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Telephone Subsidy
An Effective Incentive for Successful Participation in Home Memory Monitor Study
Carl E. Hunt, MD;
Jane K. Durham, RN, MSN;
Susann J. Guess, RN, MSN;
Linda E. Kapuniai, DrPH;
Howard Golub, MD, PhD;
and the Collaborative Home Infant Monitoring Evaluation Study Group
Arch Pediatr Adolesc Med. 2001;155:954-959.
ABSTRACT
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Context The Collaborative Home Infant Monitoring Evaluation (CHIME) study enrolled
healthy term infants and 3 groups of infants considered to be at increased
risk for sudden infant death syndrome to evaluate apnea and bradycardia events
in the home. Mother-infant pairs without a telephone were ineligible for enrollment.
Objective To determine whether mother-infant pairs who were offered a telephone
subsidy would agree to enroll in CHIME and achieve protocol compliance rates
comparable with those of matched subjects able to afford telephones.
Design Thirty-one telephone subsidy subjects were retrospectively compared
with 55 control subjects matched for study group, site, birth weight, and
maternal race, age, and education.
Setting Collaborative Home Infant Monitoring Evaluation clinical research centers
in Honolulu, Hawaii, and Toledo, Ohio.
Intervention Provision of telephone subsidy to otherwise eligible enrollees for CHIME.
Main Outcome Measures Frequency of compliance with protocol requirements for follow-up evaluations
and for extent of home monitoring.
Results Subsidy subjects achieved protocol completion rates that were comparable
with those of control subjects, for developmental assessments at 56 and 92
weeks postconceptional age (PCA), and for the polysomnogram. Unexpectedly,
however, subsidy subjects were more likely to have a developmental assessment
at 44 weeks PCA (P = .02), as well as a cry analysis
(P = .04). They were also more likely to use the
CHIME home monitor for more hours during weeks 2 through 5 (P = .004), have a higher percentage using the monitor for 10 or more
hours per week during weeks 2 through 5 (P = .009),
and have a higher total number of days of monitor use throughout 6 months
(P <.001). Mean cost of the subsidy was $3.25
per day of monitor use, and monitor use per day was directly related to total
cost of the subsidy (P = .02).
Conclusions Telephone subsidy is an effective financial incentive. At least within
the context of the CHIME study, telephone subsidy enhanced access to health
care, and in some categories it resulted in enhanced protocol compliance.
INTRODUCTION
THE COLLABORATIVE Home Infant Monitoring Evaluation (CHIME) study of
home memory monitoring was performed at 5 clinical sites. It was designed
to test the hypothesis that preterm infants, siblings of infants who died
of sudden infant death syndrome (SIDS), and infants who have experienced an
idiopathic apparent life-threatening event have a greater risk of experiencing
apnea or bradycardia events than healthy infants.1
Eligible infants met 1 of the following 3 criteria: (1) infants younger than
1 month with a history (autopsy required) of SIDS in a prior sibling (SIDS-sibs);
(2) infants experiencing an idiopathic apparent life-threatening event who
enrolled within 2 weeks of an event requiring significant intervention; and
(3) preterm infants of 34 weeks gestational age or younger, weighing less
than 1750 g at birth and enrolled within 2 weeks of hospital discharge. Exclusion
criteria at enrollment included illicit drug use by the current caregiver,
continuous home oxygen requirement, a congenital heart disease, brain anomalies,
a ventriculoperitoneal shunt, home anticonvulsant therapy, congenital and
chromosomal anomalies, and the inability to communicate due to language barrier
or absence of a home telephone.
Low socioeconomic status (SES) is a powerful contributor to morbidity
and mortality and is a risk factor for SIDS.2
Since the CHIME study included 3 groups of infants believed to be at increased
risk for SIDS, there was a desire to include infants of low SES in these groups.
