Skip to main content

Table 1 Characteristics of included studies

From: Increasing participation of cancer patients in randomised controlled trials: a systematic review

Study details Study design Target of intervention (who received the intervention; and the number of trials across which it was assessed) Patient Participants Experimental Intervention/and comparator Summary of threats to validity
Angiolillo et al. (2004)[24] United States Controlled observational study Parents of children with cancer
Four Children Cancer Group Trials
I: n = 36;
C: n = 104
Parents of children with acute leukaemia
Age of children I: Mean 4.9 yrs (SD 2.5);
C: 7.8 yrs (SD 5.1)
Ethnicity not stated
Intervention: A two-stage process was used for one trial. 1. Written parental consent was sought for the induction phase of the trial during which all patients received the same induction chemotherapy. Written consent (4 weeks later) was then obtained for randomisation to one of four therapeutic regimens.
Comparator: Parents of children in the other three trials did not receive the staged approach. No further details provided.
A high possibility of selection bias due to lack of randomisation and no reported process for selecting individual participants. The intervention was not implemented in a standardised way. Due to poor reporting the risk of contamination was unclear. There was a particular risk of performance bias.
Coyne et al. (2003)[22] United States Cluster randomised controlled trial Adult cancer patients
Three trials (C9741; E1594; E2197)
I: n = 78;
C: n = 129
Breast (85%) and lung cancer patients
I: 92.3% female;
C 90.7% female
I: Mean 53 yrs;
C: mean 53 yrs
I: 94% white;
C: 92% white
Intervention: Easy to read version of the original written consent document (different for each of the three trials). Changes included text style, page layout, font size and vocabulary. Content was not altered. Readability was seventh to eighth grade level and length was 16 pages.
Comparator: Original consent document (different for each of the three trials). E1594: 4 pages long and fourteenth grade reading level. C9741 and E2197: 7–8 pages long and twelfth to thirteenth grade reading level.
This was a randomised study. The unit of randomisation was at the institutional level and this was maintained for the statistical analysis. However, due to poor reporting it is unclear whether the study was properly designed to protect against selection bias. The design appeared to protect against contamination as only one consent statement was used at an individual centre.
Donovan et al. (2003)[19] United Kingdom Randomised controlled trial Adult cancer patients
Single trial
I: n = 75;
C: n = 75
Prostate cancer patients
100% male
Age not stated
Ethnicity not stated
Intervention: Nurse conducted information appointment with the patient to recruit to the trial.
Comparator: Urologist conducted information appointment with the patient to recruit to the trial.
A good quality RCT: appropriate randomisation, concealed allocation, at least 80% of patients considered at follow-up and ITT analysis conducted. It is possible that contamination between the two groups and performance bias may have influenced the findings.
Donovan et al. (2002)[20] United Kingdom Before and after Healthcare professionals
Single trial
Baseline: n = 30;
I1: n = 45;
I2 n = 67;
I3: n = 83;
I4: n = 155
Prostate cancer patients
100% male Age not stated
Ethnicity not stated
Intervention: Three successive documents§ regarding how best to recruit patients to the trial were circulated to recruiters followed by a training programme. Consent to randomisation was measured at baseline and following circulation of each document. This is an uncontrolled study therefore there is a risk of factors other than the intervention influencing patient participation.
Fleissig et al. (2001)[21] United Kingdom Nonrandomised controlled study Healthcare professionals and adult cancer patients
Forty trials
I: n = 135;
C: n = 130
10 different cancers
I: 72% female;
C: 72% female
Age range 19–65 yrs
I: 58% 45–64 yrs;
C: 50% 45–64 yrs
Ethnicity not stated
Intervention: Patients completed the Patient Preferences for Information Questionnaire, Patient Attitudes to Trials Questionnaire and Spielberger State Trait Anxiety Inventory prior to consultation with their doctor. Doctors were then provided with each patient's completed questionnaires (only the first 2 questionnaires) prior to their consultation during which consent was sought for a specific trial.
Comparator: Patients completed the same questionnaires prior to consultation with their doctor. Doctors were not provided with this information prior to their consultation with individual patients during which consent was sought for a specific trial.
