Psychometric Properties of the Icelandic Version of the
Generalized Anxiety Disorder-7
Rósa Ingólfsdóttir
2014 BSc in Psychology
Author: Rósa Ingólfsdóttir ID number: 010688-2059 Department of Psychology School of Business
PSYCHOMETRIC PROPERTIES OF THE ICELANDIC GAD-7 2
Foreword
Submitted in partial fulfillment of the requirements of the BSc Psychology degree,
Reykjavík University, this thesis is presented in the style of an article for submission to a
peer-reviewed journal.
PSYCHOMETRIC PROPERTIES OF THE ICELANDIC GAD-7 3
Abstract
The Generalized Anxiety Disorder-7 (GAD-7) is a self-report anxiety scale that screens for
Generalized Anxiety Disorder. The aim of this study was to assess the psychometric
properties of the Icelandic version of the GAD-7. The study included 358 participants
consisting of two samples, one clinical and one non-clinical. All participants completed the
GAD-7 and PHQ-9 questionnaires and participants in the clinical sample answered diagnostic
specific questionnaire based on main diagnosis evaluation as well. The participants in the
non-clinical sample more over completed additional questionnaires, BAI, CORE-OM and
QOLS, as well as GAD-7 on a second occasion. Internal reliability was good and both
convergent validity and divergent validity were supported. The comparison of participants in
the clinical sample and participants in the non-clinical sample showed that there was a
statistically significant difference between the two groups on scores on the questionnaires.
Patients diagnosed with anxiety disorder more over had higher scores on GAD-7 than
patients without such diagnosis, indicating good discriminant validity of the GAD-7. It is
concluded that the psychometric properties of the Icelandic version of the GAD-7 are
satisfactory.
Útdráttur
GAD-7 er sjálfsmatskvarði sem skimar fyrir einkennum almennrar kvíðaröskunar. Markmið
þessarar rannsóknar var að kanna próffræðilega eiginleika íslenskrar útgáfu GAD-7.
Þátttakendur í rannsókninni voru 358 einstaklingar í tveimur hópum, tilraunahóp og
samanburðarhóp. Allir þátttakendur svöruðu GAD-7 og PHQ-9 spurningalistunum og auk
þess svöruðu þátttakendur í tilraunahópnum sérstökum spurningalistum byggðum á
greiningarmati. Þátttakendur í samanburðarhóp svöruðu jafnframt þremur öðrum
spurningalistum, BAI, CORE-OM og QOLS, auk þess að svara GAD-7 í annað sinn. Innri
áreiðanleiki var talinn góður og niðurstöðurnar studdu bæði samleitniréttmæti og
aðgreiningarréttmæti GAD-7. Samanburður á þátttakendum í hópunum tveimur sýndi að það
var munur á milli stigaskors þeirra á spurningalistunum. Jafnframt voru sjúklingar með
kvíðagreiningu með hærra skor á GAD-7 en sjúklingar án kvíðagreiningar, sem bendir til
góðs aðgreiningarréttmætis GAD-7. Íslenska útgáfan af GAD-7 er talin hafa viðunandi
próffræðilega eiginleika.
PSYCHOMETRIC PROPERTIES OF THE ICELANDIC GAD-7 4
Introduction
Anxiety disorders are an umbrella term that include a variety of disorders that share
common features of excessive fear and anxiety and related behavioral disturbances
(American Psychiatric Association, 2013). The diagnostic and statistical manual of mental
disorders fifth edition (DSM-5) identifies seven main types of anxiety disorders and one of
the most common is Generalized Anxiety Disorder (GAD) (American Psychiatric
Association, 2013; Spitzer, Kroenke, Williams, & Löwe, 2006). GAD involves chronic
worrying, nervousness and tension and DSM-5 states that individuals have to experience
excessive anxiety and worry, that they find difficult to control, for at least six months to be
diagnosed (American Psychiatric Association, 2013; Hansell, 2005). Given the estimated
prevalence of GAD, that is 2.8% to 8.5% in general practice and 0.4% to 5.7% among the
general population, it is important to have measuring devices that can assess GAD in an
accessible and reliable way (American Psychiatric Association, 2013; Butcher, Mineka, &
Hooley, 2013; Hansell, 2005; Roy-Byrne & Wagner, 2004). One such measuring device is
the Generalized Anxiety Disorder-7 (GAD-7), a 7-item self-report anxiety scale that screens
for GAD (Spitzer et al., 2006). The GAD-7 does not only screen for GAD but has as well
proved to be a good screening device for probable cases of panic disorder, social anxiety
disorder and post-traumatic stress disorder (PTSD) (Kroenke, Spitzer, Williams, Monahan, &
Lowe, 2007). The fact that the scale does not require a clinician administration makes it more
desirable since other diagnostic interviews, such as Primary Care Evaluation of Mental
Disorders (PRIME-MD), The Structured Clinical Interview (SCID) and The Mini-
International Neuropsychiatric Interview (MINI), are more time consuming and that alone
can create problems in primary care settings where most visits are 15 minutes or less
(Delgadillo et al., 2012; Sheehan et al., 1998; Spitzer et al., 1994; Spitzer, Kroenke, &
PSYCHOMETRIC PROPERTIES OF THE ICELANDIC GAD-7 5
Williams, 1999; Spitzer RL, Williams JW, Gibbon M, & First MB, 1992). Recent research
has showed that the GAD-7 can be self-administered in less than 5 minutes.
