Subgroups of chronic fatigue syndrome based on psychiatric disorder onset and current psychiatric status

doi:10.4236/health.2010.22015

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Vol.2, No.2, 90-96 (2010)

doi: 10.4236/health.2010.22015

SciRes

Health

Subgroups of chronic fatigue syndrome based on

psychiatric disorder onset and current psychiatric status

Molly M. Brown, Carly Kaplan, Leonard A. Jason, Christopher B. Keys

Center for Community Research, DePaul University, Chicago, USA; mbrown59@depaul.edu

Received 22 October 2009; revised 2 December 2009; accepted 4 December 2009.

ABSTRACT

Few studies have examined the effects of psy-

chiatric disorders occurring over a long dura-

tion among patients with chronic fatigue syn-

drome (CFS). The role of premorbid and current

psychiatric disorders in impairment was ex-

plored with a sample of 113 participants with

CFS. Subgroups were created based on past

and current psychiatric status including those

whose psychiatric history was premorbid and

current, postmorbid and current, past but not

current, and those with no lifetime diagnosis.

Results from a one-way MANOVA revealed that

patients with a premorbid and current psychiat-

ric disorder reported significantly higher pain

severity, more somatic symptoms, poorer sleep

quality, and poorer quality of life than those with

no psychiatric history. Levels of fatigue and

physical functioning among patients with CFS

were unrelated to the four subgroups in this

study. Although those with a premorbid and

current psychiatric disorder were differentiated

from those with no psychiatric history on some

markers of impairment, the sample as a whole

had severe fatigue-related impairment, which is

the cardinal symptom of CFS. Implications for

research are discussed.

Keywords: Chronic Fatigue Syndrome; Psychiatric

Comorbidity; Subgroups; Impairment

1. INTRODUCTION

Chronic fatigue syndrome (CFS) is a chronic, debilitat-

ing illness that remains poorly understood. Some pa-

tients with CFS experience psychiatric symptoms, but

the role of these symptoms in the development, mainte-

nance, and severity of the illness is unclear. Several

studies have found high rates of psychiatric comorbidity

among patients with CFS in the range of 45% to 50%, [1,

2] and up to 82% for a lifetime psychiatric diagnosis, [3]

exceeding rates in the general population.

A number of studies have examined the role of co-

morbid psychiatric issues in the course of CFS. While

one study found that patients with CFS who had a co-

morbid psychiatric diagnosis had significantly more se-

vere fatigue than those without a psychiatric disorder, [4]

most research has not found that psychiatric comorbidity

increases impairment in CFS. Studies comparing pa-

tients with and without psychiatric comorbidity have

found no differences in impairment in sleep, [5] neuro-

cognitive functioning, [6,8] physical functioning, [9,11]

fatigue severity, [5] and widespread pain. [11] These

results suggest that psychiatric comorbidity is not related

to higher illness severity in this population.

Due to the unexpected lack of evidence for a relation-

ship between psychiatric comorbidity and illness sever-

ity in CFS, it is perhaps more important to explore

long-term psychiatric status in CFS, as opposed to pre-

sent psychiatric comorbidity only. Individuals with psy-

chiatric illness early in life may be more likely to de-

velop CFS later in life, [12] indicating that a subgroup of

patients with CFS may have a long-term history of psy-

chiatric disorder beginning prior to the onset of CFS. It

has been hypothesized that an onset of psychiatric dis-

order predating CFS may be indicative of a long history

of poor coping skills, leading to increased impairment.

[13].

Tiersky, Matheis, DeLuca, Lange, and Natelson [13]

developed psychiatric subgroups based upon whether the

onset of the psychiatric disorder was before (premorbid)

or after (postmorbid) CFS onset. They found that pa-

tients with CFS with a premorbid and current psychiatric

diagnosis performed significantly worse on neuropsy-

chological tests than patients with no history of psychi-

atric disorder and healthy controls. However, they did

not find increased physical impairment in this subgroup.

