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We highlight several critical challenges that must be
addressed to accelerate the advancement of the sci-
ence on recruitment and retention of ethnically
diverse older adults into health research. These
include the relative lack of attention by researchers to
methodological issues related to recruitment and
retention of ethnically diverse populations and the
inadequacy of funding to advance systematically this
field. We describe strategies used by the Resource
Centers on Minority Aging Research and other
National Institute of Aging–funded programs to
advance the science of recruitment of ethnically
diverse older adults. Finally, we propose a set of
broad recommendations designed to generate a
body of evidence on successful methods of recruit-
ment and retention of ethnically diverse populations
in health research. To eliminate health disparities
and better understand aging processes in ethnically
diverse populations, much more research is needed
on effective strategies for increasing minority enroll-
ment in health research. Comparative effectiveness
research on more intensive recruitment and retention
methods, which are often needed for including
diverse populations, will require dedicated funding
and concerted efforts by investigators.
Key Words: Health research, Enrollment, Racial and
ethnic minorities, Race, Ethnicity
The National Institutes of Health (NIH) Revi-
talization Act of 1993 and the Agency for Health-
care Research and Quality Healthcare Research
and Quality Act of 1999 identified recruitment
and retention of diverse populations as a priority
for clinical researchers. (Agency for Healthcare
Research and Quality, 2003; NIH, 2001) The need
to include ethnically diverse groups in health
research will grow even more acute as the United
States becomes increasingly multicultural.
Systematic reviews have examined factors
affecting the equitable representation of minority
groups in research (Ford et al., 2008; Lai et al.,
2006; UyBico, Pavel, & Gross, 2007; Yancey,
Ortega, & Kumanyika, 2006). These reviews share
one overarching recommendation, that is, the need
for more systematic research to test the efficacy of
specific methods, with greater methodological
rigor, in specific subpopulations. The recruitment
literature on older ethnically diverse adults is par-
The Resource Centers for Minority Aging
Research (RCMARs) were established originally
by the National Institute on Aging (NIA), with co-
funding from the National Institute of Nursing
Research, and the Office of Research in Minority
Health. The RCMAR program is currently funded
by the NIA and the National Center for Minority
Advancing the Science of Recruitment and
Retention of Ethnically Diverse Populations
Anna M. Nápoles, PhD, MPH*,1,2 and Letha A. Chadiha, PhD, MSW3,4
1Division of General Internal Medicine, University of California San Francisco.
2Center for Aging in Diverse Communities, University of California San Francisco.
3School of Social Work, University of Michigan-Ann Arbor.
4Institute for Social Research, University of Michigan-Ann Arbor.
*Address correspondence to Anna M. Nápoles, PhD, MPH, University of California San Francisco, 3333 California Street, Suite 335, San Francisco, CA
94118-1944. E-mail: firstname.lastname@example.org
Vol. 51, No. S1, 2011
Health and Health Disparities, to address health
disparities among older ethnic minority adults.
The RCMARs foster academic-community part-
nerships and conduct research on recruitment and
retention of older ethnic minority adults for health
research to develop evidence-based approaches.
Some of the challenges and successes in advancing
the science of recruitment have been described
in this supplement to The Gerontologist entitled,
“The Science of Recruitment and Retention among
Ethnically Diverse Older Adults.”
In this commentary, we aim to highlight several
critical challenges that must be met to accelerate
the advancement of the state of the science on
recruitment of ethnically diverse older adults for
health research. These include the relative lack of
attention by researchers to methodological issues
related to recruitment and retention of ethnically
diverse populations and the inadequacy of fund-
ing to advance systematically this field. Then, we
will illustrate some of the strategies used by the
RCMARs and other NIA-funded programs to
advance the science of recruitment of ethnically
diverse older adults. Finally, we will propose a set
of broad recommendations designed to generate a
body of evidence on successful methods of recruit-
ment and retention of ethnically diverse popula-
tions in health research.
Lack of Attention by Health Researchers to Issues
of Recruitment and Retention of Ethnically Diverse
The paucity of evidence on effective recruitment
and retention methods for use with ethnically
diverse populations is largely a reflection of their
de facto exclusion in research and the omission by
health researchers of published ethnic group–
specific data on recruitment and retention results.
