Predictors of pulmonary involvement in children with COVID-19: How
strongly associated is viral load?
Abstract
This study aimed to investigate epidemiological, clinical, and
laboratory features of children with COVID-19 to identify predictors for
pulmonary involvement. We conducted a retrospective, single-center study
of pediatric COVID-19 at a tertiary care hospital in Turkey between
December 2020 and June 2021. A total of 126 children (70 males, 55.6%)
were examined during the study period. Their mean age was 74.73 ± 81.11
months (range, 1–216 months). The most frequent COVID-19 symptoms were
fever (65.9%), cough (52.4%), and shortness of breath (18.3%). Ten
patients required noninvasive mechanical ventilation. Sixty-nine
patients (54.8%) had pneumonia. Longer duration of fever and the
presence of cough were significantly associated with pulmonary
involvement. In children with pneumonia, the C-reactive protein (CRP),
procalcitonin levels, erythrocyte sedimentation rate (ESR), and viral
load were significantly higher and lymphocyte and thrombocyte counts
were significantly lower than in children without pneumonia. The cutoff
viral load, CRP, and procalcitonin values for predicting pulmonary
involvement were 26.5 cycle threshold (Ct; 95% confidence interval
[CI], 0.54–0.74; sensitivity, 0.65; specificity, 0.56; area under
curve [AUC]: 0.647, p = 0.005), 7.85 mg/L (95% CI,
0.56–0.75; sensitivity, 0.66; specificity, 0.64; AUC = 0.656; p= 0.003) and 0.105 ng/mL (95% CI, 0.52–0.72; sensitivity, 0.55;
specificity, 0.58; AUC = 0.626; p = 0.02), respectively. High
CRP, procalcitonin levels, ESR, and viral load and low lymphocyte and
thrombocyte counts can predict pulmonary involvement in children with
COVID-19, so better management may be provided for good prognosis.
Keywords: COVID-19, children, predictor, viral load, pulmonary
involvement.
Introduction
Coronavirus disease 2019 (COVID-19), caused by a novel coronavirus, the
severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), rapidly
spread worldwide and became a major public health problem. By February
2022, almost 420 million people had been infected throughout the world,
with more than 5,840,000 deaths.1 The clinical
spectrum can vary widely from asymptomatic infection to acute
respiratory distress syndrome in adults, but it appears to result in
milder disease in children.2 However, most patients
hospitalized because of COVID-19 have pulmonary
involvement.3 To date, studies have investigated the
association between SARS-CoV-2 viral load and disease severity,
mortality, age, comorbidities, and outcomes.4Nevertheless, there is no information regarding the associations among
viral load, inflammatory biomarkers, and pulmonary involvement in
children. Therefore, we aimed to investigate the epidemiological,
clinical, and laboratory characteristics of children with COVID-19 and
compare the clinical and laboratory features of children with and
without pulmonary involvement to identify the factors affecting
pulmonary involvement.
Materials and methods
Study design, data collection, and definitions
This prospective, single-center study involved examinations of 126
children with COVID-19 at Başakşehir Çam ve Sakura City Hospital between
December 2020 and June 2021.
Among the study participants, COVID-19 diagnosis was confirmed by
reverse-transcriptase polymerase chain reaction (PCR) analysis of
samples taken from oropharyngeal and nasopharyngeal swabs. The COVID-19
patients were divided into two groups: patients with pulmonary
involvement and patients without pulmonary involvement according to
clinical symptoms, vital signs (especially respiratory rate, body
temperature, and oxygen saturation on room air) chest X-ray, computed
tomography (CT) findings and laboratory tests.
The following demographic information, clinical features, laboratory
results, and treatment modalities data were examined: age, gender,
underlying medical conditions, duration of symptoms and hospitalization,
complete blood count, liver and kidney function, inflammatory biomarkers
(procalcitonin, erythrocyte sedimentation rate [ESR], and C-reactive
protein [CRP]), biologic enzyme levels (lactate dehydrogenase and
creatine kinase), D-dimer, coagulation tests, cardiac biomarkers
(troponin-T and probrain natriuretic peptide), SARS-CoV-2 PCR, viral
load, chest X-ray, and CT scan imaging.
SARS-CoV-2 detection by RT-qPCR and viral load assessment
A combined nasopharyngeal and oropharyngeal specimen collected with a
synthetic fiber swab was inserted into a sterile tube containing 3 ml of
vNAT (viral nucleic acid isolation tampon; Bio-speedy, Bioeksen,
Istanbul, Turkey). Detection of SARS-CoV-2 RNA was accomplished by
one-step reverse transcription and real-time PCR targeting
SARS-CoV-2-specific RNA-dependent RNA polymerase and N gene fragments
using the SARS-CoV-2 Double Gene RT-qPCR kit (Bio-speedy, Bioeksen,
Istanbul, Turkey). For internal control, the kit targets the
ribonuclease (RNase) P gene. RT-qPCR was performed on the Bio-Rad CFX96
Touch instrument (Hercules, CA, USA) using the following conditions: 52
°C for 5 minutes and 95 °C for 10 seconds, 40 cycles of amplification at
95 °C for 1 second and 55 °C for 1 second. The cycle threshold (Ct)
value represents the number of amplification cycles required for the
target gene to exceed a threshold level. A low Ct value is indicative of
a high viral load. If the Ct value is below 38, it is considered
positive for SARS-CoV-2.
