Characteristics of the studied external randomised pilot trial publications
| Completed (n=37) n (%) | Protocol (n=123) n (%) | Total (n=160) n (%) | |
| Journal | |||
| British Medical Journal (BMJ) Open | 11 (30) | 34 (28) | 45 (28) |
| Pilot and Feasibility Studies (PAFS) | 21 (57) | 56 (46) | 77 (48) |
| Trials | 2 (5) | 33 (27) | 35 (22) |
| Public Library of Science (PLoS) One | 3 (8) | 0 (0) | 3 (2) |
| Country | |||
| Australia | 6 (16) | 4 (3) | 10 (6) |
| Brazil | 0 (0) | 1 (1) | 1 (1) |
| Canada | 4 (11) | 15 (12) | 19 (12) |
| China | 0 (0) | 4 (3) | 4 (3) |
| Denmark | 0 (0) | 1 (1) | 1 (1) |
| Germany | 1 (3) | 1 (1) | 2 (1) |
| Korea | 0 (0) | 1 (1) | 1 (1) |
| Nepal | 1 (3) | 2 (2) | 3 (2) |
| New Zealand | 2 (5) | 1 (1) | 3 (2) |
| Norway | 1 (3) | 0 (0) | 1 (1) |
| Ireland | 0 (0) | 5 (4) | 5 (3) |
| Sweden | 1 (3) | 1 (1) | 2 (1) |
| Tanzania | 0 (0) | 1 (1) | 1 (1) |
| Thailand | 0 (0) | 1 (1) | 1 (1) |
| The Netherlands | 0 (0) | 2 (2) | 2 (1) |
| UK | 19 (51) | 68 (55) | 87 (54) |
| USA | 2 (5) | 14 (11) | 16 (10) |
| Zimbabwe | 0 (0) | 1 (1) | 1 (1) |
| Funder | |||
| Industry | 2 (5) | 2 (2) | 4 (3) |
| Non-industry | 32 (86) | 115 (94) | 147 (92) |
| A combination | 1 (3) | 4 (3) | 5 (3) |
| Unknown | 2 (5) | 1 (1) | 3 (2) |
| Trial did not receive funding | 0 (0) | 1 (1) | 1 (1) |
| Therapeutic areas | |||
| Complementary medicine | 0 (0) | 1 (1) | 1 (1) |
| Anaesthesia | 1 (3) | 1 (1) | 2 (1) |
| Cardiology | 0 (0) | 3 (2) | 3 (2) |
| Critical care | 1 (3) | 7 (6) | 8 (5) |
| Endocrinology | 0 (0) | 6 (5) | 6 (4) |
| Gastroenterology | 1 (3) | 3 (2) | 4 (3) |
| Geriatrics | 1 (3) | 4 (3) | 5 (3) |
| Hepatology | 0 (0) | 1 (1) | 1 (1) |
| Infectious diseases | 0 (0) | 3 (2) | 3 (2) |
| Musculoskeletal | 6 (16) | 4 (3) | 10 (6) |
| Nephrology | 0 (0) | 1 (1) | 1 (1) |
| Neurology | 3 (8) | 12 (10) | 15 (9) |
| Obstetrics/gynaecology | 2 (5) | 6 (5) | 8 (5) |
| Oncology | 4 (11) | 7 (6) | 11 (7) |
| Ophthalmology | 0 (0) | 1 (1) | 1 (1) |
| Orthopaedics | 2 (5) | 1 (1) | 3 (2) |
| Other | 2 (5) | 3 (2) | 5 (3) |
| Otolaryngology (ENT) | 2 (5) | 1 (1) | 3 (2) |
| Paediatrics | 2 (5) | 3 (2) | 5 (3) |
| Pain | 1 (3) | 0 (0) | 1 (1) |
| Palliative care | 0 (0) | 3 (2) | 3 (2) |
| Psychiatry/psychology | 2 (5) | 19 (15) | 21 (13) |
| Public health | 2 (5) | 15 (12) | 17 (11) |
| Respiratory | 0 (0) | 2 (2) | 2 (1) |
| Rheumatology | 0 (0) | 1 (1) | 1 (1) |
| Surgery | 3 (8) | 8 (7) | 11 (7) |
| Trauma | 2 (5) | 7 (6) | 9 (6) |
| Intervention type | |||
| Drug | 4 (11) | 9 (7) | 13 (8) |
| Surgery/procedure | 6 (16) | 13 (11) | 19 (12) |