Several systematic reviews have documented the
general lack of attention by clinical researchers
to enrolling and reporting on ethnically diverse
groups in studies. For example, one review that
examined more than 700 articles published
between 1970–2003 on obesity-related lifestyle
interventions, identified only 23 that included a
large enough sample of an underserved ethnic
group to enable ethnic group–specific analyses and
only 5 of these presented ethnic group–specific
outcomes data (Yancey et al., 2004). Another
review of 261 Phase III cancer prevention and
treatment trials from 1990 to 2000 found that,
although 92% of these trials reported the age and
gender composition of their samples, race/ethnic-
ity was reported in only 35% of treatment and
54% of prevention trials. None of the trials used
race or ethnicity in their selection criteria, whereas
gender was specified in 44% and age in 29% of the
trials’ selection criteria (Swanson & Bailar, 2002).
Finally, a review of arthritis-related behavioral
intervention studies from 1997 to 2008 found that
only 11 of the 25 studies provided data on the
racial/ethnic diversity of their samples and only 2
of these stratified their results by White and minority
participants (McIlvane, Baker, Mingo, & Haley,
2008). Inattention to recruitment of ethnic minor-
ity groups and failure to report on the racial and
ethnic group composition of samples (and strati-
fied outcomes data) limits our ability to address
Inadequate Funding of Recruitment- and
Despite the importance of establishing evidence-
based recruitment strategies, federal funding
opportunities to support rigorous research on the
science of recruitment and retention in diverse
populations are lacking. To illustrate the lack
of federal funding opportunities for studies of
recruitment or retention methods in health
research, we conducted searches using two major
Web sites listing federal funding opportunities
and solicitations: the Federal Business Opportunities
(FedBizOpps.gov) and NIH Office of Extramural
Research (http://grants.nih.gov/grants/guide/) Web
sites. We used search terms of “recruitment OR
retention AND research,” searching for active and
inactive funding opportunities between 1992 and
The FedBizOpps.gov search yielded 857 oppor-
tunities. Reviewing the title and synopsis of each
one identified no opportunities that specifically
requested research studies to test the effectiveness
of recruitment or retention methods. Two that
were closest to this intent were a contract award
opportunity to generate a representative sample
for the Healthy Aging in Neighborhoods of Diver-
sity across the Life Span Study (solicitation num-
ber: 260-03-15) and a solicitation for an AIR
National Guard Recruiting and Retention CD-
ROM Planning Tool to assist recruiters in tracking
progress toward recruitment goals (solicitation
number: W9133N-04-CD-ROM). The search of
the NIH Office of Extramural Research Web site
yielded nine funding opportunities. None focused
on studying the effectiveness of recruitment or
Accumulating an Evidence Base on Recruitment
and Retention of Ethnically Diverse Older Adults
The RCMARs and other NIA-funded programs
have implemented strategies to build an evidence
base on effective recruitment strategies in diverse
populations in the face of limited funding. One of
these strategies involves conducting nested studies
of recruitment methods within funded health
research studies. For example, at the University of
California San Francisco RCMAR, called the Cen-
ter for Aging in Diverse Communities, researchers
have conducted randomized trials of several types
of supplemental recruitment materials that have
been nested within patient-reported quality of care
studies, such as the addition of pamphlets that
describe the nature of research or invitation letters
that are culturally tailored (Napoles-Springer,
Fongwa, Stewart, Gildengorin, & Perez-Stable,
2004). Conducting comparative effectiveness
studies of recruitment and retention methods will
require targeted funding, but in the absence of
such funding, conducting nested recruitment stud-
ies is a useful interim strategy. However, nested
studies without supplemental funding are only
economically feasible for low-intensity recruitment
Another strategy that is used within funded
studies is to conduct supplemental analyses related
to recruitment and retention outcomes. For exam-
ple, such analyses have included reporting of
enrollment rates stratified by race/ethnicity and
stage of recruitment or retention (e.g., contact
attempt, contact, invitation, enrollment, mainte-
nance; Napoles-Springer, Santoyo, & Stewart,
2005; Ofstedal & Weir, 2011) or examining
participant and site characteristics associated
with retention (Manson et al., 2011). Formative
research can also be used to collect data prior to
(or even after) studies to examine barriers and
facilitators of participation of underrepresented
groups (Napoles-Springer et al., 2000; Williams,
Meisel, Williams, & Morris, 2011).
The RCMAR at the University of Michigan/
Wayne State University, called the Michigan Cen-
ter for Urban African American Aging Research,
has developed a registry of research study volun-
teers composed mostly of older African Americans
(Chadiha et al., 2011). If multiple research centers
could share the costs to support the development
and maintenance of such registries, this strategy
might prove to be especially cost-effective across
centers. Moreover, registries may serve as a
resource for creating samples of older adults from
underrepresented groups, particularly racial/ethnic
minority persons, and for collecting data on their
health status and outcomes of care. A more
resource intensive approach adopted by the NIA-
funded Alzheimer’s Disease Research Center at
Washington University involved setting up an
African American Outreach Satellite, which con-
ducts strategic outreach and recruitment programs
and training for community health care providers
(Williams et al., 2011).
