depresja a leczenie u I a II.pdf

General Hospital Psychiatry 25 (2003) 246–252

The relationship of depressive symptoms to symptom reporting,

self-care and glucose control in diabetes

Paul S. Ciechanowski, M.D.,MPH a, *, Wayne J. Katon, M.D. a , Joan E. Russo, Ph.D a ,

Irl B. Hirsch, M.D. b

a Department of Psychiatry and Behavioral Sciences, University of Washington, Seatlle, WA 98195, USA

b Department of Medicine, University of Washington, Seattle, WA, USA

Abstract

Depressive symptoms are common among patients with diabetes and may have a signiﬁcant impact on self-management and health

outcomes. In this study we predicted that: 1) there would be a signiﬁcant association between depressive symptoms and diabetes symptom

burden, physical functioning, diabetes self-care, and HbA1c levels; and, 2) that the association between depressive symptoms and HbA1c

levels would be signiﬁcantly greater in type 1, as compared to type 2 diabetic patients. This cross-sectional observational study of 276 type

1 and 199 type 2 diabetes patients took place in a tertiary care specialty clinic. We collected self-reported data on depressive symptoms,

complications, medical comorbidity, diabetes symptoms, diabetes self-care behaviors, physical functioning, and demographics. From

automated data we determined mean HbA1c levels over the prior year. We performed linear regression analyses to assess the association

between depressive symptoms and diabetes symptom perception, diabetes self-care behaviors, physical functioning, and glycemic control.

Among patients with type 1 and 2 diabetes, depressive symptoms were associated with greater diabetes symptom reporting, poorer physical

functioning, and less adherence to exercise regimens and diet. There was a signiﬁcant association between depressive symptoms and HbA1c

levels in type 1, but not type 2 diabetic patients. Because of their association with clinical aspects of diabetes care such as diabetes symptom

Keywords: Depression; Diabetes; Diabetes symptoms; Self-care; Glucose control

1. Introduction

While a number of cross-sectional studies have shown

that depression is signiﬁcantly associated with hyperglyce-

mia in type 2 diabetic patients, as many studies have found

that this association is not signiﬁcant [5]. When examined

meta-analytically, the association between poorer glucose

control and depression has been found to be more signiﬁ-

cant in type 1 as compared to type 2 diabetic patients across

studies, particularly when standardized interviews were

used (Effect Size 0.28 vs. 0.15) [5]. A recent cross-sectional

study also found the correlation between Beck Depression

Inventory scores and HbA1c levels in type 1 diabetic pa-

tients was moderately high ( r

A recent meta-analysis has shown that among patients

with diabetes, the prevalence of major depression and sig-

niﬁcant depressive symptoms was 11% and 31%, respec-

tively [1]. The presence of comorbid depressive symptoms

can have a signiﬁcant impact on health outcomes, health

care utilization, and overall functioning in patients with

diabetes [2,3]. In a recent study of predominantly type 2

primary care diabetes patients ( N

.44) as compared to that in

.06) [6]. A number of differ-

ences in type 1 and 2 diabetes – such as different etiologies,

age of onset and treatment regimens – may lead to different

mechanisms operating to cause hyperglycemia in depressed

type 1 and 2 diabetic patients. In type 1 diabetes, patients

develop complete insulin deﬁciency due to an autoimmune

destruction of the beta cells of the pancreas. In type 2

* Corresponding author. Tel.: 1-206-543-8848; fax: 1-206-221-

5414.

E-mail address: pavelcie@u.washington.edu (P. Cliechanowski).

doi:10.1016/S0163-8343(03)00055-0

367), we found that de-

pressive symptoms were associated with signiﬁcantly

poorer physical and mental functioning, decreased adher-

ence to dietary recommendations, less adherence to oral

hypoglycemic medications, higher health care costs and

nonsigniﬁcant increases in HbA1c levels [4].

type 2 diabetic patients (r

P. Ciechanowski et al. / General Hospital Psychiatry 25 (2003) 246 –252

247

diabetes there is a relative lack of insulin based in part on

resistance to this hormone at both the liver and the muscle.

