Table 2 Trial characteristics and mismatches of demographics by subgroup

Surgical specialty

 Hepatobiliary

8 (7.5)

204 (152–250 [37–414])

6.8 (3.9–9.8 [0.8–28.8])

5 (62.5)

8 (72.7)

4 (50)

5 (45.5)

 Vascular

3 (2.8)

60 (49–60 [38-60])

6.3 (3.5–10.3 [0.6–14.4])

3 (100)

4 (100)

3 (100)

3 (75)

 Gynaecology

17 (16.0)

191 (108–321 [54–651])

15 (4.3–23.3 [1.2–25.7])

17 (100)

25 (78.1)

8 (47.1)

10 (31.3)

 Colorectal

46 (43.4)

227 (122–522 [30–1354])

15.1 (6.9–23.3 [0–34.9])

44 (95.7)

70 (78.7)

40 (87)

40 (44.9)

 Upper gastrointestinal

6 (5.7)

111 (87–123 [48–447])

13.2 (8.1–16.5 [0.6–27.8])

5 (83.3)

7 (58.3)

5 (83.3)

5 (41.7)

 Urology

3 (2.8)

96 (65–183 [34–270])

5.3 (4.4–10.5 [3.5–15.7])

3 (100)

3 (75)

0 (0)

0 (0)

 Mixed specialty

23 (21.7)

482 (347–1099 [137–4352])

13 (4.6–19.5 [1.0–34.4])

23 (100)

47 (88.7)

13 (56.5)

19 (35.8)

Topic of trial

 Post-op ileus

10 (9.4)

306 (122–463 [79–1941])

11.5 (7–15 [4.3–18.0])

10 (100)

21 (84)

7 (70)

11 (44)

 Antibiotics

20 (18.9)

321 (209–476 [78–3137])

24.7 (14.5–30.7[1.6–34.9])

17 (85)

22 (75.9)

11 (55)

12 (41.4)

 Antiemetics

3 (2.8)

702 (454–925 [205–1147])

4.3 (4–10.5 [3.7–16.7])

3 (100)

6 (100)

2 (66.7)

4 (66.7)

 IV fluids/GDT

5 (4.6)

142 (60–482 [60–775])

6.3 (2.7–8.1 [1.0–14.4])

5 (100)

12 (80)

5 (100)

8 (53.3)

 Blood transfusion/iron

5 (4.7)

642 (116–697 [70–1051])

18.4 (15.5–25.2 [5.7–28.7])

5 (100)

6 (75)

5 (100)

5 (62.5)

 Thromboprophylaxis

6 (5.7)

620 (411–1168 [225–4352])

8.4 (5.3–14.3 [0–22.1])

5 (83.3)

9 (81.8)

3 (50)

3 (27.2)

 Bowel prep

6 (5.7)

359 (196–509 [153–1354])

17 (15.3–17.8 [2.9–23.7])

6 (100)

8 (88.9)

6 (100)

8 (88.9)

 Nutrition

12 (11.3)

122 (106–234 [37–447])

10.5 (5.5–16.1 [0.5–23.8])

11 (91.7)

21 (75)

9 (75)

13 (46.4)

 Analgesia

6 (5.7)

228 (190–314 [100–523])

25.6 (19.8–27 [15–27.8])

6 (100)

7 (70)

1 (16.7)

1 (10)

 Other

33 (31.1)

159 (98–350 [30–1395])

7 (3.1–18.6 [0.3–29.8])

32 (97)

52 (81.3)

24 (72.7)

26 (40.6)

Outcome

 Significant

54 (50.9)

190.5 (111–332 [34–1147])

13.4 (4.8–19.7 [0.5–29.8])

53 (98.1)

86 (80.4)

0.35

37 (68.5)

44 (41.1)

0.08

 Non-significant

52 (49.10

335 (148–622 [30–4352])

13.7 (5.4–20.6 [0–34.9])

47 (90.4)

78 (79.6)

36 (69.2)

47 (48)

Trial size

  <  = 253

53 (50)

-

11.6 (5.3–18.6 [0.5–34.9])

49 (92.5)

78 (74.3)

 < 0.001

42 (79.2)

53 (50.5)

0.006

  > 253

53 (50)

-

15.0 (4.6–20.6 [0–34.4])

51 (96.2)

86 (86)

31 (58.5)

38 (38)

Years since publication

 More recent than 13.4

53 (50)

529 (376–729 [34–4352])

-

52 (98.1)

91 (76.5)

 < 0.001

42 (79.2)

55 (46.2)

0.002

 Older than 13.4

53 (50)

299 (159–517 [30–3137])

-

48 (90.6)

73 (84.9)

31 (58.5)

36 (41.9)