Table 1

Summary of studies included in the systematic review

Lead author/country/yearInclusion/exclusion criteriaParticipant illnessParticipant demographicsTotal number of participants (response rate)Study designSampling strategyAnalysisKey themes exploredStudy strengthsStudy limitations
Walkup,20 USA, 2009None providedNoneGender: not reported57 (not provided)Exploration of conversation and questionnaireConvenienceDescriptive summary statisticsStudy purpose, voluntariness, study method, risks, benefits, confidentiality and review board approval
  • Participants approached in a public setting and invited to complete a questionnaire and researcher recorded study information spontaneously requested

  • Did not specify a disease group

  • No inclusion/exclusion criteria

  • Participant demographics not reported

Age: not reported
Education/deprivation: not reported
Ethnicity: not reported
Bento,21 Brazil, 2008Female participants aged 18–49 years who had taken part in a clinical trial of women's health in the previous 12 months and lived in Metropolitan area of Campinas, Sao Paulo, BrazilWomen's healthGender: only female
  • 51 participants

  • 8 focus groups (not provided)

Focus groupsConvenienceFramework analysisStudy methods, risks and benefits
  • Participants of different ages and educational level likely to have different needs and opinions regarding topic

  • Focus groups homogeneous for age and educational level; suitable to ensure they were comfortable expressing opinions

  • Recruitment continued until data saturation point

Demographics not representative of the general population as the study only included women and was limited to participants from a trial of a contraceptive intervention
Age: 18–49
Education/deprivation: 4 focus groups 8th grade or less, 4 focus groups above 8th grade education
Ethnicity: not reported
Hutchinson,7 Australia, 1996Participants of clinical trials of COPD, asthma, diabetes, osteoporosis, rheumatoid arthritis and the influenza vaccine. Excluded if clinical trial for acute, life-threatening or debilitating conditions with inadequate therapyChronic illnessGender: 52% male259/324 (80%)QuestionnaireConvenienceDescriptive summary statistics and multivariate logistic regressionConflicts of interest (CoI)/organisation and funding of the researchDemographics not representative of the general population as median age 70
Age: median age 70 (range not reported)
Education/deprivation: range of backgrounds
Ethnicity: not reported
Gray,22 USA, 2007Participants enrolled onto a phase I research trial, spoke English and were medically and mentally capable of participatingPhase I research trialGender: 52% male102/119 (86%)QuestionnaireConsecutive participants enrolling onto parent trialDescriptive summary statistics, χ2 tests and multivariate logistic regressionCoI/organisation and funding of the researchSame interviewer conducted all interviewsDemographics not representative of the general population as the median age was 61 and was limited to cancer patients participating in an early phase clinical trial
Age: median age 61 (range 26–82)
Education/deprivation: range of backgrounds
Ethnicity: 81% white
Fernandez,23 Canada, 2007English-speaking adolescent with cancer or parents of children with cancer. Excluded acutely unwell or recently relapsedCancer
  • Gender: adolescents not reported

  • Parents mostly women (23/30; 77%)

40/43—10 adolescent, 30 parent participants (93%)QuestionnaireRandomDescriptive summary statistics and χ2 testsReturn of study resultsDemographics not representative of general population as participants were well educated, mostly Caucasian and limited to adolescents with cancer/parents of children with cancer
  • Age: adolescents median age 16 (range 13–20)

  • Parents median age 40.9 (range 28–53)

  • Education/deprivation: adolescents predominantly in education (no figures reported)

  • Parents 50% with post secondary education

  • Ethnicity: adolescents 80% Caucasian

  • Parents 100% Caucasian

Bento,33 USA, 2006Participants of HIV, hepatitis, arthritis and surgical oncology trials who were >18 years and English speakingVariousGender: 61% male33 (not provided)Face-to-face semi-structured interviewsConvenienceTranscripts coded and themes and major concepts identifiedCoI/organisation and funding of the research
  • Open questions used during interviews

  • Data collection continued to saturation point

  • Two authors independently conducted analysis

  • Used hypothetical scenario

  • Demographics not representative of general population as participants were more often men and limited to adults participating in HIV, hepatitis, arthritis or surgical oncology trials

