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\begin{document}

\title{Clinical characteristics of 2019 novel coronavirus-infected pneumonia in
China: A systematic review and meta-analysis of observational studies}



\author[1]{Mingjin Yang}%
\author[1]{Yan Zhang}%
\author[1]{Yuejun Du}%
\author[2]{Depeng Jiang}%
\affil[1]{Chengdu Second People's Hospital}%
\affil[2]{Chongqing Medical University Affiliated Second Hospital}%


\vspace{-1em}



  
  \date{May 16, 2024}


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\selectlanguage{english}
\begin{abstract}
Background: As of March 31, 2020, about 82,545 COVID-19-infected
patients in China have been confirmed. Several observational studies
have reported clinical characteristics of pneumonia caused by COVID-19
in China. But there are doubts about the clinical significance of
differences reported in the different studies. The objective of this
paper is to meta-analyze all available data from observational studies
in China to enable an objective reappraisal of the clinical
characteristics. Methods: PubMed, CNKI, EMBASE, and Cochrane Library
were searched. Observational studies were included if they reported
information on clinical characteristics of COVID-19-infected pneumonia.
Statistical heterogeneity was assessed using the I2 test, with a value [?]
50\% indicating a substantial level of heterogeneity. Results: Pooled
results exhibited that the proportion of male (58\%) was higher in
patients with COVID-19-infected pneumonia. Fever (89\%), cough (74\%),
fatigue (44\%), and shortness of breath (31\%) were the common clinical
manifestations. Cardiovascular disease (8\%), endocrine system disease
(9\%), and digestive system disease (5\%) were the common comorbidities.
Moreover, hypertension (29\%), endocrine system disease (16\%), and
cardiovascular disease (8\%) were the most common comorbidities in
severe patients. Acute cardiac injury (5\%), ARDS (11\%), shock (3\%),
and AKI (2\%) were the common complications. Conclusions: Men may be
more susceptible to COVID-19. The people with hypertension and endocrine
system disease are more likely to develop severe pneumonia. The most
common symptoms are fever and cough. The heart and kidneys may be also
important organs for the COVID-19 to attack in addition to the lungs.
Most patients have bilateral imaging abnormalities.%
\end{abstract}%



\sloppy


\textbf{Introduction}

In December 2019, several cases of novel coronavirus-infected pneumonia
have been reported in Wuhan, a large city of 11 million people in China
{[}1-3{]}. Then, the novel coronavirus was identified by the Chinese
Center for Disease Control and Prevention from the throat swab and
bronchoalveolar lavage fluid samples of patients in Wuhan, and was next
named COVID-19 by WHO {[}4{]}. The disease spread rapidly from Wuhan to
other parts of China. As of March 31, 2020, about 82,545
COVID-19-infected patients in China have been confirmed. More than 50
countries have reported confirmed cases worldwide. Most patients have
mild symptoms and good prognosis, while a few develop severe pneumonia,
acute respiratory distress syndrome (ARDS), multiple organ failure, or
even death.

At present, several observational studies have offered information
regarding the epidemiology and clinical features of pneumonia caused by
COVID-19{[}5-13{]} Clinical manifestations of patients with
COVID-19-infected pneumonia mainly include fever, headache, muscle ache,
cough, dyspnea, fatigue, etc. A few patients developed ARDS, and
multiple organ failure (eg. shock, acute cardiac injury, and acute
kidney injury). However, data from different studies also showed
significant differences in the incidence of fever, cough, dyspnea, etc.
Huang et al found that the most common symptoms were fever (98.6\%),
fatigue (69.6\%), and dry cough (59.4\%) at onset of illness {[}6{]}.
Less common symptoms were dizziness, headache, abdominal pain, etc. Guan
et al revealed that only a few patients had symptoms of fever (43.8\%)
at onset of illness {[}10{]}. Accordingly, there are doubts about the
clinical significance of differences reported in the different studies.
We set out to meta-analyses of all available data from observational
studies in China to enable an objective reappraisal of the clinical
characteristics.

