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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