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Table 1 Evidence for comprehension in informed assent processes.

From: Improving assent in health research: a rapid systematic review

AuthorsStudy designIntervention & ControlOutcomeFindingsCritical appraisal
Abramovitch et al. (1995) [8]Non-RCT
Participants: 177 healthy children (7-12 years)
Description: 3 sub-studies on memory, hearing loss and personality
Simulated scenario
Control: Standard descriptions of the sub-studies (n=131)
Intervention: Standard descriptions + probing questions after descriptions of each study (n=46)
Measurement: Understanding of purpose, good things, and bad things
Time point: after the description of all 3 studies
With probing questions, children understood purpose and good things better than without interspersed questions; no effect on understanding of bad thingsQuality Rating: 2
Incomplete outcome reporting
Non-comparable data provided
Recruitment methods and selection unclear
Adcock et al. (2012) [9]Crossover-RCT
Participants: 217 school children (7-11 years)
Description: studies on blood pressure and gastroesophageal reflux
Simulated scenario
Control: Standard assent form with 2 pages in paragraph form (n=190)
Intervention: KidSent assent booklet with 16 pages with sentences and pictures (n=195)
First, participants read one of the documents; 3 days later, they read the other document
Measurement: Understanding of study purpose, risks, procedures, and right to withdraw
Time point: immediately after reading the respective document
Mean of correct answers for standard form 78.5% and for KidSent booklet 71.8%; significant difference between both groups
Other results: more children in KidSent booklet group had perfect scores (34,7%) than in standard form group (22,1%); most children stated that they understood the KidSent booklet better
Quality Rating: 1
2 different studies were covered by the control and intervention form; one might have been more difficult to understand
Randomization methods partly unclear
Annett et al. (2017) [10]RCT
Participants: 64 healthy and ill adolescents (12-17 years)
Description: clinical trial on asthma
Real scenario
Control: Standard assent process with adolescent and parent together (n=34)
Intervention: Separate assent process for adolescent and parent in different rooms (n=34)
Measurement: Understanding of asthma trial medicines, research process, rights and privileges, and risks and benefits
Time point: immediately after assent process
In knowledge about risks and benefits, minors over 15 years scored better when assent was separate
Younger children showed no difference
Other results: Parents of older minors also showed better understanding when assent was separate; 15-17-year-olds scored better in asthma medicine than 12-14-year-olds
Quality Rating: 1
Incomplete outcome reporting
Values for understanding between intervention and control not provided
No description of randomization process
Barnett et al. (2005) [11]RCT
Participants: 374 school children (9-11 years, first language English)
Description: in 7 schools; study how to convey concept of RCTs
Simulated scenario
Control: Standard block text format (n=123)
Interventions: (1) Question and answer (Q&A) format (n=126) and (2) Story presentation (n=124)
Measurement: Understanding of randomization, safety and effectiveness, voluntariness, and avenue of redress
Time point: immediately after reading information
Mean of correct answers for block text 70.4%, for Q&A 66.9%, and for story 64.2%
Other results: Significant difference for amount of participants that answered all questions per topic correct (story presentation scored best)
Quality Rating: 1
No statistics provided for comparison of mean scores
No description of randomization process
Blake et al. (2015) [12]RCT
Participants: 120 adolescents (15-17 years, English-speaking, from youth serving agencies)
Description: hypothetical HIV vaccine trial
Simulated scenario
Control: Standard paper assent (n=31)
Interventions: (1) Standard paper assent with interspersed questions (n=29) and (2) Web-based assent with interspersed questions, videos, and clip arts (n=60)
Measurement: Understanding of assent content
Time point: immediately after assent process
Mean of correct answers for paper assent 74.8%, for paper assent with questions 81.8%, and for web-based assent 78.1%; no significant differences
Other results: No significant difference for amount of participants that answered at least 80% correct (paper assent with questions best)
Quality Rating: 1
Less interaction with researcher in web-based assent
Randomization methods stated
Chappuy et al. (2008) [13]Retrospective interviews
Participants: 29 ill children (HIV or cancer, 8,5-18 years)
Description: participants recently recruited for other clinical trials
Real scenario
Linking personal and disease factors and understanding of study processesMeasurement: Understanding of study purpose, protocol design and procedures, risks, direct and indirect benefits, right to withdraw, duration, alternatives, voluntariness
Time point: after recruitment for respective clinical trial
Mean of correct answers when trial recruitment took place more than 7 days after diagnosis 46% and when it took place earlier 20.8%; significant difference between both groups
Other results: adolescents older than 14 years scored better than younger ones
Quality Rating: 3
No controlled groups
Inclusion of several different clinical trials may have influenced outcomes
Small sample, potential bias by group imbalances
Coors et al. (2016) [14]Non-RCT
