The explosion of COVID-19 on a global scale represents an epochal change in lifestyle, in personal relationships and puts the world medical and scientific community in front of a unique challenge; for the first time the whole of humanity is faced with a disease still largely unknown regarding virus itself, but also its pathophysiological damages and, more than all, its treatment.
None health-system, whether the single professional or the national and international health structures, can refrain from giving its contribution. In this scenario, some countries found themselves facing the emergency first, others had a few weeks to prepare and organize their defences. At present, however, despite the efforts of all, we still find ourselves having to chase a virus that runs faster than we do.
Within the pandemic declared by the WHO last March (6), the primary role turns out to be to identify early and certainly patients positive for COVID-19: to start as soon as possible experimental therapies and to isolate positives to effectively counteract the spread of virus transmission. The massive influx of patients suffering from respiratory symptoms, risked tilting, and sometimes had got, the emergency’s nets of many countries, among the most developed in the world with national health systems considered at the top of the world. The solution was to change the face of hospitals, to make them suitable for the management of these patients: to create dedicated pathways, often having to use professional resources normally employed in other activities.
Why should surgeons handle with patients with a viral infection of respiratory tract? We, as Trauma and Acute Care Surgeons (TACS), believe that, as during others MCIs, surgeons should be the first choice. Because TACS are used to manage many patients from EDs and to work closely with emergency physicians and/or ICU staff; they are prepared for these challenging clinical scenarios, and have the adequate skill to manage suspected COVID19 post-triage patients.
During exceptional periods, Acute Care Surgery’s staff (both medical and nursing staff) is crucial: it can relieve the pressure on the EDs and take care of the post-triage management, also it being used to the management of complex surgical patients and their medical complications more than ultra-specialised surgical branches and certainly more inserted in the network relationships of modern hospitals, cause their daily routines (7).
Medical scores are widely used to help physicians in ranking patients by dubious medical diagnoses. Also Emergency Surgeons still face frequent with these clinical scenarios: an example is lower right abdominal pain, suspected for acute appendicitis, which represents one of the most frequent for which a surgical evaluation is required: in this clinical scenario the use of risk scores, such as the AIR Score, is of great use: by collecting clinical information and laboratory data it allows to group patients into subgroups at progressive risk of being affected by it (8).
COVID-19 erupted in early 2020 worldwide, clinicians are fighting against a new disease, largely unknown, and with a high virulence. Diagnostic tests are still perfectible and, even more seriously, not always available. Diagnosis of COVID-19 is still difficult; symptoms appear compatible with flu-like ones, different and aspecific. Regarding the epidemiological history of the patients, as contacts with positives or residence / travelling in endemic areas, in our opinion, the latter appear to be of limited utility: since the disease spread worldwide and because submerged portion of asymptomatic positives, thus distorting the aspect.
False-negative results in SARS-CoV-2 nucleic acid detection are caused by various reasons, such as the quality of the samples taken, the number of viruses and the stage of the disease. There are limited data on the rates of false-positive and false negative results for the various RT-PCR tests available. If a negative result is obtained from a patient with a high suspicion for COVID-19, additional specimens should be carried out, especially if only upper respiratory tract specimens were collected, as we do in our ED, prolonging the time needed for diagnosis (9).
Lung CT has been proposed as diagnostic tool, but its findings dependent on experience of radiologists and disease stage, and it needs specific "dirty" machines and results in more expensive and time-consuming step.
The British Society of Thoracic Imaging (BSTI) recommends CT in seriously ill patients with suspected COVID-19 after chest x-ray is uncertain or normal (10). On the other side of the Atlantic Ocean, the American College of Radiology recommends CT for hospitalised, symptomatic patients with specific clinical indications, but radiological findings appears not to exclude a priori diagnosis (11).
Also, CT appears to be more specific in the later stages of COVID19, or on disease progression (12).
Ai and colleagues (13) showed that the sensitivity of chest CT in suggesting COVID-19 was 97% (95%CI, 95-98%, 580/601 patients) in positive RT-PCR samples, but 308/413 (75%) patients with negative RT-PCR results, showed radiological findings.
The analysis of prospectively collected data of the first 100 patients admitted to our department and waiting for viral RNA RT-PCR confirmation, highlighted four significant risk factors for COVID-19 infection, which have become part of the Ri.S.I.Co.: age lower than 60 years, presence of ground-glass on lung-CT, an increased serum LDH and a normal neutrophil count. In order to maximize sensitivity e specificity of the score, we have identified two threshold values, allowing us to distinguish 3 groups of patients, with a progressive increase in the risk of being affected by COVID-19: low risk (Score 0-2), intermediate risk (Score 3-6), high risk (7- 9).
The use of the Ri.S.I.Co. appears easy to use in daily clinical practice: it consists of 4 variables that are normally performed; even in the evaluation of CT only the radiological identification of the ground glass areas is necessary, without any measurements, or needing to evaluate multiple radiological parameters.