\textbf{Methods}

\textbf{Protocol and search strategy}

The study was conducted following the Preferred Reporting Items for
Systematic review and Meta-Analysis{[}14{]}. Ethics committee approval
is not applicable for this study. The search strategy was developed by
experts in respiratory medicine. Search terms were as follows:
(``COVID-19'' or ``novel coronavirus-infected pneumonia'' or ``NCIP'' or
``SARS-CoV-2'' or ``2019-nCoV'') and (``Clinical characteristics'' or
``CT manifestations'' or ``symptom'' or ``epidemiological
characteristics'' or ``clinical features'') (e-Table 1). Two reviewers
(Mingjin Y. and Yan Z.) independently searched PubMed, China National
Knowledge Infrastructure (CNKI), EMBASE, and Cochrane Library from May
05, 2020 to May 27, 2020. Articles in Chinese or English were included.

\textbf{Study selection}

Studies were included if they met the following criteria: (1) original
research, (2) patients with 2019 novel coronavirus-infected pneumonia,
(3) reported incidences of clinical manifestations (including fever,
headache, muscle ache, cough, dyspnea, fatigue, etc.) and/or
complication (including ARDS, shock, acute cardiac injury, AKI, etc.),
(4) Chinese or English. Disagreements pertaining to the inclusion of
articles were resolved by discussion until a consensus was reached.

Two independent reviewers (Mingjin Y. and Yan Z.) extracted data in
duplicate from included studies. The standard assessment tools were used
for evaluation of the quality of included studies. Each included article
was given a quality score (0 to 8) based on fulfillment of the quality
criteria{[}15{]}.

\textbf{Statistical analysis}

The statistical analyses were performed using R version 2.14
{[}16-17{]}. The meta pack was used to calculate and generate the pooled
estimates and forest plots. Publication bias was also investigated
statistically using Egger and Begg tests {[}18-19{]}. Statistical
heterogeneity was assessed using the I\textsuperscript{2} test, with a
value [?] 50\% indicating a substantial level of heterogeneity. Random
effects models would be used when substantial statistical heterogeneity
was present. A p-value [?] 0.05 was defined as statistically significant.

\textbf{RESULTS}

\textbf{Study selection and characteristics}

Our search strategy yielded a total of 2087 published studies. After
further screening by reading the title, abstract, and/or full text, 9
studies met the inclusion criteria for further analysis. The 9 included
studies enrolled 1,795 patients. The flowchart is shown in Fig.1. The 9
included studies were published from January 24, 2020 to February 22,
2020. Population sizes ranged from 29 to 1,099 patients. All patients
were admitted to the hospital for treatment. Among the studies, eight
were retrospective analysis and one was a descriptive study. Five
reported clinical symptoms, complications, computed tomography (CT)
images, and laboratory findings. Seven reported clinical symptoms and CT
images. One studies only provided the information of chronic medical
illness, symptoms, and complications (Table 1).

Each included study was given a quality score (0 to 8) based on
fulfillment of the quality criteria. Of the included trials, one study
was assessed as 7 (range 0-8). Seven studies were assessed as 5. One was
assessed as 4 (e-Table 2).

\textbf{Baseline characteristics}

All the included studies provided information about the gender of
patients. The pooled results revealed that the proportion of male in
patients was 0.58 (95\% CI 0.55, 0.60) (I\textsuperscript{2}=69\%,
p\textless{}0.01) (Fig.2) (Table 2). Moreover, all the included studies
also provided information about chronic respiratory diseases,
hypertension, and endocrine system disease. The pooled results revealed
that the proportion of patients with chronic respiratory diseases,
hypertension, and endocrine system disease was 0.01 (95\% CI 0.01, 0.02)
(I\textsuperscript{2}=0\%, p=0.91), 0.14 (95\% CI 0.07, 0.24)
(I\textsuperscript{2}=94\%, p\textless{}0.01), and 0.09 (95\% CI 0.07,
0.10) (I\textsuperscript{2}=45\%, p=0.02), respectively. Of the eligible
trials, eight provided information about cardiovascular disease,
malignant tumour, and digestive system disease. The pooled results
revealed that the proportion of patients with cardiovascular disease was
0.08 (95\% CI 0.03, 0.17) (I\textsuperscript{2}=95\%, p\textless{}0.01),
malignant tumour was 0.02 (95\% CI 0.01, 0.04)
(I\textsuperscript{2}=52\%, p=0.03), and digestive system disease was
0.05 (95\% CI 0.03, 0.09) (I\textsuperscript{2}=79\%, p\textless{}0.01).
(Fig.3A,B,C,D,E, and F) (Table 2).