Participants: 76 healthy and ill adolescents (substance use disorder, 14-17 years, no intellectual deficiency)
Description: biobanking and genomics study in several stages
Real scenario
Control: Standard risk information
Intervention: Standard risk information + additional information on 7 previously identified salient risks
Measurement: Understanding of risks
Time point: immediately after assent process
In patients, the additional information on salient risks improved scores significantly
In healthy adolescents, there was no significant difference
Quality Rating: 2
Incomplete outcome reporting
No description of allocation of participants; numbers per group unclear
Friedman et al. (2016) [15]RCT
Participants: 568 healthy adolescents (14-17 years, male only, gay or bisexual)
Description: survey on online behaviour of gay youth
Real scenario
Control: Study information (n=186)
Interventions: (1) Study information + requirement to answer 2 questions correctly (n=187) and (2) Study information + requirement to answer 7 questions correctly (n=195)
Measurement: Understanding of risks and voluntariness
Time point: immediately after survey
Mean of correct answers for information without questions 63%, with 2 questions 92.5%, and with 7 questions 93%; significant difference between conditions with and without questions
Other results: assent significantly rarer completed when questions interspersed
Quality Rating: 1
Questions to assess understanding at the end are the same as used in the intervention
Online study with high number of dropouts
Male participants only
Randomization methods stated
Grootens-Wiegers et al. (2015) [5, 16]Interventional study
Participants: 101 school children (10-13 years)
Description: comic about characteristics of research studies
Simulated scenario
Intervention: Comic strip with information on medical research (n=101)Measurement: Understanding of 8 research aspects
Time point: after reading the comic strip
Mean of correct answers for comic strip 83.0%; best score for side effects, worst score for anonymity
Other results: survey on user satisfaction
Quality Rating: 4
No control group
Recruitment methods and selection unclear
Dropouts not described
Lally et al. (2014) [17]RCT
Participants: 120 adolescents (16-19 years old, male/female who have sex with men)
Description: consent and brochures on characteristics of an HIV vaccine trial
Simulated scenario
Control: Standard informed consent (n=42)
Interventions: (1) Informed consent with 1-sided supplemental information (presentation of pertinent facts) (n=39) and (2) Informed consent with 2-sided supplemental information (n=39) (presentation of common misconceptions and rebuttal with factual information)
Measurement: Understanding of randomization, interpretation of side effects, and unproven efficacy (part of consent and intervention brochures); understanding of non-brochure topics
Time point: immediately after reading the information
Mean of correct answers for consent alone 72.1%, for consent + 1-sided information 78.6%, and for consent + 2-sided information 80.2%; significant difference between consent only and consent + 2-sided information for randomization and side effects
Other results: no significant differences for topics not covered by the supplemental brochures
Quality Rating: 1
Some participants are older than 18 years
Randomization methods stated
5-point Likert-type response scale potentially inappropriate for understanding items
Lee et al. (2013) [18]Interventional study
Participants: 123 adolescents (12-17 years)
Description: study on Hepatitis B vaccination in youth
Real scenario
Intervention: Simplified assent form with every day, non-medical language and supporting graphs in a Q&A formatMeasurement: Understanding of procedure, randomization, future benefits, blinding, direct benefit, voluntariness
Time point: immediately after reading the form
Mean of correct answers for the simplified assent form 85.8%
Other results: 56.1% answered all questions correctly
Quality Rating: 4
No control group
Dropouts not described
Mayne et al. (2017) [19]Case series with intervention
Participants: 2 children (3 years)
Description: Story of a toymaker who makes science toys
Simulated scenario
Intervention: Interactive nonfiction narrative (powerpoint with photos, clip arts, active buttons) on touch computer; concepts: dialogic reading, sustained shared thinking, cycle telling and retellingMeasurement: Understanding of research purpose and context, participatory rights, and consent
Time points: 1 week before, 2 and 9 weeks after outreach
Understanding of the basic research concepts improved or stayed high after presentation of the interactive narrativeQuality Rating: 4
No control group
Only 2 selected participants
Incomplete outcome data due to erratic interest of participants
Miranda et al. (2017) [20]Interventional study
Participants: 42 hospitalized children (5-10 years, clinically stable)
Description: study on vulnerability during illness and hospitalization
Real scenario
Intervention: Illustrated booklet (text, images, illustrations for colouring)Measurement: Understanding of research proposal
Time point: during application of booklet
All children understood the research proposal
Other results: Children wanted the booklet to be able to colour it
Quality Rating: 4
No control group
Understanding was assessed only by “observations by researcher”
Inconclusive outcome reporting
Murphy et al. (2007) [21]RCT
Participants: 187 healthy adolescents (15-19 years, male/female/ transgender, at risk for HIV, English-speaking)
Description: study on HIV vaccination
Simulated scenario
