Early and accurate diagnose of COVID-19 plays an important role in disease treatment and control. According to the 7th version diagnosis and treatment program by the National Health Commission of China [8], the method of definitive diagnosing suspected cases of COVID-19 involves RT-PCR testing, deep sequencing and immunoglobulin (Ig) M/E. And the typical lung CT findings is demonstrated to help in early screening of patients with suspected COVID-19. Based on the results of this current study, we do not recommend routine lung CT examination for screening COVID-19 in low-risk areas among patients undergoing selective arthroplasties.
The typical clinical manifestation of COVID-19 is not specific, while the reported symptoms range from mild to severe, with some severe patients leading to death. The most commonly symptoms are fever, cough, fatigue, various degrees of pneumonia and dyspnea. Also, there are some less common symptoms including headache, myalgia, nasal obstruction, runny nose, expectoration and diarrhea [1]. In our current study, there were 1085 patients with fever and without other specific symptoms of COVID-19. And these 1085 patients were excluded COVID-19 by special fever clinic and respiratory department consultation with RT-PCR or lung CT scan again. Our experience for preoperative and postoperative fever is that patient and attendant isolation is the first step and that the second step is to consult special fever clinic and respiratory department with or without further to screen RT-PCR testing or lung CT scan.
RT-PCR testing has been regarded as the gold standard for COVID-19 diagnosis. Although gene sequencing has shown that SARS-CoV-2 shared around 80% identity sequencing with SARS-CoV, which also resulted in 8096 confirmed deaths all over the world in 2002-2003 [12]. Many previous studies suggested that RT-PCR of COVID-19 was different from SARS-CoV, which had modest viral loads in the early stage and peaked approximately 10 days after symptoms onset [13]. Xiao et al [14] explored the correlation between clinical characteristics and viral shedding in COVID-19 patients and they found that prolonged viral nucleic acid conversion tended to be older with more comorbidities. In our study, RT-PCR testing was also identified as the gold standard for COVID-19 diagnosis. And there is no confirmed patient with COVID-19. Therefore, RT-PCR is recommended as an effective screening test in low-risk areas.
Lung CT is considered as the primary screening tool for diagnosis and monitoring the care of COVID-19, which helps in early detection of lung abnormalities for ruling out patients with highly suspected cases, especially in patients with an initial negative RT-PCR testing result [10]. Ai et al [15] reported the results of lung CT features and RT-PCR testing of 1014 cases and found the sensitivity and specificity of lung CT imaging for COVID-19 diagnosis was 97% and 25%, respectively. And of 308 patients with negative RT-PCR result, the lung CT images showed COVID-19 with lung lesions consisting of GGO (41%) and consolidation (56%). In our study, the most common features found on the lung CT images were nodular lesions (26.3%) and striplike lesions (19.7%), which needed no special treatment. However, the positive rate of GGO and consolidation on the lung CT image were only 5.1% and 2.3%, respectively. And all these patients with positive lung features were ruled out COVID-19 by clinical manifestation, contact and travelling history and negative RT-PCR. The diagnostic effectiveness of lung CT in our current population is almost zero.
What is more, exposure to radiation with lung CT scan could be a potential risk for patients receiving elective surgery. The dose length product for a lung CT scan was average 110 (range 78 to 160) mGy/cm, which is much higher than the dose of chest radiographs [16]. As a result, we do not recommend routine lung CT examination for diagnosing COVID-19 in low-risk areas after strict screening for symptoms, history and RT-PCR.
There are several limitations in the present study. First, this is a retrospective study and may have some data bias. Second, we do not manage a real patient with COVID-19, which may result in some experience loss. On the other hand, the flowchart of prevention and control COVID-19 in our hospital was worthy of reference. While our hospital has maintained an admission rate more than 60% from pandemic, there is no conformed patient with COVID-19 during hospital stay.
In conclusion, after strict screening for symptoms, history (contact COVID-19 patients or travelling to high-risk areas) and RT-PCR testing, lung CT image was not recommended as routine examination for patients receiving selective surgery from the low-risk areas of COVID-19.