SLEEP-RELATED BREATHING DISORDERS
Types of Coping Strategies are Associated with Increased Depressive Symptoms
in Patients with Obstructive Sleep Apnea
Wayne A. Bardwell PhD,1,2 Sonia Ancoli-Israel PhD,1,2 and Joel E. Dimsdale MD1
1University
of California, San Diego, Department of Psychiatry; 2Veterans Affairs San Diego Healthcare System
Study Objectives: Some, but not all, researchers report that obstructive
sleep apnea (OSA) patients experience increased depressive symptoms.
Many psychological symptoms of OSA are explained in part by other OSA
comorbidities (age, hypertension, body mass). People who use more passive and less active coping report more depressive symptoms. We examined relationships between coping and depressive symptoms in OSA.
Setting: N/A
Design/Participants: 64 OSA (respiratory disturbance index (RDI)≥15)
patients were studied with polysomnography and completed Ways of
Coping (WC), Profile of Mood States (POMS), Center for Epidemiological
Studies-Depression (CESD) scales. WC was consolidated into Approach
(active) and Avoidance (passive) factors. Data were analyzed using SPSS
9.0 regression with CESD as the dependent variable and WC Approach
and Avoidance as the independent variables.
Interventions: N/A
Measurements and Results: WC Approach factor (B=-1.105, ß=-.317,
p=.009) was negatively correlated and WC Avoidance factor (B=1.353,
ß=.376, p=.007) was positively correlated with CESD scores. These factors explained an additional 8% of CESD variance (p<.001) beyond that
explained by the covariates: demographic variables, RDI, and fatigue (as
measured by the POMS).
Conclusions: More passive and less active coping was associated with
more depressive symptoms in OSA patients. The extent of depression
experienced by OSA patients may not be due solely to effects of OSA
itself. Choice of coping strategies may help determine who will experience
more depressive symptoms.
Key words: Obstructive sleep apnea; depression; coping; mood; personality
INTRODUCTION
toms of OSA can be explained in part by other OSA comorbidities (e.g., age, hypertension, body mass).1 We wondered if
aspects of behavior and personality might also play a role in
determining the extent of depressive symptoms experienced by
OSA patients. One factor frequently associated with depression
involves the choice of coping strategies for dealing with stress.
Coping strategies are defined as "conscious, rational ways for
dealing with the anxieties of life"20 and are often categorized into
active (or approach) and passive (or avoidance) strategies. The
Ways of Coping Questionnaire-Revised21 is one of the more frequently used instruments for assessing coping strategies. Active
strategies include confrontive coping, seeking social support,
planned problem solving and positive reappraisal. Passive strategies include distancing, self-control, accepting responsibility, and
escape/avoidance. These strategies are defined in Table 1.
The use of more passive and less active coping strategies has
been shown to be associated with higher levels of depressive
symptoms in patients having various chronic illnesses, including
HIV22,23 and breast cancer.24 We wondered if these relationships
would hold in a population of OSA patients. We examined relationships between coping and depressive symptoms in OSA
patients, while controlling for OSA severity and fatigue to ensure
that choice of coping strategies wasn't simply a matter of illness
severity or lack of energy.
OBSTRUCTIVE SLEEP APNEA (OSA) HAS SUBSTANTIAL
PSYCHOSOCIAL COMORBIDITIES.1 Affecting up to 9% of
middle-aged adults and higher percentages in the elderly, OSA is
a devastating illness that leaves patients exhausted from sleep
deprivation.2-4 An OSA patient experiences multiple periods during the night in which the airway collapses and breathing stops
(over 100 events per hour in severe cases) resulting in repeated
disruption of normal sleep patterns. In addition to significant
daytime fatigue, this disruption can lead to serious decreases in
blood oxygen levels with potentially life-threatening cardiovascular consequences.
The literature is mixed regarding the role played by psychosocial factors in OSA (for review, see Bardwell et al 1999).1
Many researchers have found associations between OSA and
overall psychosocial distress and, more specifically, clinical
depression,5-8 or increased levels of depressive symptoms.9-15
Others have reported that patients with sleep apnea do not show
clinically significant levels of depression or have levels of
depressive symptoms no higher than control groups16-18 or
patients with other chronic illnesses.19
We have reported previously that many psychosocial symp-
METHODS
Disclosure Statement
This work was supported by grants HL44915, RR00827, AG08415, and
CA85264 from the National Institutes of Health.