What is demanded within the field is reliable and valid measures for anxiety disorders in
clinical strategy, especially when there is high prevalence and disability (Delgadillo et al.,
2012). The psychometric properties of the GAD-7 have been assessed and when conducting
the list Spitzer et al. assessed the reliability and validity of the measuring device (2006). The
results showed that the internal consistency was excellent (Cronbach α = 0.92) and the test-
retest reliability was good (intraclass correlation = 0.83). The convergent validity of the
GAD-7 was furthermore proved by its correlations to Beck Anxiety Inventory (BAI) (r =
0.72) and the anxiety subscale of the Symptom Checklist 90 (r = 0.74). The scale was
furthermore strongly correlated with the PHQ-8 depression measure (r = 0.75), which
includes all items from the PHQ-9 except for the item about suicidal ideation, and that is
consistent with results from previous studies of anxiety and depression. Previous research has
stated that the psychometric properties of the GAD-7 are good and the scale is clinically
useful and therefore a good measuring device for GAD (Delgadillo et al., 2012; Löwe et al.,
2008). The GAD-7 has been translated into several languages, e.g. Dutch, Spanish, German
and Turkish, and all items on the translated scales measure the same concepts as the original
one (Donker, van Straten, Marks, & Cuijpers, 2011; Garcia-Campayo et al., 2010; Konkan,
Senormanci, Guclu, Aydin, & Sungur, 2013; Löwe et al., 2008). The adapted versions all
showed excellent psychometric properties and the validity and reliability of the translated
versions of the GAD-7 have been confirmed. The GAD-7 has been translated into Icelandic
and in the present study the psychometric properties of the Icelandic version were assessed
for the first time.
PSYCHOMETRIC PROPERTIES OF THE ICELANDIC GAD-7 6
Method
Participants
The study included 358 participants consisting of two samples, one clinical sample and
one non-clinical sample. The clinical sample consisted of 233 individuals, 192 females
(82.4%) and 41 males (17.6%), the mean age was 37.4 years (SD: 13.29, range 18 – 77
years). All participants were experiencing mental health problems as evaluated by a General
Practitioners (GPs) or a clinical psychologist administering MINI and all attended a
transdiagnostic cognitive behavioral group therapy (TCBGT) that was offered in 9 primary
health care centers in Reykjavík and surrounding towns. All referrals came from GPs and
criteria for referral was being over 18 years of age and showing signs of emotional problems
based on the GP clinical evaluation. Exclusion criteria for the treatment were: 1) obvious
signs of dementia or another generalized cognitive impairment, 2) presence of symptoms
suggesting current psychotic condition and 3) current self-reported substance abuse.
Non-clinical sample consisted of 125 individuals, 94 sports science students, 57 females
and 37 males, at Reykjavík University and 31 employees, 17 females and 14 males, at a
leisure center in Reykjavík. The mean age for the students’ sample was 25 years (SD = 3.4,
range 20 – 39 years) and for the employees it was 27 years (SD = 8.0, range 20 – 64 years).
The study used a convenience sample and there was no exclusion criteria.
Of the total sample, 264 (74%) participants were included in the study. The return of
completed questionnaires among the non-clinical sample was 125 (100%) and in the clinical
sample 139 (60%) patients fulfilled the study’s inclusion criteria and attended at least one
treatment session. Of the 125 individuals in the non-clinical sample 73 (58%) returned
completed questionnaire two weeks later for test-retest analysis.
PSYCHOMETRIC PROPERTIES OF THE ICELANDIC GAD-7 7
Measures
GAD-7 is a self-report scale that is used to screen for and measure the severity of GAD
(Spitzer et al., 2006). Even though the scale was developed to screen for GAD it has proven
to be a good screener for probable cases of PTSD, social anxiety disorder and panic disorder.
The GAD-7 tests seven items and asks respondents how often, over the last two weeks, they
have been bothered by certain problems, e.g. not being able to sleep or control worrying or
feeling nervous, anxious or on edge (Appendix I). Response options are “not at all”, “several
days”, “more than half the days” and “nearly every day” and the answers are scored as 0, 1,
2, and 3. The total score of the scale ranges from 0 to 21 and cut points might be interpreted
as 5 being mild, 10 being moderate and 15 being severe levels of anxiety. Research has
showed that the internal consistency of the GAD-7 is excellent (Cronbach α = 0.92) and the
test-retest reliability is good (intraclass correlation = 0.83) (Spitzer et al., 2006). The results
from Spitzer’s et al. study revealed a strong association between increasing GAD-7 severity
scores and declining functional status, which indicates good construct validity. The results
from the same study furthermore showed that the convergent validity of the scale was good.
This was shown by its correlations to BAI (r = 0.72) and the anxiety subscale of the
Symptom Checklist 90 (r = 0.74). The divergent validity was also good where more than half
of patients with high anxiety scores did not have high depression scores.
