Integrating Biomarkers into Research with Latino Immigrants in the United States

Advances in Anthropology

2013. Vol.3, No.2, 112-120

Published Online May 2013 in SciRes (http://www.scirp.org/journal/aa) http://dx.doi.org/10.4236/aa.2013.32015

112

Integrating Biomarkers into Research with Latino Immigrants

in the United States

Heather H. McClure1,2, J. Josh Snodgrass2, Charles R. Martinez Jr.1, J. Mark Eddy3,

Thomas W. McDade4, Melanie J. Hyers5, Anne Johnstone-Díaz6

1Center for Equity Promotion, College of Education, University of Oregon, Eugene, USA

2Department of Anthropology, University of Oregon, Eugene, USA

3School of Social Work, University of Washington, Seattle, USA

4Department of Anthropology and Institute for Policy Research, Northwestern University,

Evanston, USA

5Department of Romance Languages, University of Oregon, Eugene, USA

6Family Resource Center, Bethel School District, Eugene, USA

Email: hmcclure@uoregon.edu

Received February 5th, 2013; revised March 5th, 2013; accepted March 15th, 2013

mons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, pro-

vided the original work is properly cited.

Despite extensive research into the toll of persistent psychosocial stress on individual physiology and

health, little is known about the effects of chronic biosocial stress for immigrant populations. In the pre-

sent paper, the authors review challenges encountered when integrating minimally-invasive stress-related

biomarkers (e.g., blood pressure, Epstein-Barr Virus [EBV] antibodies, C-reactive protein [CRP], and

salivary cortisol), as well as anthropometric (e.g., height, weight, waist circumference) and metabolic

measures (e.g., glucose, cholesterol), into research with Latino immigrant adults and families in Oregon,

USA. Finally, the authors present lessons learned and discuss strategies to support the full engagement of

Latino immigrants as participants in studies that rely on the collection of biological data as a central

component of research into psychosocial stress and its effects.

Keywords: Biomarker; Latino; Immigrant; Psychosocial Stress

Introduction

Despite the size of the Latino population in the United States

(16.7% of the US population [US Census Bureau, 2011]), the

role of stress as a contributor to poor mental and physical health

outcomes among Latinos is little known. This is especially true

for the approximately 40% of Latinos in the United States who

are foreign born (Lopez & Taylor, 2010), and the over 50% of

Latino families in which children are US born of immigrant

parents (The Urban Institute, 2010).

Many immigrant families, particularly if recently arrived to

the US, experience stressors (i.e., exposure to circumstances)

that can contribute to profound psychosocial stress (i.e., the

extent to which an individual is challenged to maintain function

[McEwen, 2000]). Common stressors for immigrant families

include low socioeconomic status (SES), challenges of adapting

to life in the U.S. (acculturation), employment uncertainty, dis-

crimination, and concerns about legal status, among others

(Rumbaut & Portes, 2001; Vega & Kolody, 1985; Vega et al.,

2004). In states with unprecedented recent population growth of

immigrants, such as Oregon and North Carolina, there may be

few formal buffers (e.g., well-established ethnic enclaves, cul-

turally-competent services) against such stressors (Capps et al.,

2002; Smokowski & Bacallao, 2007). Though extensive re-

search has been conducted on the toll of persistent psychosocial

stress on individual physiology and health (e.g., Kiecolt-Glaser

et al., 1994; McDade et al., 2007), little is known about the

effects of chronic biosocial stress for Latino immigrants.

Research with US born populations suggests that chronic

psychosocial stress is a key link between challenging social

contexts and negative health outcomes (Dressler et al., 2005;

William et al., 2003). The measurement of stress among immi-

grant populations, however, may present unique challenges. As

the notion of “stress” is deeply culturally-bound, dominant no-

tions regarding “stress” in the US may be distinct from and

even unrecognizable to immigrants, especially if they are re-

cently arrived. Attempts to measure self-reported Latino immi-

grant stress and its effects using standardized instruments,

which are often validated through studies with second and third

generation Latinos in the US, may fail to resonate with immi-

grant respondents. More sensitive and objective measures of

stress are needed for a clearer understanding of links between

contexts favoring stress and health outcomes among Latino

immigrants (Martinez, 2006).

To begin to fill these knowledge gaps, in 2007, the Latino

Research Team (LRT) at the Oregon Social Learning Center

(OSLC) initiated two pilot research projects to determine the

feasibility of collecting biological data among Latino immi-

grants, and to better “map” the pathways through which psycho-

social stressors related to acculturation, discrimination, and

SES, among others, influence self-report and biological meas-

ures of immigrant stress. Both projects utilized minimally-

H. H. MCCLURE ET AL.

invasive techniques (i.e., saliva collection and pricking a par-

ticipant’s finger with a lancet for the collection of a few drops

of blood on filter paper cards). Our use of multiple, complemen-

tary biological markers of stress is novel, as most investigations

into stress and health have relied upon measures of self-re-

ported stress, rather than upon physiological measures such as

stress biomarkers (McDade et al., 2007); this is particularly true

for studies involving immigrant populations.