Mother-infant pairs of low SES without home telephones, however, were ineligible
for enrollment in CHIME, even though they likely represented a higher risk
for adverse health outcomes (including SIDS) than otherwise comparable mother-infant
pairs able to afford a telephone.3
We did not know beforehand whether the telephone subsidy would be accepted
and, if accepted, whether these mother-infant pairs with low SES would have
characteristics that would lead to early dropout or to unsatisfactory protocol
compliance. We hypothesized, however, that providing a subsidy to establish
and maintain telephone service would be a cost-effective and successful strategy
for enrolling mother-infant pairs with very high risk for adverse health outcomes
(including SIDS), and that once enrolled, telephone subsidy subjects would
achieve protocol compliance rates comparable with those of the mother-infant
pairs with low SES who were selected as controls.
SUBJECTS AND METHODS
Comprehensive demographic and medical information, including maternal
and infant medical history, was obtained at enrollment. The home memory monitor
developed for CHIME (Non-Invasive Monitoring Systems, Miami, Fla) recorded
cardiorespiratory waveforms, oxygen saturation, and position and movement
whenever the recording threshold for apnea or bradycardia was reached.1 The monitor recorded the time turned on or off, and
stored all physiological signals taking place 75 seconds before an event,
during an event, and 30 seconds following the event. Parents were instructed
to use the monitor during sleep time and during unsupervised time when the
infant was awake. The number of hours of monitor use during each day of monitoring
was stored in the monitor memory. The first week of home monitoring was defined
as beginning with midnight of the first night of monitoring, and it included
7 consecutive 24-hour periods. Compliance during weeks 2 through 5 was used
to calculate initial monitor compliance so as to exclude home monitor problems
causing limited monitor use during the first week of monitoring. Total days
of monitor use were an additional measure of monitor compliance.
At entry into the study, there was standardized training in the operation
and use of the monitor. There was 24-hour availability of CHIME staff for
questions related to study protocols or clinical care, and caregivers were
contacted at least weekly by telephone to complete a scripted interview. Home
visits, including replacement of the memory cartridge in the monitor, were
scheduled for the first week of monitoring, at 1 month of use, and every 4
weeks thereafter. If review of the most recent memory cartridge indicated
monitor use for less than 8 hours per day, additional support or intervention
was provided. The intended duration of home monitoring was through 66 weeks
of postconceptional age (PCA) for healthy term infants and SIDS-sibs, 56 weeks
of PCA for preterm infants, and 4 months from enrollment for infants with
an idiopathic apparent life-threatening event. In addition, mothers used the
monitor until the infants were free of events exceeding monitor alarm thresholds
for at least 3 months. A total of 1079 infants was enrolled in May 1994 through
February 1998, including 306 healthy term infants, 178 SIDS-sibs, 152 infants
with an idiopathic apparent life-threatening event, and 443 preterm infants
with a birth weight less than 1750 g.
Each infant was scheduled for an overnight polysomnogram; a follow-up
visit with CHIME staff 1 month following enrollment; visits at 44, 50, and
56 weeks PCA and every 2 months thereafter while using the home monitor; and
a final visit at 92 weeks PCA. Since there is a correlation between cry sound
changes, early neurological development, and risk for SIDS, cry analysis was
performed at enrollment and 1 month later.4
We hypothesized that there would be a relationship between abnormal cry sounds
and the probability of cardiorespiratory events (as defined and measured in
CHIME). Two 30-second crying periods were recorded at each age using a standardized
stimulus and tape recorder. Developmental assessments using the Bayley Scales
of Infant Development–Revised (BSID-II)5
were performed at 44, 56, and 92 weeks of PCA. Institutional review board
approval was obtained, and the parents of all subjects gave written informed
consent.
Two sites (Honolulu, Hawaii, and Toledo, Ohio) elected to provide a
telephone subsidy for mother-infant pairs who were otherwise eligible for
CHIME and desired enrollment. Each institutional review board approved the
telephone subsidy as a means of enhancing enrollment of high-risk mother-infant
pairs. Funds to support the subsidy expense were obtained from the CHIME budget
(Toledo) and from the Children's Miracle Network Telethon (Honolulu). Telephone
service was maintained until protocol completion or voluntary withdrawal from
the study. There was no minimum threshold of monitor use below which the subsidy
would be withdrawn. Cost of the subsidy for individual mother-infant pairs
included payment of any delinquent accounts and basic monthly expenses. A
block was placed on each telephone to prevent long-distance calls. Monthly
telephone bills were submitted to the local CHIME office, and payments were
made directly to the telephone company. Once enrolled, these 31 subjects were
managed according to the same protocols as the other 1048 CHIME enrollees
who used the home monitor. The telephone subsidy was in addition to limited
financial incentives for all enrollees in CHIME, consisting of gift certificates
to such stores as "Toys-R-Us" following completion of individual protocol
requirements (to a maximum of $100), or for small items such as diapers offered
to families at follow-up visits.
