www.elsevier.com/locate/jad

Journal of Affective Disorders 78 (2004) 73–80

Brief report

Burden of dysthymia and comorbid illness in adults in a

Canadian primary care setting: high rates of psychiatric illness

in the offspring

Barbara Bella,h,i, Lori Chalklina,h,i, Michael Millsa,h,i, Gina Brownea,c,d,h,*,Meir Steinera,b,g, Jacqueline Robertsa,c,d, Amiram Gafnia,d,e, Carolyn Byrnea,c,

David Wallikh, James Kraemerh, Michelle Webba, Ellen Jamiesona,Susan Whittakera, Edward Dunnf,g

aSystem-Linked Research Unit on Health and Social Service Utilization, McMaster University, Faculty of Health Sciences,

1200 Main Street West, HSC-3N46, Hamilton, Ontario, Canada L8N 3Z5bDepartment of Psychiatry and Behavioural Neurosciences, McMaster University, Hamilton, Ontario, Canada L8N 3Z5

cSchool of Nursing, McMaster University, Hamilton, Ontario, Canada L8N 3Z5dDepartment of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, Ontario, Canada L8N 3Z5

eCentre for Health Economics and Policy Analysis, McMaster University, Hamilton, Ontario, Canada L8N 3Z5fDepartment of Pathology and Molecular Medicine, McMaster University, Hamilton, Ontario, Canada L8N 3Z5

gThe Father Sean O’Sullivan Research Centre, St. Joseph’s Hospital, Hamilton, ON, CanadahThe Caroline Medical Group, Burlington, ON, Canada

iDepartment of Community Health and Family Medicine, The University of Toronto, Toronto, ON, Canada

Received 3 April 2002; accepted 28 May 2002

Abstract

Background: The burden of comorbid dysthymia and other comorbid psychiatric illnesses in a Canadian primary care

setting was measured. Two groups of primary care patients: those who scored positive for comorbid dysthymia versus those

who scored negative for any psychiatric disorder were compared. Methods: This was a cross-sectional survey in a Health

Service Organization (HSO) in Ontario, Canada. The subjects were patients of the HSO. The main outcome measures were:

health status, mood, social adjustment, coping ability, children’s psychiatric disorders, child development, family function,

and health and social service utilization. Results: Of the 6280 eligible adults who were patients at the HSO, 68.9%

consented to be screened for psychiatric disorders; 5.1% screened positive for dysthymia, of which 90% had at least one

comorbid psychiatric disorder. The following statistically significant differences were found between people with dysthymia

and other comorbid psychiatric disorders versus people without any psychiatric disorder. People with dysthymia were more

likely to have worse health status, worry more about their health, and report levels of pain that impaired their function; they

had higher MADRS depression scores, lower social role function scores, lower social adjustment scores, and lower coping

ability. More children of people with comorbid dysthymia met criteria for one or more childhood psychiatric disorders and

there were more families with a parent with dysthymia that were dysfunctional. People with dysthymia used a greater

0165-0327/$ - see front matter D 2002 Elsevier B.V. All rights reserved.

doi:10.1016/S0165-0327(02)00174-X

* Corresponding author. Tel.: +1-905-525-9140x22293; fax: +1-905-528-5099.

E-mail address: browneg@fhs.mcmaster.ca (G. Browne).

B. Bell et al. / Journal of Affective Disorders 78 (2004) 73–8074

proportion of health and social services, had higher per person annual health care costs (excluding hospital services), and

had higher per person annual indirect costs (lost wages). Conclusion: This analysis demonstrated the burden of illness and

costs that this disorder imposes on individuals, their families, and society as a whole.

D 2002 Elsevier B.V. All rights reserved.

Keywords: Dysthymic disorder; Comorbidity; Primary health care; Burden of illness

1. Introduction Epidemiologic data suggests that the lifetime prev-

Family physicians and other primary care health

professionals have known for some time that patients

with dysthymia are very often first identified in a

primary care setting. However, it hasn’t been until the

last decade that this issue has become recognized in

the medical literature (Williams et al., 2000).

