A review of chest radiographic patterns in mild to moderate novel corona virus disease 2019 at an urban hospital in Ghana

Summary Introduction The novel corona virus disease 2019 (COVID-19) was diagnosed in Wuhan, China in December 2019 and, in Ghana, in March 2020. As of 30th July 2020, Ghana had recorded 35,142 cases. COVID-19 which can be transmitted by both symptomatic and asymptomatic individuals usually manifest as pneumonia with symptoms like fever, cough, dyspnoea and fatigue. The current non-availability of a vaccine or drug for COVID-19 management calls for early detection and isolation of affected individuals. Chest imaging has become an integral part of patient management with chest radiography serving as a primary imaging modality in many centres. Methods The study was a retrospective study conducted at Ga East Municipal Hospital (GEMH). Chest radiographs of patients with mild to moderate disease managed at GEMH were evaluated. The age, gender, symptom status, comorbidities and chest x-ray findings of the patients were documented. Results 11.4 % of the patients had some form of respiratory abnormality on chest radiography with 88.9% showing COVID-19 pneumonia features. 93.8% showed ground glass opacities (GGO), with 3.1% each showing consolidation (CN) only and CN with GGO. There was a significant association between COVID-19 radiographic features and patient's age, symptom status and comorbidities but not with gender. Conclusion Most radiographs were normal with only 11% showing COVID-19-like abnormality. There was a significant association between age, symptom status and comorbidities with the presence of COVID-19 like features but not for gender. There was no association between the extent of the lung changes and patient characteristics. Funding None declared


INTRODUCTION
The novel corona virus disease 2019 (COVID-19) was first diagnosed in Wuhan, China in December 2019 [1][2][3][4] and named Corona Virus Disease-2019 by the World Health Organization (WHO) on February 13, 2020. 5 Ghana recorded its first two cases on 12 th March 2020 both of which were imported. 6 As at 30 th July, 2020, Ghana had recorded 35,142 cases with 31,286 recoveries and 175 deaths. 7 COVID-19 patients usually have a pneumonia and show symptoms like fever, cough, dyspnoea and fatigue and less commonly rhinorrhoea, sore throat, loss of smell, loss of taste and diarrhoea. [8][9][10] The disease can be transmitted by both symptomatic and asymptomatic individuals. 8,11 There is currently no widely accepted vaccine or drug for treatment of corona virus disease 2019. Early detection and isolation of affected individuals from the general population is key in preventing the spread of the disease. 12 The gold standard for diagnosing COVID-19 is viral nucleic acid assay test by reverse transcription polymerase chain reaction (RT-PCR). This method of diagnosis has a high sensitivity but fraught with challenges like long processing time, relative unavailability, sampling errors and insufficient stability. 12 Chest imaging has become an integral part of the management of COVID-19 pneumonia.
In several centres, chest radiography is seen as a primary imaging modality for patient management. 1 Its acceptance has been potentiated by the long turn-around time of RT-PCR tests and the fact that it is easier to decontaminate compared to computed tomography (CT) scan which is seen as a more sensitive modality. 8 The American College of Radiology (ACR) therefore recommends the use of portable chest radiography in the management of COVID-19 patients to facilitate easy decontamination of the equipment. 2,8 Chest radiography has a low sensitivity (69%) compared to CT scan (97%) and RT-PCR (91%) in diagnosing COVID-19 but has the potential of predicting disease outcome in the current pandemic. 1 Reports on the nature and distribution of abnormalities on chest radiography in COVID-19 patients are varied. Interpretation of chest xray (CXR) findings may be confounded by underlying comorbid conditions. 12 A multinational consensus statement from the Fleischner Society reported in the July 2020 edition of the CHEST journal made recommendations on the use of chest imaging in COVID-19 disease based on three severity scenarios. Chest imaging should only be used in mild disease when the patient is at a high risk of disease progression. Chest imaging was recommended for moderate to severe and severe disease especially in situations with worsening respiratory status. The group of experts further suggested that in resource constrained communities where CT scan is not readily accessible chest x-ray could be used except in situations where there is severe respiratory compromise. 13 The most common findings on chest radiography are lung consolidation (CN) and ground glass opacity(GGO). 2,14 These changes tend to be in multiple lobes compared to changes in community acquired bacterial pneumonia which tend to involve one lobe on one side of the lung. They tend to be bilateral and have lower zone distribution but pleural effusion is rare. 2,8,10 A lot of studies have been done on imaging patterns and role in the management of COVID-19 during this pandemic. No large study has been done on some of these findings which will build local capacity in the management of the condition. This study was designed to document the radiographic features in patients with mild and moderate COVID-19 disease and also find out if there is a relationship between the radiographic findings and patient characteristics. The study also sought to find out if chest radiography had a role to play in the management of mild to moderate COVID-19 patients.

