Does being a retired or employed caregiver affect the association between behaviours in Alzheimer’s disease and caregivers’ health-related quality-of-life?
Majoni and Oremus BMC Res Notes
Does being a retired or employed caregiver affect the association between behaviours in Alzheimer's disease and caregivers' health-related quality-of-life?
Melissa Majoni 1
Mark Oremus 0
0 School of Public Health and Health Systems, University of Waterloo, 200 University Avenue West , Waterloo, ON , Canada
1 Department of Epidemiology and Biostatistics, Western University , 1151 Richmond Street, London, ON , Canada
Objective: We examined whether caregivers' employment status (i.e., retired or employed) might modify the association between the behaviours of persons with Alzheimer's disease (PwAD) and caregivers' health-related quality-of-life (HRQoL). Data came from a cross-sectional study of the primary informal caregivers of 200 persons with mild or moderate Alzheimer's disease. Caregivers completed the EQ-5D-3L to rate their HRQoL and generate health utility scores, and the Dementia Behaviour Disturbance Scale (DBDS) to assess the degree to which PwAD exhibited each of 28 behaviours. Caregivers' health utility scores were regressed on overall DBDS scores, with caregiver employment status (retired, employed) treated as an effect modifier and confounder in separate regression models. We also controlled for age, sex, income, education, caregivers' relationship to the PwAD, and whether caregivers gave up paid employment/ cut down working hours to care for PwAD. Results: Effect modification by caregiver employment status is possible, with the inverse association between DBDS score and health utility score largely existing for retired versus employed caregivers. Research using larger samples and longitudinal data would further inform this area of inquiry.
Alzheimer's disease; Behaviour; Caregiver; Employment; Health-related quality-of-life; Retirement
Alzheimer’s disease (AD) is characterized by cognitive
decline that disrupts the capacity to think, understand,
remember and communicate information [
projections suggest more than one million cases of AD
will occur by 2038 [
]. No cure exists for AD [
Although the clinical presentation of the disease varies,
80% of persons with AD (PwAD) can expect to exhibit
multiple behavioural disturbances over time [
including apathy, depression, aggression, anxiety, and sleep
]. These behaviours can adversely affect PwAD
lifestyles and management, and caregiver health [
Caregiver health is important because PwAD receive
much of their care at home and the onus of care
provision generally falls on primary informal caregivers [
typically spouses or adult children [
]. Caregiving for
PwAD is a physically and emotionally challenging role,
especially as the disease progresses and caregivers devote
more time to meeting their loved ones’ basic needs and
less time to their own interests [
]. The demands of
caring for PwAD impact caregivers’ health, well-being,
and health-related quality-of-life (HRQoL) [
] to the
point where caregivers are called the “hidden victims”
] or “secondary patients” [
] of AD. Evidence suggests
the behavioural disturbances associated with AD have
more impact on caregiver health than PwAD’s cognitive
Understanding the factors affecting PwAD behaviours
and caregiver health is important given the crucial role
of caregivers in managing AD. We undertook this study
to examine whether caregiver employment status (retired
versus employed full- or part-time) would modify the
association between PwAD’s behavioural disturbances
and caregiver HRQoL. Caregivers cover many of the
costs of caring out of their own pockets. Retired
caregivers who live on fixed incomes may be less able than
employed caregivers to absorb these costs or seek relief
through respite care or daycare programs, thereby
amplifying the effects of their loved ones’ behavioural
challenges on HRQoL. To date, no other study has examined
the role of caregiver employment status in this area.
This study included 200 primary informal caregivers of
persons with mild or moderate AD. These individuals
were initially recruited to assess the willingness-to-pay
for AD medications in a study led by one of the authors
]. Recruitment took place in nine memory and
geriatric clinics across Canada between November 2008
and August 2011. The investigators selected these clinics
because they were based in research-intensive academic
settings with extensive aging-related research programs,
which promoted recruitment and attention to study
rigour. Further details about recruitment and the study
process are available elsewhere [
Eligible caregivers had to be retired or employed
fullor part-time, be the primary informal (unpaid) caregiver,
and be fluent in English or French. We excluded
caregivers who reported their employment status as student,
homemaker, or unemployed, who cared for someone
with severe AD, or who cared for someone who could not
give informed consent.