Dysthymia, as defined in the Diagnostic and Sta-

tistical Manual of Mental Disorders, fourth edition

(DSM-IV) (American Psychiatric Association, 1994),

is characterized in adults by a state of chronic de-

pressed mood with low-grade symptomatology that

persists for at least two years, for more days than not,

with no more than 2 months without symptoms. Other

symptoms include change in appetite, sleep distur-

bance, fatigue, low self-esteem, poor concentration,

and feelings of hopelessness. Dysthymia is categorized

by age into early onset (before age 21) and late onset

(after age 21) types (American Psychiatric Associa-

tion, 1994). Typically, dysthymia, also known as

dysthymic disorder (Brieger and Marneros, 1997),

has an insidious onset at an early age with a fluctuating

course of symptoms that have since become a part of

the individual’s day-to-day experience (Akiskal, 1983;

Akiskal et al., 1995). Dysthymia is frequently comor-

bid with anxiety disorders, substance abuse, emotional

and physical disability, and impairment of social and

occupational role functions (Leader and Klein, 1996)

and it may adversely influence the outcome of co-

occurring medical conditions (Lane and McDonald,

1994). In addition, it commonly occurs concurrently

with a major depressive episode, a condition termed

‘double depression’ (Keller et al., 1995; Kessler et al.,

1997). Questions remain about whether dysthymia and

double depression are distinct disorders or an almost

inevitable continuum. The etiology of dysthymia is

still unknown and its tendency for comorbidity makes

it especially challenging to isolate.

alence of dysthymia in the general population (US)

ranges from 3.2 to 6.4% and the 12-month prevalence

rate is 2.5% (Kessler et al., 1994). Yet, despite the

high prevalence of this condition, dysthymia often

goes undiagnosed (Keller, 1994) and untreated (Shel-

ton et al., 1997). Even when accurately diagnosed, the

full impact of this illness on an individual’s health

status and role function can remain unaddressed.

The burden of illness that dysthymia creates for

individuals, their families, and society as a whole,

cannot be ignored. It has been shown that depressive

illnesses in general, and particularly those that are

comorbid with other medical or psychiatric condi-

tion(s), are associated with considerable economic

burden both to the individual and to society through

direct costs of treatment (primary care and hospital)

(Lane and McDonald, 1994), greater health service

utilization (Howland, 1993), as well as indirect costs

related to reduced productivity due to illness (Lane

and McDonald, 1994; Kessler and Frank, 1997). In

addition, the findings of recent family studies point

out that there is a higher rate of dysthymia and

personality disorder in the first-degree relatives of

patients with dysthymia as well as in patients with

double depression (Klein et al., 1995; Donaldson et

al., 1997). Furthermore, there is accumulating evi-

dence that children of parents with mood disorders

fare poorer than those whose parents are healthy

(Beardslee et al., 1996). Evidence is lacking about

the burden of illness specifically associated with

comorbid dysthymia.

2. Methods

This cross-sectional survey was part of a large

study that was conducted in a primary care univer-

sity-affiliated Health Service Organization (HSO)

B. Bell et al. / Journal of Affective Disorders 78 (2004) 73–80 75

serving a roster of 11 000 patients in Southern,

Ontario, Canada within a publicly funded national

system of health care. This is a predominately

English-speaking, middle-class, suburban, family

community (population 137 000) with few visible

minority groups. Written informed consent was

obtained from all subjects prior to study enrollment.

Over a 12-month recruitment period, all of the

HSO’s 6280 adults who were z18 and V75 years

of age were approached to be screened for partic-

ipation in a multi-arm clinical trial. Recruitment

was conducted during regularly scheduled visits

or, alternately, a letter was mailed out followed

by a telephone call to individuals who did not

attend the HSO during the recruitment period.

Consenting participants were screened over the

telephone by trained research interviewers using a

modified form of the University of Michigan Com-

posite International Diagnostic Interview (UM-CIDI)

(Kessler et al., 1994). The UM-CIDI, itself a modified

version of the World Health Organization Internation-

al Diagnostic Interview, screens for the prevalence in

the previous 12 months of nine psychiatric disorders:

dysthymia, major depressive disorder, generalized

anxiety, social phobia, simple phobia, panic, agora-

phobia, alcohol dependence, and drug dependence.