Tiersky et al. developed more specific psychiatric sub-

groups of patients with CFS compared to previous stud-

ies. Nonetheless, their study did not include patients who

had a psychiatric disorder in the past but did not cur-

M. M. Brown et al. / HEALTH 2 (2010) 90-96

rently meet criteria for the disorder. In other words, it

may also be important to examine CFS severity for peo-

ple who have recovered from a past psychiatric disorder,

as remission from a psychiatric illness is associated with

increased self-efficacy [14] and may be indicative of

adaptive coping leading to better functioning. Further,

the authors did not explore some key features of CFS

severity such as sleep quality, pain severity, and diversity

of symptoms.

The present study examined four groups of patients

with CFS: those with a premorbid and current psychiat-

ric diagnosis, those with a postmorbid and current psy-

chiatric diagnosis, those with a past (either premorbid or

postmorbid) but no current psychiatric diagnosis, and

those with no history of psychiatric diagnosis. We hy-

pothesized that patients with a premorbid and current

psychiatric disorder would have increased physical and

psychiatric impairment compared to patients with a

postmorbid and current psychiatric diagnosis, those with

a past but not current psychiatric disorder, and those

with no history of psychiatric disorder.

2. METHOD

2.1. Participants

The present investigation used baseline data derived

from a larger longitudinal study of non-pharmacological

treatment interventions for CFS. [15] Participants were

recruited from physician referrals, media advertisements,

and CFS support groups.

Participants were at least 18 years of age, not pregnant,

able to read and speak English, and considered to be

physically capable of attending scheduled appointments.

Participants were included if they met the Fukuda et al.

[16] criteria for CFS (i.e., six or more months of persis-

tent fatigue accompanied by four of the following eight

symptoms: tender lymph nodes, sore throat, new or dif-

ferent headaches, muscle pain, joint pain, post-exertional

malaise, unrefreshing sleep, and memory or concentra-

tion difficulties). Medical and psychiatric examinations

were provided to rule out exclusionary medical or psy-

chiatric diagnoses according to the Fukuda et al. criteria.

In addition, participants in the current study must have

provided self-reported date of onset for CFS and psychi-

atric diagnoses. A total of 113 participants were included

in the present investigation. The DePaul University In-

stitutional Review Board approved all procedures. All

participants provided written informed consent.

2.2. Materials

2.2.1. CFS Questionnaire

The CFS Questionnaire was used to collect date of CFS

onset, demographic, health status, medication usage, and

symptom data. This screening scale has demonstrated

adequate validity and inter-rater and test-retest reliability.

[17,18]

Jason, Corradi, and Torres-Harding [19] explored 22

theoretically derived symptoms of CFS from the CFS

Questionnaire for diagnostic importance. The authors

found that these 22 symptoms are common among pa-

tients with CFS and are indicators of symptom clusters,

including: neurocognitive (e.g., slowness of thought),

vascular (e.g., dizzy after standing), inflammatory (e.g.,

allergies), muscle/joint (e.g., muscle pain), infectious

(e.g., flu-like symptoms), and sleep/post-exertional (e.g.,

unrefreshing sleep) symptoms. This study utilized these

22 symptoms to measure total somatic complaints

among participants. The total number of currently pre-

sent symptoms endorsed by participants was used to

determine the breadth of current symptoms experienced

by participants.

2.2.2. Structured Clinical Interview for DSM-IV

(SCID)

The SCID [20] was administered in order to establish

Axis I psychiatric diagnoses. While a coding scheme is

included in the instrument, the SCID allowed for clinical

judgment in the assignment of symptoms to psychiatric

or medical categories, a crucial distinction in the as-

sessment of symptoms that overlap between CFS and

psychiatric disorders, e.g., fatigue, concentration diffi-

culty, and sleep disturbance. [21] A psychodiagnostic

study [22] validated the use of the SCID in a sample of

CFS patients. Through questioning about psychiatric

symptom onset, an approximate date of psychiatric dis-

order onset is determined on the SCID.