METHODS
The study is a retrospective study conducted at Ga East Municipal Hospital (GEMH). Ethical clearance was obtained from the Ghana Health Service Ethics Review Committee (GHS-ERC 006/05/20). Codes, rather than personal identifiers were used throughout the process of data collection and analysis to ensure anonymity and maintain patient confidentiality.
The chest radiographs used in this study were images of patients with mild to moderate disease managed at the Ga East Municipal Hospital between 11 th April, 2020 and 17 th July, 2020. Ga East Municipal Hospital is a modern state of the art 100 bed-capacity hospital located in the Ga East Municipality in the Greater Accra Region of Ghana. It serves communities on the eastern side of Accra and Aburi in the Eastern Region of Ghana. This facility has since the onset of COVID-19 been used as a treatment centre for patients with mild and moderate disease.
Chest radiographs of patients were acquired using a Philips Duradiagnost F30 digital radiography equipment. For most of the patients, the images were taken in posteroanterior projections with an object image distance of 1.8m and at the end of inspiration. Twenty patients could not stand for their radiograph to be taken hence had their images taken in the anteroposterior projections. The images were reviewed by two general radiologists with between 8 and 11 years of experience and consensus was reached on the findings before they were documented.
The age, gender, symptom status, co-morbidities and chest x-ray findings of the patients were also documented. Chest x-ray findings were documented based on a method adopted by Wong et al. 8 The pattern of opacification was grouped into consolidation, ground glass opacity, pulmonary nodules and other (if finding did not fit any of these patterns). The disease distribution was recorded as peripheral dominance, perihilar dominance or neither as well as in the upper, middle or lower zones of the lung. The site of the lung abnormality was noted as right, left or bilateral. The presence of pleural effusion and non-respiratory findings were also noted. The extent of the disease was quantified by assigning a score of 0-4 to each lung depending on the extent of involvement by consolidation or GGO (0 = no involvement; 1 = <25%; 2 = 25-50%; 3 = 51-75%; 4 = >75% involvement). The age, gender, symptom status, presence or absence of the comorbidities as well as the imaging findings were summarised using tables and charts.
Tests of association, Pearson's R and Pearson Chi-Square were used to find relationships between features suggestive of COVID-19 and age, gender, symptom status and comorbidities as well as between the lung finding score and age, gender, symptom status and comorbidities. The radiologists were blinded to symptom status and comorbid conditions during the evaluation.