Those who screened positive for any of the nine

disorders were asked to consent to an evaluation by

one of the five study physicians using the Structured

Clinical Interview for DSM-IV, non-patient edition

(SCID-NP) (First et al., 1996) to confirm a diagnosis

of dysthymia (Gwirtsman et al., 1997). A random

sample of those who screened negative and not on

antidepressants or antipsychotics were also ap-

proached for an evaluation by a study physician using

the SCID-NP to confirm the absence of dysthymia.

No information was obtained on individuals who

declined screening.

Table 1

12-Month prevalence of dysthymia in a primary care sample (Steiner et a

UM-CIDI/DSM-IV diagnosis

Dysthymia (D) alone

D in combination with major depressive disorder (MDD)

D in combination with MDD and panic

D in combination with MDD and simple phobia

D in combination with MDD and generalized anxiety disorder

D in combination with other psychiatric disorders

This study compares participants diagnosed with

dysthymia or co-morbid dysthymia versus a random

sample of participants who screened negative for

dysthymia. Measurements were collected by inter-

view and included demographic characteristics,

health status, mood, social adjustment, coping abil-

ity, children’s psychiatric disorders, child develop-

ment, family function, and utilization of health and

social services.

3. Measures

Health Status was measured by three questions

from the Ontario Health Survey (1990) General

Health, worry about health and pain. Mood was

measured using The Montgomery Asberg Depression

rating scale (Montgomery and Asberg, 1979). Social

Adjustment was measured using the Social Adjust-

ment Scale (Weissman et al., 1978) and coping ability

by the Coping Response Inventory (Moos et al.,

1984).

Children psychiatric disorders were measured us-

ing the Child Behaviour checklist of the Survey

Diagnostic Instrument developed by the Ontario Child

Health Study (Offord et al., 1987) and Child Devel-

opment using The Minnesota Child Development

Inventory (Gottfried et al., 1983).

The McMaster Family Assessment Device (Epstein

et al., 1983) measured Family Function and the Health

and Social Service Utilization Questionnaire (Browne

et al., 1990) was also used.

4. Results

Of the 6280 adults z18 and V75 years of age who

were approached to participate in the study, 4327

l., 1999) (n=4327)

n (%)

21 (9.4)

64 (28.8)

21 (9.4)

19 (8.6)

19 (8.6)

78 (35.2)

B. Bell et al. / Journal of Affective Disorders 78 (2004) 73–8076

(68.9%) consented to be screened with the UM-CIDI

(Table 1). Of these, 1279 (29.6%) met criteria for at

least one psychiatric disorder within the past 12

months with a total of 222 (5.1%) respondents screen-

ing positive for dysthymia. The prevalence of dysthy-

mia was greater in females than in males (5.9 and

3.9%, respectively; P<0.002). In addition, 90% of

those who were positive for dysthymia also screened

positive for one (or more) other psychiatric disor-

der(s), in particular major depressive disorder, panic

attack, simple phobia, and generalized anxiety disor-

der. Because 90% of the participants that had dysthy-

mia also had another comorbid psychiatric disorder,

for simplicity, the results will be presented as ‘adults

with comorbid dysthymia’ versus ‘adults without

dysthymia’. Data was available for analysis for 172

adults with comorbid dysthymia and 641 adults with-

out dysthymia.

4.1. Demographics

The comparison between people with comorbid

dysthymia versus people without dysthymia on

socio-demographic characteristics is presented in

Table 2. There were statistically significant differ-

ences in mean age and gender between the two

groups, with those with comorbid dysthymia being

younger and more likely to be female. A greater

Table 2

Characteristics of adults with and without dysthymia at baseline

Comorbid dysthymia

(n=172)

Mean age [years (S.D.)] 42.6 (F13.6)

Mean MADRS score (S.D.) 22.9 (F8.8)

Gender/female (%) 70.9

Male (%) 29.1

No. of children (%)

0 26.5

1–2 52.9

3+ 20.6

Marital status (%)

Never married 18.6

Married/comlaw/remarried 60.5

Separated/divorced/widowed 20.9

Income (%)

Any social assistance 14.0

Wages only 64.0

No wages/no social assistance 22.0

Less than grade 12 education (%) 19.0

proportion of the adults with comorbid dysthymia

had never married, had been separated or divorced,

had no children, were more likely to be on social

assistance or unemployment insurance, and were

more likely to have less than grade 12 education

(see Table 2).