2.2.3. Medical Outcomes Study-Short Form-36

(SF-36)

The SF-36, was used to measure self-reported functional

status related to health. [23] The full measure included

36 self-report items that identified eight health concepts,

or scales. This study used the Physical Functioning scale

to measure overall disability. Higher scores indicated

better health. Test construction studies for the SF-36

[24,25] found adequate internal consistency and dis-

criminant validity across the eight scales of this measure.

2.2.4. Fatigue Severity Scale (FSS)

The FSS [26] was used to measure fatigue. This scale

included 9 items rated on 7-point scales, and higher

scores indicated more severe behavioral consequences of

fatigue. Previous findings have demonstrated the utility

of the FSS to discriminate between individuals with CFS,

multiple sclerosis, and primary depression. [27] Within a

CFS-like group, the FSS was found to be closely associ-

ated with severity ratings for the eight Fukuda et al. [16]

CFS symptoms as well as with functional outcomes re-

lated to fatigue. [28]

M. M. Brown et al. / HEALTH 2 (2010) 90-96

2.2.5. Brief Pain Inventory (BPI)

The BPI [29] was administered to measure the intensity

of pain (pain severity) and the interference of pain in the

patient's life (pain interference). This measure consisted

of 14 questions with scores on each scale ranging from 0

to 10. Higher scores indicated more pain. This measure

exhibited adequate levels of reliability to assess pain in

non-cancer samples, with alpha coefficients of .70 and

above. [29] It also evidenced good concurrent validity

with other generic pain measures. [30]

2.2.6. Pittsburgh Sleep Quality Index (PSQI)

The PSQI was a self-report measure developed to assess

sleep quality in psychiatric research. [31] This index

measured sleep disruptions and sleep quality. There were

19 questions (on 0-3 scale) which generated seven

“component” scores: subjective sleep quality, sleep la-

tency, sleep duration, habitual sleep efficiency, sleep

disturbances, use of sleeping medication, and daytime

dysfunction. The sum of scores for these seven compo-

nents yielded one global score, which ranged from 0 to

21. Higher scores indicated worse sleep quality. The

global scale demonstrated adequate internal consistency,

test-retest reliability, and discriminant and concurrent

validity. [31]

2.2.7. Quality of Life Scale (QLS)

The QLS measured satisfaction with different life activi-

ties for individuals with various chronic illnesses. [32]

The scale consisted of 16 items answered on a Likert-

type 1 to 7 scale asking how satisfied individuals are

with each item. Higher scores indicated more overall life

satisfaction. This scale demonstrated high test-retest

reliability, convergent, discriminant, and construct valid-

ity among individuals with various stable chronic ill-

nesses. [32]

2.3. Procedure

Once study eligibility criteria were met and no exclu-

sionary illnesses were found based on the medical ex-

amination or SCID findings, participants completed

self-report measures. The 113 participants were then

divided into four psychiatric subgroups based on onset

of psychiatric disorder in relation to CFS onset and cur-

rent psychiatric status. In order to determine whether

participants had a psychiatric disorder that predated the

onset of CFS, the date of psychiatric disorder onset de-

rived from the SCID was compared with self-reported

date of CFS onset from the CFS Questionnaire. Specifi-

cally, participants with a current psychiatric disorder

who reported having a psychiatric disorder at any point

in their life prior to developing CFS were considered to

have a premorbid and current psychiatric disorder (n =

32; 28.3%). Those with a current psychiatric diagnosis

and a history of psychiatric disorder that never predated

CFS onset were considered to have a postmorbid and

current disorder (n = 12; 10.6%). Those with a history of

psychiatric disorder who do not currently meet criteria

for a psychiatric disorder comprised a third subgroup

referred to past but not current psychiatric disorder (n =

28; 24.8%). Finally, patients with no lifetime psychiatric

diagnosis were placed into a fourth subgroup (n = 41;

36.3%).