Of the eligible trials, 2 studies provided a detailed age profile of
patients with severe pneumonia. Data from one of the studies revealed
that 28.8\% developed severe pneumonia in patients over the age of 65,
and only 13.9 \% developed severe pneumonia in patients under the age of
65{[}10{]}. Another study suggested that 69.0\% developed severe
pneumonia in patients over the age of 70, and only 34.2 \% developed
severe pneumonia in patients under the age of 70{[}13{]}. Thus, the
above hinted that older patients are more likely to develop severe
pneumonia. But the data cannot be pooled due to the lack of further
detailed information. Further subgroup analysis revealed that the
proportion of severe patients with chronic respiratory system disease
was 0.04 (95\% CI 0.02, 0.08) (I\textsuperscript{2}=0.00\%, p=0.28),
cardiovascular disease was 0.08 (95\% CI 0.04, 0.15)
(I\textsuperscript{2}=43\%, p=0.06), malignant tumour was 0.03 (95\% CI
0.01,0.06) (I\textsuperscript{2}=0.00\%, p=0.17), digestive system
disease was 0.03 (95\% CI 0.00, 0.19) (I\textsuperscript{2}=76\%,
p\textless{}0.01), endocrine system disease was 0.16 (95\% CI 0.11,0.21)
(I\textsuperscript{2}=0.00\%,p=0.66), and hypertension was 0.29 (95\% CI
0.20,0.39) (I\textsuperscript{2}=52\%,p=0.04). The proportion of
non-severe patients with chronic respiratory system disease was 0.01
(95\% CI 0.00, 0.04) (I\textsuperscript{2}=63\%, p=0.01), cardiovascular
disease was 0.02 (95\% CI 0.01, 0.03) (I\textsuperscript{2}=0.00\%,
p=0.27), malignant tumour was 0.01 (95\% CI 0.00,0.04)
(I\textsuperscript{2}=55\%, p=0.02), digestive system disease was 0.05
(95\% CI 0.02, 0.13) (I\textsuperscript{2}=87\%, p \textless{}0.01),
endocrine system disease was 0.06 (95\% CI 0.05,0.08)
(I\textsuperscript{2}=0.00\%,p=0.06), and hypertension was 0.17 (95\% CI
0.11,0.25) (I\textsuperscript{2}=70\%,p \textless{}0.01) (Table 3).

\textbf{Signs and symptoms}

Nine studies provided information on fever, cough, shortness of breath,
diarrhea, and fatigue in patients. The pooled results revealed that the
proportion of patients with fever was 0.89 (95\% CI 0.81,0.94) )
(I\textsuperscript{2}=91\%, p\textless{}0.01), cough was 0.74 (95\% CI
0.59,0.84) (I\textsuperscript{2}=96\%, p\textless{}0.01), shortness of
breath was 0.31 (95\% CI 0.17,0.51) (I\textsuperscript{2}=97\%,
p\textless{}0.01), diarrhoea was 0.08 (95\% CI 0.04,0.17)
(I\textsuperscript{2}=92\%, p\textless{}0.01), and fatigue was 0.44
(95\% CI 0.31,0.59) (I\textsuperscript{2}=95\%, p\textless{}0.01).
Moreover, of the eligible trials, eight, seven, and four provided
information about headache, muscle ache, and sore throat, respectively.
The pooled results revealed that the proportion of patients with
headache was 0.14 (95\% CI 0.09,0.22) (I\textsuperscript{2}=90\%,
p\textless{}0.01), muscle ache was 0.030 (95\% CI 0.20,0.42)
(I\textsuperscript{2}=92\%, p\textless{}0.01), and sore throat was 0.03
(95\% CI 0.00,0.19) (I\textsuperscript{2}=98\%, p=0.12) (eFigure 1 in
the Supplement).