In the present paper, we review challenges encountered when

integrating stress-related biomarkers (e.g., blood pressure, Ep-

stein-Barr Virus [EBV] antibodies, C-reactive protein [CRP],

and cortisol), as well as anthropometric (e.g., height, weight,

waist circumference) and metabolic measures (e.g., glucose, cho-

lesterol), into research with Latino immigrant adults and fami-

lies in Oregon. Finally, we present lessons learned and discuss

strategies to support the full engagement of Latino immigrants

in studies that rely on the collection of biological data as a com-

ponent of research into psychosocial stress and its effects.

Overview of Pilot Studies

Despite the apparent value of incorporating stress biomarkers

into research with Latino immigrants in the US, few previous

studies had done so and many questions regarding feasibility

remain (Ryan et al., 2006; Steffen et al., 2006). To examine

questions relating to participants’ comfort with biomarker me-

thods, in 2007, we began a two-phase Latino stress and health

study (a.k.a. “The Farmworker Study” or TFS) in collaboration

with a highly respected farmworker housing and social service

organization, and with biological anthropologists at the Univer-

sity of Oregon and Northwestern University. This cross-sec-

tional study took place in three geographically distant housing

complexes in Oregon’s northern Willamette Valley; analyses

involved 132 Latino immigrant adults (≥18 years of age; 86

females, 46 males; 96% Mexican origin; 96% were parents).

Approximately 38% of men and 33% of women had a third

grade education or less, with 11% of men and 19% of women

completing high school or receiving post-secondary education.

Ninety-three percent of men and 46% of women were em-

ployed. Heads of household reported an annual median house-

hold income of $15,825 to support an average household of five

people (SD = 1.5).

This project was followed by the 2009-2010 Stress and Ac-

culturation Project (SAP), which focused on links among stress,

health, and parenting in 44 Latina immigrant mothers and their

young children in the 1st to 3rd grades (93% Mexican origin),

and collaboration with the University of Oregon. About a third

of mothers (32%) had a third grade education or less, and 23%

completed high school or received post-secondary education.

Forty-three percent of mothers worked outside the home. Mo-

thers reported an annual median household income of $18,750

to support an average household of five people (SD = 1.5).

Recruitment for Studies

Study samples were drawn from non-probability designs and

recruitment was conducted through trusted social networks, and

by recruiters who share characteristics of the target study popu-

lation (Martinez et al., 2012; Villarruel et al., 2006). TFS took

place during the busiest time of year for agricultural workers.

Despite this, recruitment was completed quickly with staff of

our partner organization recruiting all participants within 10 days.

In the SAP pilot, 24 families in the Eugene/Springfield area

were recruited in one week. Our participation rate for both pilot

studies was 98%.

The Farmworker Study

On a single day, residents participated in a health assessment

and responded to a 20 minute interview. Senior staff from the

LRT and the farmworker organization collaborated on the de-

sign of the interview. Due to its brevity, specific questions were

drawn from a larger assessment battery that had been exten-

sively developed by the LRT for use with the Latino population

in Oregon (see Martinez & Eddy, 2005; Martinez et al., 2009).

A focus group composed of Latino immigrant farmworkers

reviewed the questionnaire, and changes were made per focus

group findings. The SAP interview was modeled after that for

TFS, with items added relating to depression and parenting.

The Institutional Review Boards at OSLC and the University of

Oregon approved all research protocols and all participants

provided written consent prior to the assessment. All respon-

dents were assessed in Spanish.

Assessors for TFS included LRT professional interviewers,

staff from our partner organization, volunteer undergraduate

students, and community members. All assessors received four

hours of intensive training in how to conduct the interview and

collect biological and health data, and between four and eight

hours of on-site supervision. Assessments were scheduled for

Saturday and Sunday mornings (residents were given a choice

of days), and childcare was provided.

Assessments for the first study were conducted in the com-

munity center in each housing complex. The health exam in-

volved measures of blood pressure, height, weight, and waist

circumference (WC). Staff used a lancet to prick the partici-

pant’s finger to collect a drop of blood for the immediate meas-

urement of fasting glucose and total cholesterol (all participants

had fasted [>8 hours]), and two drops of blood to dry onto filter

paper for later laboratory analyses of EBV antibodies and CRP.

Assessors then conducted the interview and provided a one-on-

one saliva collection demonstration (see cortisol measurement

section below for detail). Finally, each participant met with a

health educator to review their health values. Participants with

measures indicating need for follow-up were referred to part-

nering public health agencies. During the following week, staff

made reminder calls to participants the evening before and the

day of each saliva collection. A week after the health assess-

ment, a staff member collected participants’ saliva samples and

transported them to the laboratory for later analysis. Partici-

pants received $30 in compensation. Findings from this study

have been reported elsewhere (McClure et al., 2010a, 2010b,

2010c, 2012; Midttveit et al., 2010; Squires et al., 2012).