Patient Health Questionnaire-9 (PHQ-9) is used to screen and assess depression severity
(Kroenke & Spitzer, 2002). The scale has 9 items and asks respondents how often, over the
last two weeks, they have been bothered by certain problems, e.g. feeling tired and having
little energy or feeling down, depressed or hopeless (Appendix II). Response options are “not
at all”, “several days”, “more than half the days” and “nearly every day” and the answers are
scored as 0, 1, 2, and 3. The scale provides a 0 to 27 severity score and cut points of 5, 10, 15
and 20 might be interpreted as mild, moderate, moderately severe and severe depression.
PSYCHOMETRIC PROPERTIES OF THE ICELANDIC GAD-7 8
Research has shown that PHQ-9 is a reliable and valid measure of depression severity
(Kroenke, Spitzer, & Williams, 2001). The internal reliability was good (Cronbach α = 0.86 -
0.89) and the test-retest reliability was excellent. The results furthermore revealed that there
was a strong association between PHQ-9 scores and functional status, symptom related
difficulty and self-reported sick days and clinic visits, which indicates that construct validity
was good. The PHQ-9 has been translated into Icelandic by Hafrún Kristjánsdóttir, Agnes
Agnarsdóttir, Pétur Tyrfingsson and Jakob Smári (as cited in Valdís Eyja Pálsdóttir, 2007).
The psychometric properties of the Icelandic version have been assessed and the results
revealed that the internal reliability is good (Cronbach α = 0.61 – 0.95) (Valdís Eyja
Pálsdóttir, 2007). The convergent validity of the PHQ-9 is good and that was shown by its
correlations to Beck Depression Inventory-II (r = 0.80) and Clinical Outcomes in Routine
Evaluation – Outcome Measure (CORE-OM) (r = 0.81). The correlations of PHQ-9 to
Quality of Life Scale (QOLS) furthermore proved the divergent validity of the scale (r = -
0.65).
BAI measures anxiety in adults and adolescents (Beck, Epstein, Brown, & Steer, 1988).
The scale consists of 21 questions and respondents are asked to report the extent to which
they have been bothered by each of the symptoms, e.g. numbness or tingling, unsteady and
fear of losing control, over the last week. Each symptom item has four response options: “not
at all”, “mildly - it did not bother me much”, “moderately – it was very unpleasant but I could
stand it” and “Severely – I could barely stand it” and the answers are scored as 0, 1, 2, and 3.
The scale ranges from 0 to 63 and a total score of 0 – 7 is interpreted as a minimal level of
anxiety, 8 – 15 as mild, 16 – 25 as moderate and a total score of 26 – 63 as severe level of
anxiety. The research conducted by Beck et al. showed that BAI has high internal reliability
(Cronbach α = 0.92) and test-retest reliability is also good (r = 0.75) (1988). The convergent
validity of the BAI is also good and that is proved by its moderate correlation with the
PSYCHOMETRIC PROPERTIES OF THE ICELANDIC GAD-7 9
revised Hamilton Anxiety Rating Scale (r = 0.51) and mild correlation with the revised
Hamilton Depression Rating Scale (r = 0.25). The results furthermore revealed that the BAI
discriminates anxious diagnostic groups from nonanxious diagnostic groups. The BAI has
been translated into Icelandic and its psychometric properties have been assessed and are
considered satisfactory (Sæmundsson et al., 2011). The results showed that the translated
version of BAI has high internal reliability (Cronbach α = 0.92 - 0.96) and that test-retest
reliability is also good (r = 0.81). The convergent and divergent validity were furthermore
assessed and the results revealed that BAI had higher correlations with the DASS Anxiety
scale than with both the DASS Depression scale and the DASS Stress scale, which supports
good convergent validity and divergent validity (Sæmundsson et al., 2011).
CORE-OM measures participants’ psychological distress (Evans et al., 2002). The scale
consists of 34 items that measure well-being, function, symptoms and risk (Appendix III).
Each item has five response options: “not at all”, “only occasionally”, “sometimes”, “often”
and “all or most of the time” and the answers are scored as 0, 1, 2, 3 and 4. Total scores range
between 0 and 4 and higher scores reflect more severe problems. The research conducted by
Evans et al. revealed that the internal reliability and test-retest reliability of the scale were
good (0.75 – 0.95). The convergent validity was proved by its correlations with seven other
instruments and divergent validity was proved by the large difference between clinical and
non-clinical samples. It has furthermore a good sensitivity to change. The scale has been
translated into Icelandic and its psychometric properties have been evaluated (Kristjánsdóttir
et al., 2013). The Icelandic version has excellent internal reliability (Cronbach α = 0.94),
good test-retest reliability (r = 0.80), acceptable convergent validity and seems to be sensitive
to changes.
QOLS measures quality of life (Burckhardt & Anderson, 2003). It is a 16-item instrument
that measures material and physical well-being, relationships with other people, social,
PSYCHOMETRIC PROPERTIES OF THE ICELANDIC GAD-7 10
community and civic activities as well as personal development and fulfillment, recreation
and independence (Appendix IV). Each item has seven response options: “Terrible”,
“Unhappy”, “Mostly Dissatisfied”, “Mixed”, “Satisfied”, “Mostly pleased” and “Delighted”
and the answers are scored from 1 to 7, 1 being terrible and 7 being delighted. The scale is
scored by adding up the score on each item to yield a total score for the instrument. Scores
can range from 16 to 112 whereas higher score indicates higher quality of life and average
total score for a healthy population is about 90. The scale has good internal reliability
(Cronbach α = 0.82 – 0.92) and has high test-retest reliability over 3 weeks (r = 0.78 – 0.84)
(Burckhardt & Anderson, 2003). Convergent validity was proved by its high correlations
with Life Satisfaction Index (r = 0.67 – 0.75). There was furthermore evidence that groups of
patients with persistent condition have lower scores on the scale than healthy adults and
adults with more stable chronic illnesses, which indicates divergent validity. The scale has
been translated into Icelandic and the psychometric properties have been assessed (Ólafur V.