The complete insulin deﬁciency in type 1 diabetes may

result in greater lability in glycemic control in response to

behavioral or neuro-hormonal effects of depression, than

may be the case in type 2 diabetes. There is also typically

more treatment heterogeneity in type 2 patients who may be

treated with diet and exercise only, oral hypoglycemics,

insulin or a combination of these. The main – and essential

– treatment in type 1 diabetes is insulin, though diet and

exercise also play an important secondary role in achieving

glucose control. Such differences in diabetes treatment may

result in differential treatment outcomes given changes in

self-care behavior resulting from depression. For example,

in a type 2 diabetic patient treated with diet only, lack of

treatment adherence is not likely to cause as signiﬁcant an

increase in glucose levels as lack of adherence to an insulin

regimen in a type 1 diabetic patient.

Another important feature of the coexistence of diabetes

and depression is the increased potential for symptom re-

porting among depressed diabetic patients. While there is

overlap of symptoms associated with both disorders (e.g.,

fatigue, hyperphagia), depression is known to cause non-

speciﬁc symptom ampliﬁcation in patients with chronic

medical illnesses [7]. Thus, patients with depression may

have a lower threshold in reporting all physical symptoms

including common diabetes symptoms such as thirst, poly-

uria, and blurry vision. This tendency to amplify physical

symptoms may result in higher health care use and in-

creased laboratory testing by providers [8].

In the current study, we assessed the impact of depres-

sive symptoms on patients with diabetes in a tertiary care

university-based clinic. We sought to determine if diabetes

self-care behaviors, physical functioning, diabetes symptom

reporting and glucose control correlated signiﬁcantly with

depressive symptoms in both type 1 and 2 diabetes. We

hypothesized that higher levels of depression would be

signiﬁcantly associated with greater diabetes symptom re-

porting, lower diabetes self-care, lower physical functioning

in both type 1 and 2 diabetes, and we predicted that there

would be effect modiﬁcation so that higher levels of depres-

sion would be signiﬁcantly associated with higher HbA1c

levels in type 1, but not type 2 diabetes.

the study and requested permission for a review of their

automated records. Subjects not returning the questionnaire

within three weeks were sent an identical second question-

naire and consent form. Subjects received a $3 compensa-

tion for their time in participating in the study. The ques-

tionnaire and all patient correspondence were approved by

the University of Washington institutional review board.

2.1. Self report instruments

2.1.1. Depression

The Hopkins Symptom Checklist-90, Revised (SCL-

90-R) [9] is a self-report instrument, that has been validated

in previous studies of medical patients and has been found

to be highly reliable [10,11]. The twenty items from the

depression and additional symptom subscales (SCL-20)

were used in the current study.

2.1.2. Diabetes complications

Patients were given a score from 0–3 to reﬂect the

number of self-reported diabetes-related complications from

the following: retinopathy, nephropathy, and peripheral

neuropathy [12]. This method has been shown to be highly

correlated with ratings of severity of diabetes from indepen-

dent physicians ( r

.001) [12].

2.1.3. Medical comorbidity

Based on the methods of Wells et al. [13], we estimated

medical comorbidity by having patients check whether they

did or did not have each of eighteen medical conditions

(e.g., asthma, hypertension, ulcer) on a checklist. The total

number of conditions was calculated by summing positive

responses and for analyses each patient was given a score of

0, 1, 2 or more than 2 medical conditions.

2.1.4. Diabetes self-care

The Summary of Diabetes Self-Care Activities [14] is a

12-item questionnaire that measures absolute levels of self-

care behavior and the percentage of activities recommended

by the physician that were actually performed. This ques-

tionnaire has been shown to be a valid and reliable measure

of diabetes self-management in multiple trials. In this study,

diet amount, diet type, exercise, and glucose testing were

assessed, and since items within each domain have different

scales, raw scores for each were converted to standard

scores having a mean of 0 and an SD of 1. Standardized

scores were averaged to form a composite z score for each

regimen behavior. A higher z score indicates better adher-

ence to the self-care behavior.

