i77

The Depression Anxiety Stress Scales (DASS): detecting

anxiety disorder and depression in employees absent
from work because of mental health problems
K Nieuwenhuijsen, A G E M de Boer, J H A M Verbeek, R W B Blonk, F J H van Dijk
.............................................................................................................................

Occup Environ Med 2003;60(Suppl I):i77–i82

Aims: To (1) evaluate the psychometric properties and (2) examine the ability to detect cases with
anxiety disorder and depression in a population of employees absent from work because of mental
health problems.
Methods: Internal consistency, construct validity, and criterion validity of the Depression Anxiety Stress
Scales (DASS) were assessed. Furthermore, the ability to identify anxiety disorders or depression was
See end of article for evaluated by calculating posterior probabilities of these disorders following positive and negative test
authors’ affiliations
....................... results for different cut off scores of the DASS-Depression and DASS-Anxiety subscales.
Results: Internal consistency of the DASS subscales was high, with Cronbach’s alphas of 0.94, 0.88,
Correspondence to: and 0.93 for depression, anxiety, and stress respectively. Factor analysis revealed a three factor solu-
Drs K Nieuwenhuijsen,
Coronel Institute for
tion, which corresponded well with the three subscales of the DASS. Construct validity was further sup-
Occupational and ported by moderately high correlations of the DASS with indices of convergent validity (0.65 and
Environmental Health, 0.75), and lower correlations of the DASS with indices of divergent validity (range −0.22 to 0.07).
Academic Medical Center, Support for criterion validity was provided by a statistically significant difference in DASS scores
University of Amsterdam,
PO Box 22700, 1100 DD
between two diagnostic groups. A cut off score of 5 for anxiety and 12 for depression is
Amsterdam, Netherlands; recommended. The DASS showed probabilities of anxiety and depression after a negative test result of
K.Nieuwenhuijsen@ 0.05 and 0.06 respectively. Probabilities of 0.29 for anxiety disorder and 0.33 for depression after a
amc.uva.nl positive test result reflect relatively low specificity of the DASS.
Accepted Conclusion: The psychometric properties of the DASS are suitable for use in an occupational health
7 November 2002 care setting. The DASS can be helpful in ruling out anxiety disorder and depression in employees with
....................... mental health problems.

O
ccupational physicians in the Netherlands spend much or depression, patients with adjustment disorders require less
of their time advising sick employees about return to treatment and are able to return to work sooner.11
work. Ideally, this management of the return to work The growing attention for the recognition of employees
process will consist of a diagnostic process and several interven- with an anxiety disorder or depression is not restricted to
tions including the drawing up of a return to work plan.1 occupational health care alone. In primary care, recognition of
Approximately 30% of employees seen by their occupational anxiety disorders and depression by general practitioners is
physician are absent from work because of mental health considered an important condition to ensure accurate
problems.1 These problems encompass both common mental treatment of these disorders. However, research12 has shown
disorders, such as stress symptoms, as well as psychiatric disor- that the ability of general practitioners to recognise mental
ders. In terms of the DSM-IV classification, the majority of these disorders is rather poor. Most studies find detection rates
employees are suffering from the more common adjustment
varying from 30 to 40%.13–15 Three factors may have
disorders, while a smaller yet substantial proportion suffers
contributed to such poor recognition rates. Firstly, recognition
from depression or an anxiety disorder.2 In DSM-IV, an adjust-
of depression and anxiety disorders is impeded by the presen-
ment disorder diagnosis is not allowed when the severity and
tation of multiple badly defined complaints by primary care
duration threshold for another disorder is reached.3
Anxiety disorders and depression are considered to be more patients.12 13 16 As a result, general practitioners tend to recog-
severe disorders than adjustment disorders.4 The International nise only the more severe cases.17 In contrast, in- and
Consensus Group on Depression and Anxiety underlines the outpatient psychiatric clinics treat only those patients referred
necessity of treatment with antidepressant medication for
patients suffering from either an anxiety disorder or
depression.5–7 Furthermore, the level of depressive symptoms Policy implications
is related to the level of work impairment, with severe impair-
ment when the threshold for depressive disorder is reached.8 • The DASS can be used to assist occupational physicians in
However, work impairment decreases significantly as depres- a two-phase diagnostic process.
sion is treated.9 10 Compared to patients with anxiety disorders • The DASS may be administered to all employees absent
from work because of mental health problems (phase 1).
• Occupational physicians should conduct a clinical inter-
Main messages view with all employees who are identified by the DASS as
possible cases of anxiety disorder or depression (phase 2).
• The psychometric properties of the DASS are suitable for
use in a population of employees absent from work
because of mental health problems.
• The DASS can be helpful in ruling out cases with an anxiety .............................................................
disorder or depression in a population of employees with
mental health problems. Abbreviations: CIDI, Composite International Diagnostic Interview;
DASS, Depression Anxiety Stress Scales