Hrafnsson & Matthías Guðmundsson, 2007). The internal reliability of the translated version
is good (Cronbach α = 0.82 - 0.89) and test-retest reliability is also good (r = 0.72). The scale
has strong positive correlation with Satisfaction With Life Scale, which indicates convergent
validity and its divergent validity was proved by its negative correlation with Beck
Depression Inventory, BAI and Perceived Stress Scale.
MINI is a structured diagnostic interview used to explore 17 mental disorders according to
the diagnostic criteria of the DSM-IV and ICD-10 (Lecrubier et al., 1997; Sheehan et al.,
1998). It was developed for epidemiological studies and multicentre clinical trials. Previous
study has shown that the original scale has excellent reliability, good inter-rater reliability
and good test-retest reliability (Lecrubier et al., 1997). The psychometric properties of the
Icelandic version of the MINI have not been thoroughly studied but one preliminary study
does give some support to its validity (as cited in Kristjánsdóttir et al., 2013).
PSYCHOMETRIC PROPERTIES OF THE ICELANDIC GAD-7 11
Procedure
The GAD-7, PHQ-9, BAI, CORE-OM and QOLS were administered to the participants in
the non-clinical sample and the GAD-7 again two weeks later. The participants in this sample
were informed that the participation was optional and they could leave the study at any time,
for any reason. The GPs made clinical evaluations for the patients in the clinical sample and
could refer them to the TCBGT. The referred patients were assessed by a clinical
psychologist in a participation interview, with MINI and psychological scales. If the patients
had more than two disorders and by that fulfilled the MINI criteria a clinical psychologist
gave them a main diagnosis. Patients in the clinical sample filled out GAD-7, PHQ-9 and a
diagnostic specific questionnaire, that was based on main diagnosis evaluation, in diagnostic
interview and every treatment session. Therapy sessions were once a week for six weeks and
lasted for two hours each session.
Permission for the study was obtained from the National Bioethics Committee in Iceland
(VSNb2005090003) and the study was approved by the Icelandic Data Protection Authority
(S2602/2005).
Statistical analysis
All analysis were conducted with SPSS, except the ROC that was conducted with
MedCalc. Test-retest was assessed using the intra-class correlation coefficient (ICC) and the
internal consistency was assessed using Chronbach’s alpha. Calculating the Pearson
correlation coefficient between the GAD-7 and the four other lists, PHQ-9, BAI, CORE-OM
and QOLS, assessed convergent and divergent validity of the GAD-7. The comparison of
patients and participants in the non-clinical sample was determined by independent t-test and
the comparison of patients with or without anxiety disorder diagnosis was determined by
independent t-test as well. Signal detection analysis was conducted for the GAD-7 with
regard to the diagnosis of an anxiety disorder with the MINI. A receiver operating
PSYCHOMETRIC PROPERTIES OF THE ICELANDIC GAD-7 12
characteristics (ROC) curve that plots specificity versus sensitivity for every possible cutoff
point was obtained and Youden’s Index (J) was used to evaluate the cutoff point.
Results
Means and Standard Deviations
The mean score for the GAD-7 in the patient sample was 8.60 (SD = 4.77). The mean
score for males was 7.11 (SD = 4.43) and for females 8.90 (SD = 4.79). There was a
statistically significant difference between the genders as determined by independent t-test,
t(219) = 2.104, p = .036.
The mean score in the non-clinical sample for the first administration of the GAD-7 was
1.05 (SD = 2.32). The mean score for males was .55 (SD = 1.57) and for females 1.39 (SD =
2.67). There was a statistically significant difference between the genders as determined by
independent t-test, t(123) = 2.024, p = .045. The mean score for the second administration of
the GAD-7 in the non-clinical sample was 2.00 (SD = 2.89). The mean score for males was
.71 (SD = 1.41) and for females 3.18 (SD = 3.38). There was a statistically significant
difference between the genders as determined by independent t-test, t(71) = 4.010, p = .000.
Internal reliability and test-retest reliability
Internal reliability of the GAD-7 in the clinical sample was α = .867 and in the non-
clinical sample it was α = .863. The two weeks test-retest reliability was assessed in the non-
clinical sample and it was r = .584.
Validity
Pearson correlation coefficient was calculated between the GAD-7 scale and the four other
scales, BAI, CORE-OM, PHQ-9 and QOLS, to assess the convergent and divergent validity
of the GAD-7 scale. This was done both for the non-clinical sample and the clinical sample
(see Table 1).
PSYCHOMETRIC PROPERTIES OF THE ICELANDIC GAD-7 13
Table 1. Correlations of the GAD-7 with the BAI, CORE-OM, QOLS and PHQ-9 in both samples BAI CORE-OM QOLS PHQ-9
GAD-7 in the non-clinical sample
.654* (n = 125)
.641* (n = 125)
-.373* (n = 125)
.653* (n = 125)
GAD-7 in the clinical sample
.652* (n = 197)
.709* (n = 204)
-.409* (n = 193)
.631* (n = 211)
Note. * p < .01.