The Stress & Acculturation Project

The SAP study incorporated similar indicators and involved

only LRT assessors. This study was conducted in the homes of

participating families and involved two visits approximately

one week apart. At the first home visit, data were collected on

mother and children’s height, weight, WC, and blood pressure.

Staff also conducted a 30 - 40 minute interview with mothers

and provided training in the collection of saliva samples.

Though we measured blood pressure for both mothers and chil-

dren, our focus was on mothers’ blood pressure; we measured

children’s blood pressure as part of the health information

H. H. MCCLURE ET AL.

provided to families as an incentive for participation. Mothers

received $15 at the completion of the first home visit, and chil-

dren were given a toy of their choice.

The second home visit occurred upon completion of saliva

collection. A few drops of blood generated through finger stick

were analyzed for separate measures for mother and child.

Mothers’ fingers were pricked first and analyzed for fasting

glucose and lipid levels (i.e., total cholesterol, HDL cholesterol,

triglycerides, and calculated LDL cholesterol; equipment in-

formation below). The assessor then pricked the child’s finger

to test for hemoglobin levels (a test for anemia; equipment in-

formation below). Mothers were given a copy of their own and

their child’s health values, health information in Spanish, and a

list of local clinics for follow-up if indicated. An exit interview

(5 minutes) was administered to the mother regarding her and

her child’s experience in the project. Assessors also picked up

saliva samples and delivered them to a lab for later analysis.

For compensation, mothers received $15 and children chose a

toy.

Measurement of Psychosocial Stress

Our investigation of physiological measures of psychosocial

stress is informed by a large body of research dating back to

Selye (1956), and integrates complementary biomarkers to bet-

ter understand how stress gets “under the skin” to affect health

(McDade, 2007). The following briefly reviews the specific

biomarkers and health measures used in TFS and SAP and

measurement techniques.

Cortisol

The hypothalamic-pituitary-adrenal (HPA) axis has been

recognized for its important role in the stress response and, in

particular, its role in energy mobilization (Sapolsky et al., 2000).

Cortisol, the primary glucocorticoid hormone in humans and a

marker of HPA activity, has a strong diurnal rhythm with high-

est levels typically occurring in the early morning hours and

lowest levels in the late evening (Kirschbaum & Hellhammer,

2000). Over time, everyday negatively perceived experiences

can contribute to atypical cortisol fluctuation with either high or

blunted cortisol levels in the morning, and flatter diurnal curves

over the day. Although increased cortisol release in response to

acute stressors can be adaptive, the prolonged activation of the

HPA axis can lead to HPA dysregulation with downstream

effects including the progression of various diseases, such as

obesity, type 2 diabetes, and cardiovascular disease (McEwen

& Wingfield, 2003). Studies indicate that Latinos have signifi-

cantly flatter diurnal cortisol slopes than Caucasians due per-

haps to greater stress exposure, including perceived discrimina-

tion (DeSantis et al., 2007).

Measurement. In TFS, cortisol was measured from six saliva

samples: each participant collected three samples each day for

two consecutive days. The SAP study involved nine samples per

participant with mothers collecting their own and their child’s

saliva three times a day for three consecutive days. Adult par-

ticipants collected 1.0 mL of saliva in Eppendorf tubes from

themselves (and from any participating child) upon awakening,

within 30 minutes of awakening, and a half-hour before bed-

time. In addition, adult participants were asked to record the

date and time of the collection of each sample. In SAP, mothers

were asked to maintain a saliva diary for themselves and their

child that recorded the exact time and date of sample collection,

substances used in the prior 24 hours that might interfere with

cortisol assay (e.g., medications, tobacco, and alcohol), and

major events during the day. Participants were instructed not to

eat, smoke, brush their teeth, drink alcoholic or caffeinated

beverages, or engage in intense physical activity in the 30 min-

utes prior to each sample due to possible changes in salivary

cortisol concentrations (Pollard & Ice, 2007). To ensure the

stability of salivary cortisol (Kirschbaum & Hellhammer, 2000),

participants were instructed to refrigerate all saliva samples

until a staff member collected them during a follow-up visit and

transported them in an ice chest to the Snodgrass laboratory.

Once in the lab, all samples were stored frozen at −30˚C in a

secure location until analysis. All cortisol samples were ana-

lyzed using enzyme immunoassay with a commercially avail-

able salivary cortisol assay kit (Salimetrics, State College, PA).

