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Table 1 Basic characteristics of COVID-19-related, peer-reviewed original articles

From: COVID-19-related medical research: a meta-research and critical appraisal

Type of original article studies involving patients

Number of studies (%)

Number of patients

Median (IQR)

Number of studies at risk of bias (%)

Patient consent

Low

Intermediate

High

Written informed consent

N (%)

Oral consent

N (%)

Open data

N (%)

No consent

N (%)

Case-control

68 (9.5)

108 (62–211)

11 (16.2)

25 (36.7)

32 (47.1)

22 (32.4)

2 (2.9)

2 (2.9)

42 (61.8)

Cohort

50 (7.0)

110 (54–327)

7 (14.0)

20 (40.0)

23 (46.0)

15 (30.0)

1 (2.0)

4 (8.0)

30 (60.0)

Cross-sectional

306 (42.9)

217 (80–730)

10 (3.3)

43 (14.0)

253 (82.7)

89 (29.1)

18 (5.9)

75 (24.5)

112 (40.5)

Case series

129 (18.1)

18 (9–53)

9 (6.9)

26 (20.2)

94 (72.9)

24 (18.6)

15 (11.6)

3 (2.3)

87 (67.4)

Diagnostic

37 (5.2)

84 (49–215)

0 (0)

0 (0)

37 (100.0)

3 (8.1)

0 (0)

0 (0)

34 (91.9)

Prognostic

8 (1.1)

143 (66–217)

3 (37.5)

1 (12.5)

4 (50.0)

0 (0)

0 (0)

0 (0)

8 (100.0)

Simulation

185 (25.9)

1428 (14–40,696)

16 (8.6)

47 (25.4)

122 (66.0)

3 (1.6)

1 (0.5)

131 (70.8)

50 (27.0)

Non-randomized trial

8 (1.1)

35 (29–58)

1 (12.5)

1 (12.5)

6 (75.0)

4 (50.0)

0 (0)

0 (0)

4 (50.0)

Randomized controlled trial

4 (0.6)

56 (29–111)

0 (0)

2 (50.0)

2 (50.0)

2 (50.0)

0 (0)

0 (0)

2 (50.0)

  1. This table displays the basic characteristics of the 713 clinical, peer-reviewed, COVID-19-related, original articles we critically appraised based on several risk of bias tools, according to the type of studies. Eighty-two studies were assessed using two tools, to better reflect their design. Shown are the number of studies, the median number of patients, the overall risk of bias after quality assessment, and how patient consent was addressed by authors