Sixty-four men and women with OSA were recruited by
advertising and word of mouth to participate in our research on
sympathetic nervous system physiology in OSA. To qualify, participants had to be between 100% and 150% of ideal body weight
as determined by Metropolitan Life Insurance tables.25 Although
OSA is more common among the obese, those participants who
Accepted for publication September 2001
Address correspondence to: Wayne A. Bardwell PhD, UCSD, La Jolla, CA
92093-0804; Tel: 619-543-6685; Fax: 619-543-7519;
E-mail: [email protected]
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Increased Depressive Symptoms in Patients with OSA—Bardwell et al
Table 1—Description of coping scales
Active (Approach) Strategies
Confrontive Coping:
Describes aggressive efforts to alter the situation and suggests some degree of hostility and risktaking.
Seeking Social Support:
Describes efforts to seek informational support, tangible support, and emotional support.
Planful Problem Solving:
Describes deliberate problem-focused efforts to alter the situation, coupled with an analytic
approach to solving the problem.
Positive Reappraisal:
Describes efforts to create positive meaning by focusing on personal growth. It also has a religious dimension.
Passive (Avoidant) Strategies:
Distancing:
Describes cognitive efforts to detach oneself and to minimize the significance of the situation.
Self-Controlling:
Describes efforts to regulate one's feelings and actions.
Accepting Responsibility:
Acknowledges one's own role in the problem with a concomitant theme of trying to put things
right.
Escape-Avoidance:
Describes wishful thinking and behavioral efforts to escape or avoid the problem. Items on this
scale contrast with those on the Distancing scale, which suggest detachment.
From: Folkman & Lazarus, 1988.21; Patterson et al., 1993.22
disturbance index (RDI). OSA was defined as RDI ≥15.
Participants completed the Ways of Coping QuestionnaireRevised (WC),21 the Center for Epidemiological StudiesDepression (CESD) Scale,27 and Profile of Mood States
(POMS).28 The WC is used to gauge how participants respond to
stressful situations and is a process-oriented measure of coping
activity.21 After writing about a particularly stressful situation of
their choice, participants were asked to respond to a series of 66
questions, using a 0—3 scale. This instrument yields eight subscales derived from factor analysis: confrontive coping, seeking
social support, planned problem solving, positive reappraisal,
distancing, self-control, accepting responsibility, escape avoidance. Data from this instrument were consolidated into Approach
and Avoidance factors, as demonstrated by Patterson et al.22
These factors can be thought of as representing active and passive coping strategies, respectively. Approach coping includes
the first four subscales, while Avoidant coping includes the
remaining four subscales listed above.22,29 Both factors were
dichotomized into Hi/Lo groups using median splits.
The WC has been shown to be an adequately reliable and valid
instrument which has been used to assess coping strategies in a
variety of general and patient populations.21 It has also been used
in patients living with a variety of chronic illnesses having a significant fatigue component, such as HIV,22,30 multiple sclerosis
and spinal cord injury,31 and chronic fatigue syndrome.32 We are
unaware of studies that have used the WC to assess coping strategies in OSA patients.
The CES-D is a frequently used 20-item self-report scale that
has been shown to be reliable and valid for assessing depressive
symptoms.22 In a variety of populations, a large percentage of
subjects with a score ≥16 have been shown to meet diagnostic
criteria for dysthymia or major depression.33,34 When used with
medically ill patients, depression rating scales are sometimes
were more than 150% of ideal body weight were excluded due to
the possibility of confounding by other conditions associated
with obesity. Potential participants were also excluded if they had
major medical illnesses other than OSA: congestive heart failure,
pulmonary disease requiring ongoing treatment, symptomatic
coronary or cerebral vascular disease (history of myocardial
infarction, angina, stroke, transient ischemic attack), history of
life-threatening arrhythmias, cardiomyopathy, history of psychosis, current drug or alcohol abuse, known secondary hypertension, creatinine levels >1.4mg%, kidney disease, renal bruit
on physical examination, prior diagnosis or treatment of diabetes,
fasting blood glucose >120mg%, other known sleep disorder
(e.g., narcolepsy). The protocol was approved by the University
of California, San Diego, Human Subjects Committee and written consent was obtained from all participants prior to enrollment.