For the non-clinical sample the GAD-7 had highest correlation with BAI indicating good
convergent validity (p < .01) and lower correlation with QOLS supporting good divergent
validity (p < .01). The correlation with PHQ-9 was similar to the correlation of GAD-7 with
BAI. For the clinical sample the GAD-7 had highest correlation with CORE-OM followed by
BAI, indicating convergent validity (p < .01). The scale had lower correlation with QOLS
indicating divergent validity (p < .01). The correlation with PHQ-9 was similar to the
correlation of GAD-7 with BAI.
Comparison of Patients in Clinical-Sample and Participants in Non-Clinical Sample
and Comparison of Patients With or Without Anxiety Disorder Diagnoses
The difference between patients scores and scores of participants in the non-clinical
sample on the GAD-7 was determined by independent t-test. This was done to assess the
discriminant validity of the list as a screener for GAD. The mean score on GAD-7 for
patients in the clinical sample was 8.60 (SD = 4.77) and for the individuals in the non-clinical
sample it was 1.06 (SD = 2.32), the difference between the two groups was statistically
significant (p < .001).
In order to assess the discriminant validity of the GAD-7 for screening for GAD the scores
of patients with diagnosis of anxiety disorder were compared with patients’ scores that did
not have anxiety disorder diagnosis. The mean score on GAD-7 for patients with anxiety
disorder diagnosis was 10.23 (SD = 4.50) and for patients without diagnosis the mean score
was 5.50 (SD = 3.59). The mean score for males with diagnosis was 8.67 (SD = 4.28) and for
females it was 10.44 (SD = 4.51). For patients without anxiety disorder diagnosis the mean
PSYCHOMETRIC PROPERTIES OF THE ICELANDIC GAD-7 14
score for males was 5.63 (SD = 4.14) and for females it was 5.46 (SD = 3.43). The difference
between the patient groups, that is with or without anxiety disorder diagnosis, was
statistically significant (p < .001).
Signal Detection Analysis/Receiver Operating Characteristic Analysis
Signal detection analysis was conducted for the GAD-7 in the clinical sample in order to
map the scores on the GAD-7 to the MINI diagnoses. A ROC curve that plots specificity
versus sensitivity for every possible cutoff point was obtained. In all, 147 of 225 patients
were diagnosed with an anxiety disorder. The analysis showed that the GAD-7 discriminates
well between patients diagnosed with anxiety disorder and other patients (Area Under the
Curve (AUC) = .80, 95% confidence interval = .74 - .85). The Yuden’s Index (J) was used to
determine the optimal cutoff value from the ROC analysis and it was obtained for the value
>7 (Youden, 1950). At this point the sensitivity was 66.67% and specificity was 78.21% (see
Table 2).
Table 2. Operating Characteristics of GAD-7 at Different Cutoffs Criterion Sensitivity % 95% CI Specificity % 95% CI
> 3 97.28 93.2 – 99.3 26.92 17.5 – 38.2 > 4 91.84 86.2 – 95.7 46.15 34.8 – 57.8
> 4,67 91.84 86.2 – 95.7 47.44 36.0 – 59.1 > 5 82.31 75.2 – 88.1 56.41 44.7 – 67.6 > 6 75.51 67.7 – 82.2 64.10 52.4 – 74.7 > 7 66.67 58.4 – 74.2 78.21 67.4 – 86.8 > 8 59.86 51.5 – 67.9 83.33 73.2 – 90.8
> 8,17 59.18 50.8 – 67.2 83.33 73.2 – 90.8 > 9 54.42 46.0 – 62.6 87.18 77.7 – 93.7
> 10 51.02 42.7 – 59.3 88.46 79.2 – 94.6 > 11 42.18 34.1 – 50.6 93.59 85.7 – 97.9 > 12 31.29 23.9 – 39.5 96.15 89.2 – 99.2 > 13 25.17 18.4 – 33.0 97.44 91.0 – 99.7 > 14 17.01 11.3 – 24.1 97.44 91.0 – 99.7 > 15 12.24 7.4 – 18.7 98.72 93.1 – 100 > 16 8.16 4.3 – 13.8 100 95.4 - 100
PSYCHOMETRIC PROPERTIES OF THE ICELANDIC GAD-7 15
Discussion
The present study assessed for the first time the psychometric properties of the Icelandic
version of the GAD-7 in clinical and non-clinical samples. The results support the
psychometric properties of the Icelandic version of the GAD-7 and the use of it as a
measuring device for GAD.
The means and standard deviations for the participants in the non-clinical sample on the
GAD-7 in this study were slightly lower than the means in the general population in a study
conducted by Löwe et al., where it was 2.97 (2008). This difference could be due to the age
difference as the mean age was higher in the general population in Löwe’s study than in the
non-clinical sample in this study. The age difference could indicate more responsibilities and
burdens among the general population in Löwe’s study and due to that these individuals
might experience increased anxiety symptoms. The means and standard deviations for
patients diagnosed with anxiety disorder were slightly lower in this study than in previous
studies of patients with GAD (14.4 in Spitzer et al., 2006 and 14.18 in Löwe et al. 2008). For
patients without diagnosis of anxiety disorder the mean score in this study was similar to the
mean score in previous studies (5.57 in Löwe et al. 2008 and 4.9 in Spitzer et al. 2006).