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i78 Nieuwenhuijsen, de Boer, Verbeek, et al

to them by general practitioners. Therefore, psychiatric popu- be met: the previous consultation with their occupational phy-
lations consist of patients with more severe and well defined sician was longer ago than three months; a 100% absence from
symptoms than primary care populations. Secondly, the work; sickness absence because of mental health problems,
limited time available to general practitioners for assessment defined as suffering from psychological symptoms that were
is deemed to contribute to low detection rates of depression not caused by a somatic disorder; and onset of sickness absence
and anxiety disorders.18 The third reason for low recognition no longer than six weeks previously.
rates may be that general practitioners lack comprehensive From March 2001 until February 2002, data on 326
diagnostic knowledge concerning psychopathology.19 employees with mental health problems were reported to us
It is likely that the same factors that impede the recognition by the occupational physicians. Of these 326 employees, 32
of anxiety disorders and depression apply to occupational were excluded because they did not meet the inclusion crite-
physicians since they see all employees who have been on sick ria. Another 17 were excluded because they were unable to
leave for longer than about two weeks and there is no referral read Dutch (n = 2), were fully recovered (n = 5), were to be
from another health care professional. Moreover, an average treated by another occupational physician (n = 6), were
consultation with an occupational physician lasts approxi- unable to fill out the questionnaire because of severe psychiat-
mately 20 minutes, which is not substantially longer than the ric problems (n = 2), or could not be contacted by telephone
time spent by general practitioners. Finally, occupational phy- (n = 2).
sicians do not receive any more training in diagnosing Of the remaining 277 patients eligible to participate in the
psychopathology than general practitioners do. study, 66 (24%) refused to participate. Of all 211 employees
Considering these problems in identifying anxiety disorders who signed an informed consent form, 198 filled out the
and depression, it follows that a self administered instrument questionnaire. Of these 198 employees included in this study,
for case finding might prove helpful to occupational physi- 192 were interviewed. In the other six cases, the interview was
cians. Such an instrument could be filled out by the employee not conducted because the participant could not be contacted
prior to the consultation, thereby assisting occupational phy- by telephone.
sicians in identifying employees with anxiety disorders and
depression. One condition for implementation would be that Procedure
this instrument is able to identify high risk cases within a All participants were asked by their occupational physician to
group of patients similar to a primary care population. participate in the study. Each participant, after first having
However, many of the validated instruments for use in signed an informed consent form, was interviewed by the
primary health care either aim at reaching one specific researchers via the telephone. Subsequently, questionnaires
diagnosis (for example, Goldberg screen for depression20) or were sent to the participants by mail.
are elaborate diagnostic instruments requiring specific train-
ing (for example, CIDI-PC,21 PRIME-MD22). Measures
The Depression Anxiety Stress Scales (DASS)23 would seem Participants were diagnosed by means of a short telephone
to be a promising instrument for use in occupational health version of the structured Composite International Diagnostic
care. Theoretically, this instrument corresponds with the Interview (CIDI).31 An interview by telephone was used