2. Materials and methods

This cross-sectional observational study was carried out

at the University of Washington Diabetes Care Center

(DCC), Seattle, Washington. Eligible participants included

all English-speaking DCC patients already enrolled in both

1998 and 1999, age 18 or over. Potential subjects with

severe cognitive or language deﬁcits were excluded. In July

1999, 826 potential subjects were sent an approach letter

brieﬂy describing the study. Two weeks later subjects were

sent a questionnaire and consent form which fully explained

2.1.5. Functional impairment

The Short-Form 12 Health Survey (SF-12) [15] is a

generic measure of health status that is a shorter version and

valid alternative to the SF-36 [16]. The SF-12 measures

functioning in medical populations and assesses physical

functioning, role limitations due to physical health prob-

.72, P

248

P. Ciechanowski et al. / General Hospital Psychiatry 25 (2003) 246 –252

lems, bodily pain, general health, and social functioning,

which are represented in mental and physical component

scores. We report only the physical component score since

there is typically strong collinearity between depression and

the mental functioning score.

the signiﬁcance of the demographic variables [age, gender,

marital status, education, race and income] was tested using

backward and forward stepwise techniques in the ﬁrst step.

Only signiﬁcant demographic variables were retained in the

models. In the second step, medical comorbidity and num-

ber of diabetes complications was forced into each model.

In the third and fourth steps diabetes type (type 1

2.1.6. Symptom reporting

To assess diabetes symptoms, we used the Self-Comple-

tion Patient Outcome [17] instrument to measure the fol-

lowing diabetes symptoms: blurred vision, thirst, polyuria,

excessive hunger, shakiness, fatigue, parasthesias, and feel-

ing faint. Items were rated on a Likert scale and we calcu-

lated the total number of symptoms that were experienced at

least “several days” in the past month.

Demographic and clinical data were determined from

questionnaire responses (race, education, income, and mar-

ital status) and from automated data (age, gender and dia-

betes type). We also used automated data to determine mean

glycosylated hemoglobin (HbA1c) values for each subject

from the preceding twelve months. Mean number of HbA1c

tests in this population was 2 per year (range 0–6). To

analyze HbA1c levels, the University of Washington DCC

uses a Bayer DCA2000, which is certiﬁed by the National

Glycohemoglobin Standardization Program as having doc-

umented traceability to the Diabetes Control and Compli-

cations Trial Reference Method.

1; type

0) and depression score were entered, respectively. In

the model assessing the association between depression and

HbA1c levels, the a priori hypothesis that diabetes type

would modify this association was tested by forcing in, as

the ﬁfth step, the interaction of diabetes type and depres-

sion.

3. Results

Of 826 patients, 475 (58%) responded to the survey, of

which 276 (58%) had type 1 diabetes and 199 (42%) had

type 2 diabetes. There were no signiﬁcant differences be-

tween respondents and nonrespondents in age (48.8

15.9

vs. 50.0

16.4, respectively; t

1.13, df

825, P

.26) and

.95).

All subsequent analyses are based on those respondents who

had at least one HbA1c level documented in the electronic

records within a twelve-month period ( N

( df

1 )

0.04, P

407). Clinical

and demographic characteristics of the respondents are out-

lined in Table 1.

2.2. Diabetes classiﬁcation

Subjects were classiﬁed in this clinic based on their

clinical characteristics. In general, individuals with type 1

diabetes presented in childhood, adolescence, or as young

adults with acute symptoms, often ketoacidosis. Those with

type 2 diabetes usually presented later in life and were

overweight. Since 1991 the clinic staff has had access to the

measurement of islet antibodies (islet cell antibody, glu-

tamic acid decarboxylase, insulinoma-associated-2 autoan-

tibodies, and insulin autoantibodies) and in those cases

where the diagnosis was not obvious, these antibodies were

measured. If one of these antibodies was positive the patient

was considered to have type 1 diabetes.

3.1. Glycemic control

In the multiple regression model (Table 2), being married

was associated with a lower HbA1c level, whereas number

of complications was strongly positively associated with

HbA1c level. There was a signiﬁcant statistical interaction

of diabetes type and depression with respect to HbA1c level.

