Table 3 Missing data interventions and reported evaluations into their effectiveness (registered Clinical Trial Unit (CTU) survey Questions 6 and 7)
From: Identifying research priorities for effective retention strategies in clinical trials
Missing data intervention | Respondents who have used the intervention (% of all survey respondents, n = 33) | Used routinely (% of all survey respondents, n = 33) | Used occasionally (% of all survey respondents, n = 33) | No response for frequency of use (% of respondents who used intervention) | Before/after evaluation (informal) | Nested RCT evaluation (formal) | Total evaluations |
|---|---|---|---|---|---|---|---|
Newslettersa | 30 (91%) | 23 (70%) | 5 (15%) | 2 (7%) | 2 | 2 | 4 |
A timeline of participant visits for sites | 24 (73%) | 19 (58%) | 4 (12%) | 1 (4%) | 0 | 0 | 0 |
Inclusion of prepaid envelope (questionnaires)b | 28 (85%)c | 19 (58%) | 6 (18%) | 1 (4%) | 0 | 1 | 1 |
Telephone reminders | 28 (85%) | 18 (55%) | 9 (27%) | 1 (4%) | 2 | 1 | 3 |
Data collection scheduled with routine care | 25 (76%) | 18 (55%) | 6 (18%) | 1 (4%) | 1 | 1 | 2 |
Site initiation training on missing data | 19 (58%) | 18 (55%) | 0 (0%) | 1 (5%) | 0 | 0 | 0 |
Investigator meetings face to face | 22 (67%) | 17 (52%) | 5 (15%) | 0 (0%) | 0 | 1 | 1 |
Routines site visits by CTU staff | 23 (70%) | 15 (45%) | 8 (24%) | 0 (0%) | 1 | 0 | 1 |
Targeted recruitment of sites/GPs | 21 (64%) | 15 (45%) | 6 (18%) | 0 (0%) | 0 | 2 | 2 |
Flexibility in appointment times | 21 (64%) | 15 (45%) | 4 (12%) | 2 (10%) | 1 | 1 | 2 |
Communication of trial results | 20 (61%) | 15 (45%) | 3 (9%) | 2 (10%) | 1 | 0 | 1 |
Investigator teleconferences | 22 (67%)d | 15 (45%) | 8 (24%) | 0 (0%) | 0 | 1 | 1 |
Questionnaires completed in clinicb | 22 (67%) | 15 (45%) | 5 (15%) | 2 (9%) | 1 | 1 | 2 |
Minimising frequency of questionnairesb | 21 (64%) | 15 (45%) | 3 (9%) | 3 (14%) | 0 | 0 | 0 |
Short questionnaireb | 24 (73%) | 14 (42%) | 9 (27%) | 1 (4%) | 0 | 1 | 1 |
Collecting multiple contact details | 22 (67%) | 13 (39%) | 8 (24%) | 1 (5%) | 2 | 1 | 3 |
Email reminders | 21 (64%) | 13 (39%) | 6 (18%) | 2 (10%) | 4 | 0 | 4 |
Postal reminders | 23 (70%) | 12 (36%) | 10 (30%) | 1 (4%) | 2 | 2 | 4 |
Total design method for Questionnairesb | 15 (46%) | 12 (36%) | 3 (9%) | 0 (0%) | 1 | 1 | 2 |
Re-imbursement of participant expenses | 24 (73%)e | 11 (33%) | 12 (36%) | 0 (0%) | 1 | 1 | 2 |
Triggered site training on missing data | 23 (70%) | 11 (33%) | 12 (36%) | 0 (0%) | 0 | 0 | 0 |
Use of routinely collected data | 29 (88%) | 10 (30%) | 17 (52%) | 2 (7%) | 2 | 1 | 3 |
Contact GPs for missing data/trace patients | 27 (82%) | 10 (30%) | 14 (42%) | 3 (11%) | 0 | 1 | 1 |
Patient diaries | 26 (79%) | 10 (30%) | 13 (39%) | 3 (12%) | 1 | 0 | 1 |
Enhanced cover letter (questionnaires)b | 14 (43%) | 9 (27%) | 5 (15%) | 0 (0%) | 1 | 2 | 3 |
Staggered per patient payments to sites | 20 (61%) | 8 (24%) | 12 (36% | 0 (0%) | 0 | 0 | 0 |
Patient data entry | 18 (55%) | 8 (24%) | 8 (24%) | 2 (11%) | 0 | 1 | 1 |