tripartite model of anxiety and depression.24 This model states because of its convenience and its comparability with face to
that anxiety and depression possess unique features as well as face interviews.32–34 The telephone interview included the
common ones. Depression is uniquely characterised by low following diagnostic groups: major depressive disorder, panic
positive affect and anhedonia, while anxiety has physiological disorder, social phobia, somatoform disorder, bipolar disorder,
hyperarousal as a unique feature. Depression and anxiety have obsessive-compulsive disorder, post-traumatic stress disorder,
a non-specific factor of general distress in common. This gen- and psychotic disorder. For the first three diagnoses we
eral distress includes symptoms such as irritability and nerv- administered the full CIDI scales, while we used only the stem
ous tension, which are comparable to the symptoms reported (or screen) questions for the other categories. It was allowed
by employees with adjustment disorders.25 Therefore, the for a participant to meet the criteria for more than one diag-
structure of the DASS seems to support the view that both nosis. Anxiety disorder was operationalised as meeting the
anxiety disorders and depression need to be distinguished criteria for one or more of the following disorders: panic
from adjustment disorders in spite of their communality. disorder, social phobia, somatoform disorder, obsessive-
The psychometric properties of this instrument appear to be compulsive disorder, or post-traumatic stress disorder. Depres-
sound enough to be applied to both healthy and psychiatric sion was operationalised as meeting the criteria for major
populations. For these populations, the three factor solution depressive disorder. All interviews were conducted or super-
has been determined by several authors.26–30 Internal consist- vised by a mental health professional. All interviews were
ency of the three subscales ranged from 0.81 to 0.97.27–29 More- tightly scripted, including the use of standardised introduc-
over, convergent and divergent validity have been shown to be tory statements. The length of the telephone interview varied
satisfactory in these studies.26 27 29 30 However, the DASS has not from 15 to 20 minutes.
yet been studied in either a primary care or an occupational Following the diagnostic interview, patients completed a
health care population. The aim of this study is therefore to self report questionnaire that comprised the DASS-42, the
evaluate the psychometric properties of the DASS in an occu- Hospital Anxiety and Depression Scale (HADS),35 and the
pational health care population. This study examines internal Utrecht Coping List (UCL).36 Participants respectively take 3, 7,
consistency, construct validity, and criterion validity of the and 10 minutes to complete the HADS, DASS, and the UCL.
DASS. A further aim of this study is to evaluate its ability to The DASS-42 consists of 42 symptoms divided into three sub-
identify cases with an anxiety disorder or depression in this scales of 14 items: depression scale, anxiety scale, and stress
population. scale. Participants rated the extent to which they had experi-
enced each symptom over the previous week on a four point
METHODS Likert scale ranging from 0 (did not apply to me at all) to 3
Participants (applied to me very much, or most of the time).
As part of a longitudinal study on determinants of recovery and In order to assess concurrent validity of the DASS,
return to work in employees with mental health problems, 30 participants also completed the HADS.35 The HADS is a 14
occupational physicians from nine occupational health services item screening scale that measures the presence of anxiety
provided data on patients seen over consecutive periods of one and depressive states. It contains two seven-item subscales: a
or more days a week. The following inclusion criteria needed to depression subscale and an anxiety subscale, each item being

