In this longitudinal project, a comprehensive approach was used for recruitment and retention. Despite recruiting from a low-income and minority population, few barriers to study enrollment were encountered in this clinic-based research study. This was most likely because the intervention itself was part of clinical care and was not perceived to be ‘experimental,’ although data were not specifically collected on this issue. Clinical staff buy-in appeared to be strong throughout the study. Furthermore, buy-in was likely achieved as the study design did not add any more tasks to the daily work-load in providing clinical care.
As noted by other studies in a similar population, recruitment and retention efforts were successful because of several strategies. Although not discussed previously in the literature as a recruitment or retention strategy, designating a nurse leader to oversee the leaders and interviewers at all three clinics provided excellent role modeling patient/health professional interactions and for integrating research processes into a clinical environment. Nurses are familiar with the clinic flow as well as the needs of the new mother. Clinic patients and parents seek guidance from the nurse as the person with the most time to devote to their needs. It is very likely that this bond helped initially form relationships between the research staff, clinical staff, and participants.
From the outset, retention was a priority of the research leadership. Our comprehensive approach to both recruitment and retention was selected based on the historical challenges faced in conducting prospective research within low-income and minority populations. Several of our strategies have been validated in previous studies and included face-to-face recruiting, consistent and repeated contact with the target population, financial incentives, participant tracking, and continuous monitoring. In addition, we developed a project logo and identity and used it on all mailings to participants and aided participant convenience with the use of a dedicated phone line. Despite the additional costs, we believe this investment of resources is essential for research projects attempting to follow a similar population. As such, all research staff, from the principal investigator to the data collection members of the team, must have the willingness to undertake a more involved protocol when working with a population which is often difficult to reach and retain.
The retention rate for this project was high at 6 months and fairly high at 12 months relative to other projects among low-income mothers. In their smoking cessation study, a different project with a similar population, French & Groner had an excellent retention rate at 3 months (over 75% depending on the group) but at 6 months only 60% of the cohort could be contacted [20
] despite a planned, systematic approach of participant follow-up. Chang and colleagues [8
] yielded a similar retention rate among low-income overweight and obese mothers. A parenting intervention study, which recruited women with inadequate prenatal care, similarly yielded a 59% retention rate at 12 months post intervention [21
One factor that may contribute to reduced retention of low-income mothers is that an infant’s first two years of life is a very busy time for any mother. A study by Hambridge and colleagues examined if attendance at infant well-child visits could be increased if a stepped intervention of reminder, recall, and case management were employed [21
]. In this urban population, those who received the stepped intervention were significantly more likely to have had ≥5 well-child visits by 15 months of age (65%), compared to those without the intervention (47%). The total cost per child for the intervention arm was $23.30 per child, per month [22
]. This further emphasizes the logistical and cost challenges associated with retention of low-income mother-infant dyads during the first two years of life. To facilitate a similar retention plan, we had multiple team members in the clinics regularly to increase our visibility, with repeated efforts to call and contact mothers after missed appointments, and worked within the normal well-child visit schedule to reduce the burden on mothers.
Another factor that may influence participant retention may relate to the study topic. Senturia et al. [23
] reported that 89% of participants completed 3-, 6-, and 9-month surveys in an inner-city pediatric asthma study. Asthma is a chronic disease that can have quite severe symptoms, and therefore missing clinic visits may be frightening for parents. In the MOMS study, one possible explanation for the drop in retention at 12 months may be related to the relatively benign topic of nutritional anticipatory guidance at a well-child visit. Because parents may have felt that they could ‘catch-up’ in their child’s immunization schedule and information several months later, adherence to the study protocol may not have been perceived as important. Likewise, more participants were lost in the Maternal Focused Eating group than the other two groups. This may reflect a lack of interest in establishing a healthy diet for themselves and the focus of the new mother on the dietary needs of her infant, which was more of the focus for the other groups.
A randomized clinical trial of diabetes self-management intervention at five community health centers in Massachusetts among low-income Latinos with type 2 diabetes retained 71% of the sample with all measures at both baseline and 12-month follow-up [24
]. Similar to our study, researchers of this study attribute their retention success largely to a coordinated effort between the research team and the infrastructure support at the community health centers. What we term clinical staff buy-in in this manuscript includes the clinical infrastructure support we received from the three clinics. Having access to schedules and charts, being able to work with the nurses and doctors to finish surveys during down time in the well-child visits, use of desk space and chart areas in the clinics with assistance were essential elements of administrative support.
Our retention rates were analyzed by age, race, education, relationship status, use of WIC and food stamps to see if certain groups were inadvertently ‘selectively’ retained. When analyzing retention rates, we found that African-American women and those of older ages had higher retention at 6 months, but that there was no difference by race or age at 12 months and at both time points combined. There is no clear explanation for this finding, but we can state that our approach to recruitment and retention certainly did not select for non-minority or participants of older ages.
Failure to track refusals is a limitation of this study because future recruitment and retention strategies can be used that address these issues. For instance, parents who did not agree to their child’s participation in a school-based diabetes study cited that they did not understand the informed consent (37%), ran out of time to complete paper work (32%) and communication difficulties [25
]. The parent’s suggestions for increasing recruitment include offering encouragement (53%), involving parents with previous experience in research (24%) and providing educational information (19%). Our study did offer encouragement through continued face-to-face and verbal communication. Involving previous research participants as recruiters is a novel idea that may be beneficial in these low-income, diverse populations because of the potential to decrease the distrust of health care providers and researchers.