Previous assessments of sociodemographic characteristics of parents volunteering their children for therapeutic trials have shown conflicting results.10,11,12
One study found non‐volunteering fathers to be better educated, with a greater proportion of prestigious and skilled occupations than volunteering fathers.10
Similarly, non‐volunteering mothers were over‐represented in the professional and administrative occupational categories. This was thought to be a reflection of families of lower socioeconomic status perhaps having less access to the healthcare system and wanting to increase their access and social contact by volunteering.10
Another study found no negative correlation with parent's education level—which, however, tended to be high as a whole—in a group of children participating in a trial of asthma medication.11
The discrepant results may have been influenced by national differences in socioeconomic characteristics and in health service provision between Australia and the United States, which influenced families' access to the healthcare system. To some extent these studies may have been biased by insufficient, or even the complete absence of, comparative groups. In the present study, which applied an adequate comparative group of children who chose not to assent to the study of growth factors, no variations in sociodemographic characteristics could be detected between families who consented and families who did not. The finding suggests that socioeconomic status related factors such as social vulnerability, health seeking behaviour, and poor economy, which may be of some importance to parents of children with chronic diseases consenting to therapeutic trials, do not affect recruitment of children to non‐therapeutic research.10
Whether that holds true in countries with sociodemographic distributions that are different from those in Denmark remains to be investigated.
A few studies have evaluated parent's motives for volunteering their children for therapeutic research; however, children's motives for participating in therapeutic or non‐therapeutic research have not been assessed. Parents may be motivated by a desire to help others and to contribute to medical science and/or by a desire to learn more about their child's illness, and thereby help to make their child better.10,11,12
In line with the parental motives, the children in the present study volunteered for the non‐therapeutic research project for two significant reasons. They wanted to be of help to children with illnesses and they wanted to gain experience by participating in a study. In a majority of the children the altruistic and educational motives were supported by teachers, parents, and classmates. Remarkably, however, 13–20% of six to eleven year olds and 33–53% of twelve to sixteen year olds had not discussed their decision to assent with their parents. The findings in the oldest age group are in accordance with the results of a questionnaire in which adolescents were asked about their view as to the need for parental consent for adolescents to take part in studies involving blood or urine testing. A total of 42% of the adolescents felt that parental consent was not needed for these procedures.13
It was therefore, perhaps, more surprising that so many of the young children in the present study reported that they did not discuss their participation with their parents. We believe, however, that this was a consequence of us informing parents separately and specifically asking them to allow their children to decide about participation on their own if they felt they were able to do so. It must be remembered also that we encouraged the children to make up their own minds about giving assent or dissent before presenting the information and consent form to their parents, which probably helped to explain the fact that assent to the study did not depend on whether or not the children had discussed their participation with parents or classmates.
Though 19–46% of the children had worried about blood sampling, urine collection, or the doctor's examination, only the latter came out as a statistically significant difference between assenters and dissenters. Worries about the doctor's examination were associated with a higher dissent rate. In spite of the worries about these procedures, however, a great majority of children who were worried chose to assent. This suggests that there may be inherent differences between assenters' and dissenters' ability to cope with worries about invasive procedures. To some extent, not being able to cope with worries about having a blood sample taken was probably related to lack of experience of this procedure, since having had a blood sample taken recently was associated with a statistically significantly increase in assent rate.
Studies using objective methods for assessment of parent's and children's consent or assent have found an apparent discrepancy between parent's subjective perception of adequate information and objective assessments of understanding in parents and children.14,15,16
In an interview study in 102 seven to seventeen year old children and adolescents who participated in anaesthetic or surgery research, the subject's perceived understanding of the core elements of consent was significantly greater than their objectively measured understanding, which varied from 30–90%.15
In the present study we were interested in assessing whether the perceived understanding of written and verbal information in children who were invited to participate in non‐therapeutic research influenced assent and dissent rates. We agree with the perception that whether or not a child is able to achieve complete understanding of informed consent may be different from whether he or she has the capacity to meaningfully assent or dissent to a study.17
Therefore, we used the subjective method of asking the children to judge themselves whether they felt they could understand the information given. It was evident that the perception of understanding and the feeling of grasping the information given were associated with increased assent rate. From the age of nine approximately 95% of the children felt they were able to read some or all of the written information, and in the six to eight year old group more than 85% felt that they were able to understand it when they were assisted by a parent. Furthermore, approximately half of the six year olds and more than two thirds in the seven to sixteen year old group felt they understood the verbal information completely; very few felt they did not understand it at all. The findings indicate that when focused one‐page written information is used in combination with age differentiated verbal information, and given in the setting of a school, very few children are left without understanding, and in fact the great majority of them are able to meaningfully assent or dissent to non‐therapeutic research. The low percentage of children who felt they did not understand any of the verbal information could probably have been reduced by giving the children verbal information individually, in addition to the verbal information they were given in class.
The present study has provided evidence that sociodemographic characteristics do not influence healthy children's decisions to volunteer for non‐therapeutic research. A majority of children give assent for altruistic reasons and because they want to gain experience by participating in a research project. Worries about procedures such as venipuncture, urine collection, and a doctor's examination cause a minority of children to dissent. When age differentiated information procedures are used a great majority of school children and adolescents are capable of understanding and of giving meaningful assent or dissent to non‐therapeutic research.