Table 3.
Quantifying treatment contamination where treatment receipt was defined as binary
| Reference | Control treatment | Active intervention | Measure of contamination | Contamination (control participants receiving intervention) |
|---|---|---|---|---|
| Aveyard et al. [40] | Basic behavioural support for smoking cessation | Behavioural support for smoking cessation | Nurse visit (1st extra); Telephone call; Nurse visit (2nd extra) |
12/469 (3%) 12/469 (3%) 5/469 (1%) |
| Barton et al. [41] | No treatment | Mammography education (pamphlet and videotape) focusing on anxiety | Patient recall of: Pamphlet; Videotape |
9% 1% |
| Bernstein et al. [42] | No treatment | Cognitive behavioural therapy | Service Questionnaire of anxiety treatment | 0/24 (0%) |
| Borland et al. [43] | Minimal information | Behavioural support | Patients reporting use of extensive behavioural support | 45/378 (12%) |
| Clarkson et al. [36] | Routine care | Self-efficacy education | Participants reporting use of electric toothbrush | 9/113 (8%)p 9/180 (5%)c |
| Courneya et al. [44] | Group psychotherapy | Group psychotherapy and exercise programme | Patient-reported exercise | 10/45 (22%) |
| Dilley et al. [45] | Usual care | Cognitive counselling | Patient-reported receipt of counselling | 45/158 (29%) |
| Forchuk et al. [46] | Usual care | Transitional discharge from hospital | Patient-reported receipt of peer support and staff contact | 27% |
| Heirich & Sieck [47] | Health education | Proactive follow-up counselling | Patients requesting personal counselling | 56% |
| Johnson et al. [20] | Usual treatment | Clinical training in dual diagnosis of psychosis and substance misuse | Patients not taken on by trained case manager | 19/105 (18%) |
| Khumalo-Sakutukwa et al. [48] | Standard HIV voluntary counselling and testing | HIV counselling, testing and self-management | Participants seeking out treatment from intervention centres | 1% |
| Lamers et al. [49] | Usual care | Nurse-led minimal psychological intervention (MPI) | Patients who reported knowledge of MPI | 9/178 (5%) |
| Lee & Gayp [37] | Attention control | Sleep hygiene package | Patient-reported use of: Bassinet; White noise device; Low lighting |
33/46 (72%)p 47/75 (62%)c 11/75 (14%)c 27/75 (36%)c |
| Merritt et al. [50] | No intervention | Postcards with information about depression | Patients reporting having seen the postcards | 7/78 (1%) |
| Moadel et al. [51] | Standard care | Smoking cessation group support and encouragement | Patients reporting discussion of active intervention patients; Patients reporting familiarity with program’s strategies |
6% 17% |
| Mohr et al. [52] | Treatment as usual | Cognitive behavioural therapy | Patients who had contact with non-study therapist | 18/44 (41%) |
| Phillips et al. [53] | Routine public health practice | Community engagement in healthy eating | Participants reporting participation in intervention programme | 1% |
| Saitz et al. [54] | Usual care | Chronic care management (multidisciplinary care coordination; motivational therapy; counselling) | Patients who received a session of motivational enhancement therapy | 9/281 (3%) |
| Shemilt et al. [55] | No funding for breakfast club | Funding for school-based breakfast club | School pupils with school breakfast club | 77% |
| Stewart-Brown et al. [56] | No intervention | Incredible Years (parenting techniques) training | Participants attending community-based parenting programme | 4/44 (9%) |
| Waghorn et al. [57] | Enhanced routine mental health case management | Supported employment and specialist illness management | Patients opting to transfer to intervention after 6 months | 28/102 (27%) |
| Walpole et al. [58] | Social skills training | Motivational interviewing (MI) | Patients whose treatment was MI adherent | 37% |
| Wells et al. [59] | Usual care | Quality improvement therapy (CBT) and medications (assessment and education) | Receipt of speciality counselling within 6 months | 13% |
pUsing participant-level treatment allocation
cUsing cluster-level treatment allocation