\textbf{Complications and Chest CT Manifestations}

Five studies reported that a small number of patients developed shock.
Estimates of the proportion of patients developing shock were 0.03 (95\%
CI 0.01, 0.07) (I\textsuperscript{2}=81\%, p\textless{}0.01). Data from
6 studies that reported information on ARDS was pooled. The results
revealed that the proportion of patients developed ARDS was 0.11 (95\%
CI 0.05, 0.22) (I\textsuperscript{2}=92\%, p\textless{}0.01). There were
five or three studies offering data of patients developing acute kidney
injury (AKI) or acute cardiac injury, respectively. The pooled results
showed that the proportions of patients developing AKI or acute cardiac
injury were 0.02 (95\% CI 0.01, 0.04) (I\textsuperscript{2}=55\%,p=0.04)
or 0.05 (95\% CI 0.01, 0.17) (I\textsuperscript{2}=72\%, p=0.61),
respectively (Fig.4A,B,C,and D).

Eight studies provided information on chest x-ray or CT findings. The
pooled results revealed that the proportion of patients with bilateral
pneumonia was 0.79 (95\% CI 0.69, 0.87) (I\textsuperscript{2}=92\%,
p\textless{}0.01), unilateral pneumonia was 0.11 (95\% CI 0.04, 0.27)
(I\textsuperscript{2}=97\%, p\textless{}0.01) (eFigure 2 in the
Supplement).

\textbf{DISCUSSION}

This systematic review and meta-analysis of observational studies in
China used subgroups analyses to objectively reappraise the clinical
characteristics of patients with COVID-19-infected pneumonia, including
age, sex, chronic medical illness, symptoms, complications, chest
radiogram, etc. To our knowledge, this is the first systematic review
and meta-analysis of all available trials in China to explore the
clinical characteristics of patients with COVID-19-infected pneumonia.

Previous studies have suggested that people of all ages are susceptible
to the COVID-19, but older people or those with chronic medical illness
are more likely to develop severe pneumonia, ARDS, multiple organ
failure, or even death {[}20-22{]}. Congruent with previous descriptive
reports, we also found that COVID-19-infected pneumonia is common in all
age groups. Moreover, our results also revealed that people with
cardiovascular disease or endocrine system disease have a higher risk of
developing ARDS, multiple organ failure, or even death. However, there
were insufficient data from those studies to perform a further
meta-analysis. Sex may also contribute to differences in incidence of
COVID-19-infected pneumonia. Several observational studies have reported
that the incidence of COVID-19-infected pneumonia was higher in men
{[}6-9{]}. Our results were also consistent with previous report.
However, the sex dependence of COVID-19 infections is different from
that of severe acute respiratory syndrome (SARS), which as one of the
beta-coronavirus family was more than 82\% identical to RNA sequence of
COVID-19 {[}23-24{]}. But our results were limited by the sample size.
Future research may shed more light on the issue. In addition, when data
on symptoms, complications, and comorbidities were pooled, statistical
heterogeneity was detected. The source of heterogeneity may be that the
proportion of each type of symptoms, complications, and comorbidities
varied widely among the included studies. Recent publications have
reported that the clinical characteristics of COVID-19-infected
pneumonia mimicked those of SARS {[}24{]}. The dominant symptoms include
fever and cough. Fatigue and shortness of breath are also common
symptoms, whereas gastrointestinal symptoms were rare. Our results were
also consistent with previous report. Notably, Guan and colleagues
reported that fever occurred in only 43.8\% of patients at onset of
illness and developed in 87.9\% following hospitalization {[}10{]}. But
Wang and colleagues reported that the most common symptoms at onset of
illness were fever (98.6\%) {[}9{]}. The above differences may confuse
readers. In combination with our results, it is considered that fever
may be the most common symptom in the course of pneumonia but not in the
onset. Huang and colleagues reported that a few patients developed ARDS
(29\%), acute cardiac injury (12\%), and acute kidney injury (7\%), and
suggested that the heart and kidneys are also important organs for the
COVID-19 to attack in addition to the lungs {[}6{]}. Consistent with
previous studies, our results also exhibited that COVID-19-related heart
and kidney injury were also common in severe patients. It seems to
further suggest that the lungs may be just a channel for the COVID-19 to
attack vital organs in severe patients. But the results also need to be
further verified in future studies. In terms of laboratory tests, the
included studies-suggested that lymphocyte absolute counts were
decreased in most patients, while the white blood cell counts were not
detected to be significantly abnormal. This result hinted that COVID-19
might also act on lymphocytes, especially T lymphocytes, as does
SARSCoV {[}25-26{]}. However, impaired function of immune system may
significantly increase the risk of secondary infection in patients with
COVID-19-infected pneumonia. The above may also be the reason why a few
patients progressed rapidly with severe bacterial infections, which was
eventually followed by multiple organ failure. The included studies
showed that abnormalities in chest CT images were detected among all
patients on admission. The pooled results revealed that most patients
(68\%) had bilateral pneumonia. The typical findings of chest imaging
showed bilateral ground glass opacity and multiple lobular of
consolidation. However, chest imaging of patients usually changes
dynamically. In clinical work, we should observe dynamically chest
imaging of patients according to their conditions. In addition, it
should not be overlooked that some carriers of COVID-19 may have no any
clinical symptoms or exhibit typical clinical symptoms but no abnormal
changes in chest imaging {[}27-28{]}. Some limitations of this
systematic review and meta-analysis should be taken into account. First,
this paper was limited to 9 observational studies with 1,795 patients.
This sample size was not large enough to provide decisional clinical
evidence. Second, some observational studies with insufficient
information were excluded, which might lead to selection bias. Third,
due to incomplete laboratory results provided by included studies, it is
not possible to further explore the relationship between biomarkers and
COVID-19-infected pneumonia.