Participants had their sleep monitored all night in the Clinical
Research Center with polysomnography, which included standard central and occipital electroencephalogram (EEG); bilateral
electrooculogram (EOG); submental electromyogram (EMG);
nasal/oral airflow using a thermistor; thoracic and abdominal
excursions with Respitrace respiratory inductive plethysmography; and bilateral tibialis EMG. Tracings were scored according
to the criteria of Rechtshaffen and Kales26 and the number of
apnea/hypopnea events was recorded. Apneas were defined as
decrements in airflow of ≥90% from baseline for a period of ≥10
seconds. Hypopneas were defined as decrements in airflow of
≥50% but <90% from baseline for a period ≥10 seconds. The
majority of subjects had solely obstructive type events; only a
few subjects showed evidence of central apneas. Potential participants who showed predominant central apneas (>50% of total
apneas) were excluded from this study. The number of apneas
and hypopneas per hour were calculated to obtain the respiratory
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Increased Depressive Symptoms in Patients with OSA—Bardwell et al
of the patients' degree of illness. Therefore, RDI and POMS
Fatigue were employed as covariates, along with mean O2 saturation levels, gender, age, and body mass index (BMI). Gender,
BMI, and age differences have been previously reported in studies of OSA, depression, and coping strategies. In linear regression, all the covariates were entered in the first block, then the
continuous versions of the WC Approach and Avoidance factors
were entered, followed by the Approach X Avoidance interaction.
Initially, we conducted the analysis using only RDI and
POMS Fatigue as covariates. To be more conservative, as a check
to ensure that demographic differences were not driving the
results, the other covariates were included in the model. Because
results did not differ meaningfully, the more conservative model
that includes the full set of covariates is reported below.
Table 2—Subject characteristics (mean±standard deviation).
N
64
Age
49.3 + 7.9
Body Mass Index
29.8 + 4.5
Respiratory Disturbance Index
51.5 + 28.5
Mean Oxygen Saturation
91.8 + 4.0
Center for Epidemiological Studies-Depression
12.5 + 10.9
Profile of Mood States-Fatigue
10.8 + 7.2
influenced by the symptoms of their illness. For example, moodrelated observations in OSA patients could be confounded by the
fatigue/sleepiness they experience. However, the CES-D primarily taps the cognitive/affective symptoms of depression and has
been shown to be useful in chronically ill groups experiencing
fatigue (e.g., HIV, cancer),35,36 including OSA patients.1,37
The POMS is a well-established factor analytically derived
measure of psychological distress for which high levels of reliability and validity have been documented.28 The POMS consists
of 65 adjectives that are rated on a 0—4 scale. Data from this
instrument can be consolidated into six subscales: fatigue-inertia,
vigor-activity, tension-anxiety, depression-dejection, anger-hostility, confusion-bewilderment. The POMS has been used in a
variety of chronically ill and well populations,28,38-44 including
OSA patients.45-47 We were particularly interested in controlling
for scores on the fatigue-inertia subscale. This subscale measures
weariness, inertia, and low energy level (states commonly experienced by OSA patients) and has been validated as a separate
factor in several studies.28 Norms have been published for a variety of patient and non-patient groups. For example, depressed
patients reported a mean POMS Fatigue score of 14.7 while normal females and males reported mean scores of 8.4 and 7.0,
respectively.28
Data were analyzed using SPSS 9.0 software (1999) linear
regression. The CES-D was used as the dependent variable and
WC Approach, WC Avoidance, and the WC Approach X WC
Avoidance interaction as independent variables. The interaction
term was entered because we hypothesized that patients who
used more passive and less active coping strategies would show
the highest levels of depression.
Several covariates were also employed in these models.
Because our sample varied in terms of RDI and fatigue, and
because it seems plausible that fatigue could influence the preference for active vs. passive coping strategies, we wanted to
ensure that coping strategy selection was not simply a reflection
RESULTS
Table 2 shows demographic and other subject characteristics.
Subjects included 54 men and 10 women averaging 49.3 years of
age (range 32-64 years) with a mean BMI of 29.8. Mean RDI
was 51.5 (range 15-142) with a mean O2 saturation of 91.8. One
third of the subjects had a CESD score ≥16, suggesting the presence of a diagnosable mood disorder. POMS Fatigue scores averaged 10.8 with 30% of subjects exceeding the mean score of 14.7
from the POMS normative sample for depressed patients.
Table 3 shows Pearson correlations for demographic variables
vs. CESD and the WC Approach and Avoidance factors.