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Detecting anxiety disorder and depression in employees i79

scored on a four point scale (0–3). The HADS has been devel-
Table 1 Characteristics of participants (n=198)
oped as a screen for detecting depressive and anxiety disorders
in hospitalised patients. Items referring to symptoms that may Sociodemographic
have a physical cause (for example, weight loss or insomnia) Gender, male–female 77–121
Age, mean years (SD) 44 (9)
are not included in the scale.
Diagnosis
To measure divergent validity, participants also filled out the Adjustment disorder 117
UCL.36 The UCL is a Dutch questionnaire that measures Anxiety disorder 27
habitual coping styles. This questionnaire consists of 47 state- Depression 30
Both anxiety disorder and depression 14
ments concerning ways of coping with problems. The UCL
Other psychiatric disorder (i.e. psychotic or 4
comprises seven subscales measuring seven coping styles. bipolar disorder)
Correlations between the DASS subscales and the subscales of Unknown 6
“active problem solving” (UCL-Active), “seeking social sup-
port” (UCL-Social Sup), and “comforting cognitions” (UCL-
Comf) served as indices for divergent validity in the analysis.

RESULTS
Statistical analysis Participants
Cronbach’s alphas were calculated for each of the DASS Table 1 presents the characteristics of the participants. Of the
subscales in order to evaluate the internal consistency. 66 employees who refused to participate and the 49 that were
To examine construct validity of the DASS, exploratory fac- excluded, 26 were male and 58 were female; the gender of 31
tor analyses were performed first. A principal component was unknown. With respect to this variable, no significant
extraction was used, after which the number of factors was difference (t test, p = 0.21) between the participants and
determined by both eigenvalues (>1) and the Scree test.37 We non-participants was observed.
applied a varimax rotation on this initial solution. To further
examine construct validity, a correlational (Pearson’s) analysis Reliability
of convergent and divergent validity was conducted by corre- Internal consistency of the DASS subscales was found to be
lating the subscales of each of the three questionnaires. It was high, with Cronbach’s alphas of 0.94, 0.88, and 0.93 for
hypothesised that DASS-Depression would be moderately cor- depression, anxiety, and stress subscales respectively.
related to HADS-Anxiety and highly correlated to HADS-
Depression. Furthermore, a high correlation between DASS- Factor analysis
Anxiety and HADS-Anxiety was expected, while a moderate The three factor solution accounted for 53% of all variance,
correlation between DASS-Anxiety and HADS-Depression with eigenvalues of 16.2, 3.3, and 2.8. Table 2 shows factor
was hypothesised. DASS-Stress was expected to correlate loadings for the 42 items. The first factor that emerged
moderately high with both HADS subscales. It was hypoth- consisted of all items from the depression scale plus one item
esised that all three DASS subscales would show low correla- (item 22) from the stress scale. The range of factor loadings
tions with the UCL subscales. (after varimax rotation) was 0.44 to 0.82. None of these items
In order to test concurrent validity of the DASS, a loaded higher than 0.40 on another factor. The second factor
multivariate one way analysis of variance (MANOVA) was comprised 12 items from the stress scale plus one item from
conducted. Employees were split into two diagnostic groups: the anxiety scale (item 19), with eigenvalues ranging from
one group with members suffering from an adjustment disor- 0.38 to 0.83. Of these 13 items, one item (item 8) also loaded
der and the other group with members suffering from a high (>0.40) on the depression factor and one item (item 39)
depression or anxiety disorder, as assessed by the CIDI inter- loaded high (>0.40) on the anxiety factor. The final factor
view. Employees with other disorders were excluded from this corresponded fairly well with the anxiety scale, with eigenval-
analysis. The analysis was conducted with group as between- ues ranging from 0.39 to 0.78. All items from the anxiety scale,
subject factor and the DASS-subscales as within-subjects fac- except item 19, loaded highest on this anxiety factor, while
one item (item 33) from the stress scale loaded higher on this
tor. Tukey post hoc analyses were carried out in order to test
factor than on the stress factor (0.57 versus 0.41 respectively).
differences for each of the subscales.
Subsequently, we evaluated the ability to identify cases for
Convergent and divergent validity
the depression and anxiety subscales by using the CIDI inter-
Table 3 shows the correlations between the three DASS
view as the gold standard. Sensitivity was determined by cal- subscales on the one hand and the indices for convergent and
culating the proportion of cases based on the DASS subscale divergent validity on the other. As expected, table 3 reveals high
among the cases according to the CIDI interview. Specificity correlations between both DASS-Anxiety and HADS-Anxiety
was defined as the proportion of non-cases according to the (r = 0.66) as well as between DASS-Depression and HADS-
DASS subscale among non-cases according to the CIDI. Depression (r = 0.75). Correlations between the DASS-Stress
Furthermore, we calculated likelihood ratios for positive and scale and the HADS scales were moderately high (0.58 and
negative test results.38 Finally, we assessed posterior probabili- 0.60). This pattern of correlations confirms the hypothesis of
ties of the disorders following a positive test result (positive good convergent validity. As can be seen from table 3, all three
predictive value) or a negative test result (complement of DASS scales showed low correlations (range −0.29 to 0.02) with
negative predictive value) in our population for a range of cut the UCL subscales, indicating good divergent validity.
off values.
Considering the need for treatment of patients with an Criterion validity
anxiety disorder or depression, false negative cases were Multivariate analysis of variance (MANOVA) revealed a
regarded as more undesirable than false positive cases. There- significant overall effect of group (F = 17.25, df = 3.171,
fore, we considered a negative likelihood ratio of 0.19 to be p < 0.001). Table 4 presents the mean scores and standard
sufficient, which is comparable to the negative likelihood deviations of the DASS subscales for both employees with
ratios found in a review of validated instruments for detecting adjustment disorders and employees with a depression or
depression.39 anxiety disorder. The post hoc analyses showed that employ-
Differences were tested at a significance level of p < 0.05. ees with a depression or anxiety disorder scored significantly
All data were analysed using the SPSS 10.0 software package. higher on DASS-Depression (p < 0.001), DASS-Anxiety