Furthermore the mean score for females on the GAD-7 was higher than for males, both in the
clinical sample and in the non-clinical sample, and the difference was statistically significant.
Based on this finding it might be worth considering changing the cut points of the GAD-7 for
males.
The internal reliability of the Icelandic version of the GAD-7 was good, .867 for patients
in the clinical sample and .863 for participants in the non-clinical sample, and that is
comparable to previous studies where the internal reliability of the GAD-7 has proven to be
good (Delgadillo et al., 2012; Donker et al., 2011; Garcia-Campayo et al., 2010; Löwe et al.,
2008; Spitzer et al., 2006). The two weeks test-retest reliability was lower in this study than
PSYCHOMETRIC PROPERTIES OF THE ICELANDIC GAD-7 16
in previous research (Spitzer et al., 2006). The reasons for lower test-retest reliability vary
and among them are passage of time, interventions and emotional trauma (Cohen, Swerdlik,
& Sturman, 2013). In the research conducted by Spitzer et al. the participants filled out the
GAD-7 scale within one week from completing the research questionnaire but in this study
the time between the two trials was two weeks (2006). The passage of time might therefore
help explain why the test-retest reliability was lower in this study than in the study conducted
by Spitzer et al. The fact that the second administration of the scale was done during
midterms might as well have effects and lower the test-retest reliability since students
possibly experience increased anxiety symptoms as a consequence of the midterms.
The convergent and divergent validity of the Icelandic version of the GAD-7 were
supported in this study. The correlation coefficient between the GAD-7 and BAI was
relatively high in both samples and that indicates good convergent validity and is similar to
the findings of Spitzer et al. where correlation of GAD-7 with BAI was 0.72 (2006). Lower
correlation of the GAD-7 in both samples with QOLS support good divergent validity as this
questionnaire measures quality of life (Burckhardt & Anderson, 2003). The correlation with
PHQ-9 was similar to the correlation with BAI in both samples and that is in accordance with
previous studies of anxiety and depression. The comorbidity of depressive and anxiety
disorders in addition to the correlation of GAD-7 scores with scores on depression measures
is a well known fact (as cited in Spitzer et al., 2006).
The discriminant validity of the GAD-7 was assessed by examining the difference
between the patients scores and scores of participants in the non-clinical sample. The
difference between the two groups was statistically significant for the scale and the
questionnaire proved to be good and valid screener for GAD. Research has emphasized that it
is important in clinical strategy to have reliable and valid measures of disorders and it is
probably as important that these measuring devices can discriminate between symptoms and
PSYCHOMETRIC PROPERTIES OF THE ICELANDIC GAD-7 17
disorders (Delgadillo et al., 2012). The discriminant validity of the GAD-7 for screening for
GAD was assessed as well. This was done by comparing scores of patients diagnosed with
anxiety disorder on GAD-7 to scores of patients that did not have such diagnosis. The results
support the GAD-7 as a screener for GAD since the mean score of patients with anxiety
disorder diagnosis was higher than the scores of patients without anxiety disorder diagnosis
and the difference was statistically significant. This is consistent with previous findings
where the mean score for individuals diagnosed with GAD (mean = 13.96, SD = 4.19) was
higher than the mean score in the control group (mean = 3.54, SD = 3.32), and the difference
between the groups was significant (Garcia-Campayo et al., 2010).
The signal detection analysis revealed that GAD-7 discriminates well between
patients diagnosed with anxiety disorder and patients without such diagnosis. When
developing the scale Spitzer et al. proposed a cutoff value of 10 or greater as a reasonable cut
point for identifying cases of GAD (2006). In this study the cutoff score for the GAD-7 was 7
or greater which is slightly lower than in previous studies where the cutoff score has been 8-
10 or greater (Delgadillo et al., 2012; Kroenke et al., 2007).
The findings in this study are consistent with findings from previous research that state
that GAD-7 is a valid and reliable measuring device. The results of this study support the use
of the Icelandic version of the GAD-7 as a screener for GAD both in the general population
and among patients. The psychometric properties of the Icelandic version are similar to the
properties of the original GAD-7 scale and are considered satisfactory.
PSYCHOMETRIC PROPERTIES OF THE ICELANDIC GAD-7 18
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PSYCHOMETRIC PROPERTIES OF THE ICELANDIC GAD-7 22
Appendix I
GAD - 7
Hversu oft á síðastliðnum 2 vikum hefur þér liðið illa vegna eftirfarandi? Aldrei Nokkra
daga
Oftar en helming daganna
Næstum daglega
1. Verið spennt/-ur á taugum, kvíðin/-n eða hengd/-ur upp á þráð
2. Ekki tekist að bægja frá þér áhyggjum eða hafa stjórn á þeim
3. Haft of miklar áhyggjur af ýmsum hlutum
4. Átt erfitt með að slaka á
5. Verið svo eirðarlaus að þú áttir erfitt með að sitja kyrr
6. Orðið gröm/gramur eða pirruð/pirraður af minnsta tilefni
7. Verið hrædd/-ur eins og eitthvað hræðilegt gæti gerst
PSYCHOMETRIC PROPERTIES OF THE ICELANDIC GAD-7 23
Appendix II
PHQ-9
______________________ _____ ________
Hversu oft hefur eftirfarandi vandamál truflað þig síðastliðnar
tvær vikur?