We chose clinically meaningful cut-scores to illustrate this

interaction in Fig. 1. A cut-score of 1.72 on the SCL-20 is

associated with the highest positive predictive value for the

diagnosis of major depression [18]. A cut-score of 8% for

HbA1c levels was chosen since current clinical guidelines

recommend additional clinical action for patients whose

HbA1c levels are above this range [19]. The proportion of

subjects with HbA1c levels over 8% was signiﬁcantly

higher among patients with type 1 diabetes who were de-

pressed (66.7%) compared to those with type 1 who were

not depressed (38.6%) as well as compared to both de-

pressed and nondepressed type 2 diabetes patients (37.5%

and 40.3%, respectively) (

2.3. Statistical analysis

2 tests with corrections for continuity were

used to compare respondents and nonrespondents on age

and gender. Appropriate human subjects approval to utilize

aggregate data of nonrespondents on these variables was

obtained.

Multiple regression modeling with a combination of hi-

erarchical and stepwise techniques was used to determine if

depressive symptoms were associated with the following

dependent variables: HbA1c levels, diabetes symptoms,

self-care behaviors [diet type, diet amount, exercise, glu-

cose monitoring] and physical functioning. In each model

.02).

Because we looked at HbA1c over the prior year, and the

self-report measure of depression asks about symptoms in

the past 2 weeks, we conducted a sensitivity analysis to

examine the correlation of depression and HbA1c levels

when only considering those HbA1c levels from the past 4

months ( N

( df

3 )

9.6, P

146), after control-

ling for the covariates from the linear model (married status

253) and past 2 months ( N

gender (52.5% in both groups;

Data were analyzed using SPSS 10.0 for Windows. Two-

tailed t tests or

P. Ciechanowski et al. / General Hospital Psychiatry 25 (2003) 246 –252

249

Table 1

Demographic and clinical characteristics by diabetes type

Characteristic

Diabetes Type

Total (N 407)

Type 1 (N

235)

Type 2 (N

172)

Analysis

Mean

Age (years)

48.8

15.9

41.5

13.8

58.7

13.0

12.7***

HbAlc (%)

7.82

1.29

7.81

1.29

7.84

1.29

.29

SCL-20 score*

0.92

0.75

.85

0.74

1.01

0.77

2.25

%**

2 (df 1)

Female gender

214

52.7

127

54.3

50.6

.54

Caucasian race

369

91.1

222

94.5

147

86.5

7.8**

At least 1 year college

363

89.4

212

90.2

151

88.3

.38

Married or cohabitating

278

68.8

162

69.2

116

68.2

.05

Income $40,000

255

65.9

155

69.2

100

61.3

2.6

At least 1 medical comorbidity

313

77.3

165

70.5

148

86.5

14.5***

At least 1 diabetes complication

189

47.3

108

46.6

48.2

.11

Diabetes treatment in type 2

diabetes patients

Insulin only

–

42.3

–

Oral hypoglycemics only

–

35.6

–

Insulin and oral hypoglycemics

–

14.8

–

Diet only

–

7.4

–

* Range of SCL-20 values: type 1 diabetes: 0–3.4; type 2 diabetes: 0–3.3.

**Number of subjects on which percents are based varies because of missing data from some items. SCL Symptom Checklist

and complications). In type 1 and 2 diabetic patients the

correlations were: 1) for 4 months, r

.33, P

.001, r

.08,

which represent a mixture of dysthymic, and minor and

major depressed patients, as well as patients with adjust-

ment disorders with anxious and/or depressed mood [20–

22].

NS, respectively; and, 2) for 2 months, r

.42, P

.001,

.14, NS, respectively. Therefore, when SCL-20 scores

and HbA1c levels were more tightly associated in time of

measurement, there was a higher correlation in type 1 dia-

betes between the two measures. The mean SCL-20 depres-

sion score in this sample (0.9

3.2. Diabetes symptom reporting

0.8) corresponds to a sub-

diagnostic range of depressive and anxiety symptoms,

In the multiple regression model assessing diabetes

symptom reporting, being married and higher education

Table 2

Multiple regression modeling of the association of depression and selected variables