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i80 Nieuwenhuijsen, de Boer, Verbeek, et al

depression, the LR+ is 1.69, the posterior probability of a

Table 2 Factor structure of the DASS (n=198) depression after a positive test result is 0.33. The posterior
Factor probability of a depression after a negative test result is 0.06.
Given the same LR−, for anxiety, the LR+ is 1.53, the posterior
Depression Stress Anxiety
probability of an anxiety disorder following a positive test
DASS-Depression result is 0.29, and 0.05 following a negative test result. Corre-
3 0.62 0.38 0.19 sponding cut off scores would be 12 for DASS-Depression and
5 0.49 0.32 0.18
5 for DASS-Anxiety.
10 0.70 0.15 0.27
13 0.57 0.29 0.22
16 0.82 0.22 0.01 DISCUSSION
17 0.65 0.31 0.17 The results of our study suggest that the psychometric proper-
21 0.69 0.14 0.27
ties of DASS are suited for use in a population of employees
24 0.78 0.21 0.11
26 0.69 0.27 0.19 who are off work because of mental health problems. Internal
31 0.77 0.27 0.11 consistency of the three DASS scales was high. Furthermore,
34 0.76 0.18 0.18 the factor analysis revealed three factors, which yielded
37 0.80 0.14 0.22 support for the construct validity of the DASS. In addition, all
38 0.79 0.01 0.26
correlations of the DASS with indices of convergent and diver-
42 0.67 0.20 0.21
DASS-Anxiety gent validity were as predicted. The DASS showed good crite-
2 0.14 0.01 0.46 rion validity since employees from different diagnostic groups
4 0.15 0.22 0.41 differed in their score on the DASS. Low posterior probabilities
7 0.01 0.33 0.59 of the disorders following a negative test result indicates that
9 0.20 0.13 0.73
the DASS can be helpful in ruling out cases with an anxiety
15 0.01 0.01 0.59
19 0.22 0.38 0.25 disorder or a depression. However, the relatively low probabili-
20 0.28 0.13 0.72 ties of the disorders following a positive test result indicates a
23 0.18 0.01 0.53 considerable rate of false positives.
25 0.16 0.33 0.39 The psychometric properties of the DASS in our population
28 0.13 0.25 0.78
are consistent with DASS studies in other populations. High
30 0.30 0.33 0.54
36 0.30 0.01 0.73 internal consistency was observed in both student and clinical
40 0.24 0.23 0.66 populations.26 27 29 Moreover, both criterion and construct valid-
41 0.01 0.28 0.54 ity proved to be adequate in previous studies with student,
DASS-Stress clinical, and community samples.26–30 This indicates that the
1 0.10 0.63 0.27
DASS can provide occupational physicians with detailed
6 0.15 0.79 0.19
8 0.42 0.43 0.32 information on the level of depression, anxiety, and stress
11 0.24 0.63 0.37 symptoms in their patients. Ours was the first study to evaluate
12 0.21 0.76 0.17 the quality of the DASS in case findings of employees with an
14 0.19 0.63 0.18 anxiety disorder or depression. Recently, Williams and col-
18 0.23 0.83 0.01
leagues published a review of case finding studies for
22 0.44 0.37 0.25
27 0.30 0.81 0.01 depression39 in primary care. They found a median likelihood for
29 0.25 0.61 0.39 a positive test result of 3.3 and a median likelihood for a nega-
32 0.27 0.59 0.20 tive test result of 0.19. Our study revealed similar likelihood
33 0.32 0.41 0.57 ratios for a negative test result, but lower likelihood ratios for a
35 0.28 0.69 0.14
positive test result for both anxiety disorder and depression.
39 0.31 0.51 0.43
A unique feature of this study is that it evaluates the ability
Bold indicates a factor loading of >0.40. to detect anxiety disorder and depression among employees
with mental health problems. Until now, most DASS studies
addressed the distinction between subjects with and without
(p < 0.001), and DASS-Stress (p < 0.01) compared to em- an anxiety disorder or depression, while this study addressed
ployees with adjustment disorders. the distinction between employees with adjustment disorders
and those with an anxiety disorder or depression. This
Case finding distinction is less clear cut, but is highly relevant for practice,
The ability to identify employees with either a depression or an while it has important consequences for the treatment of
anxiety disorder was assessed for DASS-Depression and these employees. The DASS appears to be able to detect anxi-
DASS-Anxiety respectively. Table 5 shows sensitivity and spe- ety disorders and depression despite the communality in
cificity rates for different cut off scores of these two subscales. symptoms between these disorders and adjustment disorders.
Furthermore, table 5 shows both likelihood ratios for positive Caution is required when generalising these results across
(LR+) and negative (LR−) test results as well as posterior the entire occupational health care population. This study
probabilities of the disorders following positive or negative encompassed a population of employees with mental health
test results. As can be seen from this table, high sensitivity in problems who were absent from work. This entails that the
identifying anxiety and depressive disorders results in prevalence of anxiety disorder and depression is substantially
relatively low specificity rates. If LR− is set at >0.19, then, for higher than in a general occupational health care population.