In summary, people of all ages are susceptible to COVID-19, but older
people or those with chronic medical illness are more likely to develop
severe pneumonia, ARDS, multiple organ failure, or even death. Moreover,
the incidence of COVID-19-infected pneumonia may be higher in men. The
dominant symptoms include fever and cough. Fatigue and shortness of
breath are also common symptoms, whereas gastrointestinal symptoms were
rare. The heart and kidneys may be also important organs for the
COVID-19 to attack in addition to the lungs. Lymphocyte absolute counts
in most patients were decreased, and that patients with secondary
bacterial infections might appear elevated leucocytes. Most patients may
have bilateral imaging abnormalities. The typical findings of chest
imaging showed bilateral ground glass opacity and multiple lobular of
consolidation.

\textbf{Acknowledgments}

The authors are indebted to all members of the Respiratory Diseases
Laboratory of Chengdu Second People's Hospital. All authors contributed
substantially to the study design, data analysis and interpretation, and
the writing of the manuscript. Conceived and designed the experiments:
Mingjin Yang, Depeng Jiang. Performed the experiments: Yan Zhang.
Analyzed the data: Mingjin Yang, Zhibo Xu, Depeng Jiang. Contributed
reagents/materials/analysis tools: Yuejun Du. Wrote thefirst draft of
the manuscript: Zhang Yan, Mingjin Yang.

\textbf{Ethics approval and consent to participate}

As this is a meta-analysis, ethics committee approval is not applicable.

\textbf{Declaration of Interest}

The authors declare no conflicts of interest.

\textbf{Funding/Support}

None.