Statistical analysis
Statistical analysis was performed using SPSS version 22.0 (IBM, SPSS).
Data are summarized as frequencies, medians, and means with standard
deviations. Normally distributed data were assessed using means and the
Student’s t-test. The nonparametric data’s significance was assessed
using the Mann–Whitney U test. The statistical significance of
dichotomous outcomes was determined using the chi-square test, Fisher’s
exact test, the Fisher–Freeman–Halton test, and Yates’s continuity
correction. A multivariate logistic regression analysis was performed
with the variables found to be statistically significant in the
univariate analysis. A receiver operating characteristic (ROC) curve
analysis was performed to determine the cutoff levels of viral load,
CRP, and procalcitonin to predict pulmonary involvement. A value ofp < 0.05 was considered statistically significant.
The Ethics Committee at Basaksehir Cam ve Sakura City Hospital and the
Turkish Ministry of Health (Date: August 4, 2021; Decision no: 161)
approved this study.
Results
Patient characteristics and treatment modalities
A total of 126 patients were examined between December 2020 and June
2021. Of all the patients, 70 (55.6%) were male. The mean age was 74.73
± 81.11 months (range, 1–216 months). On admission, the most common
symptoms were fever (83 patients, 65.9%) and cough (66 patients,
52.4%), followed by shortness of breath (23 patients, 18.3%) and
myalgia (21 patients, 16.7%). Forty-three patients (34.1%) had
underlying medical conditions. All of 10 patients (7.9%) required
noninvasive mechanical ventilation had pneumonia. Favipiravir was given
to 15 patients (11.9%). Ninety-eight of the patients received
broad-spectrum antibiotics for possible bacterial superinfections. The
patients’ characteristics and treatment modalities are presented in
Table 1. One patient diagnosed with metabolic disease without pulmonary
involvement died. All other patients were discharged without any
complications.
Laboratory and radiological findings
On admission, the mean white blood cell count, lymphocyte count, and CRP
levels were 7903.49 ± 4751.29 thousand cells per mm3(range, 1030–24,810 thousand cells per mm3), 3302.94
± 2918.32 thousand cells per mm3 (range, 270–15,890
thousand cells per mm3) and 24.42 ± 47.65 mg/dl
(range, 0.1–280 mg/dl), respectively. Lymphopenia and neutropenia were
present in 25 (19.8%) and 28 (22.2%) patients, respectively. The
patients’ laboratory findings are presented in Table 2.
Chest X-rays were performed in all patients. While 57 (45.2%) of the
patients had normal chest X-ray findings, 69 (54.8%) patients had
potentially pathological findings. Chest CT scans of 51 patients
revealed bilateral ground-glass opacity in 62.7% of them and unilateral
ground-glass opacity in 27.5%. The patients’ radiological findings are
presented in Table 3.
Factors associated with pulmonary involvement
The patients were divided into two groups: patients with pulmonary
involvement (Group 1; n = 69) and patients without pulmonary
involvement (Group 2; n = 57). We compared the groups’
epidemiological, clinical, and laboratory characteristics. Group 1’s
mean age was significantly higher than that of Group 2. The complaint of
cough was significantly more frequent in Group 1. The durations of fever
and hospitalization were significantly longer in Group 1 than in Group
2. Lymphopenia was significantly more frequent in Group 1. Favipiravir
and low-molecular-weight heparin usage were significantly higher in
Group 1 than in Group 2. No other epidemiological or clinical
characteristics or treatment modalities demonstrated significant
differences between the two groups (Table 1).
According to the univariate analysis, total protein, creatinine levels,
CRP, procalcitonin, ESR, and viral load were significantly higher in
Group 1 than in Group 2 (p < 0.05). Lymphocyte,
monocyte, thrombocyte, and eosinophil counts; total bilirubin; troponin
T; and folate were significantly lower in Group 1 (p <
0.05; Table 2).
In the multivariate logistic regression analysis, lower lymphocyte
counts and higher ESR demonstrated a significant association with
pulmonary involvement (Table 4).
Predictors of pulmonary involvement
According to the ROC curve analysis, the cutoff levels of viral load,
CRP, and procalcitonin were 26.5 Ct (95% CI, 0.54–0.74; sensitivity,
0.65; specificity, 0.56; AUC = 0.647, p = 0,005), 7.85mg/L (95%
CI, 0.56–0.75; sensitivity, 0.66; specificity, 0.64; AUC = 0.656,p = 0.003), and 0.105 ng/mL (95% CI, 0.52–0.72; sensitivity,
0.55; specificity, 0.58; AUC = 0.626, p = 0.02), respectively
(Figures 1A, 1B, and 1C).