Through an in-person questionnaire, administered by
trained interviewers, caregivers completed the
Dementia Behaviour Disturbance Scale (DBDS) [
assessed the presence and intensity of 28 different PwAD
behaviours on a 5-point Likert scale (0 = never, 4 = all of
the time). The responses were summed to determine an
overall behaviour disturbance score ranging from 0 (no
disturbance) to 112 (maximum disturbance).
Caregivers also completed a generic HRQoL
instrument called the EQ-5D-3L [
], which asks respondents
to report their health status on each of five dimensions
(mobility, self-care, usual activities, pain/discomfort,
anxiety/depression). Three response options are available
per dimension (no problems, some/moderate problems,
extreme problems/unable to do). A Canadian algorithm
converted EQ-5D-3L responses into health utility scores
ranging from 0 (equivalent to death) to 1 (equivalent to
perfect health) [
The study questionnaire also asked participants about
their sex, employment status, relationship to the PwAD,
type and length of care provided, satisfaction with
caregiving, and level of AD knowledge [
For sample characteristics, the continuous variables
were summarized using medians and 25th/75th
percentiles and the categorical variables were summarized
using frequencies. We compared sample
characteristics between retired and employed caregivers using the
Mann–Whitney U test for continuous variables and the
Chi square or Fisher exact test for categorical variables.
We regressed caregivers’ health utility scores on DBDS
scores using ordinary least squares regression and
nonparametric bootstrap estimated standard errors (1000
bootstrap samples), which yielded bias corrected and
accelerated confidence intervals. The initial regression
model contained only DBDS score. Additional models
included employment status (retired versus employed)
and an interaction term (DBDS × employment status).
We also constructed a full model containing DBDS score,
employment status, the interaction term, and the sample
characteristics that were statistically significantly
different between retired and employed caregivers (Table 1).
We used multiple imputation by chained equations
to account for missing values on three sample
characteristics (age, relationship to PwAD, income) in the full
regression model. The imputation dataset included all
of the variables in the full model, with predictive mean
matching to impute for age and the multinomial logit
model to impute for relationship and income. The
process created five imputed datasets, which were combined
to obtain a new set of regression coefficients for the full
model. Prior to imputation, graphical assessment showed
the missing values to be missing completely at random.
We used R v3.4.1 (R Foundation for Statistical
Computing, Vienna, Austria) to conduct the statistical analysis;
the criterion for statistical significance was α = 0.05.
The sample included 140 retired caregivers, 5% of whom
reported giving up paid work or reducing work hours to
care for PwAD in the time prior to retirement. Many of
the retired caregivers were spousal caregivers (86%), with
the remaining 14% being either adult children, friends,
or other relatives. Sixty caregivers reported working
fulltime (62%) or part-time (38%). Half of the employed
caregivers gave up paid work or reduced work hours to care
for their loved ones. Seventy percent of the employed
caregivers were either adult children or other relatives,
with the remainder being spousal caregivers (30%).
Table 1 compares sample characteristics between retired
and employed caregivers.
Median health utility scores were 0.80 for retired
caregivers and 0.84 for employed caregivers (p = 0.02); both
sets of scores were left skewed (Fig. 1). Median DBDS
scores were 16 for retired and 19 for employed caregivers
(p = 0.35) (Fig. 1).
The interaction term for DBDS and employment
status was not statistically significant in the full regression
model nor the model containing only DBDS and
employment status (Table 2). The interaction term’s regression
coefficient was the same (i.e., − 0.003) in both models, as
was the upper bound of the 95% confidence interval (CI)
For DBDS, the regression coefficient in all four models
suggested a small inverse association between AD
behaviours and caregivers’ HRQoL. The addition of covariates
to the model diminished, but did not entirely eliminate,
the behaviour-HRQoL association. Caregiver
employment status was not a confounder because adding it to
the model with DBDS alone did not change the
regression coefficient for DBDS.