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\textbf{Table 1.} The characteristics of the literature.\selectlanguage{english}
\begin{longtable}[]{@{}llllllll@{}}
\toprule
\begin{minipage}[b]{0.12\columnwidth}\raggedright\strut
\textbf{Authors}\strut
\end{minipage} & \begin{minipage}[b]{0.12\columnwidth}\raggedright\strut
\textbf{No. of Patients}\strut
\end{minipage} & \begin{minipage}[b]{0.12\columnwidth}\raggedright\strut
\textbf{Male(\%)}\strut
\end{minipage} & \begin{minipage}[b]{0.12\columnwidth}\raggedright\strut
\textbf{Mean~Age} \textbf{(SD), y}\strut
\end{minipage} & \begin{minipage}[b]{0.12\columnwidth}\raggedright\strut
\textbf{Region}\strut
\end{minipage} & \begin{minipage}[b]{0.12\columnwidth}\raggedright\strut
\textbf{Research Type}\strut
\end{minipage} & \begin{minipage}[b]{0.12\columnwidth}\raggedright\strut
\textbf{Clinical Characteristics}\strut
\end{minipage} & \begin{minipage}[b]{0.12\columnwidth}\raggedright\strut
\textbf{Clinical Characteristics}\strut
\end{minipage}\tabularnewline
\midrule
\endhead
\begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
Wang et al(2020)\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
138\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
54\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
56(19)\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
China\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
Retrospective~Study\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
Retrospective~Study\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
Chronic medical illness Signs and symptoms laboratory findings
Complications Chest x-ray and CT findings\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
Huang et al(2020)\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
41\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
73\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
49(13)\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
China\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
Retrospective Study\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
Retrospective Study\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
Chronic medical illness Signs and symptoms laboratory findings
Complications Chest x-ray and CT findings\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
Liu et al(2020)\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
137\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
45\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
55(16)\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
China\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
Retrospective Study\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
Retrospective Study\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
Chronic medical illness Signs and symptoms Chest x-ray and CT
findings\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
Lu et al(2020)\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
50\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
56\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
50(17)\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
China\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
Retrospective Study\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
Retrospective Study\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
Chronic medical illness Signs and symptoms Chest x-ray and CT
findings\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
Zhang et al(2020)\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
140\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
51\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
57\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
China\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
Retrospective Study\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
Retrospective Study\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
Chronic medical illness Signs and symptoms Chest x-ray and CT
findings\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
Chen et al(2020)\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
99\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
68\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
55.5(13)\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
China\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
Retrospective Study\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
Retrospective Study\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
Chronic medical illness Signs and symptoms laboratory findings
Complications Chest x-ray and CT findings\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
Guan et al(2020)\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
1099\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
58\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
47(17)\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
China\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
Retrospective Study\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
Retrospective Study\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
Chronic medical illness Signs and symptoms laboratory findings
Complications Chest x-ray and CT findings\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
Chen Lei et al(2020)\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
29\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
72\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
56\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
China\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
Retrospective Study\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
Retrospective Study\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
Chronic medical illness Signs and symptoms Complications\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
Xu et al(2020)\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
62\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
58\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
41(15)\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
China\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
Retrospective Study\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
Retrospective Study\strut
\end{minipage} & \begin{minipage}[t]{0.12\columnwidth}\raggedright\strut
Chronic medical illness Signs and symptoms Complications Chest x-ray and
CT findings\strut
\end{minipage}\tabularnewline
\bottomrule
\end{longtable}

SD, standard deviation. y,years.