Table 3 Intercorrelations among DASS subscales and indices of convergent and divergent validity (n=198)
DASS-D DASS-A DASS-S HADS-A HADS-D UCL-Active UCL-Soc Sup UCL-Comf

DASS-D – 0.58** 0.65** 0.53** 0.75** −0.24** −0.29** −0.02

DASS-A – 0.67** 0.66** 0.46** −0.29** −0.18* 0.002
DASS-S – 0.60** 0.58** −0.08 −0.06 0.02

*p<0.05, **p<0.01.

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Detecting anxiety disorder and depression in employees i81

Table 4 Comparisons of anxiety disorder/depression group with adjustment

disorder group on the DASS
Adjustment disorder Anxiety and/or
(n=117) depression (n=71)

Group (n=188) Mean SD Mean SD Post hoc comparisons*

DASS-Depression 12.91 8.7 20.63 9.7 Anx/depr>Adj

DASS-Anxiety 7.73 6.4 13.98 8.2 Anx/depr>Adj
DASS-Stress 17.43 9.5 21.22 8.5 Anx/depr>Adj

*Tukey HSD test, all main effects significant at p<0.01.

Table 5 Effect of different cut off scores on sensitivity and specificity, likelihood
ratios for positive (LR+) and negative (LR−) test results, and posterior probabilities of
the disorder following positive and negative test results of the DASS-Depression and
DASS-Anxiety scales
Posterior Posterior
Cut off probability after probability after
point Sensitivity Specificity LR+ LR− positive test negative test

DASS-Depression
8 0.95 0.31 1.38 0.16 0.29 0.05
9 0.95 0.35 1.46 0.14 0.30 0.04
10 0.91 0.40 1.52 0.23 0.31 0.06
11 0.91 0.44 1.63 0.20 0.33 0.06
12 0.91 0.46 1.69 0.20 0.33 0.06
13 0.91 0.50 1.82 0.18 0.35 0.05
14 0.86 0.56 1.95 0.25 0.37 0.07
15 0.84 0.58 2.00 0.28 0.38 0.08
16 0.81 0.62 2.13 0.28 0.39 0.09
DASS-Anxiety
2 1 0.19 1.23 0 0.25 0
3 0.95 0.26 1.28 0.19 0.25 0.05
4 0.92 0.35 1.42 0.23 0.27 0.06
5 0.92 0.40 1.53 0.20 0.29 0.05
6 0.84 0.44 1.50 0.36 0.29 0.09
7 0.78 0.51 1.59 0.43 0.30 0.10
8 0.76 0.54 1.65 0.44 0.31 0.11

