Objectives:
What is the prevalence of comorbidities in the confirmed COVID-19 patients?

Study design:
This review article included 33 studies (32 papers from China and 1 paper from Taiwan).
All 33 papers were in English language. In total, these studies included 9,249 patients comprising of 5,036 men and 4,191 women with confirmed COVID-19 since December 2019.

Results and conclusions:   

Objectives:
An association among the use of angiotensin converting enzyme inhibitors (ACEI) and angiotensin-receptor blockers (ARBs) with the clinical outcomes of coronavirus disease 2019 (COVID-19) is unclear. Therefore, this review article has been conducted.

Objectives:
There is mounting evidence related to the association between obesity and severity of COVID-19. However, the direct relationship of the increase in the severe COVID-19 risk factors, with an increase in body mass index (BMI), has not yet been evaluated. Therefore, this review article has been conducted.

Objectives:
What are the demographic characteristics, clinical symptoms, laboratory findings and imaging features of coronavirus disease 2019 (COVID-19) in pediatric patients?

Study design:
This review article included 48 studies with 5,829 pediatric patients (pediatrics is the branch of medicine that involves the medical care of infants, children and adolescents).

Results and conclusions:   
The investigators found children at all ages were at risk for COVID-19.

Objectives:
What is the impact of cancer on serious events including ICU admission rate and mortality in COVID 19 patients?

Study design:
This review article included 13 studies with a total of 3,775 COVID-19 patients, of whom 63 (1.66%) had a cancer.

Results and conclusions:   
The investigators found pooled estimates of ICU admission in COVID 19 patients with and without cancer were 40% versus 8.42%.

Objectives:
Many concerns still exist regarding the safety of hydroxychloroquine (HCQ) in the treatment of Coronavirus Disease 2019 (COVID-19). Therefore, this review article has been conducted.

What is the safety of hydroxychloroquine (HCQ) in the treatment of Coronavirus Disease 2019 (COVID-19)?

Study design:
This review article included 53 RCTs, involving 5,496 COVID-19 patients.

Objectives:
Antioxidant status is considered as important factor in the pathogenesis (the manner of development of a disease) of vitiligo. However, there are controversial findings about serum status of antioxidants in vitiligo patients. Therefore, this review article has been conducted.

Is there a relationship between serum antioxidant level (e.g. vitamin C, E, zinc and selenium) and risk of vitiligo?

Study design:
This review article included 11 studies including 570 vitiligo cases and 580 controls (people without vitiligo).

Objectives:
There have been no published systematic reviews that combine clinical, laboratory, epidemiologic and mortality findings. Also, the effect of gender on the outcomes of COVID-19 has not been well-defined. Therefore, this review article has been conducted.

What are the clinical, laboratory, epidemiologic and mortality findings and the effect of gender on the outcomes of COVID-19?

Study design:
This review article included 34 studies with a total of 5,057 COVID-19 patients with a mean age of 49 years.

Objectives:
The number of positive and death cases from coronavirus disease 2019 (COVID-19) is still increasing. The identification of risk factors for severe outcomes is important. Dyslipidemia (is an abnormal amount of lipids (e.g. triglycerides, cholesterol and/or fat phospholipids) in the blood) has been shown as a long-known risk factor for cardiovascular disease. Therefore, this review article has been conducted.

Objectives:
What are the diagnostic characteristics of serological-based COVID-19 testing?

Study design:
This review article included 5 studies with 1,166 patients underwent serological testing for COVID-19. Of these, 623 had the disease. Therefore, the prevalence of COVID-19 in the studied population was 53.43%.

There was no evidence of publication bias based upon a Deeks’ funnel plot.