A high possibility of selection bias: only the order in which doctors conducted intervention and control group consultations were randomised (in blocks of 5 patients). The process by which patients were selected for inclusion was not reported. There was a high possibility of contamination as the same doctors were involved administering the experimental intervention and the comparison. The intervention was not implemented in a standardised way. The process of completing the questionnaires may have influenced patient decision-making in both groups.
Gross et al. (2004)[25] United States Controlled observational study System level
Global target (National Cancer Institute phase II and III Clinical Trials Cooperative Group trials)
I: n = 4569;
C: n = 20,443 (2,440 were in phase II trials)
Breast, colon, lung and prostate cancer patients
Sex not stated
Age not stated 89% white
Intervention: Four states (Illinois, Louisiana, Virginia, New Jersey) that enacted legislation or developed a co-operative agreement with health insurers in 1999 to cover clinical trial patient care costs (coverage states).
Comparator: 35 states that had not enacted any policies to cover clinical trial patient care costs by the end of 2001 (non-coverage states)
The baseline enrolment rate was statistically significantly higher in intervention group than the comparator group introducing the risk of regression to the mean. Lack of enforcement in the intervention group and behaviour of physicians in the comparator states to compensate for lack of coverage could have had an influence.
Paskett et al. (2002)[23] United States Nonrandomised controlled study Adult cancer patients, healthcare professionals
All trials available to patients in a given geographical area.
Total number of participants not stated
Breast and colorectal cancer patients
Majority female
Age not stated for I and C (mean age, which was reported by time period of recruitment and cancer type ranged from 62 to 75 yrs)
75% white
Intervention: There were four elements: 1) a rapid tumour reporting system, 2) a nurse facilitator responsible for alerting physicians about appropriate clinical trials for their patients, 3) a quarterly newsletter about cancer treatment and clinical trials targeted at physicians and 4) a health educator who provided community-based education about screening and treatment and trained lay health educators. Implemented in five rural counties in North Carolina.
Comparator: No intervention in five rural counties in South Carolina.
The risk of selection bias is unclear. Data on patient trial participation were obtained from medical records; however it was unclear how specific cancer patients within regions were selected or whether all cases were detected. The study was susceptible to contamination: improving participation of patients in all rural areas was a major focus of the Community Clinical Oncology Program (CCOP) and both geographical areas had active CCOP physicians.
Simes et al. (1986)[26] Australia Randomised controlled trial Adult cancer patients and healthcare professionals
Thirteen trials at a single oncology unit
I: n = 28;
C: n = 29
8 different cancers
I: 82% female;
C: 62% female
I: mean 56 yrs (31–63 yrs);
C mean 55 yrs (40–74 yrs)
I: 96% white;
C: 100% white
Intervention: Uniform policy of total disclosure of all information relevant to the trial to the patient. There was an opportunity to ask further questions. Information was provided verbally and in a written consent form.
Comparator: Information about the aims, anticipated results and potential toxicities of treatment were provided with details of treatment provided at the discretion of the consultant. There was an opportunity for the patient to ask questions. Verbal consent was obtained.
This was a randomised study though it was not possible to assess from the information reported whether the method of assignment was truly random and whether it was concealed. There was a high possibility of contamination as the same doctors were involved in delivering the experimental. Attempts were made to establish whether the intervention and comparison were standardised across patients though it was not possible to establish whether the method used was sufficiently rigorous.
  1. I: experimental intervention, C: comparator
  2. §Document 1 asked recruiters to present the three treatment options in a particular order and provide equivalent detail on advantages and disadvantages. They were asked to avoid the terms trials and 'watchful waiting' to describe monitoring and place emphasis on patients being eligible for all treatments; document 2 re-emphasised monitoring as an active process, eliciting and challenging patients' views if at odds with the evidence and re-emphasised there was no compulsion to accept treatment allocation; document 3 provided good and not so good examples of how to present information about treatments in an equal way.