Epstein-Barr Virus Antibodies

Over the past two decades, EBV antibody levels have been

applied as a useful biomarker of chronic psychosocial stress

(McDade, 2007). EBV is a ubiquitous herpes virus for which

80 to 90 percent of adults and adolescents in the US test posi-

tive by the age of 40 (Jones & Straus, 1987), though little is

known about EBV prevalence among children. Once infected,

individuals harbor the virus for life in infected cells. Adequate

cell-mediated immune function maintains the virus in a latent

state and most adults infected with EBV are clinically asymp-

tomatic (Henle & Henle, 1982). Stress-induced immunosuppres-

sion, however, allows EBV to reactivate, which may trigger an

antibody response (Glaser et al., 1991). Thus, EBV antibodies

provide a measure of cell-mediated immune function over the

duration of several days or weeks (McDade, 2007). Researchers

have found elevations in EBV antibody levels among adults in

poor quality marriages (Kiecolt-Glaser et al., 1994), children

experiencing family stress (McDade et al., 2000), and Latino

men who report discrimination stress (McClure et al., 2010a,

2010b). Because of EBV’s utility as a marker of chronic psy-

chosocial stress, it has been incorporated into the National

Longitudinal Study of Adolescent Health (Add Health) and the

World Health Organization’s Study on Global Ageing and

Adult Health (SAGE).

Measurement. EBV was measured through the collection of

dried blood spot samples. Following standard procedures

(McDade et al., 2000), each participant had their finger pricked

with a sterile disposable lancet; 2 - 5 drops (approximately 50

µL) of whole blood were then collected on standardized filter

paper (No. 903; Whatman). Blood spot samples were then dried

overnight, and stored at −80˚C until laboratory analysis. Blood

spot EBV antibodies were measured using DiaSorin (Stillwater,

MN) EBV VCA IgG kits according to a high-sensitivity en-

zyme-linked immunosorbent assay (ELISA) protocol described

elsewhere (McDade et al., 2000). In our studies, all participants

were seropositive for EBV antibodies. Protocols in English and

Spanish are available online

(http://www.bonesandbehavior.org/dbsprotocol.pdf).

C-Reactive Protein

CRP is a nonspecific acute phase reactant that rapidly in-

creases in plasma concentration in response to inflammation,

infection, and injury (Pepys & Hirschfeld, 2003). Studies have

114

H. H. MCCLURE ET AL.

linked minor CRP elevations, previously considered clinically

normal, with increased cardiovascular risk (Ridker et al., 1998).

Elevated levels of CRP are linked to factors such as obesity

(Rexrode et al., 2003), and with several dimensions of psycho-

social stress, including lack of social integration (Ford et al.,

2006) and low SES (Nazmi & Victora, 2007). Few studies in-

volving CRP have been conducted with Latino populations

(Midttveit et al., 2010).

Measurement. CRP was measured through the collection of

dried blood spot samples following the same procedure descry-

bed above for EBV. CRP samples were used for two purposes.

First, CRP was used to identify acute infection or tissue injury,

which could potentially impact EBV antibody levels. Second,

subclinical CRP concentrations were used as indicators of chro-

nic inflammation, and for the examination of whether low-

level elevations CRP concentrations related to psychosocial

stressors. CRP was analyzed using a high-sensitivity enzyme

immunoassay protocol (McDade et al., 2004) that uses Bio-

Design International (Saco, ME) capture and detection anti-

bodies.

Blood Pressure

It is well-established that blood pressure is associated with

diet and physical activity, among other lifestyle factors. In ad-

dition, psychosocial stress related to perceived discrimination

and low SES have been shown to correlate with elevated sys-

tolic blood pressure (SBP) and diastolic blood pressure (DBP;

Dressler et al., 2005). The few studies among Latino adults in

the US reveal important gender differences (Steffen et al.,

2006), with higher discrimination stress relating to higher SBP

among men only (McClure et al., 2010a).

Measurement. For the first pilot study, blood pressure (SBP

and DBP) was measured using an Omron HEM-422CRLC

manual inflation oscillometric blood pressure monitor (Vernon

Hills, IL); for each individual, blood pressure was measured

twice, separated by at least 10 minutes. In a few cases involving

obese participants, blood pressure was measured with a manual

sphygmomanometer by a registered nurse. In the second pilot

study, blood pressure was measured using an Omron HEM-

907XL professional oscillometric instrument (Bannockburn, IL).

In both studies, blood pressure was measured by a trained as-

sessor using standard procedures (Chobanian et al., 2003).

Anthropometric and Metabolic Values

Chronic stressors such as job strain, divorce, and perceived

discrimination have been associated with greater levels of fast-

ing glucose, lipids, and insulin (Vitaliano et al., 2002). Findings

from the British Whitehall studies indicate that the degree to

which individuals were treated unfairly independently predicted

larger waist circumference, higher hypertension, triglycerides,

and fasting glucose, and lower serum HDL cholesterol, even

after controlling for SES, behavioral risk factors, and other

psychosocial factors (DeVogli et al., 2007). Extensive evidence

also illustrates links between chronic stress and depression,

which can lead to increased caloric intake, elevated BMI, and

associated metabolic and coronary risks (Dallman et al., 2003).

