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Table 3 Quantifying treatment contamination where treatment receipt was defined as binary

From: A scoping review of the problems and solutions associated with contamination in trials of complex interventions in mental health

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%

  1. pUsing participant-level treatment allocation
  2. cUsing cluster-level treatment allocation