Imaging trend and disease course in admitted COVID-19 patients

Discussion

Most of our study results pertaining to patterns of radiographic findings on both chest radiographs and CTs matched with international observations.13-16 We found patterns of single or multiple single lobar GGO with or without consolidations on serial CXRs and CTs in most of the patients at the time of admission and during their ward stays, that later became multi-lobar, mixed, and bilateral during worsening disease course leading to ICU admissions. These patterns were seen associated with increased reticulation and pleural effusions probably because of element of respiratory failure or superimposed cardiac decompensation. Patients who recovered from ICU and shifted back to ward (and later on discharged), ICU stays were approximately 5-12 days, while for the 6 patients who had prolonged ICU stays 3 died and 3 remained intubated with unknown outcome till end of study. On chest x-rays, single or multiple unilateral or bilateral opacities were seen at the time of ICU admissions in some patients, mainly at mid and lower zones. Shi et al14 categorized 81 admitted COVID-19 positive patients in 4 groups according to duration of onset of symptoms and timings of CTs, with consolidations and mixed patterns more frequent in group 3 (>1 week to 2 weeks) and group 4 (>2 weeks to 3 weeks). In our study, most of the patients fall in the group 3 category as patients who needed ICU stays developed worsening of symptoms or appearance of chest radiographic findings in a short period, warranting CTs to be performed in less than 2 weeks intervals. Lomoro et al15 found typical CT features of bilateral multi-lobar GGO with peripheral distribution in approximately 60% of 58 laboratory confirmed COVID-19 cases in their single-center retrospective study. Although we did not include pregnant patients, such kind of mixed or complete consolidations were also observed by Liu et al12 while observing data of 16 COVID-19 positive pregnant patients and comparing these with 14 non-pregnant positive patients. Bai et al13 found that while considering CT findings of peripherally distributed GGOs, fine reticular opacity, and vascular thickenings in a study that reviewed 424 CT interpretations of 205 patients from 7 Chinese hospitals, radiologists were able to distinguish COVID-19 from other viral pneumonias with high specificity and moderate sensitivity.

Another important aspect to highlight in our study were patients’ characteristics, the age and gender. We found males to be more affected than females, and middle-aged group (40-60 years) showing variable and at times devastating worsening of symptoms or chest radiographic abnormalities leading to ICU admissions. However, this group recovered from ICU care. Although, advanced age (of 60 years and above) and with co-morbidities or immunocompromised statues were the ones who had prolonged ICU stays and unknown outcomes (with persistent intubations and no favorable signs of recoveries). These are the patients who are amongst the vulnerable group of any pandemic, other being the paediatric population that was not included in our study.6 Concept of ‘herd immunity’ stems from the effects of individual immunity scaled to the level of the population (referring to the indirect protection from infection conferred to susceptible individuals when a sufficiently large proportion of immune individuals exist in a population). Therefore, vaccination programs aim to establish this herd immunity so that those who cannot be vaccinated, including the young and immunocompromised, are still protected against disease.8,9 One important measure to evaluate the impact of disease spread is the case fatality rate (CFR), that is the proportion of deaths attributed to a certain disease among all individuals diagnosed with that disease over a specified period. Although fatality rate in our study measured 2.8%; however, it seems not an accurate figure as some death cases might be left unchecked or might not get hospital admissions. It is worth noting that there is still significant uncertainty in the CFR for COVID-19 due to variation in the testing capacity of each country, selection bias for individual testing, and officially attributed deaths to COVID-19. Case fatality rate is also sensitive to variation in age and presence of comorbidities among populations. Consequently, CFRs may differ considerably over time and between countries. Like many other infectious diseases, a non-uniform COVID-19 CFR has been reported across age groups, with many deaths occurring among individuals 60 years old or greater.9,10

We also found that more than half of the patients were non-Saudis (expatriates) and those too amongst the low socioeconomic statuses (workers; drivers, mechanics, housekeeping). This finding though not statistically significant however, emphasizes on clinical relevance of such group being affected more or earlier probably due to their shared livings or accommodations, social lifestyles and close contacts or environmental interactions because of job requirements. Corona virus typically spreads via droplets when people are in sustained, proximity to someone sick.17 Studies have shown that factors that increase risk of catching the corona virus are enclosed or congested spaces, crowds, close contact with others, and difficulty social distancing.18,19 It is wise to suggest that more close interactions with others, the longer the interactions, and greater the number of people involved in interactions, the higher the risk of COVID-19 spread. Three Cs, referring to closed spaces, crowded places, and close-contact settings need to be avoided.