2.4. Statistical Analyses

Pearson chi-square analyses and one-way analysis of

variance (ANOVA) were used to examine differences

among the four psychiatric groups with regard to demo-

graphic variables. Fisher’s Exact Tests were computed

using SAS Proc Freq to compare the three groups with a

history of psychiatric disorders on DSM-IV diagnostic

categories. A one-way ANOVA was used to compare

total number of lifetime psychiatric diagnoses between

the three groups.

One-way multivariate analysis of variance (MAN-

OVA) was used to test the primary hypotheses of this

study with psychiatric group (premorbid and current,

postmorbid and current, past but not current, and no life-

time psychiatric disorder) as the independent variable.

The use of MANOVA reduced the likelihood of Type I

error when making comparisons of multiple related de-

pendent variables. [33] Upon examination of the correla-

tion matrix of the outcome variables used in this study,

all outcome variables were moderately correlated (r ≥ .3)

with at least two other outcomes, indicating that

MANOVA would be appropriate. Wilks’ Lambda F ap-

proximation was used for interpretation of the multivari-

ate test, and Bonferroni tests were used for post hoc

comparisons.

3. RESULTS

3.1. Demographic Characteristics

In regards to demographic characteristics, 83.2% of par-

ticipants were female. The average age was 43.8 years.

Regarding ethnicity, 87.6% were White, 4.4% were Af-

rican American, 4.4% were Latino, and 3.5% were Asian

American. As for marital status, 48.7% were married or

living with a partner, 32.7% were single, and 17.7%

were divorced or separated. In terms of work status,

40.7% were working or full time students and 59.3%

were part-time students, retired, unemployed or on dis-

ability. With regards to education, 46.9% had earned a

standard college degree, 22.1% had a graduate or pro-

fessional degree, 21.2% had partial college, and 9.7%

had a high school/GED degree or less. No significant

M. M. Brown et al. / HEALTH 2 (2010) 90-96

Table 1. Lifetime Psychiatric Diagnoses for Psychiatric Subgroups.

Premorbid and current

(n = 32)

Postmorbid and current

(n = 12)

Past but not current

(n = 28)

Sig.

Any Mood Disorder 59.4% 58.3% 50.0%

Major Depressive Disorder 50.0% 58.3% 46.4%

Dysthymic Disorder 18.8% 0.0% 0.0% *

Other Mood Disorder 0.0% 0.0% 3.6%

Any Anxiety Disorder 56.3% 33.3% 46.4%

Generalized Anxiety Disorder 9.4% 8.3% 3.6%

Panic Disorder (with or without Agoraphobia) 25.0% 16.7% 17.9%

Posttraumatic Stress Disorder 37.5% 0.0% 10.7% **

Other Anxiety Disorder 6.3% 8.3% 10.7%

Adjustment Disorder 21.9% 33.3% 7.1%

Other 25.0% 0.0% 14.3%

Total Lifetime Psychiatric Disorders (Mean) 1.97 a, b 1.25 a 1.25 b ***

Notes: *p < .05, **p < .01, ***p < .001; Similar letters across rows indicate significant difference

differen ce s were found among the four groups in terms

of demographic variables.

3.2. Diagnostic Outcomes

Total lifetime psychiatric diagnoses and rates of different

psychiatric diagnostic categories were compared for the

three groups with a history of psychiatric disorder (Ta-

ble 1). Fisher’s Exact Tests revealed that the three groups

did not differ in terms of lifetime presence of anxiety or

mood disorders. When comparing differences among the

three psychiatric groups for specific psychiatric diagno-

ses, a significant difference was revealed for lifetime

dysthymic disorder (p = .02), and the premorbid and

current psychiatric group had the highest rate (18.8%)

compared to the other two groups with rates of 0%. A

significant difference between groups was also found for

lifetime posttraumatic stress disorder (p = .01). The

premorbid and current group had the highest rate of

posttraumatic stress disorder (37.5%), the past but not

current group had the second highest rate (10.7%), and

no participants from the postmorbid and current group

met criteria during their lifetime.