Age: not reported
Education/deprivation: range of backgrounds
Ethnicity: 70% white
Hampson,24 USA, 2006Participants with cancer and enrolled in a clinical trial who were English speaking and >18 yearsCancerGender: 56% male252/272 (93%)Structured face-to-face interviewsNot providedDescriptive summary statistics and Fishers exact test/Kruskal–Wallis testCoI/organisation and funding of the researchValidated interview questionsDemographics not representative of general population as the study population were well educated, financially secure and limited to adult participants of a clinical trial
Age: 24%, <50; 32%, 50–59; 26%, 60–69; 16%, >70
Education/deprivation: well educated and financially secure
Ethnicity: 92% white
Weinfurt,25 USA, 2006Healthy adults or those with a mild chronic illness. Excluded if they had participated in another focus group within the previous 6 months or were working or had worked for an organisation involved in the conduct of clinical trialsHealthyGender: 42% male16 focus groups (not provided)Focus groupsConvenienceInitial content codes based on transcripts developed that were summarised and reviewed to identify main themesCOI/organisation and funding of the researchParticipants not limited to disease group
  • Only one moderator conducted focus groups

  • Non-verbal communication not recorded

  • Demographics not representative of general population as the study population were well educated, financially secure and the majority had previously shown interest in research

Age: 12%, 18–29; 51%, 30–49; 37%, >50
Education/deprivation: well educated and financially secure
Ethnicity: 56% white
Partridge,26 USA, 2005All participants of the parent trial (chemotherapy trial)CancerGender: only female94/135 (69.6%)QuestionnaireConvenienceSimple descriptive statisticsReturn of study results
  • Participant selection biased towards participants that wanted to know study results

  • Demographics not representative of general population as the study population were mostly Caucasian, only included females and was limited to participants of a breast cancer trial

Age: mean age 55 (range not reported)
Education/deprivation: range of backgrounds
Ethnicity: 96% white
Kim,27 USA, 2004Potential research participants >18 years, diagnosed with heart disease, breast cancer or depression and listed on the Harris Interactive Chronic Illness DatabaseVariousGender: 50% male5478/20205 (27%)Online questionnaireRandomTwo-way ANOVA modified for ordinal data and multinomial logistic regressionCoI/organisation and funding of the research
  • Validated questionnaire

  • Participants chosen at random but from the subset of those registered on the Harris Interactive Chronic Illness Database

Demographics not representative of general population as it was limited to internet users
Age: 4% 18–29, 16% 30–44, 61% 45–64, 19% 65+
Education/deprivation: range of backgrounds
Ethnicity: 92% white
Partridge,28 USA, 2003Any participant enrolled into the parent study (chemotherapy trial)Breast cancerGender: not reported51/55 (93%)QuestionnaireConvenienceSimple descriptive statisticsReturn of study resultsMulticentre
  • Unvalidated questionnaire

  • Demographics not representative of general population as the study was limited to participants of a breast cancer trial. Gender was not presented but expect most were women given disease area

Age: median age 54 (range 29–82)
Education/deprivation: range of backgrounds
Ethnicity: 84% white
Casarett,29 USA, 2001Participants with a current telephone number, enrolled at a pain clinic, who had chronic non-malignant pain, were taking scheduled opioids and had experienced the pain for at least 6 monthsChronic painGender: 40% male40/86 (46.5%)Semi-structured telephone interviewsConvenienceDescriptive summary statistics and bivariate analysis with non-parametric testsVoluntariness, study methods, expenses, risks and the drug/device/procedure being tested
  • Validated interview topic guide

  • Questions spontaneously asked by participants were recorded

Demographics not representative of general population as participants were more often men and limited to chronic pain patients
Age: mean age 47 (range 30–86)
Education/deprivation: range of backgrounds
Ethnicity: 85% white
Maslin,30 UK, 1994Attending a breast unit and were patients with a breast cancer diagnosis or asymptomatic women with a family history of breast cancerCancerGender: only female213/300 (71%)Postal questionnaireRandomSimple descriptive statisticsStudy purpose, voluntariness, study methods, risks, benefits and confidentialityParticipants chosen at random but from a subset of those attending a breast unitDemographics not representative of general population as the study only included women and was limited those with breast cancer
Age: median 47 (range 24–81)
Education/deprivation: not reported
Ethnicity: not reported
Sand,31 Norway, 2008Participants eligible for the parent study (all lung cancer patients)CancerGender: 57% male21/33 (64%)Semi-structured interviewsConvenienceIdentification and categorisation of themes and analysis based on deductive and inductive categoriesVoluntariness, study methods and treatment alternatives
  • No inclusion/exclusion criteria stated but 11 potential participants were not invited

  • Technical problems with 3 recordings

  • Demographics not representative of the general population as participants were more often men, had a median age of 69 years and were limited to lung cancer patients

Age: median age 69 (range 44–84)
Education/deprivation: range of backgrounds
Ethnicity: not reported