COVID-19 screening of asymptomatic patients admitted through emergency departments in Alberta: a prospective quality-improvement study
Bibliographic record
Abstract
<h3>Background:</h3> The prevalence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection among asymptomatic patients admitted to hospital has implications for personal protective equipment use, testing strategy and confidence in the safety of acute care services. Our aim was to estimate the positivity rate of reverse transcription polymerase chain reaction (RT-PCR) testing among people admitted to hospital without symptoms of coronavirus disease 2019 (COVID-19) in Alberta, Canada. <h3>Methods:</h3> Between Apr. 9 and May 24, 2020, we screened for COVID-19 symptoms and tested for SARS-CoV-2 infection in all consecutive adult patients (≥ 18 yr) admitted via emergency department to 3 Alberta hospitals. We summarized the parameters of the epidemic curve and assessed the performance of symptom screening versus RT-PCR results on nasopharyngeal or oropharyngeal swab samples. <h3>Results:</h3> The study period encompassed Alberta’s initial epidemic curve, with peak active cases per 100 000 of 71.4 (0.07%) on Apr. 30, 2020, and 14.7 and 14.6 at the beginning (Apr. 9, 2020) and end (May 24, 2020), respectively. Testing for SARS-CoV-2 infection (64.9% throat and 35.1% nasopharyngeal swabs) was done on 3375 adults (mean age 51, standard deviation 21, yr; 51.5% men). None of the asymptomatic patients (<i>n</i> = 1814) tested positive, and 71 of those with symptoms tested positive (<i>n</i> = 1561; 4.5%, 95% confidence interval [CI] 3.6%–5.7%). Sensitivity of symptom screening (v. RT-PCR) was 100% (95% CI 95%–100%), and specificity was 55% (95% CI 53%–57%). Posttest probabilities for prevalence of SARS-CoV-2 infection ranging from 1.5 to 14 times the peak prevalence of active cases during the study did not change when we assumed lower sensitivity (92%). <h3>Interpretation:</h3> In a region with low disease prevalence where protocolized symptom assessment was in place during the admission process, we did not identify people admitted to hospital without COVID-19 symptoms who were RT-PCR positive. There may not be additive benefit to universal testing of asymptomatic patients on hospital admission in a setting of low pretest probability and strong public health containment.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.003 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".