Whereas in primary care settings around the world the preva- occupational health care. Treatment with medication and spe-
lence of both major depressive disorder and anxiety disorder cific psychological treatment has been proven to be effective in
was found to be 10% for each disorder,18 this study revealed a treating both anxiety disorders and depression.3 Because
prevalence of 21% for anxiety disorder and 23% for depression. adequate treatment is available, we consider high sensitivity
Two methodological aspects of this study require further con- the most important asset of the DASS. In line with this pref-
sideration. The first aspect concerns the use of a structured erence, a cut off point of 12 for the depression subscale and 5
interview administered by a mental health professional (CIDI for the anxiety subscale is recommended. The prevalence of
interview) as a gold standard. Although a true gold standard for anxiety disorder and depression was 21% and 23% respec-
depression and anxiety is not available, the diagnosis of a tively. Given the prevalence, sensitivity, and specificity rates of
psychiatrist might have been more accurate than the CIDI anxiety disorders and depression, this means that an occupa-
interview. In this respect it should be noted that a recent study tional physician seeing 100 patients per month who are absent
identified several articles in which semistructured interviews from work because of mental health problems, can expect 66
were conducted by mental health professionals in order to diag- patients to screen positive for anxiety disorder and 63 to
nose major depressive disorders.39 These studies revealed inter- screen positive for depression. After a more elaborate and
rater agreements (Cohen’s kappa) between the semistructured detailed clinical interview with these employees, 19 employees
interview and psychiatrists of 0.64 to 0.93, indicating that men- will prove to have an anxiety disorder and 21 will meet the
tal health professionals are capable of diagnosing major depres- criteria for a depression. Of the employees who screen
sion reliably. A second methodological aspect of the present negative on the DASS, two will still have an anxiety disorder
study concerns possible selection bias as a result of the large and two will still have a depression. Taking these considera-
number of employees who refused to participate. The reasons tions into account, occupational physicians can be advised to
for refusing to participate were recorded. Further examination use the DASS in a two phase diagnostic process. First, the
revealed that these reasons were diverse. Reasons for refusing to DASS should be used to alert the occupational physician to all
participate were that employees were “too busy”, “did not feel possible cases of anxiety disorder and depression. The second
like it”, “were too tired”, or “were okay now and did not want to step would be to conduct an elaborate clinical interview.
be reminded of those bad times”. Selection could also have led Occupational physicians can either perform this second step
to a population with missing extremes. This may have led to an themselves, or refer the employee to a mental health
underestimation of the diagnostic qualities of the DASS. professional for that purpose.
Furthermore, the gender ratio of the non-participants did not Three aspects of quality assessment of occupational health
differ from that of the participants. care instruments can be distinguished.40 The first aspect is
An important aim of this study was to evaluate the quality technical quality, which addresses issues of reliability and
of the DASS as a case finding instrument for use in validity of an instrument. The second characteristic of quality

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i82 Nieuwenhuijsen, de Boer, Verbeek, et al