\textbf{Table 2.} Pooled estimates for each type of baseline
characteristics of patients infected with COVID-19.\selectlanguage{english}
\begin{longtable}[]{@{}ll@{}}
\toprule
\begin{minipage}[b]{0.48\columnwidth}\raggedright\strut
\textbf{Variable}\strut
\end{minipage} & \begin{minipage}[b]{0.48\columnwidth}\raggedright\strut
\textbf{Included in the Meta-analysis (n=9)} \textbf{Estimate (95\%
CI)}\strut
\end{minipage}\tabularnewline
\midrule
\endhead
\begin{minipage}[t]{0.47\columnwidth}\raggedright\strut
Age,y\strut
\end{minipage} & \begin{minipage}[t]{0.47\columnwidth}\raggedright\strut
47.91(47.70,48.12)\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.47\columnwidth}\raggedright\strut
Sex (\%)\strut
\end{minipage} & \begin{minipage}[t]{0.47\columnwidth}\raggedright\strut
\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.47\columnwidth}\raggedright\strut
Male\strut
\end{minipage} & \begin{minipage}[t]{0.47\columnwidth}\raggedright\strut
0.58(0.52,0.63)\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.47\columnwidth}\raggedright\strut
Female\strut
\end{minipage} & \begin{minipage}[t]{0.47\columnwidth}\raggedright\strut
0.42(0.40,0.45)\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.47\columnwidth}\raggedright\strut
Chronic medical illness (\%)\strut
\end{minipage} & \begin{minipage}[t]{0.47\columnwidth}\raggedright\strut
\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.47\columnwidth}\raggedright\strut
Respiratory system disease\strut
\end{minipage} & \begin{minipage}[t]{0.47\columnwidth}\raggedright\strut
0.01(0.01,0.02)\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.47\columnwidth}\raggedright\strut
Cardiovascular disease\strut
\end{minipage} & \begin{minipage}[t]{0.47\columnwidth}\raggedright\strut
0.08(0.03,0.17)\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.47\columnwidth}\raggedright\strut
Malignant tumour\strut
\end{minipage} & \begin{minipage}[t]{0.47\columnwidth}\raggedright\strut
0.02(0.01,0.04)\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.47\columnwidth}\raggedright\strut
Digestive system disease\strut
\end{minipage} & \begin{minipage}[t]{0.47\columnwidth}\raggedright\strut
0.05(0.03,0.09)\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.47\columnwidth}\raggedright\strut
Endocrine system disease\strut
\end{minipage} & \begin{minipage}[t]{0.47\columnwidth}\raggedright\strut
0.09(0.07,0.10)\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.47\columnwidth}\raggedright\strut
Hypertension\strut
\end{minipage} & \begin{minipage}[t]{0.47\columnwidth}\raggedright\strut
0.14(0.07,0.24)\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.47\columnwidth}\raggedright\strut
Signs and symptoms (\%)\strut
\end{minipage} & \begin{minipage}[t]{0.47\columnwidth}\raggedright\strut
\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.47\columnwidth}\raggedright\strut
Fever\strut
\end{minipage} & \begin{minipage}[t]{0.47\columnwidth}\raggedright\strut
0.89(0.81,0.94)\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.47\columnwidth}\raggedright\strut
Cough\strut
\end{minipage} & \begin{minipage}[t]{0.47\columnwidth}\raggedright\strut
0.74(0.59,0.84)\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.47\columnwidth}\raggedright\strut
Fatigue\strut
\end{minipage} & \begin{minipage}[t]{0.47\columnwidth}\raggedright\strut
0.44(0.31,0.59)\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.47\columnwidth}\raggedright\strut
Shortness of breath\strut
\end{minipage} & \begin{minipage}[t]{0.47\columnwidth}\raggedright\strut
0.31(0.17,0.51)\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.47\columnwidth}\raggedright\strut
Headache\strut
\end{minipage} & \begin{minipage}[t]{0.47\columnwidth}\raggedright\strut
0.14(0.09,0.22)\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.47\columnwidth}\raggedright\strut
Diarrhoea\strut
\end{minipage} & \begin{minipage}[t]{0.47\columnwidth}\raggedright\strut
0.08(0.04,0.17)\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.47\columnwidth}\raggedright\strut
Muscle ache\strut
\end{minipage} & \begin{minipage}[t]{0.47\columnwidth}\raggedright\strut
0.30(0.20,0.42)\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.47\columnwidth}\raggedright\strut
Sore throat\strut
\end{minipage} & \begin{minipage}[t]{0.47\columnwidth}\raggedright\strut
0.03(0.00,0.19)\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.47\columnwidth}\raggedright\strut
Complications (\%)\strut
\end{minipage} & \begin{minipage}[t]{0.47\columnwidth}\raggedright\strut
\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.47\columnwidth}\raggedright\strut
Shock\strut
\end{minipage} & \begin{minipage}[t]{0.47\columnwidth}\raggedright\strut
0.03(0.01,0.07)\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.47\columnwidth}\raggedright\strut
ARDS\strut
\end{minipage} & \begin{minipage}[t]{0.47\columnwidth}\raggedright\strut
0.11(0.05,0.22)\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.47\columnwidth}\raggedright\strut
AKI\strut
\end{minipage} & \begin{minipage}[t]{0.47\columnwidth}\raggedright\strut
0.02(0.01,0.04)\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.47\columnwidth}\raggedright\strut
Acute cardiac injury\strut
\end{minipage} & \begin{minipage}[t]{0.47\columnwidth}\raggedright\strut
0.05(0.01,0.17)\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.47\columnwidth}\raggedright\strut
Chest x-ray and CT findings (\%)\strut
\end{minipage} & \begin{minipage}[t]{0.47\columnwidth}\raggedright\strut
\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.47\columnwidth}\raggedright\strut
Bilateral pneumonia\strut
\end{minipage} & \begin{minipage}[t]{0.47\columnwidth}\raggedright\strut
0.79(0.69,0.87)\strut
\end{minipage}\tabularnewline
\begin{minipage}[t]{0.47\columnwidth}\raggedright\strut
Unilateral pneumonia\strut
\end{minipage} & \begin{minipage}[t]{0.47\columnwidth}\raggedright\strut
0.11(0.04,0.27)\strut
\end{minipage}\tabularnewline
\bottomrule
\end{longtable}

Abbreviations: CI, confidence interval; CT, computed tomography; y,
years; ARDS, acute respiratory distress syndrome; AKI, acute kidney
injury.