| Counselling/lifestyle/physiotherapy | 22 (59) | 72 (59) | 94 (59) |
| Equipment | 4 (11) | 5 (4) | 9 (6) |
| Other | 1 (3) | 24 (20) | 25 (16) |
| Sample size target* | |||
| Mean (SD) | 72.8 (62.5) | 258.5 (1215.7) | 217.3 (1074.9) |
| Median (IQR) | 60 (32–90) | 60 (40–100) | 60 (40–100) |
| Min-Max | 6–300 | 20–12 000 | 6–12 000 |
| Cluster randomised pilot trials | (n=3) | (n=18) | (n=21) |
| Number of clusters | |||
| Mean (SD) | 7.3 (2.3) | 9.7 (11.6) | 9.3 (10.7) |
| Median (IQR) | 6 (6–10) | 6 (3–10) | 6 (4–10) |
| Min-Max | 6–10 | 2–45 | 2–45 |
| Number of arms | |||
| 2 | 32 (86) | 111 (90) | 143 (89) |
| >2 | 5 (14) | 12 (10) | 17 (11) |
| Number of centres | |||
| Single centre | 19 (51) | 36 (29) | 55 (34) |
| Multicentre | 18 (49) | 84 (68) | 102 (64) |
| Unclear | 0 (0) | 3 (2) | 3 (2) |
| Feasibility objective/s explicitly described as primary | |||
| Yes | 9 (24) | 62 (50) | 71 (44) |
| No | 28 (76) | 61 (50) | 89 (56) |
| Trial outcomes address trial objectives | |||
| Yes | 18 (49) | 91 (74) | 109 (68) |
| No | 0 (0) | 1 (1) | 1 (1) |
| Somewhat† | 19 (51) | 31 (25) | 50 (31) |
| Completely defined prespecified assessments or measurements stated | |||
| Yes | 27 (73) | 113 (92) | 140 (88) |
| Not for every outcome | 10 (27) | 10 (8) | 20 (13) |
| Hypothesis testing | |||
| Yes | 2 (5) | 16 (13) | 18 (11) |
| Yes, exploratory/caution advised | 18 (49) | 43 (35) | 61 (38) |
| No | 17 (46) | 64 (52) | 81 (51) |
| Number of uncertainties reported | |||
| One | 0 (0) | 1 (1) | 1 (1) |
| Multiple | 37 (100) | 122 (99) | 159 (99) |
| Where uncertainties are first reported (excluding abstract) | |||
| Introduction | 0 (0) | 1 (1) | 1 (1) |
| Research question(s) | 2 (5) | 4 (3) | 6 (4) |
| Aim(s) | 5 (14) | 16 (13) | 21 (13) |
| Objective(s) | 10 (27) | 62 (50) | 72 (45) |
| Outcome(s) | 9 (24) | 17 (14) | 26 (16) |
| Outcome measure(s) | 7 (19) | 16 (13) | 23 (14) |
| Analysis | 0 (0) | 2 (2) | 2 (1) |
| Within the text under a feasibility/uncertainty heading | 2 (5) | 1 (1) | 3 (2) |
| Throughout the text, not in one specific area | 2 (5) | 4 (3) | 6 (4) |
Percentages may not sum up to 100 due to rounding.
*Where publications reported a sample size target range (eg, 12–16 participants), the lower bound of the target is included. A sample size target was not reported in two publications (both reporting completed pilot trials and including the actual number of recruited participants).
†Trial objective was vague (eg, to ‘assess feasibility’) and the specific areas of feasibility were not explicitly stated.
ENT, ear, nose and throat.