Following completion of the CHIME protocols by all enrollees, each telephone
subsidy subject was matched with 2 control subjects, with the closest prior
and subsequent enrollee at the same site meeting match requirements. The subsidy
and control subjects were matched by study group and maternal race and, as
surrogates for SES, by maternal age (SD, 2 years) and education (12 years,
< 12 years, or >12 years). All preterm subjects were also matched for birth
weight (SD, ±100 g). The dependent variables of interest included completion
rates for the BSID-II assessment at each test age, cry analysis, polysomnogram,
and the extent of home monitor use. As developed for a study of CHIME monitor
compliance,6 the parameters for monitor use
included total hours of monitor use, percentage of subjects with 10 or more
hours of monitor use during weeks 2 through 5 of monitoring, and total number
of days of monitor use by 6 months of age. Each day the monitor was turned
on was counted as a monitor day.
Comparisons between the telephone subsidy and control subjects were
made across both sites using the t test for continuous
variables and the Fisher exact test for categorical variables. Outcome variables
of interest (ie, BSID-II assessment and monitor use) were compared between
the subsidy and control groups using general estimating equations to account
for matching in the study design. For all statistical analyses, we used a
significance level of P = .05.
RESULTS
The telephone subsidy was implemented in Toledo 6 months after the CHIME
study was started and then 11 months later in Honolulu. Among the 64 mother-infant
pairs screened in Honolulu and Toledo after the subsidy was implemented who
were ineligible for CHIME because of absence of a home telephone, 31 (48%)
accepted the telephone subsidy and enrolled in CHIME. Among the 33 families
(52%) who were eligible for the subsidy but who did not enroll, the primary
reason was inability to contact mothers in a timely and effective manner to
explain the subsidy and seek consent. In a few instances, however, we could
not offer the subsidy because of unresolved issues regarding place of residence.
At the time of retrospective matching for analysis, only 1 match could be
found for 7 subsidy infants before overlapping with a control for another
subsidy infant. This resulted in a total of 55 controls for the 31 subsidy
infants.
Compared with telephone subsidy subjects in Toledo (Table 1), subsidy subjects in Honolulu were less likely to be preterm
but more likely to be in the apparent life-threatening event group, and less
likely to be African American, but more likely to be Asian (Japanese, Filipino)
or of other ethnicity (Hawaiian, part Hawaiian, mixed). As defined by the
matching requirements, the subsidy subjects and control group subjects are
similar for birth weight, maternal age, gestational age, group, race, and
maternal education (Table 1, "Total"
columns).
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Table 1. Subject Characteristics and Data*
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The total cost of providing home telephone service for all participants
was $12 132 and included preenrollment delinquent bills plus monthly
service charges. The mean total cost was $402 (SD, $342), and the median was
$359. The total cost was greater than $700 in only 3 subsidy subjects, and
the highest cost was $1794. Total costs in excess of monthly charges for routine
service were primarily related to delinquent accounts that had to be paid
before telephone service could be reinstituted, but also included occasional
malfunction of the long-distance block or placing calls to 1-900 numbers or
acceptance of collect calls. The mean cost of the subsidy was $3.25 per day
of home monitor use. The subsidy was continued until all follow-up components
of the protocols were completed or until voluntary withdrawal of a subject
from the CHIME study. The subsidy was never discontinued, however, for failure
to complete an individual protocol requirement or failure to reach any specified
minimum extent of home monitor use.
