction (RT-PCR) at a diagnostic molecular laboratory at a tertiary care hospital in central India. Patient-related data on demographic profile and indication for testing were obtained from laboratory requisition forms. The results of the inconclusive repeat samples were also noted. The data were analysed using SPSS v24.0. Results. A total of 46 898 samples were received from April to December 2020, of which 41 410 were included in the study; 90.6 % of samples belonged to adults and 9.4 % belonged to children. The overall positivity rate in the samples was 19.3 %, although it varied over the period. The yield was significantly high in the elderly age group (25.5 %) and symptomatic patients (22.6 %). On repeat testing of patients whose first test was inconclusive, 17.1% were positive. There was a steady increase of both the number of tests and the rate of positivity in the initial period of the study, followed by a sharp decline. Conclusion. We can conclude that rigorous contact tracing and COVID-appropriate behaviour (wearing a mask, social distancing and hand hygiene) are required to break the chain of transmission. Elderly people are more susceptible to infection and should follow stringent precautions. It is also important to perform repeat testing of those individuals whose tests are inconclusive with fresh samples so that no positive cases are missed. Understanding of demographics is crucial for better management of this crisis and proper allocation of resources.

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