Discussion
This study was aimed to evaluate the clinical and laboratory
manifestations that can identify the risk of pulmonary involvement in
children with COVID-19. Our study’s major findings indicated that
increased CRP ( > 7.85 mg/L), procalcitonin (
> 0.105 ng/mL), and viral load
( < 26.5 Ct) threshold values could be a predictor for
pulmonary involvement in children with COVID-19. There is limited
research investigating factors associated with pulmonary involvement in
children with COVID-19; hence, we believe our study makes an important
contribution to the current literature regarding this challenging issue.
Previous studies have reported that COVID-19’s prevalence in children is
lower compared to adults, but individuals of all ages can be
infected.5,6 Similarly, we found that the age range
was 1 to 216 months with a median of 24 months.
To date, previous epidemiological studies have reported that most
children had milder disease courses in comparison with adult
patients.2,5,7,8 Clinical findings related to COVID-19
usually resemble other respiratory viral infections, with fever and
cough being common in most studies. Our findings were similar to those
of previous studies.2,5,9
Data from previous studies demonstrate that infants and young children
seem to have a high risk of severe disease.2,6 Unlike
these reports, we found that older age was associated with increased
risk of pulmonary involvement.
Many studies have investigated the association between viral load and
disease mortality and severity, but there is no information on the
correlation between viral load and pulmonary involvement in
SARS-CoV-2-infected children. Previous studies have shown that a higher
viral load is associated with increased disease severity and worse
outcomes.4,10-12 In addition to these reports, El Zein
et al.13 demonstrated that a high viral load was an
independent risk factor for in-hospital mortality and intubation. A
prospective cohort study by Knudtzen et al.14conducted on adult patients reported that a higher viral load can
predict disease severity in hospitalized patients. Extensive lung
involvement was found to be one of the identifying factors associated
with increased disease severity.15 Our study added to
this knowledge that a high viral load can predict the risk for pulmonary
involvement in children with COVID-19.
Elevated inflammatory biomarkers suggesting excessive cytokine
production correlate with COVID-19 pneumonia and disease severity. Many
mechanisms, including inflammatory biomarker release, alveolar tissue
macrophage activation, mononuclear cell accumulation, diffuse alveolar
oedema, and interstitial inflammation, can contribute to pulmonary
injury and pneumonia.15-18 In this study, we showed
that on the one hand, CRP, procalcitonin levels, and ESR were
significantly higher and lymphocyte, monocyte, eosinophil, and
thrombocyte counts were significantly lower in children with pulmonary
involvement than in those without. Our results are consistent with
previous studies showing that patients with COVID-19 had decreased
platelet, lymphocyte, monocyte, and eosinophil counts and increased CRP
levels.19,20 There are reports investigating factors
associated with pulmonary involvement in adult patients with
COVID-19.21,22 In a retrospective study, Damar Çakırca
et al.21 reported that the neutrophil–lymphocyte
ratio, the platelet–lymphocyte ratio, and the CRP–lymphocyte ratio
were higher and the eosinophil–lymphocyte ratio was lower in adult
COVID-19 patients with pulmonary involvement than in those without. In
another study, Abrishami et al.22 showed that 25 (OH)
vitamin D levels were predictive for the amount of lung involvement
shown in chest CT. Ferritin was identified as an inflammatory biomarker
resulting in immune dysregulation in severe COVID-19
patients.23 In addition to this role of ferritin,
Carubbi et al.24 has also demonstrated that higher
ferritin levels (above the 25th percentile) were
associated with lung involvement severity. Predictors of pulmonary
involvement risk in children with COVID-19 were not clearly determined.
In the present study, we detected that high CRP, procalcitonin levels,
and ESR and low lymphocyte and thrombocyte counts may predict pulmonary
involvement risk in children with COVID-19.
Limitations
This study’s major limitations were its small sample size and
single-center design. Additionally, we did not perform chest CT for
pulmonary involvement in every patient.
Conclusions
The identification of predictors for pulmonary involvement in COVID-19
is crucial for guiding appropriate management and generating better
disease outcomes. The present study determined that high CRP,
procalcitonin levels, ESR, and viral load and low lymphocyte and
thrombocyte counts were associated with pulmonary involvement in
children with COVID-19. Procalcitonin, CRP levels, and viral load may
predict the risk for pulmonary involvement in COVID-19 patients. We
think our results could make a significant contribution to this field,
about which little is currently known.
Funding: No funding was utilized for this manuscript.
Conflicts of interest: There are no conflicts of interest.
Authors’ contribution
Nurhayat Yakut: Conception and design of the study, Acquisition of data,
Literature research, writing manuscript, Final approval of the version
to be submitted; Kahraman Yakut: Conception and design of the study,
Acquisition of data ,Analysis and interpretation of data; Zeynep
Sarihan: Data collection and processing, Conception and design of the
study, Acquisition of data; Irem Kabasakal: Acquisition of data,
Analysis and interpretation of data; Murat Aydin: Conception and design
of the study, Acquisition of data ,Analysis and interpretation of data;
Nuran Karabulut: Conception and design of the study, Acquisition of
data,Analysis and interpretation of data, Critical review.
All authors read and approved the final manuscript.
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Table 1. The comparison demographic, clinical characteristics and
treatment modalities of the patients according to pulmonary involvement.