Departments of Medicine (Ravani, Manns) and Community Health Sciences (Ravani, Manns), and O'Brien Institute for Public Health (Ravani, Manns), and Libin Cardiovascular Institute of Alberta (Ravani, Manns), Cumming School of Medicine, University of Calgary, Calgary, Alta.; Departments of Medicine, and Medical Microbiology and Immunology (Saxinger, Chandran), Faculty of Medicine and Dentistry, University of Alberta; Infection Prevention and Control (Chandran), Alberta Health Services, Edmonton, Alta.; Department of Microbiology, Immunology and Infectious Diseases (Fonseca), Cumming School of Medicine, University of Calgary; Alberta Precision Laboratories Calgary (Fonseca), Alberta Health Services, Calgary, Alta.; National Microbiology Laboratory (Murphy), Public Health Agency of Canada; Alberta Precision Laboratories Edmonton (Murphy), Alberta Health Services, Edmonton, Alta.; Department of Emergency Medicine (Lang), Cumming School of Medicine, University of Calgary, Calgary, Alta.; Alberta Health Services (McDougall), Edmonton, Alta.
CMAJ Open. 2020 Dec 18;8(4):E887-E894. doi: 10.9778/cmajo.20200191. Print 2020 Oct-Dec.
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.
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.
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 ( = 1814) tested positive, and 71 of those with symptoms tested positive ( = 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%).
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.
无症状住院患者中严重急性呼吸综合征冠状病毒 2（SARS-CoV-2）感染的流行情况对个人防护设备的使用、检测策略以及对急性护理服务安全性的信心产生影响。我们的目的是估计加拿大艾伯塔省无症状住院的 2019 年冠状病毒病（COVID-19）患者中逆转录聚合酶链反应（RT-PCR）检测的阳性率。
2020 年 4 月 9 日至 5 月 24 日，我们对通过急症室收治的 3 家艾伯塔省医院的所有成年患者（≥18 岁）进行了 COVID-19 症状筛查，并检测了 SARS-CoV-2 感染情况。我们总结了流行曲线的参数，并评估了症状筛查与鼻咽或口咽拭子 RT-PCR 结果的表现。
研究期间涵盖了艾伯塔省的初始流行曲线，2020 年 4 月 30 日，每 100000 人中有 71.4 例（0.07%）为活跃病例，2020 年 4 月 9 日和 5 月 24 日的起始（4.3%）和结束（5.4%）分别为 14.7 和 14.6。对 3375 名成年人（平均年龄 51 岁，标准差 21 岁）进行了 SARS-CoV-2 感染检测（64.9%的咽喉拭子和 35.1%的鼻咽拭子）。无症状患者（=1814 例）均未检测出阳性，而有症状的患者中有 71 例检测出阳性（=1561 例；4.5%，95%置信区间[CI]3.6%-5.7%）。症状筛查的敏感性（v. RT-PCR）为 100%（95%CI 95%-100%），特异性为 55%（95%CI 53%-57%）。当我们假设敏感性较低（92%）时，感染 SARS-CoV-2 的流行率从 1.5 倍到 14 倍于研究期间活跃病例的峰值，患病率的后验概率并没有改变。
在疾病流行率较低的地区，在入院过程中进行了规范化的症状评估，我们没有发现没有 COVID-19 症状但 RT-PCR 阳性的住院患者。在低检测前概率和强大的公共卫生控制环境下，对无症状入院患者进行普遍检测可能不会增加收益。