Alls ekki
Nokkra daga
Meira en helming tímans
Nánast
alla daga
a. Lítill áhugi eða gleði við að gera hluti.......…………….....
b. Verið niðurdregin/n dapur/döpur eða vonlaus.……….....
c. Átt erfitt með að sofna eða sofa alla nóttina.......….......
d. Þreyta og orkuleysi....................................……….....…..
e. Lystarleysi eða ofát.......................…................……….….
f. Liðið illa með sjálfan þig eða fundist að þér hafi mistekist eða ekki staðið þig í stykkinu gagnvart sjálfum þér eða fjölskyldu þinni..............................................................
g. Erfiðleikar með einbeitingu við t.d. að lesa blöðin eða horfa á sjónvarp......................................................….
h. Hreyft þig eða talað svo hægt að aðrir hafa tekið eftir þvi? Eða hið gagnstæða – verið svo eirðarlaus eða óróleg(ur) að þú hreyfðir þig mikið meira en venjulega..........……..
i. Hugsað um að það væri betra að þú værir dáin(n) eða hugsað um að skaða þig á einhvern hátt…………..........
Íslensk þýðing með leyfi höfunda: Agnes Agnarsdóttir, Hafrún Kristjánsdóttir, Jakob Smári, Jón Friðrik Sigurðson og Pétur Tyrfingsson
PSYCHOMETRIC PROPERTIES OF THE ICELANDIC GAD-7 24
Appendix III
CLINICAL OUTCOMES in ROUTINE EVALUATION ÁRANGURSMAT
MIKILVÆGT – LESIÐ ÞETTA FYRST
Á þessu eyðublaði eru 34 fullyrðingar um hvernig þér hefur gengið SÍÐUSTU VIKUNA. Vinsamlegast lestu hverja staðhæfingu fyrir sig og hugleiddu hversu oft þér leið þannig síðustu vikuna. Merktu svo í þann reit sem á best við svar þitt. Hvernig hefur þér liðið síðustu vikuna?
1 Ég hef verið hræðilega einmana og einangruð/einangraður. ! 0 ! 1 ! 2 ! 3 ! 4 !! F
2 Ég hef verið spennt(ur), kvíðin(n) eða taugaóstyrk(ur). ! 0 ! 1 ! 2 ! 3 ! 4 !! P P
3 Mér fannst ég geta leitað til einhvers eftir stuðningi þegar ég þurfti.
! 4 ! 3 ! 2 ! 1 ! 0 !! F F
4 Ég hef verið sátt(ur) við sjálfa(n) mig. ! 4 ! 3 ! 2 ! 1 ! 0 !! WW
5 Ég hef verið algjörlega orku– og áhugalaus. ! 0 ! 1 ! 2 ! 3 ! 4 !! P P
6 Ég hef beitt aðra líkamlegu ofbeldi. ! 0 ! 1 ! 2 ! 3 ! 4 !! R R
7 Þegar eitthvað hefur gengið illa hef ég getað tekist á við það.
! 4 ! 3 ! 2 ! 1 ! 0 !! F F
8 Óþægindi, verkir eða önnur líkamleg vandamál hafa truflað mig.
! 0 ! 1 ! 2 ! 3 ! 4 !! P P
9 Ég hef hugsað um að skaða sjálfa(n) mig. ! 0 ! 1 ! 2 ! 3 ! 4 !! R R
10 Mér hefur fundist of erfitt að tala við fólk. ! 0 ! 1 ! 2 ! 3 ! 4 !! F F
11 Spenna og kvíði hafa komið í veg fyrir að ég gerði mikilvæga hluti.
! 0 ! 1 ! 2 ! 3 ! 4 !! P P
12 Ég hef verið ánægð(ur) með það sem ég hef gert. ! 4 ! 3 ! 2 ! 1 ! 0 !! F F
13 Óvelkomnar hugsanir og tilfinningar hafa truflað mig. ! 0 ! 1 ! 2 ! 3 ! 4 !! P P
14 Ég hef verið gráti nær. ! 0 ! 1 ! 2 ! 3 ! 4 !! WW
Alls ekki
Stöku sinnum Stundum Oft
Næstum alltaf eða alltaf
Aðeins fyrir
starfsfólk
_____
____________________________________________________ ________________ _________ ___ ___
PSYCHOMETRIC PROPERTIES OF THE ICELANDIC GAD-7 25
15 Ég hef fundið fyrir ofsakvíða eða skelfingu. ! 0 ! 1 ! 2 ! 3 ! 4 !! P P
16 Ég hef gert áætlanir um að stytta mér aldur. ! 0 ! 1 ! 2 ! 3 ! 4 !! R R
17 Mér hafa fundist vandamál mín vera yfirþyrmandi. ! 0 ! 1 ! 2 ! 3 ! 4 !! WW
18 Ég hef átt í erfiðleikum með að sofna eða ná að sofa alla nóttina.