A one-way ANOVA revealed that the groups signifi-

cantly differed on total number of lifetime psychiatric

diagnoses, F(2, 69) = 9.19, p < .001. Bonferroni post hoc

analyses indicated that the premorbid and current psy-

chiatric group had significantly more lifetime psychiatric

diagnoses than both the postmorbid and current group (p

= .01), and the past but not current group (p = .003).

3.3. Main Outcomes

Sixteen participants had missing data for one or more of

the self-report outcome measures and were therefore

excluded, which left a total of 97 participants for analy-

sis of main outcomes (See Table 2). Results from the

one-way MANOVA revealed a significant overall mul-

tivariate effect for psychiatric group on the combined

DVs, Wilks’ Lambda = .68, p = .03.

Descriptive statistics for outcomes are reported in Ta-

ble 2. Upon examination of univariate effects, signifi-

cant differences were found for pain severity [F(3, 93) =

3.08, p = .03], pain interference [F(3, 93) = 3.27, p

= .03], total somatic symptoms [F(3, 93) = 3.86, p = .01],

sleep quality [F(3, 93) = 4.59, p = .01], and quality of

life [F(3, 93) = 3.31, p = .02]. No significant univariate

effects were found for fatigue severity or physical func-

tioning. Bonferroni post hoc tests revealed the premorbid

and current group scored significantly worse than the no

lifetime diagnosis group for pain severity (p = .02), pain

interference (p = .02), total somatic symptoms (p = .03),

sleep quality (p = .003), and quality of life (p = .02).

4. DISCUSSIONS

Patients with CFS with a premorbid and current psychi-

atric disorder reported significantly higher pain severity

and interference, more somatic symptoms, poorer sleep

quality, and poorer quality of life than those who have

never been diagnosed with a psychiatric disorder. No

ignificant differences in impairment were found for s

M. M. Brown et al. / HEALTH 2 (2010) 90-96

Table 2. Means (and Standard Deviations) for Psychiatric Subgroups on Outcome Measures.

Premorbid and current

(n = 29)

Postmorbid and current

(n = 11)

Past but not current

(n = 22)

No lifetime diagnosis

(n = 35) Sig.

Physical Functioning1 38.72 (24.00) 40.91 (28.88) 48.64 (18.01) 46.57 (22.68)

Fatigue Severity2 6.19 (1.01) 6.29 (0.64) 6.16 (0.71) 5.98 (0.69)

Pain Severity2 4.94 (2.19) a 3.98 (2.39) 4.30 (1.58) 3.33 (2.31) a *

Pain Interference2 5.33 (3.15) a 4.81 (3.25) 4.40 (2.01) 3.24 (2.56) a *

Somatic Symptoms2 16.21 (3.56) a 17.00 (3.23) 15.36 (4.67) 13.37 (3.99) a **

Sleep Quality2 9.55 (1.77) a 8.36 (3.29) 8.05 (2.28) 7.49 (2.23) a **

Quality of Life1 59.48 (15.87) a 69.91 (18.11) 65.68 (12.42) 71.03 (15.16) a *

Notes: Similar letters across rows indicate significant difference; 1Higher numbers are better; 2Lower numbers are better; *p < .05, **p < .01

participants in the other two psychiatric history groups

compared to the no lifetime diagnosis group. These re-

sults in combination with two of Tiersky et al.’s [13]

neuropsychological findings suggest that patients with

CFS who have a premorbid and current psychiatric dis-

order have significantly more impairment than those

with no psychiatric history, while patients with other

categorizations of psychiatric history are not differenti-

ated from patients without a psychiatric history in terms

of impairment. However, the postmorbid and current

psychiatric group did, in fact, demonstrate the highest

level of fatigue severity and the most somatic symptoms

compared to the other three groups, but significant dif-

ferences were not revealed due to the small sample size

for this group. Although patients with a premorbid and

current psychiatric history were found to represent a

subset of the CFS population that experiences particu-

larly severe illness symptomatology, patients with a

postmorbid and current diagnosis may also have in-

creased illness severity.