Chronic stress can trigger a complex cascade of behavioral

and physiological changes that contribute to the development of

the metabolic syndrome (MetS). MetS is characterized by a

constellation of risk factors including abdominal obesity, insu-

lin resistance, and elevated blood pressure and plasma lipid

levels that ultimately can lead to type 2 diabetes (Sattar et al.,

2008) and cardiovascular disease (Byrne & Wild, 2005). Though

there is a burgeoning literature on Latino adult and child obe-

sity, type 2 diabetes, hypertension, and their contributors, few

studies have focused on psychosocial stress and Latino meta-

bolic function (McClure et al., 2010b; Weigensberg et al.,

2008). In the SAP study, 33% of mothers had values indicating

MetS, comparable to high (and rising) national prevalence

rates.

Measurement. In both studies, stature, body mass, and WC

were recorded using established procedures (Lohman et al.,

1988). Body mass index (BMI) was calculated as mass divided

by height in meters squared (kg/m2). In the first study, glucose

and total cholesterol concentrations (mg/dL) were obtained

from fasted participants using 30 µL samples of capillary blood

collected from finger prick and using a CardioChek PA ana-

lyzer and PTS Panels (Polymer Technology Systems, Indian-

apolis, IN). This professional testing system meets standard

clinical guidelines for accuracy and precision. In the second

study, Cholestech LDX monitors (Hayward, CA) were used for

the measurement of fasting glucose and lipid levels from 35 µL

samples of capillary blood collected from finger prick. Presence

of the metabolic syndrome was assessed using the updated ATP

III criteria (Grundy et al., 2005).

Hemoglobin

Chronic childhood anemia can contribute to delays in mental

and physical development, and evidence is increasing that La-

tino toddlers have a high rate of anemia related in part to pov-

erty and acculturation factors (Brotanek et al., 2007). As parents

in our first project considered this health information highly

valuable, we included it in the SAP study to encourage recruit-

ment and retention.

Measurement. Hemoglobin is considered a standard measure

for assessing anemia, and values are interpreted based on age-

and sex-specific cutoffs. Children’s blood hemoglobin in SAP

was measured from a drop of blood obtained from finger stick,

and assessed using the HemoCue Hb201+ (Lake Forest, CA) to

determine if levels were within normal range (typically over 11

g/dL). This system has been extensively validated and its accu-

racy is within ±1.5% of the reference method.

Lessons Learned

Despite the development of new techniques for the meas-

urement of stress outside of clinical settings, there can be barri-

ers to their incorporation in studies with Latino populations in

general and with Latino immigrant groups in particular (Na-

tional Institutes of Health, 2002). We were interested to learn

whether the integration of health measures and biomarkers into

our studies reduced historic barriers or instead served as an

additional challenge to participation in research. Lessons learn-

ed (Table 1) include ways to best support participants’ com-

pliance with complex and time-sensitive protocols, especially

given long days spent in agricultural work and unpredictable

daily routines. Ultimately, our goal is to contribute to knowl-

edge about successful practices for engaging ethnic minorities,

including immigrant populations, in research in order to con-

tribute to effective interventions with these populations (Na-

tional Institutes of Health, 2001).

H. H. MCCLURE ET AL.

116

Table 1.

Summary of lessons learned: challenges, solutions, and future strategies for biomarker research with Latino immigrants.

Challenge Solution/Future Strategy

Training staff with no prior experience collecting health and biological

data Ample training time + “hands-on” supervised training

Barriers to care (BtC) Provision of health information & follow-up

referrals as indicated

BtC: Limited knowledge about pre-existing conditions that could

render ineligible for study Testing (e.g., of glucose) as pre-condition of study enrollment

BtC: Potential over-enrollment of sick/health-focused participants Eligibility criteria and encouragement of healthy enrollees

Distrust among prospective participants Recruiter characteristics + recruitment methods that rely on trusted social networks

Lack of familiarity with biological data collection

Creation of strong rapport to ensure open

communication; assessors offer clear explanations; on-line videos of data

collection techniques to increase participant exposure

Measurement of very obese participants’ blood pressure with Omron

422-CRLC

Manual blood pressure readings by trained staff person or use of Omron

HEM-907XL for automatic measure

Saliva sample return rate

One-on-one training of participants; reminders; support for participants with low

literacy;

involvement of children

Busy morning schedules Collection of one morning sample; participants advised to collect on days with less

busy morning schedules

Filling out saliva diaries Reminders; fewer questions; support for

participants with low literacy; participants call automated system

Conducting finger sticks with farmworker participants with calloused

hands

Use of BD Microtainer Contact-Activated lancets (blue) with a high flow blade

(2.0 × 1.5 mm)