\textbf{Table 3.} Pooled estimates for each type of chronic medical
illness of proportion in non-severe or severe patients with
COVID-19-infected pneumonia.\selectlanguage{english}
\begin{longtable}[]{@{}lll@{}}
\toprule
\textbf{Chronic medical illness, (\%)} & \textbf{Included in the
Meta-analysis Estimate (95\% CI)} & \textbf{Included in the
Meta-analysis Estimate (95\% CI)}\tabularnewline
\midrule
\endhead
& \textbf{Non-severe} & \textbf{severe}\tabularnewline
Respiratory system disease & 0.01(0.00,0.04) &
0.04(0.02,0.08)\tabularnewline
Cardiovascular disease & 0.02(0.01,0.03) &
0.08(0.04,0.15)\tabularnewline
Malignant tumour & 0.01(0.00,0.04) & 0.03(0.01,0.06)\tabularnewline
Digestive system disease & 0.05(0.02,0.13) &
0.03(0.00,0.19)\tabularnewline
Endocrine system disease & 0.06(0.05,0.08) &
0.16(0.11,0.21)\tabularnewline
Hypertension & 0.17(0.011,0.25) & 0.29(0.20,0.39)\tabularnewline
Overall & 0.04(0.02,0.08) & 0.08(0.04,0.14)\tabularnewline
\bottomrule
\end{longtable}

Abbreviations: CI, confidence interval;

\textbf{Figure 1} Flow of study selection\selectlanguage{english}
\begin{figure}[H]
\begin{center}
\includegraphics[width=0.70\columnwidth]{figures/image1/image1}

\end{center}
\end{figure}\selectlanguage{english}
\begin{figure}[H]
\begin{center}
\includegraphics[width=0.70\columnwidth]{figures/image2/image2}

\end{center}
\end{figure}

\textbf{Figure 2} Pooled estimates for male or female of proportion in
patients with COVID-19-infected pneumonia.

CI, confidence interval.

\textbf{Figure 3A,B,C,D,E,and F} Pooled estimates for each type of
comorbidity of proportion in patients with COVID-19-infected pneumonia.\selectlanguage{english}
\begin{figure}[H]
\begin{center}
\includegraphics[width=0.70\columnwidth]{figures/image3/image3}

\end{center}
\end{figure}

CI, confidence interval. A, chronic respiratory diseases; B,
hypertension; C, endocrine system disease; D, cardiovascular disease; E,
malignant tumour; and F, digestive system disease.

\textbf{Figure 4A,B,C,and D} Pooled estimates for each type of
complication of proportion in patients with COVID-19-infected pneumonia.\selectlanguage{english}
\begin{figure}[H]
\begin{center}
\includegraphics[width=0.70\columnwidth]{figures/image4/image4}

\end{center}
\end{figure}

CI, confidence interval. A, shock; B, ARDS; C, AKI, and D, acute cardiac
injury.\selectlanguage{english}
\begin{figure}[H]
\begin{center}
\includegraphics[width=0.70\columnwidth]{figures/Fig/Fig}

\end{center}
\end{figure}\selectlanguage{english}
\begin{figure}[H]
\begin{center}
\includegraphics[width=0.70\columnwidth]{figures/Fih/Fih}

\end{center}
\end{figure}\selectlanguage{english}
\begin{figure}[H]
\begin{center}
\includegraphics[width=0.70\columnwidth]{figures/Fii/Fii}

\end{center}
\end{figure}\selectlanguage{english}
\begin{figure}[H]
\begin{center}
\includegraphics[width=0.70\columnwidth]{figures/Fij/Fij}

\end{center}
\end{figure}

\selectlanguage{english}
\FloatBarrier
\end{document}