The variables used are normally dosed in any patient who accesses the PS, therefore widely reproducible.
In order to determine whether the Ri.S.I.Co. was advantageous, we compared their performance measures to the most adopted diagnostic tools for COVID-19 infection: the SARS-CoV-2 detection by RT-PCR in the first upper respiratory tract specimen collection (swab) and the presence of a ground glass pattern at thoracic HRCT.
Results showed that there was not significant difference between the AUC of Ri.S.I.Co., of the first SARS-COV-2 swab and of the presence of ground glass pattern at HRCT (Ri.S.I.Co: 0,754, 95% CI: 0,640-0,868; first SARS-CoV-2 swab: 0,827, 95%CI: 0,711-0,942; TC ground glass: 0,817, 95% CI: 0,721-0,913). However, although SARS-Cov-2 swab had a high specificity (100%), its sensitivity was lower than a Ri.S.I.Co. lower than 2 (low risk group) (65,4% vs 96,2%, p<0,001). The presence of ground glass pattern at HRCT had a lower sensibility than a Ri.S.I.Co. lower than 2 (low risk group) (88,5% vs 96,2%, p<0,001) and a lower specificity than a Ri.S.I.Co. higher than 6 (high risk group) (75,0% vs 96,9%, p<0,001).
Because many hospital, likely for a policy of saving resources or for an inability to subject all patients to the examination, excluded lung CT as a diagnostic tool for COVID-19 infection, we create another score by eliminating the CT data; but, even if it performed well in the internal validation cohort, it loosed discriminating capacity in the external validation cohort. Therefore, in our opinion, lung CT is a necessary as one of the first diagnostic steps in the suspicion of coronavirus (SARS-CoV-2) infection.
Since most hospitals do not have a large number of single rooms or beds with a real insulation capacity, the stratification of patients according to the risk groups coming from the proposed Ri.S.I.Co, could be mainly used to separate admitted patients according to their risk. This could avoid low risk patients being infected from high risk patients and could avoid hospitals becoming the main Covid-19 carriers, as happened in many Italian realities. Furthermore, it could be a diagnostic tool additional to the lung-TC and to the SARS-CoV-2 detection by RT-PCR, increasing diagnostic sensibility and specificity.
During writing of the manuscript of this article, we read with interest a pre-print version of the COVID-19 early warning score (COVID-19 EWS) by colleagues from China (14): they retrospectively analyzed data from patients admitted for suspected COVID-19 (Training Dataset: 73 COVID+, 231 COVID-; Validate Dataset: 18 COVID+, 77 COVID-) and, as we did, they created an easy-to-get score for COVID-19 screening. The COVID-19 EWS included signs of pneumonia on CT, age older than 44 years, male gender, fever (in two different aspects: fever itself and fever more than 37,8°C), presence of respiratory symptoms, history of contact with confirmed COVID-19 and neutrophil-to-lymphocyte ratio. Even if some risk factors were similar to our findings (sign of pneumonia on CT, neutrophil count), others were different. Among our construction sample the contact with a COVID-19 confirmed patients, the male gender, the presence of respiratory symptoms and the age older than 44 years were not significant risk factors at logistic regression analysis. We didn’t consider fever in the analysis because fever and/or respiratory symptoms were the criteria for admission to our department. Applying the COVID-19 EWS score on our internal validation cohort, we found an AUC of 0,772 (95%CI 0,668-0,877), a sensibility of 84,6% and a specificity 67,6%. So, the performance measures of the COVID-19 EWS in our population were worse than the measures of Ri.S.I.Co. This fact could be explained in the different characteristics of the two population. First of all, our patients were older and the presence of fever and/or respiratory symptoms could be expression of other pathologies (cardiac or respiratory diseases). Among Italian population a lower number of upper respiratory tract specimen were collected than in China, without mass screening programs. This fact could reflect the lower weight of confirmed COVID-19 patients contact in predicting COVID-19 infection among our patients (many patients could have had contact with COVID-19 infected patients without knowing it). Furthermore, knowing the low sensibility of the SARS-CoV-2 detection by RT-PCR in upper respiratory tract specimen, we didn’t use it to define an infected patients. We included in the definition of “COVID-19 infected patient” also patients with negative SARS-CoV-2 swab, but with strongly suspect radiological and clinical signs, after a review by a final diagnosis committee composed of internal medicine specialists and/or pneumologists.
The limits of present study were the relatively small sample size and its observational nature. Being a study born to answer to our on-the-field need to stratify patients, we weren’t able to take a longer period of time to collect a larger sample size to obtain an instrument that we needed immediately. Furthermore, present score was developed and validated only on hospitalized patients, further studies would be necessary to understand if it is generalizable to non-hospitalized patients or on the population of other countries with different mean age, different prevalence of comorbidities and different health policies.