RESULTS
Chest radiographs of 334 patients were evaluated out of which 194 (58.1%) were that of males and 140 (41.9%) were that of females. The mean age of the patients was 40.2 years with a standard deviation of 14.8 years. The 30-39-year age-group had the highest number of patients, 99 (29.6%) followed by 20-29-year age-group 64(19.2%) and 40-49-year age-group, 62 (18.6%) as shown on Table 1.    The extent of lung disease score for the patients with radiographic features consistent with COVID-19 pneumonia was also documented. Nine patients (28.1%) had a score of 1; 5 patients (15.6%) had a score of 2; another 5 patients (15.6%) manifested a score of 8; 4 patients (12.5%) had a score of 6; while 3 patients (9.4%) had a score of 5. Each category of radiographs with scores of 3, 4 and 7 was noted in 2 patients (6.25%).     This seems to suggest that the relative proportions of male to female with COVID-19 depends on the relative proportion of male and females at the location where the study was done and not on the gender per se. 8,12 The mean age of the study population was 40.2 years. This was close to 42.9 years reported by Wu et al, but lower than that reported by Wong et al, Zhou et al and Ai et al who reported 56 years, 51 years and 52.4 years respectively. 12,[15][16][17] The younger generation tend to have milder disease, it is therefore not surprising that conducting a study at a centre which sees only mild and moderate cases will have a lower mean age. 1 This belief is further supported by the fact that about two-thirds (67.4%) of the patients in this study were between 20 and 49 years of age.
This study also found out that there were more than 76% asymptomatic patients among the study population. This could be explained by the age characteristics of patients enrolled in the study. The finding will also support the notion that asymptomatic patients may be infecting people more than symptomatic patients.
Close to 25% of the patients had comorbid conditions. Hypertension was the commonest among the patients, with 61.6% of them having hypertension either alone or with other conditions. This was followed by diabetes mellitus 24.6% either alone or with hypertension and Asthma as the third 8.6%. These findings compare favourably with what was reported by Toussie et al, in their study to find out the outcome of COVID-19 pneumonia in young adults and middle age individuals. 1 Only 11.4% of the patients showed radiographic features suggestive of COVID-19 pneumonia. This seems to support the suggestion by the Fleishner Society to limit radiography to moderate to severe and severe disease. 13 Similar statements have been made by ACR and Society of Thoracic Radiologists. 1 These prominent societies have also spoken against screening populations for COVID-19 with chest radiography. Again, the low yield in this study seems to confirm that notion as well.
Ground glass opacities and consolidation were the two most common features noted on chest radiography. This is consistent with what has been reported by many authorities. 1,8,12,16 This study found more GGO far in excess of consolidation which was at variance with what was found in other chest radiography studies where consolidation was the more common finding. 8 The explanation those authors gave was that it was easier to see consolidation on chest radiography than ground glass opacities. Indeed, studies that used CT scan tend to confirm that there are more patients with GGO on their chest images than consolidation. [15][16][17] Most ( Ten percent of the patients had cardiomegaly. Fifty percent of these were between their third and fifth decades. This points out a possible additional benefit of radiography in that it may also help identify patients with significant non respiratory system findings such as cardiomegaly and anterior mediastinal lesions as noted in this study.
There was a significant association between the presence of radiographic features consistent with COVID-19 and patient's age, presence of symptoms and comorbidities but not with gender. The study by Toussie et al 1 showed that, like this study, there was a significant association between age and the presence of some comorbidities with abnormal COVID-19-like finding and severity of these findings on chest x-ray. 1 While they found gender had an association with the presence of abnormal COVID-19-like findings, our study did not show that association. In addition, Toussie et al 1 found an association between age, gender and some comorbid conditions like HIV and obesity and the severity of the chest radiography findings, our study did not find that. However both studies did not find any association between severity of lung findings and conditions like hypertension and diabetes which formed the majority of the comorbidities of our patients. 1 Being a retrospective study, we encountered some challenges as some patients' symptoms and possible comorbidities were not accurately documented and it was difficult to obtain such information after the discharge of the patients. Again, none of them had follow up radiographs after the initial radiograph, thus could not document the progress of the disease.

CONCLUSION
The study showed that most of the patients did not have any significant finding on chest radiograph with only about 11% showing significant abnormality. Among those with abnormalities there was a significant association between their age, symptom status and comorbidities with the radiographic findings but no such association was found with gender. There was also no association between the extent of the lung changes and patient characteristics. This study therefore supports the position of the Fleischner Society's stance on the use of chest radiograph in mild disease.