Trial identity cards | 14 (43%) | 8 (24%) | 5 (15%) | 1 (7%) | 0 | 0 | 0 |
Telephone questionnaires | 20 (61%) | 7 (21%) | 11 (33%) | 2 (10%) | 2 | 1 | 3 |
Trial website | 18 (55%) | 7 (21%) | 10 (30%) | 1 (6%) | 0 | 0 | 0 |
Taking contact details for a friend/family | 13 (40%) | 7 (21%) | 6 (18%) | 0 (0%) | 0 | 1 | 1 |
Long but clear questionnaireb | 10 (31%) | 7 (21%) | 2 (6%) | 1 (10%) | 0 | 0 | 0 |
Only collecting the primary outcome for patients with missing data | 17 (52%) | 6 (18%) | 10 (30%) | 1 (6%) | 2 | 1 | 3 |
Gift | 18 (55%) | 6 (18%) | 10 (30%) | 2 (11%) | 1 | 1 | 2 |
ONS flagging | 16 (49%)e | 6 (18%) | 7 (21%) | 2 (13%) | 0 | 0 | 0 |
Flexibility in appointment locations | 14 (43%) | 6 (18%) | 6 (18%) | 2(14%) | 1 | 0 | 1 |
Money/gift voucher given on completion of a milestone | 17 (52%) | 5 (15%) | 12 (36%) | 0 (0%) | 1 | 0 | 1 |
Contacting patients between visits | 13 (40%) | 4 (12%) | 9 (27%) | 0 (0%) | 0 | 0 | 0 |
Christmas and birthday cards | 13 (40%) | 4 (12%) | 9 (27%) | 0 (0%) | 0 | 1 | 1 |
Freephone number for updating contact | 7 (22%) | 4 (12%) | 3 (9%) | 0 (0%) | 0 | 0 | 0 |
Follow-up through patient notes only | 19 (58%)e | 3 (9%) | 15 (45%) | 0 (0%) | 0 | 0 | 0 |
Transport to and from appointments | 8 (25%) | 3 (9%) | 4 (12%) | 1 (13%) | 0 | 0 | 0 |
SMS text reminders | 16 (49%)e | 2 (6%) | 13 (39%) | 0 (0%) | 3 | 1 | 4 |
Trial certificate | 8 (25%) | 2 (6%) | 6 (18%) | 0 (0%) | 0 | 0 | 0 |
Medical questions first in questionnaireb | 2 (7%) | 2 (6%) | 0 (0%) | 0 (0%) | 0 | 0 | 0 |
Generic questions first in questionnaireb | 3 (10%) | 2 (6%) | 0 (0%) | 1 (33%) | 0 | 0 | 0 |
Questionnaires sent less than 3Â weeks after a visitb | 2 (7%) | 2 (6%) | 0 (0%) | 0 (0%) | 0 | 0 | 0 |
Other (questionnaires) b | 2 (7%) | 2 (6%) | 0 (0%) | 0 (0%) | 0 | 0 | 0 |
Money/gift voucher given regardless | 8 (25%) | 1 (3%) | 7 (21%) | 0 (0%) | 1 | 2 | 3 |
Case management | 3 (10%) | 1 (3%) | 2 (6%) | 0 (0%) | 0 | 0 | 0 |
Other | 2 (7%) | 1 (3%) | 1 (3%) | 0 (0%) | 0 | 0 | 0 |
Personal touch (questionnaires)b | 9 (28%) | 1 (3%) | 8 (24%) | 0 (0%) | 0 | 0 | 0 |
Questions about health issue first in questionnaireb | 1 (4%) | 1 (3%) | 0 (0%) | 0 (0%) | 1 | 0 | 1 |
Questionnaires sent before clinic visitb | 5 (16%) | 1 (3%) | 4 (12%) | 0 (0%) | 0 | 1 | 1 |
Prize draw limited to trial participants | 6 (19%) | 0 (0%) | 6 (18%) | 0 (0%) | 0 | 0 | 0 |
Social media | 5 (16%)e | 0 (0%) | 3 (9%) | 1 (20%) | 0 | 0 | 0 |
Priority or recorded post (questionnaires)b | 4 (13%) | 0 (0%) | 3 (9%) | 1 (25%) | 0 | 0 | 0 |
Crèche service | 0 (0%) | 0 (0%) | 0 (0%) | 0 (0%) | 0 | 0 | 0 |
Behavioural motivation | 0 (0%) | 0 (0%) | 0 (0%) | 0 (0%) | 0 | 0 | 0 |
Charity donation | 0 (0%) | 0 (0%) | 0 (0%) | 0 (0%) | 0 | 0 | 0 |
National lottery ticket or similar public draw | 0 (0%) | 0 (0%) | 0 (0%) | 0 (0%) | 0 | 0 | 0 |
Total | 35 | 31 | 66 | ||||
Number of strategies that have been evaluated (% of all strategies, n = 59) | 23 (39%) | 26 (44%) | 36 (61%) | ||||