can be described as process quality. Features such as 10 Simon GE, Barber C, Birnbaum HG, et al. Depression and work
productivity: the comparative costs of treatment versus nontreatment.
acceptability for employees and logistical aspects determine J Occup Environ Med 2001;43:2–9.
the process quality of an instrument. Finally, the strategic 11 Jones R, Yates WR, Williams S, et al. Outcome for adjustment disorder
quality of an instrument should be assessed. The presumed with depressed mood: comparison with other mood disorders. J Affect
Disord 1999;55:55–61.
utility of the instrument defines this aspect of quality. 12 Thompson C, Ostler K, Peveler RC, et al. Dimensional perspective on
The present study established the technical quality of the the recognition of depressive symptoms in primary care: The Hampshire
DASS. The process and strategic quality, however, still remain Depression Project 3. Br J Psychiatry 2001;179:317–23.
13 Tiemens BG, Ormel J, Simon GE. Occurrence, recognition, and outcome
to be assessed. All employees in this study filled out the DASS, of psychological disorders in primary care. Am J Psychiatry
which is a tentative indication that the DASS is user friendly. 1996;153:636–44.
This assumption should, however, be tested in a less motivated 14 Docherty JP. Barriers to the diagnosis of depression in primary care.
J Clin Psychiatry 1997;58(suppl 1):5–10.
population—that is, not in a population of employees who 15 Thompson C, Kinmonth AL, Stevens L, et al. Effects of a clinical-practice
agreed to participate in a cohort study. Whether the DASS can guideline and practice-based education on detection and outcome of
be implemented in occupational health care depends for a depression in primary care: Hampshire Depression Project randomised
large part on logistic aspects of administering the DASS. One controlled trial. Lancet 2000;355:185–91.
16 Ormel J, Tiemens BG. Recognition and treatment of mental illness in
procedure could be that the DASS is administered to all primary care. Towards a better understanding of a multifaceted problem.
employees with mental health problems prior to the consulta- Gen Hosp Psychiatry 1995;17:160–4.
tion with the occupational physician. The occupational physi- 17 Simon GE, Goldberg D, Tiemens BG, et al. Outcomes of recognized
and unrecognized depression in an international primary care study.
cian is then able to use the information from the DASS as an Gen Hosp Psychiatry 1999;21:97–105.
aid to his own diagnostic process. These aspects of process 18 Wittchen HU, Boyer P. Screening for anxiety disorders: Sensitivity and
quality and the utility of the DASS should be addressed in specificity of the Anxiety Screening Questionnaire (ASQ-15). Br J
Psychiatry 1998;173:10–17.
future implementation research. An important question is 19 Tiemens BG, Ormel J, Jenner JA, et al. Training primary-care physicians
whether routinely administering the DASS prior to the to recognize, diagnose and manage depression: does it improve patient
consultation leads to a more accurate diagnosis of occupa- outcomes? Psychol Med 1999;29:833–45.
20 Goldberg D, Bridges K, Duncan-Jones P, et al. Detecting anxiety and
tional physicians. Furthermore, the effect of the DASS on depression in general medical settings. BMJ 1988;297:897–9.
patient outcome also needs to be evaluated. Recognition of 21 Robins LN, Wing J, Wittchen HU, et al. The Composite International
anxiety disorder and depression is a necessary, though not Diagnostic Interview. An epidemiologic Instrument suitable for use in
conjunction with different diagnostic systems and in different cultures.
sufficient condition to improve outcome. Arch Gen Psychiatry 1988;45:1069–77.
In conclusion, the results of the present study suggest that 22 Spitzer RL, Williams JB, Kroenke K, et al. Utility of a new procedure for
the DASS is a valid instrument for use in occupational health diagnosing mental disorders in primary care. The PRIME-MD 1000 study.
JAMA 1994;272:1749–56.
care. It can be helpful in ruling out anxiety disorder and 23 Lovibond SH, Lovibond PF. Manual for the Depression Anxiety Stress
depression in employees with mental health problems. Scales (DASS). University of New South Wales, 1993.
Furthermore, the DASS can be used to select employees in 24 Clark LA, Watson D. Tripartite model of anxiety and depression:
psychometric evidence and taxonomic implications. J Abnorm Psychol
need of a more elaborate and accurate diagnostic process. 1991;100:316–36.
25 Klink JJL van der, Blonk RWB, Schene AH, et al. The effectiveness of an
ACKNOWLEDGEMENTS activating intervention for adjustment disorders with occupational
Grants were obtained from: The Netherlands Organization for Scien- dysfunctioning. Submitted.
26 Antony MM, Bieling PJ, Cox BJ, et al. Psychometric properties of the
tific Research (NWO): Netherlands Concerted Research Action 42-item and 21-item versions of the Depression Anxiety Stress Scales in
“Fatigue at Work”; and the Foundation for Replacement and Occupa- clinical groups and a community sample. Psychol Assessment
tional Health in Education (Stichting Vf/BGZ). 1998;10:176–81.
27 Brown TA, Chorpita BF, Korotitsch W, et al. Psychometric properties of
..................... the Depression Anxiety Stress Scales (DASS) in clinical samples. Behav
Res Ther 1997;35:79–89.
Authors’ affiliations 28 Clara IP, Cox BJ, Enns MW. Confirmatory factor analysis of the
K Nieuwenhuijsen, A G E M de Boer, J H A M Verbeek, Depression-Anxiety-Stress Scales in depressed and anxious patients.
F J H van Dijk, Coronel Institute for Occupational and Environmental J Psychopathol Behav 2001;23:61–7.
Health, Academic Medical Center, AmCOGG, University of Amsterdam, 29 Beurs E de, Dyck R van, Marquenie LA, et al. De DASS: een vragenlijst
Netherlands voor het meten van depressie, angst en stress. [The DASS: a
R W B Blonk, TNO Work and Employment, Hoofddorp, Netherlands questionnaire for the measurement of depression, anxiety, and stress].
Gedragstherapie 2001;34:35–53.
30 Lovibond PF, Lovibond SH. The structure of negative emotional states:
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