Despite findings of increased impairment on some

outcomes for those who had premorbid and current psy-

chiatric diagnoses, no differences were found between

groups for physical functioning or fatigue severity.

Moreover, it is evident from this study that patients with

and without psychiatric disorders exhibit notably high

levels of fatigue and disability. These findings are con-

sistent with previous research demonstrating that psy-

chiatric comorbidity does not differentiate patients in

terms of physical functioning [9] or fatigue severity. [5]

Of note is that fatigue is the cardinal symptom of CFS,

and findings from this and previous studies suggest that

this symptom is present at a severe level regardless of

psychiatric status.

In terms of severity of psychiatric functioning among

patients with CFS, our prediction that the premorbid and

current psychiatric group would evidence the most psy-

chiatric dysfunction as defined by more lifetime psychi-

atric diagnoses was confirmed and was consistent with

prior research. [13] This finding suggests that patients

who have had ongoing mental health issues beginning

prior to CFS onset tend to have more pervasive emo-

tional problems. High levels of psychiatric impairment

over time, in turn, may be related to increased ill-

ness-related impairment compared to those with a

shorter-term history of psychiatric disorder.

The premorbid and current group had, on average, a

total of 16.21 somatic symptoms compared to the no

history group which had an average of 13.37 symptoms.

This greater number of somatic symptoms suggests that

the clinical presentation of patients with longstanding

mental health issues is more complex than those without

a psychiatric history. Exclusion of premorbid psychiatric

disorder in CFS samples has been used to reduce sample

heterogeneity in some studies. [34] Results from this

study provide support for sample selection strategies that

take into consideration premorbid psychiatric function-

ing, as long-term psychiatric status adds complexity to

the illness symptomatology.

Several limitations can be noted for the present inves-

tigation. The use of self-reported onsets of psychiatric

disorder and CFS to determine psychiatric subgroups

may be problematic, as both are vulnerable to recall bias.

[35,36] Further, research has shown that those with a

gradual CFS onset were more likely to report long-term

depressive symptomatology gradually leading to the on-

set of the illness. [37] Thus, the self-reported onset of

CFS in the present study may not have been accurate for

all participants, particularly those who also had a gradual

illness onset. Finally, differences between groups may

not have been revealed in the analysis due to small sam-

ple sizes and low power. Future research with a larger

sample size is needed to more fully explore functioning

among patients with a postmorbid and current psychiat-

ric diagnosis.

This study added to previous research demonstrating

that neuropsychological functioning is impacted based

on premorbid and current psychiatric status. [13] The

M. M. Brown et al. / HEALTH 2 (2010) 90-96

findings indicated that long term psychiatric dysfunction

increased impairment on several key indicators of CFS

severity: sleep difficulties, pain, and wide ranging so-

matic symptoms. However, the sample as a whole had

high levels of fatigue and physical impairment which

were unrelated to the four subtypes, suggesting that even

patients without a psychiatric history suffer from severe

disability. Since the premorbid and current psychiatric

history group also evidenced the most psychiatric dys-

function, treatment targeting mental health issues may

help reduce symptom severity for this particular sub-

group of patients. Past research suggests that examining

current psychiatric status may not differentiate patient in

terms of symptomatology. Based on the findings from

this study, future research exploring the role of psychiat-

ric functioning in CFS should examine psychiatric sub-

groups based on the onset and current status of the psy-

chiatric disorder.

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