Date Published: July 9, 2012
Publisher: BioMed Central
Author(s): Nha Uyen Nguyen Luu, Lisa Cicutto, Lianne Soller, Lawrence Joseph, Susan Waserman, Yvan St-Pierre, Ann Clarke.
There has been no large study characterizing selection bias in allergy and evaluating school personnel’s ability to use an epinephrine auto-injector (EpiPen®). Our objective was to determine if the consent process introduces selection bias by comparing 2 methods of soliciting participation of school personnel in a study evaluating their ability to demonstrate the EpiPen®.
School personnel from randomly selected schools in Quebec were approached using a 1) partial or 2) full disclosure approach and were assessed on their ability to use the EpiPen® and identify anaphylaxis.
343 school personnel participated. In the full disclosure group, the participation rate was lower: 21.9% (95%CI, 19.0%-25.2%) versus 40.7% (95%CI, 36.1%-45.3%), but more participants achieved a perfect score: 26.3% (95%CI, 19.6%-33.9%) versus 15.8% (95%CI, 10.8%-21.8%), and identified 3 signs of anaphylaxis: 71.8% (95%CI, 64.0%-78.7%) versus 55.6% (95%CI, 48.2%-62.9%).
Selection bias is suspected as school personnel who were fully informed of the purpose of the assessment were less likely to participate; those who participated among the fully informed were more likely to earn perfect scores and identify anaphylaxis. As the process of consent can influence participation and bias outcomes, researchers and Ethics Boards need to consider conditions under which studies can proceed without full consent. Despite training, school personnel perform poorly when asked to demonstrate the EpiPen®.
Food allergy is a serious condition affecting 3.9% of children in the United States , and can lead to systemic life-threatening symptoms or anaphylaxis . There is currently no well-established curative treatment for food allergy and management relies on avoidance and therapy with epinephrine for reactions caused by accidental exposures . We and others have shown that despite increasing societal awareness of the potentially fatal consequences of food allergy, accidental exposures continue to occur [4-8] and about 10% of fatal food-associated anaphylactic reactions take place in school [9,10]. As school represents a situation where parents must rely on other caregivers to respond to a severe allergic reaction, school personnel must be able to recognize anaphylaxis and know how to administer epinephrine using an auto-injector device such as the EpiPen® . A delay in epinephrine administration substantially increases the risk for fatality [10,12,13].
In the partial disclosure group, 33 schools were approached and 9 schools participated (7 elementary, 2 secondary); 460 personnel were approached and 187 participated (40.7%, 95% CI, 36.1%-45.3%). In the full disclosure group, 34 schools were approached and 11 participated (9 elementary, 2 secondary); 711 personnel were approached and 156 participated (21.9%, 95% CI, 19.0%-25.2%) (Table 1).
In this study, we explored the existence of volunteer or consent bias by using 2 different methods to solicit the participation of school personnel in research evaluating competency in the use of an epinephrine auto-injector (EpiPen®): partial disclosure and full disclosure. The participation rate was higher in the partial disclosure group (between group difference 18.7%, 95% CI, 13.3%-24.1%) and participants from the full disclosure group were more likely to earn a perfect score (between group difference 10.5%, 95% CI, 1.8%-19.2%), demonstrate the 3 critical steps correctly (between group difference 20.3%, 95% CI, 10.0%-30.6%), and identify signs of anaphylaxis (between group difference 16.2%, 95% CI, 6.2%-26.2%). These results suggest the existence of a volunteer or consent bias, a form of selection bias where individuals who volunteer for a study may have specific characteristics that distinguish them from non-volunteers and that may affect outcomes; for example, participants may be more likely to find the topic interesting and usually expect to be evaluated positively . In our study, school personnel from the partial disclosure group were not given all the information about the purpose of the study and the EpiPen® assessment prior to the assessors’ visit. Consequently, they were unlikely to be reluctant to participate because of concerns regarding their knowledge and competence, but their performance was generally poorer. In contrast, those in the full disclosure group were completely aware of the purpose of the assessment and those with a greater interest and possibly knowledge in the topic were more willing to participate, leading to an overestimation of competence relative to the general population. It is also possible that those who chose to participate also practised or prepared prior to the evaluation, enhancing their performance. This suggests that the timing and the process of informed consent can affect the participation rate and the interpretation of the results. Although this threat to the validity of a study that arises from the consent process has been described previously [20,21,28,29], we are the first to explore its influence in allergy research.
Although Research Ethics Boards usually ask investigators to fully disclose the intended purpose of their research to potential participants, we have shown that the process of consent can influence participation and bias outcomes. Investigators need to appreciate and acknowledge the potential bias that may be introduced by the consent process and attempt to fulfill ethical requirements while minimizing bias. While respecting participants’ rights, ethical issues regarding the consent process have to be discussed with Research Ethics Boards whenever the scientific validity of results may be compromised. Researchers and Ethics Boards may need to be educated on circumstances under which studies can proceed without full prior disclosure. Further, we have shown that despite being trained to recognize anaphylaxis and to administer epinephrine, school personnel perform poorly when asked to demonstrate how to use the EpiPen®. The content, quality and frequency of allergy and anaphylaxis training programs for school personnel have to be re-examined. As recommended by numerous guidelines [33-35] and required by legislation in at least one Canadian province , management plans targeting allergies and anaphylaxis should be introduced in schools to create a safer environment for children with life-threatening allergies. Further studies on the process of implementation and the impact of such plans are also needed.
CI, Confidence Interval; SD, Standard Deviation.
The authors declare that they have no competing interests.
NUNL participated in the study design, recruitment process, assessment of participants, data revision and analysis, data interpretation, and drafted the manuscript. LC participated in the study design, development of data collection instruments, data interpretation. LS participated in the recruitment process, assessment of participants, data interpretation. LJ participated in the study design, data analysis, data interpretation. SW participated in the study design, data interpretation. YSP performed the statistical analysis, and participated in the data interpretation. AC participated in the study design, data analysis, data interpretation. All authors read and approved the final manuscript.
Montreal Children’s Hospital.