Effective follow-up with participants

Partner with community organization with trained staff and resources for

follow-up; hire or have volunteer trained health professional as part of research

team to conduct follow-up

Assessor Training

As previously mentioned, staff members in TFS received

four hours of intensive training followed by 4 to 8 hours of on-

site supervision to hone their newly acquired skills. Following

training, staff from our partner organization that had no prior

experience with biological measures was able to consistently

and accurately collect health data and biomarker samples. The

same training model was implemented with the SAP study with

staff measurement techniques remaining consistent across both

studies. Though assessors had ample time to gain the necessary

skills, assessor confidence was the largest issue in training staff

new to biological data collection. Assessors often reported

feeling comfortable applying their newly acquired skills only

after having completed two or three actual visits with families,

which included an experienced staff person to provide guidance

if necessary.

Recruitment and Health Information

The incorporation of biomarkers into our studies did not

serve as a disincentive or barrier to participation. On the con-

trary, participants were eager for information about their health,

and for referrals and information about bilingual/bicultural, sli-

ding scale, and immigrant-friendly health services. In exit in-

terviews, participants frequently cited our provision of their

health values as a major reason for their study participation.

Although financial compensation was appreciated, many fami-

lies regarded it as an added benefit and some stated it was un-

necessary. The value of health information was further reflected

in some families’ offers to pay to obtain measures for non-

participating family members, and in requests that we include

additional family members in future studies. In addition to pro-

viding participants with immediate information about their

levels of fasting glucose, total cholesterol and other lipids, sev-

eral participants requested their individual cortisol, EBV and

CRP measures after laboratory analyses were completed.

The provision of health information to participants raised two

critical issues: 1) the need for adequately trained health per-

sonnel and a referral system (discussed below), and 2) the po-

tential overrepresentation of sick or health-focused participants

in the study, particularly as we did not utilize a random sam-

pling approach. The second concern was addressed to some

extent by eligibility criteria stating that prospective participants

be healthy, and excluding individuals with colds, the flu, or

chronic conditions such as diabetes or autoimmune disorders

(e.g., Crohn’s disease). Given barriers to access to care that are

particularly acute for recent immigrants, a number of prospec-

tive participants had no knowledge of whether they had chronic

and potentially disqualifying conditions. For instance, some

women had been diagnosed with gestational diabetes but had

never received follow-up testing and were unaware if they cur-

rently had diabetes. In cases involving possible diabetes, asses-

sors conducted a preliminary fasting glucose test as a pre-con-

dition of study enrollment, and individuals with a glucose value

indicating diabetes were excluded from participation (and pro-

vided with referrals for follow-up). As this circumstance affect-

ed approximately 15% of all potential participants, our studies

required additional supplies and assessor time than previously

anticipated. Given pervasive barriers to care in the US among

Latinos in general and immigrant populations in particular, we

H. H. MCCLURE ET AL.

anticipate researchers nationwide will encounter this challenge.

Finally, to date, we have conducted cross-sectional studies

and have yet to confront the prospect that could arise in a lon-

gitudinal study of influencing participant behavior and subse-

quent waves of data through the provision of health information

in the first wave of assessment. Because of the risk of influenc-

ing participant behavior, some OSLC longitudinal studies that

incorporate health data and stress biomarkers have opted not to

provide participants with information about their health.

Rapport and Effe cti ve Com m unication

As in most prevention research, strong rapport between par-

ticipants and assessors in our studies was key to participants’

full engagement. This rapport was especially important for re-

cruittment of some Latino immigrants who wished to remain

part of a “hidden” population in response to a hostile social and

political climate (Martinez et al., 2012). In addition, rapport led

to open communication that facilitated participants’ learning

about potentially complex procedures (e.g., saliva collection),

their timely communication with us when there were problems,

and our ability to effectively support participants’ involvement.

Familiarity with Methods

Nearly all participants were familiar with measures of height,

weight, and blood pressure, though most were unfamiliar with

finger sticks and saliva collection. In addition to providing an

overview of methods as part of our informed consent process,

assessors took special care while performing all health assess-

ment procedures, including finger sticks, to explain each step

and invite questions. During one-on-one saliva collection train-

ing, assessors also discussed insights we hoped to gain into

stress among Latino immigrants through analysis of salivary

cortisol, and the importance of participants’ adherence to in-

structions for the accuracy of results. Finally, in the SAP study,

assessors pricked mothers’ fingers first, which often helped to

reduce any anxiety the child felt. Together, these steps may

have contributed to only one SAP mother and three children re-

porting that finger sticks were challenging, and to high return

rates of saliva samples (details below). In the future, our team

has considered creating short Spanish language demonstrations

that could be accessed via DVD or the Internet to provide fami-

lies with even more information about and exposure to biologi-

cal data collection methods.