As expected of subjects with low SES,1, 6
the subsidy control subjects seemed to be less compliant with the CHIME protocols
than CHIME enrollees in total. Among all 1079 CHIME enrollees, the 44-, 56-,
and 92-week PCA BSID-II assessments were obtained from 65%, 47%, and 26% of
subjects, respectively, compared with generally lower percentages in our controls
(Table 1). Compliance with the
92-week BSID-II assessment was low among all groups regardless of SES. As
a whole, the frequency of completion of individual protocol requirements for
the CHIME study varied depending on group, and these group differences account
for the differences observed between Toledo and Honolulu groups (Table 1).
As hypothesized, completion rates for the 56- and 92-week BSID-II assessments
and polysomnogram in telephone subsidy subjects were comparable with the rates
of control subjects. Unexpectedly, however, compliance rates for the 44-week
PCA BSID-II assessment and cry analysis were higher than those of control
subjects, and they approximated compliance rates for CHIME overall. That telephone
subsidy subjects outperformed controls with regard to home monitor use was
also unanticipated (Table 2).6 Even though no minimum level of monitor use was required
to maintain telephone service, compared with controls, subsidy subjects used
the monitor for more total hours during weeks 2 through 5, were more likely
to use the monitor for 10 hours or more per week, and used the home monitor
for almost twice as many total days.
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Table 2. Monitor Use Data*
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There was a direct relationship between total subsidy and total days
of home monitor use. Among the telephone subsidy subjects who received a total
subsidy of either less than $250 (n = 12), $250 to $500 (n = 14), or more
than $500 (n = 5), the mean (SD) total number of days of monitor use was,
respectively, 82 (64), 126 (65), and 212 (123) days. Using analysis of variance,
the overall P value was .02.
COMMENT
Providing a home telephone subsidy to mother-infant pairs unable to
afford a telephone eliminated the barrier to participation in CHIME and resulted
in enrollment of additional subjects with low SES. We confirmed our hypothesis
that these additional enrollees would achieve protocol compliance rates comparable
with those of the matched control infants with low SES. Unexpectedly, however,
subsidy subjects were actually more likely than controls to have a cry analysis
and return for the first BSID-II analysis at 44 weeks PCA, and to use the
home memory monitor more than controls.
The extent of home monitor use in the subsidy group was related to total
subsidy amount regardless of whether it was measured during the first 5 weeks
or the first 6 months (Table 2).
This relationship suggests that the subsidy was a positive incentive for monitor
use in proportion to the "up-front" costs of reinstituting telephone service.
If fear of losing the telephone had been the only motivation to use the monitor,
it is unlikely that families with larger delinquent accounts at enrollment
would have had better monitor use than families with smaller or no delinquent
accounts, since even minimal monitor use would have sufficed.
Our study was not designed to document reasons for absence of a home
telephone. These mothers, however, tended to be young, single, and to have
less education than control group mothers, including almost one third of mothers
with less than 12 years. Our study was also not designed to determine why
some families without a home telephone did not receive the telephone subsidy.
In general, however, mothers without home telephones did not have an established
home or were not accessible to CHIME personnel.
The CHIME study required considerable parental motivation to achieve
high protocol compliance rates. This was especially true for healthy term
infants, SIDS-sib infants, and preterm infants who otherwise would not have
been using a home monitor. As a consequence, only 16% of all mothers of infants
eligible for CHIME consented to enroll, varying from the 65% range in infants
with idiopathic apparent life-threatening events and SIDS-sib infants, to
28% in the preterm group, and only 7% in the healthy term group.
The number of subsidy subjects is too low to permit site-specific analyses,
especially considering the additional variability associated with clinical
group (Table 1). However, the
ability to discern significant differences between subsidy and control subjects,
despite combining enrollees from 2 diverse populations, may be indicative
of a more robust benefit of the subsidy and greater potential generalizability.
We found no precedent for use of a financial incentive to satisfy a
threshold eligibility requirement. Although other studies have utilized a
financial incentive to enhance protocol compliance, we found no precedent
for use of a financial incentive to enhance home monitor use.