It is also worth mentioning that although CT chest has high sensitivity to detect Covid-19 lung changes.20,21 However, its role as a screening tool is still debated and is usually reserved for documentation of complications (cavitation, bronchiectasis, pulmonary embolism, and pneumothoraces) if clinically suspected. Routine chest radiographs can provide useful information to check for disease course particularly with mild disease or resolving changes. Also, portable radiography of the chest may be considered for serious patients at bedside rather engaging them for CT scans that require both meticulous care for patient shifting as well as preparation at the scanner and fumigation after the scanning, thereby interrupting diagnostic assessments for other scheduled or booked cases in limited machine settings and hospitals. In our study, we also reserved CT chests for only patients with unfavorable clinical course or worsening of symptoms and to document any complications. We did not include paediatric patients in our study, however, it is also worth stating that CT features may be have different common pattern in paediatric age group like consolidation with surrounding halo sign as presented by Xia et al.22 Other limitations of our study included lack of documentation of clinical and laboratory variables (like oxygen saturation, C-reactive protein, lactic acid dehydrogenase levels, D-dimers, lymphopenia), and ongoing medications (or treatment options) that could have detected or predicted the course of disease or complications.

In our single-center short-duration study, we focused on certain demographic information of patients and radiographic findings/patterns to look for clinical course of disease and its outcome. No quantitative lobe score was obtained for imaging findings.Patients with initial presentations as shortness of breaths, comorbidities, abnormal chest radiographs (on admissions and during ward stays), and mixed radiographic findings on CT studies required ICU admissions (highlighting CT utilization during course of infection).23 However, larger scale and longer duration multi-center studies are required to validate such findings with special consideration of prognostic relevance of certain clinical and laboratory parameters (and even certain blood groups). Further research is needed to evaluate for duration of acquired immunity after natural infection in such patients, and clinical utility of antibodies (in plasmas of affected cases) for the treatment of unaffected population and for the vaccine preparation.24 Also, follow-up of COVID-19 recovered ICU patients (who required intubations during their stays) should not be overlooked and dealt with great clinical concern. Proper evaluation and attention needs to be considered in future studies, as COVID-related lung fibrosis (idiopathic pulmonary fibrosis) can develop in such patients due to increased vulnerability towards alveolar injury because of both viral affects and barotrauma leading to even life-time dependency for oxygen. Future considerations in terms of assessment of risk factors and treatment options (antiviral, immunomodulatory, and anti-inflammatory drugs) to avoid such complications need to be emphasized.

With no vaccine yet available for general masses and many countries are striving to develop promising vaccine results for prevention of COVID-19, herd immunity largely depends upon contracting the disease and developing antibodies (natural immunization) which itself is a slow process considering worldwide lockdowns or curfews, restricted travel, and limited social gatherings.2,8,9 Using personal protective measures (like face masks, face-shields, gloves and gowns), practicing frequent hand hygiene (hand washing or hand-rub using use of hand sanitizers) and social distancing (avoiding close contacts, social gatherings or crowded places) remain the choices to limit widespread human-to-human transmission (through droplets, contaminated hands or surfaces) and disease-spread, meanwhile moving forward and adopting to a new-normal.5 With its variable clinical course and disease presentation, COVID-19 remains an unanticipated threat lurking in communities and hospitals, clogging the healthcare systems in nearly all over the world.8

Although many of our study observations are similar to international studies, presenting local data and results is important to add information to global network. This does not only help to identify any regional variability in disease presentation or course due to possible emergence of different virus strains affecting different populations (as more recent studies are indicating emergence of genetic drift and mutations in genome of virus that may affect surges in infected population and also can hinder or limit effectiveness of vaccine),25 but also provides an opportunity to establish unified or consensus-based international guidelines and policies (once similar virus trend across the globe has been found and documented through world-wide studies).

In conclusion, COVID-19 is seen mostly affecting males, with less than half of symptomatic admitted patients showing abnormal chest radiographic findings as peripheral opacities on chest radiographs at or during their admissions while demonstrating mostly GGOs (with or without consolidations) on CT studies. Most of the young and middle aged patients requiring ICU admissions recover however elderly patients with co-morbidities or immunocompromised statuses, worsening radiographic findings or complications may show unfavorable outcomes (such as, prolonged ICU stays or deaths).