In the full model, the regression coefficients for DBDS
and the interaction term between DBDS and
employment status did not change following multiple
imputation. The coefficient for employment status in the full
model changed from 0.101 (complete case analysis) to
0.088 (multiple imputation), a reduction of 12.9%.
While the regression coefficient for the interaction
between DBDS and employment status was not
statistically significant, the upper bound of the 95% CI did
not exceed the null value. Thus, we cannot dismiss the
possibility of effect modification outright (see
“Limitations” below). If effect modification were to exist, then
the inverse relation between behaviour and HRQoL
would be stronger for retired versus employed
caregivers. Based on the full regression model, the effect of
DBDS on health utility score is − 0.0033 for retired
caregivers (i.e., − 0.0003 + [− 0.003 × 1]) and − 0.0003 for
employed caregivers (i.e., − 0.0003 + [− 0.003 × 0]).
Since retired caregivers are probably at home more often
than employed caregivers, and also less likely to be able
to afford paid services such as respite care, retired
caregivers have a greater chance of being exposed to difficult
PwAD behaviours. Additionally, retired caregivers might
experience more health challenges of their own
compared to employed caregivers, simply because they are
older. This can compound the experience of dealing with
difficult behaviours and exacerbate HRQoL deficits.
The findings suggest a moderate effect size for retired
caregivers. Recent work on the EQ-5D-5L [
has two additional response options per dimension
compared to the -3L, reported a change in health utility score
of 0.037 to be clinically important [
]. The DBDS score
for a retired caregiver would have to increase by 11.22
points to produce a reduction in health utility score of
0.037 points, assuming effect modification by
employment status (− 0.037 = − 0.0033 × 11.22). This degree of
change is possible for retired caregivers, as evidenced by
the interquartile range of DBDS scores, which exceeded
11.22 points. For employed caregivers, the effect is
negligible because a 124-point increase in DBDS score would
be required to reduce the health utility score by 0.037
points (− 0.0372 = − 0.0003 × 124). However, the
maximum DBDS score is 112.
No previous study has examined the effect of
employment status on PwAD behaviours and informal caregiver
HRQoL. The inverse association between these
behaviours and caregiver HRQoL largely exists among retired
caregivers. This novel finding suggests the need for
policy makers to consider programs directed specifically at
retired caregivers to provide relief from the burden of
caregiving, e.g., tax deductions to reduce taxable income
by the amount of paid respite care.
Many of the regression coefficients were not
statistically significant, although the upper bounds of the 95%
CIs either touched or slightly exceeded the null value of
0. This suggests the study was underpowered to detect
changes in health utility scores. The study was also
cross-sectional, meaning we could not assume changes
in health utility scores would follow changes in PwAD
behaviours. Future research should examine this topic
longitudinally in larger samples. The study sample
overrepresented highly educated, high income caregivers,
which suggests caution when applying the results to all
MM and MO drafted the manuscript and conducted the statistical analysis.
MO conceptualized the study. Both authors read and approved the final
The authors thank the study participants and recruiting physicians for their
efforts in making data collection possible.
The authors declare that they have no competing interests.
Availability of data and materials
The datasets generated and/or analyzed during the current study are not
publicly available due to the fact that the original research ethics board approvals
did not include provisions for said availability. The data are available from the
corresponding author on reasonable request.
Consent for publication
Data analysis for this manuscript was supported by the RBC Research
Undergraduate Fellowship Program at the University of Waterloo. Data collection
was supported by the Canadian Institutes of Health Research (Grant Number:
MOP 86487). The funders played no role in the design of the study and in the
collection, analysis, and interpretation of data, nor in writing the manuscript.
Springer Nature remains neutral with regard to jurisdictional claims in
published maps and institutional affiliations.
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