Recommendations to Advance the Science of
Recruitment and Retention
Taken together, these creative strategies are
beginning to inform future efforts to recruit and
retain vulnerable populations in research. None-
theless, much work remains to be done if we are to
eliminate health disparities in older adults. The
lack of funding for recruitment studies helps
explain the preponderance of observational stud-
ies focused on this topic. Experimental studies in
the recruitment literature that rigorously test
recruitment or retention methods are the excep-
tion, despite the valuable evidence they contribute
(Kiernan, Phillips, Fair, & King, 2000; Ramirez
et al., 2008, 2008; Wenzel et al., 2008). Although
formative and observational recruitment and
retention studies are informative and essential, the
insights they provide and methodological ques-
tions they raise can be addressed more definitively
in some cases, using experimental methods. Track-
ing the cost-effectiveness of recruitment and reten-
tion methods is also vital.
Reflecting on the content of this supplement
and our experiences through the RCMAR pro-
gram, we present in Table 1 a set of recommenda-
tions that would significantly advance the science
of recruitment and retention in diverse popula-
tions. The recommendations are listed in order of
least to most resource intensive.
A requirement of funded studies that enroll a
substantial proportion of an ethnic minority or
other vulnerable group should be that investigators
report stratified enrollment rates, as well as unique
recruitment challenges and solutions within popu-
lation subgroups. When applying for funding or
even after studies are funded, investigators can
design nested randomized trials or other types of
Vol. 51, No. S1, 2011S145
recruitment studies within the larger substantive
study that is the focus of the proposed project.
Similarly, funding agencies can incorporate a rele-
vant recruitment or retention topic within the
scope of research topics specified in funding oppor-
tunity announcements. Finally, just as special
funding initiatives have addressed the need for
measurement studies to develop innovations in
measures of complex behavioral constructs (PAR-
08-212 Methodology and Measurement in the
Behavioral and Social Sciences; http://grants.nih.
ing agencies can create targeted recruitment initia-
tives. These initiatives are especially indicated in
the case of large population-based cohort studies
involving underrepresented groups, where biologi-
cal specimens or burdensome procedures are
required that can impose particular hardships on
participants. A cost-effective way to test recruit-
ment strategies is for funding agencies to offer sup-
plemental funding to nest these studies within
To eliminate health disparities and better
understand aging processes in ethnic subpopula-
tions, much more research is needed on effective
strategies for increasing minority enrollment in
health research. Unless there are concerted efforts
(set asides) to provide funding to test the effective-
ness of specific strategies in underrepresented
groups and researchers devote attention to these
issues, scientific progress toward identifying the
most promising strategies will advance slowly
and in a piecemeal fashion. Comparative effec-
tiveness research on more intensive recruitment
and retention methods, which are often needed
for including ethnically diverse populations, will
require dedicated funding and concerted efforts
This work was supported by the Resource Centers for Minority Aging
Research program of the National Institute on Aging (NIA), the National
Institute of Nursing Research, and the National Center on Minority
Health and Health Disparities (grant numbers P30 AG15272 and P30
AG015281). The content is solely the responsibility of the authors and
does not necessarily represent the official views of the NIA, the National
Institute of Nursing Research, and the National Center on Minority
Health and Health Disparities or the National Institutes of Health.
We thank Robert J. Taylor for helpful comments on a draft of this
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Table 1. A Summary of Recommendations for Advancing the Science of Recruitment and Retention of Ethnically Diverse
Populations in Health Research Organized From Least to Most Resource Intensive
1. Investigators track and report enrollment rates stratified by race/ethnicity, related challenges, and solutions.
2. Investigators conduct nested studies of the effectiveness of recruitment or retention within other health research studies.
3. Funding opportunity announcements for primary data collection studies include a request for investigators to incorporate a
nested study that compares the effectiveness of multiple methods of recruitment and/or retention, especially studies that
include underrepresented groups.
4. Funding agencies appropriate targeted funding to investigate specific methodologically challenging recruitment issues, e.g.,
identifying alternative incentives for recruiting groups that have been discriminated against or that are impoverished in
longitudinal cohort studies that may have limited funding to pay monetary incentives to participants.
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