4.2. Health status

A greater proportion of people with comorbid

dysthymia, as compared to those without dysthymia,

perceived their health to be fair to poor (18 and 3.7%,

respectively; P<0.001), worried half to most of the

time about their health (40.1 and 3.6%, respectively;

P<0.001), and reported levels of pain which impaired

their function (34.3 and 15.3%, respectively;

P<0.001).

4.3. Mood

People with comorbid dysthymia had significantly

higher MADRS scores than people without dysthymia

(see Table 2).

4.4. SAS

As represented in their total score on the Social

Adjustment Scale, people with comorbid dysthymia

Without dysthymia v2 P

(n=641)

48.3 (F14.8) <0.0001

2.4 (F3.7) <0.0001

56.8 11.28 <0.001

43.2

18.6 8.03 0.02

51.8

29.6

9.4 30.69 <0.001

80.6

5.4

5.6 17.67 <0.001

61.9

32.5

10.0 10.48 0.001

B. Bell et al. / Journal of Affective Disorders 78 (2004) 73–80 77

endorsed significantly lower scores in all areas of

social role function compared to people without

dysthymia (P<0.0001).

4.5. Coping ability

On the Indices of Coping Responses, people

with comorbid dysthymia demonstrated significantly

lower scores ( P<0.0001) related to cognitive,

behavioural, logical, and problem solving coping

than people without dysthymia. In addition, they

had significantly higher scores (P<0.001) for emo-

tional discharge and avoidance coping as well as

decreased capacity for affective regulation.

4.6. Children’s psychiatric disorders

Table 3 shows the results of diagnostic screening

for children aged 4–16 years of parents who

participated in the study. Notably, significantly

more children who had a parent with comorbid

dysthymia versus children whose parent did not

have dysthymia, met criteria for one or more

childhood psychiatric disorders. Of the children

with a psychiatric disorder who had a parent with

comorbid dysthymia, 60% had emotional disorder

and 20% had combined hyperactive and emotional

disorder. Stepwise multiple regression revealed that

Table 3

Prevalence of childhood psychiatric disorders in children 4–16 years of a

Parent with

comorbid dysthymia

(n=97)

n %

Children with psychiatric disorders

No. of disorders

0 77 79.4

1 14 14.4

2 4 4.1

3 2 2.1

Total number with disorders 20 20.6

Types of psychiatric disorders (DSM-III criteria)

Emotional 12 12.4

Hyperactivity 2 2.1

Hyperactivity+emotional 4 4.1

Conduct+emotional 0 0.0

Conduct+hyperactivity+emotional 2 2.1

in children 4–16 years of age, having a parent with

comorbid dysthymia [F(1,396)=7.055, P=0.008]

and being a male child [F(1,396)=5.02, P=0.026]

was significantly associated with a greater degree

of conduct disorder. Having a parent with comorbid

dysthymia [F(1,396)=7.90, P=0.005] combined

with an interaction of gender and age [F(1,396)=

6.84, P=0.09] explained the greater degree of

hyperactivity in 4–16-year-olds. Younger females,

on the other hand, endorsed a greater degree of

hyperactive behaviour, approximating that ob-

served in both younger and older males. Finally,

a parent with comorbid dysthymia [F(1,396)=36.36,

P<0.0001] combined with younger female children

and older male children [F(1,396)=4.59, P=0.033]

explained a greater degree of the emotional distress

score.

4.7. Child development

There were 68 children younger than 36 months

old at baseline, but only eight of these children had a

parent with comorbid dysthymia, making it difficult to

test any association with developmental delay. Nev-

ertheless, in the 16–35 month age bracket, five of 47

children had a parent with comorbid dysthymia and

two of these children were reported to be develop-

mentally delayed (v22=7.12, P=0.03).

ge

Parent without v2 P

dysthymia

(n=301)

n %

285 92.8

19 6.2

1 0.3

2 0.7

22 7.2 14.32 <0.001

6 2.0

13 4.2

0 0.0

1 0.3

2 0.7

ective Disorders 78 (2004) 73–80

4.8. Family function

A greater proportion of families with an adult

with comorbid dysthymia were rated as dysfunc-

tional compared to families where there was no

adult with dysthymia (42.4 versus 7.5%, respective-

ly; P<0.000001).