HbAlc

Diabetes

Symptom

Reporting

Physical

Component

Score

Diet Amount Diet Type

Exercise

Glucose

monitoring

Demographic

covariates

age

.17**

3.50 .20** 3.23

.32 †

5.14

marital status

.14**

2.69

.10*

2.21

income

.12** 2.78

education

.10*

2.14

Clinical covariates

comorbidity

.01

.20 .01

.12

.36 †

7.32

.05

.79

.003

.05

.06

1.00

.03

.37

complications

.29 †

5.24

.13* 2.46

.12**

2.68

.03

.59

.04

.64

.07

1.29

.07 1.08

Diabetes type

.18*

2.24

.03

.60 .05

.99 .18

2.85 .11

1.68 .11*

2.14

.03

.44

Depression

.08

1.01 .41 †

8.50

.23**

5.13

.25 †

4.53

.14*

2.58

.15**

2.78

.07

1.10

Diabetes type

depression

.22*

2.47

Overall model

F(6,361) 10.42,

R 2

F(6,362) 23.23,

R 2

F(6,364) 42.90,

R 2

F (5,351) 9.58,

R 2

F(5,359) 8.90,

R 2

F(5,361) 6.24,

R 2

F(4,305) .56,

R 2

0.15,

p .0001

0.28,

p .0001

0.44,

p .0001

0.12,

p .0001

0.11,

p .0001

0.07,

p .0001

0.01,

p .69

*p .05, **p .01,

† p .001

250

P. Ciechanowski et al. / General Hospital Psychiatry 25 (2003) 246 –252

Fig. 1. Association between depression and HbA1c levels by diabetes type.

Depressed group has SCL-20 score 1.72, nondepressed group has

SCL-20 score 1.72.

Fig. 3. Association between depression quartiles and diabetes self-care.

Ranges of quartiles of SCL-20 depression scores are as follows: 1st: 0-.34;

2nd: .35-.69; 3rd: .70–1.35; 4th:1.36–3.40.

3.4. Diabetes self-care

were signiﬁcantly associated with lower symptom reporting

whereas higher levels of diabetes complications and depres-

sion were signiﬁcantly and independently associated with

more diabetes symptom reporting (Table 2). To illustrate

this relationship graphically, quartiles of depression were

used to derive means of symptom reporting in each quartile.

Fig. 2 shows the mean number of diabetes symptoms re-

ported as occurring at least several days in the prior month

by quartiles of SCL-20 depression scores.

Increasing age was signiﬁcantly associated with higher

self-reported adherence to diet amount and type, while a

higher level of depression was associated with lower self-

reported adherence to diet amount, diet type and exercise.

Type 1 diabetes was signiﬁcantly associated with higher

self-reported adherence with exercise. Glucose monitoring

was not associated with any of the variables in our model.

Fig. 3 illustrates the association between self-care and de-

pression for those domains of self-care that have been

shown to be signiﬁcantly associated with depression (diet

type, diet amount and exercise). Again, depression severity

was grouped into quartiles and mean z-score for each do-

main of self-care was obtained for each quartile. As shown

in the ﬁgure, as depression increased, levels of diet and

exercise adherence decreased.

3.3. Physical functioning

Increasing age, and higher levels of medical comorbid-

ity, diabetes complications and depression were all signiﬁ-

cantly associated with poorer physical functioning in our

sample, while higher income was associated with better

physical functioning (Table 2).

4. Discussion

Fig. 2. Association between depression quartiles and diabetes-related

symptom reporting. Number of symptoms refers to total number of diabe-

tes symptoms reported as occurring at least several days in prior month.

Ranges of quartiles of SCL-20 depression scores are as follows: 1st: 0-.34;

2nd: .35-.69; 3rd: .70–1.35; 4th: 1.36–3.40.

Depressive symptoms were found to be signiﬁcantly

associated with lower adherence to dietary recommenda-

tions and exercise, poorer physical functioning, and higher

diabetes symptom reporting among patients with type 1 and

type 2 diabetes in a tertiary care diabetes specialty clinic.

These associations were robust after controlling for diabetes

type and complications. These results are consistent with

other studies. For example, in our previous study of a

primary care sample of predominantly type 2 diabetic pa-

tients, dietary recommendations were not followed as

closely in patients with greater levels of depression [4].

Common symptoms of depression such as changes in ap-

petite and decreased energy and motivation may signiﬁ-

cantly affect diet and exercise. While changes in motivation

and concentration that occur in depression can conceivably

affect frequency of glucose monitoring, no evidence for this

could be found in our sample. In our previous study, we also

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