Significant correlations emerged for gender, age, BMI, and mean
O2 saturation levels, which were entered as covariates along with
RDI and POMS Fatigue. In the regression analysis, the covariates
were entered in the first block, accounting for 48.7% of the variance in CESD (F=8.242, p<.001). Next, the WC Approach (B=1.105, ß=-.317, p=.009) and WC Avoidance (B=1.353, ß=.376,
p=.007) factors were entered, accounting for an additional 8.0%
of the variance in CESD (F=8.177, p<.001). Lower scores on WC
Approach and higher scores on WC Avoidance were associated
with higher CESD scores. The interaction term did not account
for a statistically significant amount of variance in CESD.
DISCUSSION
Obstructive sleep apnea is a potentially devastating chronic
illness marked by significant levels of daytime fatigue. Findings
have been equivocal, however, in terms of other psychosocial
complications of this illness. For example, while many studies
Table 3—Pearson correlations (r, p): demographic variables vs. ways of coping factors
Gender
Age
Body Mass Index
Respiratory Disturbance Index
Mean Oxygen Saturation
Center for
Epidemiological
Studies-Depression
Ways of Coping
Approach Factor
Ways of Coping
Avoidance Factor
.27, .025*
-.19, .127
.28, .021*
.05, .705
-.17, .181
.21, .086
-.15, .241
.09, .490
-.05, .674
-.22, .089
.08, .516
-.35, .004**
.28, .021*
.04, .781
-.46,<.001**
*p<.05 ** p<.01
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Increased Depressive Symptoms in Patients with OSA—Bardwell et al
have reported higher levels of depression or depressive symptoms in OSA patients, some researchers have concluded that
OSA patients do not show higher levels of depressive symptoms
than controls. In those studies which did find increased psychosocial distress in OSA, it is unclear how much of this distress
was a direct result of the illness itself and how much could be
attributed to behavioral or personality characteristics.
According to Folkman and Lazarus (1988), "it is how individuals cope with stress, not stress per se, that influences their psychological well-being, social functioning, and somatic health."21
Choice of coping strategies is an important behavioral aspect of
personality that has been examined in studies of depression and
chronic illness. As shown in Table 1, coping strategies vary considerably, with some including elements of hostility and risk-taking and others reflecting aspects of resignation and withdrawal.
While crucial in managing the anxieties of everyday life, coping
strategies become even more important in the face of the additional distress of living with a chronic illness.
The use of less active and more passive coping strategies has
been associated with increased symptoms of depression in
patients living with chronic illness, including illnesses that have
a substantial fatigue component. We are unaware, however, of
any previous studies that have examined the role of coping strategies vis-à-vis depressive symptoms experienced by OSA
patients. Therefore, we hypothesized that OSA patients who
employed less active and more passive coping techniques would
be at higher risk for depressive symptoms than OSA patients who
used strategies that are thought to be more enhancing of mental
health (i.e., more active, less passive).
In testing this hypothesis, we wanted to ensure that the choice
of coping strategies was not simply a result of OSA severity,
fatigue or demographics. After controlling for these variables, we
observed that passive coping was positively correlated and active
coping was negatively correlated with CES-D scores: the more
passive and the less active coping strategies reported by OSA
patients, the greater the level of depressive symptoms they
reported experiencing.
Therefore, we conclude that the extent of depressive symptoms experienced by OSA patients may not be due solely to the
effects of the illness itself. Rather, behavioral and personality
characteristics (i.e., choice of coping strategies) may play an
important role in determining which OSA patients will experience greater disturbance of mood. This finding may explain, at
least in part, some of the disparate observations in the OSAdepression literature.
that this unequal distribution of gender skewed our findings.
Therefore, while our results suggest that coping strategies are
associated with level of depressive symptoms experienced by
OSA patients, replication of these results is warranted.
Summary
Obstructive sleep apnea is a relatively common chronic illness
having the potential for disturbing psychosocial sequelae. We
believe it is sometimes assumed that OSA patients will automatically experience significant mood symptoms, given the degree
of sleep disruption and concomitant fatigue they frequently experience. However, illnesses occur in people having premorbidly
varying resilience and ability to cope with life stress in general
and illness-related stress in particular. Such personality and
behavioral patterns may play an important role in determining
which OSA patients will experience higher levels of depressive
symptoms. Therefore, the assessment of coping strategies in
OSA patients could help identify those patients who might benefit most from the direct treatment of mood symptoms in addition
to treatment of the sleep disturbed breathing itself.
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