A: It's important for researchers to understand at what point people drop out, and why. The reasons for dropping out may be different at various points in the study. Having an operational definition can help researchers examine factors that predict attrition, which are needed to determine its impact on study findings, enhance recruitment procedures, and maximize retention rates.

A: Based on the literature, mostly from epidemiological research, we decided to look at 3 types of attrition: pre-inclusion, dropout, and intermittent attrition. Pre-inclusion attrition was defined as people who were eligible and did not consent to participate and people who quit before randomization into control or treatment group. Dropout attrition included those who didn't complete the intervention (treatment group) or did not complete the final follow-up (treatment or control group). Intermittent attrition meant that the participants completed the final follow-up but missed earlier follow-up portions of the study. We thought it was important to separate these different types of attrition in order to determine who was dropping out and when.

A: We found that it was the younger caregivers who were not completing the study, at least at pre-inclusion and after randomization. There were no significant differences in the intermittent group. We want to examine that phenomenon more closely now. In this first exploration, we looked at age, ethnicity, income, education, etc., but we didn't ask them "why." It's important to understand why they dropped out or did not consent. There could be several reasons for this; it could simply be that they're not as familiar or comfortable with research. They may not have been exposed to research, so they don't know what to expect and may not be aware of the advantages. Or perhaps there are other factors that play into it, such as employment, which limits time available for participation, or they may be single moms who find it difficult to find child care for their other children.

A: I think it's important to have people feel involved in the research process and to let them know that their participation is important and that we value them. A quick and simple retention method that people really seem to appreciate is when we send them birthday and holiday cards. This lets them know that we really do care about them, that we are interested in what they have to say, and that we care about their children's health.

Also, let the participants know up front what's expected of them, clarify the timeline, let them know the demands of the study, and make sure they have an overall understanding of what's going on. Also, let them know when an article comes out or give them updates at the end of the study. It just helps them get a better understanding of what we're doing, why we're doing it, and why their participation is indeed so important.

Understand and respect their needs. If you have the funding to provide transportation or child care, do so. Also, you need to take into consideration participants' own work schedules, so have morning, evening, weekend times for them to come in. It's hard to expect people to come in when they're working. They may not be willing or able to take time off or to take kids out of school. Our families have a lot of responsibilities that we need to be aware of and respect.

A: For researchers early on in their career, I think it is especially important for them to acknowledge and accept that attrition will happen and not to beat themselves up because they didn't keep every single participant. It's going to happen and that's OK, but it's also important to figure out how to minimize those attrition rates. It's important to acknowledge the barriers and face them head on.