Some authors have suggested that payment of subjects is never ethical,
but financial incentives are in fact frequently offered and sometimes considered
necessary.7 Prospective payments are more likely
to be ethically acceptable than poststudy financial rewards provided to participants
having achieved predetermined compliance goals.8
In a review of financial incentives offered in 11 US studies, with a wide
array of disciplines and a wide variation in type and magnitude of incentives,
all but 1 study demonstrated improved compliance when a financial incentive
was provided.9
Providing economic vouchers to offset out-of-pocket expenses in women
with low SES has been shown to moderately improve compliance with follow-up
requirements, but offering a financial incentive to low SES subjects may create
excessive pressure to participate owing to financial need.10
Lower SES has been associated with the willingness of parents to enroll a
child in an asthma research project.11 Consenting
mother-infant pairs in this treatment study were less educated, less likely
to have professional or administrative jobs, had less social support, displayed
greater health-seeking behavior, and consumed more habit-forming substances.
Owing to the influence of greater financial need, the concern has been expressed
that financial incentives result in disproportionately higher enrollment of
subjects with low SES in research studies, and hence in subjects with low
SES bearing an unduly large share of the risks and burdens of clinical research.7
Before implementing our telephone subsidy for potential CHIME enrollees
without a home telephone, we considered the aforementioned factors related
to the ethics and nature of financial incentives. We did not consider a telephone
subsidy to mother-infant pairs with low SES as imparting an undue clinical
research burden because these infants were at a significantly higher risk
for adverse outcomes, including SIDS, and there was hence a greater potential
health benefit to participation. Parents of all potential enrollees who were
offered the subsidy were fully informed and subjected to no pressure to consent
to participate in CHIME.12 The telephone subsidy
was not a reward for having participated in the study, but rather an incentive
provided "up front" to be eligible for enrollment and to hopefully lead to
protocol participation that would be comparable with that of otherwise equivalent
mother-infant pairs with low SES.8 Individual
subsidy amounts were directly related to financial need and were not excessive
relative to the time, effort, and inconvenience caused by enrollment. Hence,
amounts were not considered to represent undue coercion.13
Finally, by diminishing the social or medical isolation in mother-infant pairs
of low SES that is associated with the additional burden of having no home
telephone, the telephone subsidy had the potential for enhanced health-seeking
behaviors and improved access to health care that was independent of any perceived
or actual direct benefit as a result of enrollment in CHIME.
There are potential limitations to this study. This is not a study of
the factors causing or associated with an inability to afford a home telephone,
nor is it a comparison of demographic and other characteristics of mother-infant
pairs (with low SES) who were able vs those who were not able to afford a
home telephone. These would be informative studies, however, especially knowing
the results of this study. Second, this is not a randomized study of the effects
of a telephone subsidy to mother-infant pairs with and without financial need
for the subsidy. Although such a study might lead to useful insights, the
subsidy would not be comparable between groups because of variable needs for
"up-front" payment of delinquent accounts among pairs unable to afford a telephone.
In summary, providing a telephone subsidy to satisfy eligibility requirement
for CHIME was effective in increasing enrollment of mother-infant pairs with
low SES, and it resulted in protocol compliance that was equivalent or better
than that of the controls. Significant reductions in social and medical isolation
achieved by the subsidy may have been perceived as having a value-added benefit
outweighing the actual cash value of the subsidy. It is unknown to what extent
these results might be generalizable to other research settings or to nonresearch
settings in which absence of a telephone adversely affects access to health
care.
AUTHOR INFORMATION
| The CHIME Study Group Participants
Clinical Sites: Department
of Pediatrics, Case Western Reserve University School of Medicine, and MetroHealth
Medical Center, Rainbow Babies and Children's Hospital,
Cleveland, Ohio: T. M. Baird, MD; L. J. Brooks, MD (currently with
University of Louisville, Kosair Children's Hospital, Louisville, Ky); R.