! 0 ! 1 ! 2 ! 3 ! 4 !! P P
19 Ég hef fundið fyrir hlýju og væntumþykju til einhvers. ! 4 ! 3 ! 2 ! 1 ! 0 !! F F
20 Ég hef ekki getað hætt að hugsa um vandamál mín. ! 0 ! 1 ! 2 ! 3 ! 4 !! P P
21 Ég hef getað gert flest af því sem ég þarf að gera. ! 4 ! 3 ! 2 ! 1 ! 0 !! F F
22 Ég hef ógnað eða hótað einhverjum. ! 0 ! 1 ! 2 ! 3 ! 4 !! R R
23 Ég hef fundið fyrir vonleysi eða örvæntingu. ! 0 ! 1 ! 2 ! 3 ! 4 !! P P
24 Ég hef hugsað að það væri best að ég væri dáin(n). ! 0 ! 1 ! 2 ! 3 ! 4 !! R R
25 Mér hefur fundist aðrir vera að gagnrýna mig. ! 0 ! 1 ! 2 ! 3 ! 4 !! F F
26 Mér hefur fundist ég ekki eiga vini. ! 0 ! 1 ! 2 ! 3 ! 4 !! F F
27 Ég hef verið óhamingjusöm/samur. ! 0 ! 1 ! 2 ! 3 ! 4 !! P P
28 Óvelkomnar minningar eða hugsanir hafa valdið mér vanlíðan.
! 0 ! 1 ! 2 ! 3 ! 4 !! P P
29 Ég hef verið pirruð/pirraður þegar ég er með öðru fólki. ! 0 ! 1 ! 2 ! 3 ! 4 !! F F
30 Ég hef hugsað um að vandamál mín og erfiðleikar séu sjálfri/sjálfum mér að kenna.
! 0 ! 1 ! 2 ! 3 ! 4 !! P P
31 Ég hef verið bjartsýn(n) á framtíðina. ! 4 ! 3 ! 2 ! 1 ! 0 !! WW
32 Mér hefur tekist það sem ég ætlaði mér. ! 4 ! 3 ! 2 ! 1 ! 0 !! F F
33 Mér hefur fundist annað fólk hafa niðurlægt mig eða fyllt mig skömm.
! 0 ! 1 ! 2 ! 3 ! 4 !! F F
34 Ég hef skaðað mig líkamlega eða stofnað heilsu minni í alvarlega hættu.
! 0 ! 1 ! 2 ! 3 ! 4 !! R R
Alls ekki Stöku sinnum Stundum Oft
Næstum alltaf eða
alltaf
Aðeins fyrir
starfsfólk
PSYCHOMETRIC PROPERTIES OF THE ICELANDIC GAD-7 26
Appendix IV
Mat á lífsgæðum
(Quality of Life Scale)
Vinsamlegast skoðaðu hvert tölusett atriði á listanum hér fyrir neðan sem á að lýsa ákveðnum sviðum lífs þíns. Dragðu hring um þá tölu sem lýsir því best hversu ánægð(ur) eða óánægð(ur) þú ert með líf þitt á hverju sviði fyrir sig. Merktu við atriði jafnvel þótt þú sért ekki virk(ur) á því sviði. Við getum verið ánægð/óánægð með að vera ekki virk á einhverju sviði eða ekki í þeim tengslum við fólk sem spurt er um.
Mjög ánægð(ur)
Ánægð(ur)
Frekar ánægð(ur)
Hvorki ánægð(ur)
né óánægð(ur)
Frekar óánægð(ur)
Óánægð(ur)
Mjög óánægð(ur)
1. Efnisleg gæði – heimili, matur, þægindi og fjárhagslegt öryggi
7 6 5 4 3 2 1
2. Heilsa – líkamlegt heilbrigði og hreysti
7 6 5 4 3 2 1
3. Samband við foreldra, systkini og aðra ættingja – tjáning og tengsl, heimsóknir, aðstoð
7 6 5 4 3 2 1
4. Eiga og ala upp börn 7 6 5 4 3 2 1
5. Náin tengsl við maka eða aðra ástvini 7 6 5 4 3 2 1
6. Nánir vinir 7 6 5 4 3 2 1
7. Að hjálpa öðrum og hvetja, bjóða aðstoð og gefa ráð
7 6 5 4 3 2 1
8. Þátttaka í samtökum og opinberum málum (félagsmálum, þjóðmálum)
7 6 5 4 3 2 1
9. Nám – skólanám, aukin skilningur og bætt þekking
7 6 5 4 3 2 1
10.
Að skilja sjálfan mig – þekkja kosti mína og galla – vita um hvað lífið snýst
7 6 5 4 3 2 1
11.
Störf – vinna innan eða utan heimilis 7 6 5 4 3 2 1
12.
Skapandi tjáning 7 6 5 4 3 2 1
13.
Félagslíf – hitta annað fólk, vera virkur, samkvæmi o.s.frv.
7 6 5 4 3 2 1
PSYCHOMETRIC PROPERTIES OF THE ICELANDIC GAD-7 27
14.
Lestur, hlusta á tónlist og fara á sýningar
7 6 5 4 3 2 1
15.
Þáttaka í skipulögðu frístundastarfi 7 6 5 4 3 2 1
16.
Sjálfstæði, – að geta séð um mig, bjargað mér og gert hlutina sjálf(ur)
7 6 5 4 3 2 1