Blood Pressure: Me asurement Ch al le ng es

In TFS, when using Omron manual blood pressure machines

(HEM-422CRLC), we had trouble getting blood pressure read-

ings for several morbidly obese participants. Though blood pres-

sure cuffs were appropriately sized for each participant, error

messages persisted. This challenge of reading blood pressure

among some obese individuals, which has been noted in clinical

settings, was worrisome given high rates of obesity within the

study population at 30% for men and 33% for women, which

included approximately 7% with morbid obesity.

In the second phase of TFS, our staff included a registered

nurse who took manual blood pressure readings using a sphyg-

momanometer. In order to avoid stigmatizing visibly obese par-

ticipants whose blood pressure we anticipated might be difficult

to measure, the nurse worked at station one (where the first of

two blood pressure measures was taken) and volunteered to take

the participant’s blood pressure. As it was common at station

one for multiple assessors to measure participants’ blood pres-

sure at the same time, this strategy worked well to normalize

the nurse’s intervention. The nurse then tracked participants

throughout the health exam and stepped in to take the second

blood pressure reading at the final station to ensure consistency

of measurement. In the SAP study, we used Omron HEM-

907XL professional oscillometric instruments (Bannockburn,

IL) for the automatic measure of mothers’ and children’s blood

pressure. Though these devices were significantly more expen-

sive than the Omron 422-CRLC, they proved more reliable and

we encountered no measurement difficulties.

Finger Sticks: Lancets

The choice of lancets was important for ensuring that a single

finger prick was sufficient to produce an adequate number of

blood drops for the measurement of glucose and lipids (adults),

hemoglobin (children), and for blood spot cards. In TFS, we

initially used Stat-Let Auto lancets (Stat Medical Devices, Inc.)

with a depth of 2.2 mm. These lancets, however, were too shal-

low to draw sufficient blood as most male and some female

participants had thick calluses from agricultural work. The most

effective lancets we identified for use with this population are

BD Microtainer Contact-Activated lancets (blue) with a high

flow blade (2.0 × 1.5 mm). We also used BD lancets with

mothers and children in the SAP study. However, for very

young children, researchers may wish to consider using smaller

lancets (e.g., Stat-Let Auto lancets of 2.0 mm).

Saliva Collection: Supporting Participant

Engagement

In TFS, 70% of participants returned all six saliva samples.

In the SAP study, 98% of participants returned all nine saliva

samples, considered an excellent return rate (Adam & Kumari,

2009). We attribute these high return rates to training (dis-

cussed above), collection reminders, support for participants

with limited literacy and the involvement of children (in SAP).

Reminders. Participants reported that the following methods

helped them to remember to collect their saliva according to

instructions: 1) toothbrush cover labels and removable stickers

for bathroom mirrors reading “Pare! Colecte su muestra” (Stop!

Collect your sample); 2) colorful wrist “gel” bands that partici-

pants donned the evening before as a reminder to collect their

saliva when they woke in the morning; and 3) assessors’ re-

minder calls made the evening before. Additional calls the day

of collection served as a further reminder, and provided par-

ticipants with a chance to ask questions, voice concerns, or re-

quest additional supplies.

Literacy. In the first study, we learned that our saliva collec-

tion directions were difficult for participants with limited liter-

acy to understand. Though we considered designing an alterna-

tive set of instructions composed of diagrams and two or three

words in lieu of each step, staff from our partner organization

advised that a customized approach would be more useful to

participants. Ultimately, when working with participants with

low literacy, assessors handwrote instructions on the saliva col-

lection guide tailored for each participant’s comprehension level.

Involvement of children. During the SAP study, we learned

that children as young as six years of age were often eager and

quick to learn saliva collection procedures. As a result, we

H. H. MCCLURE ET AL.

actively involved both mother and child in the training, with

children often reinforcing their mother’s learning. Though we

did not formally ask about children’s involvement in saliva

collection (e.g., whether they initiated collection, or reminded

mothers of the need to collect), participant comments indicated

that children were an important factor in the family’s full par-

ticipation in the saliva collection portion of the study.

Saliva Collection: Morning Schedules

In the SAP study, early morning visits for the collection of

fasting measures, which could involve arriving at the family’s

home as early as 5 am so that the mother could leave for work

on time, were disruptive for families. In order to collect two

morning samples 30 minutes apart, busy morning schedules led

some mothers to alter their own and their youngster’s wake up

times, potentially influencing morning cortisol levels. For stud-

ies incorporating two or more morning measures, assessors may

wish to relay to participants the possible need to alter their

schedules to allow for extra time (not including an earlier

wake-up time or collection on a day that is not a typical week-

day) or discuss reducing the number of samples on a given

morning.