4.9. Health and social services utilization

Compared to people without dysthymia, people

with comorbid dysthymia used a greater proportion

of general practitioner, emergency room, physiother-

apy, psychologist, occupational therapist, social work-

er, family counsellor, and laboratory services.

Annualized figures show that those diagnosed with

comorbid dysthymia:

B. Bell et al. / Journal of Aff78

� Accrued significantly higher per person health care

costs (excluding hospital services)—$1513.25

compared to those without dysthymia at $948.67

(P<0.0001)� Accrued significantly higher per person indirect

costs (lost wages)—$698.46 compared to those

without dysthymia at $189.84 (P<0.01).

Regardless of whether parents had comorbid dys-

thymia or not, there were no significant differ-

ences in children’s utilization of health and social

services.

5. Discussion

In this primary care population, the prevalence

of comorbid dysthymia in a 12-month period was

found to be 5.1%, a rate more than double the 1-

year prevalence of dysthymia reported in the gen-

eral population (Kessler et al., 1994). Moreover, our

data support findings from multi-national studies of

depressive illnesses (Kessler et al., 1997; Kessler et

al., 1994) which indicate a two-fold higher preva-

lence of dysthymia in adult females as compared

with males. The differences in gender rates of

comorbid dysthymia have important implications

for treatment determination. For example, evidence

has emerged which supports a gender-differentiated

response to pharmacotherapy for chronic depression

(Brawman-Mintzer and Yonkers, 1999). As well,

there is increasing attention to the influence of

maternal depression on child and adolescent inter-

actions (Beardslee et al., 1996; Weinberg and Tro-

nick, 1998).

Our results also highlight the frequent comorbid-

ity of dysthymia with major depressive disorder.

This is of particular concern as there is considerable

data to suggest that chronic subacute depression is

a significant risk factor for major depression and

should therefore be the focus of efforts to treat

presenting symptoms and to prevent deterioration of

mood toward major depression (Kessler et al.,

1997). Our data, in general, demonstrated the bur-

den of illness and the negative impact of this

enduring circumstance on quality of life. This adds

to the information reported by Wells et al. (1989)

when they compared functioning in patients with

chronic depressive illness to those with chronic

major medical conditions and found that depression

and chronic medical conditions had additive com-

promising effects on functioning. Also of impor-

tance, and consistent with previous research, we

found comorbid dysthymia to be associated with

significant costs, both directly and indirectly in-

curred, due to increased use of health and social

services and decreased productivity.

This is, to our knowledge, the first study to

investigate the impact of comorbid dysthymia on

the families of primary care patients. Having a

parent with comorbid dysthymia portends a greater

incidence of childhood psychiatric disorder in off-

spring over 4 years of age. Age and gender appear

to have some bearing on the manifestation of

childhood psychiatric disorder; older male children,

in particular, seem to be at risk. This finding is

important because previous research has shown that

lifetime duration of parental depressive illness is a

predictor of serious affective disorder in adolescents

(Beardslee et al., 1996). However, further investi-

gation of developmental delay in children over and

under 4 years of age who have a parent with

comorbid dysthymia is required. Also, the associa-

tion between gender differences in adults with

comorbid dysthymia and the incidence of childhood

psychiatric disorder in their offspring has yet to be

explored.

B. Bell et al. / Journal of Affective Disorders 78 (2004) 73–80 79

6. Limitations

We have no information on the 31.1% non

participants to the survey and thus it is difficult to

assess the direction of this bias of non response on

our estimate of 5.1% of persons in primary care

endorsing symptoms of dysthymia. People with dys-

thymia often have symptoms for so much of their

life that they are unaware of and therefore under

report symptomatology. Taken together these biases

may have the effect of underestimating or over-

estimating the prevalence of dysthymia in primary

care. Under reporting could create false negatives in

the non dysthymia comparison group. This would

have the effect of minimizing differences between

people with and without dysthymia. The differences

between groups found in this study could be an

underestimate of real difference.

Acknowledgements

Sponsored by the Medical Research Council of

Canada in partnership with the Pharmaceutical

Manufacturers Association of Canada and Pfizer

Canada Inc.

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