J. Martin, MD; and R. O'Bell, RN. Department of Pediatrics,
Medical College of Ohio, Mercy Children's Hospital, and Children's Medical
Center, Toledo: C. E. Hunt, MD (currently with National Center on Sleep
Disorders Research, National Heart, Lung and Blood Institute, National Institutes
of Health, Bethesda, Md); D. R. Hufford, MD; and M. A. Oess, RN. Department of Pediatrics, Division of Respiratory Medicine, Rush Medical College
of Rush University and Rush Children's Hospital at Rush-Presbyterian-St Luke's
Medical Center, Chicago, Ill: J. M. Silvestri, MD; S. M. Smok-Pearsall,
RN; and D. E. Weese-Mayer, MD. Department of Pediatrics,
John A. Burns School of Medicine, University of Hawaii, and Kapi'olani Medical
Center for Women and Children, Honolulu: David H. Crowell, MD; Linda
E. Kapuniai, DrPH; and Larry R. Tinsley, MD (currently with Pediatric Critical
Care Medical Group, Encino, Calif). Department of Pediatrics
and Neonatology, University of Southern California School of Medicine, Los
Angeles County and University of Southern California Medical Center Women
and Children's Hospital, and Good Samaritan Hospital, Los Angeles:
T. T. Hoppenbrouwers, PhD; Paula Palmer, MA; and R. Ramanathan, MD. Children's Hospital Los Angeles: D. B. Bolduc, BA, RPFT;
T. G. Keens, MD; and S. L. D. Ward, MD.
Clinical Trials Operations Center: Department of Obstetrics and Gynecology, Case Western University School of
Medicine and MetroHealth Medical Center, Cleveland: M. R. Neuman, MD,
PhD (currently with the University of Memphis, Memphis, Tenn); and Rebecca
S. Mendenhall, MS.
Data Coordinating and Analysis Center: Departments of Pediatrics, and Epidemiology and Biostatistics,
Boston University Schools of Medicine and Public Health, Boston, Mass:
S. M. Bak, MPH; T. Colton, ScD; M. J. Corwin, MD; H. Golub, MD, PhD; M. Peucker;
S. C. Schafer, RNC, MS.
Steering Committee Chair: Department of Pediatrics, Yale University School of Medicine, New Haven, Conn: George Lister, MD.
National Institutes of Health: Pregnancy and Perinatology Branch, Center for Research for Mothers and Children,
National Institute of Child Health and Human Development, National Institutes
of Health: M. Willinger, PhD.
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What This Study Adds
Subjects with low SES may not have sufficient access to clinical research,
including studies of disease conditions for which they are at high risk. We
sought enrollment of families across the full range of SES in a study of home
memory monitoring in infants at increased risk for SIDS because low SES infants
are at increased risk for SIDS. The families with the lowest SES, however,
were ineligible because of the absence of a home telephone.
The telephone subsidy is an effective financial incentive leading to
enhanced study enrollment, and in some instances, enhanced protocol compliance.
The reductions in social and medical isolation achieved by the subsidies were
perceived as having value or added benefit beyond the actual cash value. These
results may have implications for other clinical research settings and for
nonresearch settings in which the absence of a home telephone adversely affects
access to health care.
Accepted for publication March 27, 2000.
Supported by grants 29067, 29071, 28791, 29073, 29060, 29056, and 34625
from the National Institute of Child Health and Human Development, National
Institutes of Health.
From the Department of Pediatrics, Medical College of Ohio, Toledo
(Dr Hunt and Mss Durham, and Ms Guess); the Department of Pediatrics, University
of Hawaii and the Kapi'olani Medical Center for Women and Children, Honolulu
(Dr Kapuniai); and the Departments of Pediatrics and Epidemiology and Biostatistics,
Boston University, Boston, Mass (Dr Golub). Dr Hunt is now at the National
Center on Sleep Disorders Research; National Heart, Lung, Blood Institute;
National Institutes of Health; Bethesda, Md.
Corresponding author: Carl E. Hunt, MD, National Center on Sleep
Disorders Research; National Heart, Lung, Blood Institute; National Institutes
of Health, Two Rockledge Center, 6701 Rockledge Dr, Suite 10038, MSC 7920,
Bethesda, MD 20892-7920 (e-mail: HuntC{at}nhlbi.nih.gov).
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