TABLE 1.

Study data (n = 140)

Study design
Total	148
RCT	49
Cross‐sectional	99
Size
Single	100
Multicentre	48
Sample size
<100	70
100‐500	69
>500	9
Population age
No age	53
<18	3
18‐50	23
50‐65	56
>65	13
Continent
North America	102
Europe	30
Asia	10
Other	6
Surgical specialty
Neurosurgery	2
Orthopaedic	27
Urology	15
Obstetrics	11
General Surgery	18
Plastics	39
Otolaryngology	8
Cardiovascular	8
Transplant	9
Vascular	4
Gastrointestinal	7