Saliva Collection: Saliva Diaries

In TFS, of participants who returned saliva samples, 86%

also filled out and returned a half-page form where they re-

corded the days and times they collected their saliva. In the

SAP study, 95% of participants recorded the time of day and

date they collected each sample. These data are critical because

they allow staff to track irregularities in collection schedules,

and make possible the calculation of time lapses between sam-

ples for the study of cortisol level changes throughout the day.

Again, reminder calls by staff seemed to facilitate these high

response rates.

Mothers in SAP also were asked to respond to questions in a

saliva diary for both themselves (6 - 16 Questions) and their

participating child (2 - 8 Questions) every time they collected a

saliva sample. Questions ranged from the time and day of saliva

collection to inquiries about sleep patterns and emotional state

during each 24-hour period, factors known to covary with Sali-

vary cortisol levels. Though most participants responded to items

whose range of responses were on a five-point Likert scale,

open-ended questions asking for more detail were rarely filled

out. Participant feedback to assessors indicated that some par-

ticipants lacked time to respond to all questions. In addition,

some participants reported that the saliva diaries were over-

whelming in length. In the future, assessors advised asking

fewer questions and having a binder for the saliva diaries where

all questions would be color coded to the sample collection

tubes for that day and clearly separated by collection time.

Literacy. Saliva diaries in the SAP study presented signifi-

cant challenges to the participation of a few mothers with low

literacy. In these cases, the assessor called the family at each

collection time and administered the saliva diary as a telephone

interview. Though saliva diary data collected by telephone pro-

ved to be more complete than data in saliva diaries that partici-

pants filled out themselves, telephone interviews were burden-

some schedule-wise for mothers and assessors and less cost-

effective. In the future, we will investigate new strategies that

support the inclusion of participants with low literacy, such as

requesting that participants call in and respond to pre-recorded

questions through an automated system.

Referral System and Follow-Up

As mentioned, the receipt of health information was one of

the greatest incentives for participants’ involvement in the

studies. Despite widespread enthusiasm regarding this facet of

our studies, however, several issues were raised. Approximately

one-third of all TFS and SAP participants had high levels of

glucose, total cholesterol or other lipids, and blood pressure

indicating the need for follow-up testing. Additional partici-

pants were referred for follow-up relating to chronic pain, low

blood pressure, impaired vision (needing glasses), smoking, nu-

triation, the self-administration of medication, and desire to lose

weight.

Effective follow-up in TFS was facilitated by a number of

factors. All participants were easy to re-contact as they were re-

sidents of housing complexes owned and run by the organiza-

tion, and the organization’s staff (many of whom were study

assessors) already referred residents to a range of services. Also,

a key member of the organization’s staff and of our research

team was an experienced health promoter who had strong rela-

tionships with local public health agencies and community

clinics.

The SAP study was distinct in that it was not a community-

partnered project and all follow-up was conducted by LRT asse-

ssors. In this study, some participants’ busy schedules contrib-

uted to assessors feeling rushed to explain the results, which

was worrisome to staff when trying to explain values that indi-

cated need for follow-up testing. Further, although assessors

clearly explained that they were not medical personnel and

could not offer advice, participants frequently asked health

related follow-up questions. Finally, a few families requested

assessor support in making appointments with clinics. Though

staff provided support to every participant who requested it,

future studies involving larger sample sizes and more com-

pressed assessment timelines would do well to include funding

for a health professional (or have a committed volunteer) to re-

spond to families’ questions and concerns, and to serve as a

health care navigator by assisting participants to access fol-

low-up care.

Conclusion

Though recent developments in minimally-invasive biologi-

cal measurement allow for more refined understandings of the

effects of psychosocial stress, these methods have been under-

utilized in studies with Latino populations. This is unfortunate

given existing Latino health disparities and the need to better

understand contributors to these disparities. Studies involving

recent immigrants, however, can confront unique challenges.

There is a clear need to fully support Latino immigrants’ invol-

vement in research involving biomarkers—and to identify the

strategies that make this possible—in order to better inform

public health policy and clinical practice. Further, carefully

designed studies can provide potential positive benefits to indi-

viduals who take part and to the larger communities in which

they are members. Finally, though the studies described here

focus on the Latino immigrant community, better models of

stress processes that rely on multiple measures may have im-

plications for a range of preventive interventions that target the

118

H. H. MCCLURE ET AL.

effects of stress on family health within diverse communities.

Acknowledgements

The authors thank the Oregon Latino families who partici-

pated in the studies and study assessors. We also thank Felicia

Madimenos for biomarker training assistance, Julia Ridgeway-

Díaz and Sasha Johnson-Freyd for cortisol analyses, and Lynn

Stephen and Frances White for discussions of the project. We

appreciate the support of the National Institutes on Drug Abuse,

National Institutes of Health (R01 DA017937 and R01 DA-

01965), as well as the Oregon Social Learning Center Scien-

tists’ Council, Northwestern University, the University of Ore-

gon (UO), and the UO Center for Latino/a and Latin American

Studies (CLLAS).

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