Control: HIVNET standard assent form (n=94)
Intervention: Based on HIVNET version, but reorganized, simplified text, implementation of illustrations (n=93)
Measurement: Understanding of study details including procedures, benefits and risks
Time point: immediately after assent process
Mean of correct answers for standard version 71.7% and for illustrative version with simplified text 80.5%; significant difference between both groups
Other results: understanding of procedures and benefits was also significantly better in the intervention group; illustrative version with simplified text contained fewer words, fewer words per sentence, less passive voice, and had higher reading ease
Quality Rating: 1
No description of randomization process
No indication of standard deviations
Simplified text and illustrations are tested together
Some participants are older than 18 years
O’Lonergan and Forster-Harwood
(2011) [22]
RCT
Participants: 170 children (11-14 years, no deficits in cognition, hearing, or vision, did not undergo procedures yet) together with parents
Description: study involving common procedures in paediatrics (DXA and abdominal ultrasound)
Simulated scenario
Control: Standard permission and assent process (n=87)
Intervention: Multimedia process in Microsoft PowerPoint with same text like standard process but with hyperlinks to videos and voice-overs (n=83)
Measurement: Understanding of essential elements of the permission and assent process
Time point: immediately after assent process
Mean of points for correct answers for standard process 44% and for multimedia process 51.2%; significant difference between both groups for total score, study procedures, and risks
Other results: parents also scored significantly better with multimedia process; all participants overestimated their comprehension
Quality Rating: 1
No description of randomization process
Incomplete outcome reporting (answers to some questions were not presented individually)
Tait et al. (2007) [23]RCT
Participants: 190 hospitalized children (7-17 years, no cognitive impairment, no emergent illness)
Description: study on postoperative nausea and vomiting
Simulated scenario
Control: Standard form including verbal explanation (n=95)
Intervention: Modified form with improved readability and processability as well as use of bullets, bolding, increased font size, and pictures (also including verbal explanation) (n=95)
Measurement: Understanding of purpose of study, protocol, risks, direct and indirect benefits, alternatives, voluntariness, and freedom to withdraw
Time point: immediately after assent process
Mean of points for correct answers for standard form 60.4% and for modified form 68.5%; significant difference between both groups
Other results: differences between groups were higher in younger children; most children preferred modified form; all children overestimated their comprehension
Quality Rating: 1
No description of randomization process
Large number declined participation; possibly selection bias of highly motivated children
Assessors were blinded
Tait et al. (2012) [24]Before and after study
Participants: 4 children (8-14 years, from waiting room in hospital)
Description: pilot study; trial on asthma
Simulated scenario
Intervention: 3D modelled avatars present a dialogue between a child and a doctor in an interactive programMeasurement: Pre- and post-intervention understanding of clinical trial, randomization, placebo, and blinded study; post-intervention understanding of elements of the study
Time point: directly before and after using the program
Correct descriptions of the 4 terms from pre- to post-intervention: 25% to 50%, 0% to 0%, 0% to 50%, and 25% to 50%; mean of points for correct answers about elements of the study 61.7%Quality Rating: 4
No control group
Only 4 participants
Tait et al. (2015) [25]RCT
Participants: 135 children (10-17 years, attendants of a paediatric clinic, no cognitive impairments, English-speaking)
Description: study on general aspects of trials
Simulated scenario
Control: Standard paper form (text only) (n=68)
Intervention: Interactive iPad program in written and visual formats together with voice-over and interactive exercises with corrective feedback (content identical to standard form) (n=67)
Measurement: Understanding of clinical trial, participation, protocol, randomization, placebo, blinding, double-blinding, effectiveness, and informed consent
Time point: immediately after reading the information
Mean of points for correct answers for standard form 49.2% and for interactive program 64.7%; significant difference between both groups
Other results: most children preferred the interactive program over the standard form
Quality Rating: 1
Randomization methods stated
Assessors were blinded
Ulph et al. (2009) [26]Cross-sectional study
Participants: 106 school children (7-11 years)
Description: study on methods to convey probabilities in a cup game
Simulated scenario
6 different formats were tested in all participants:
(1) verbal labels (rare)
(2) percentages (1%)
(3) pie charts
(4) proportions as words (1 in 100)
(5) proportions as notation (1:100)
(6) mixed format
Measurement: 3 trials to choose the highest probability shown for each format
Time point: during the game
Mean of points for correct answers was highest for pie charts (90%), followed by verbal labels, percentages (79%), proportions as words (64%), proportions as notation (62.7%), and mixed format (43%)Quality Rating: 4
Game may not represent complexity of medical research
Only understanding of probability was tested
Incomplete outcome reporting