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TRANSCRIPT
Abstract
Background: The psychometric properties of the Revised Child Anxiety and Depression Scale
(RCADS) have been established cross-culturally, yet psychometric evidence is lacking for
English speaking European population. Aim: The current research sought to further cross-
validate the measure in a non-clinical Irish adolescent sample, and to test for gender and
age-based differential item functioning in depression and anxiety. Method: Participants
were Irish post-primary school students (N=345; 164 male; 12-18 years, M=14.97, SD=1.44).
Confirmatory factor analysis for categorical data (confirmatory item factor analysis), and
Multiple-Indicator Multiple-Cause (MIMIC) modeling to identify items displaying possible
metric invariance, were conducted. Results: A six-factor model fit the data well in both
gender samples, and both school cycle, as a proxy for age, samples. Gender-based metric
invariance for 5 of 47 items, and age-based metric invariance for 3 items, were identified.
However, the magnitudes were small. Internal consistency and validity were also
established. Conclusions: While a number of items demonstrated minor metric invariance,
there was no evidence that they influenced overall scores meaningfully. The RCADS can
reasonably be used without adjustment in male and female, younger and older, adolescent
samples. Findings have implications for the use of the RCADS in an English speaking
European population. Declaration of Interest: The authors have no competing interests to
declare.
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Introduction
The prevalence of internalising disorders, primarily mood and anxiety, among
adolescents is well evidenced globally (Farbstein et al., 2010; Frigerio et al., 2009; Kessler et
al., 2012; Merikangas et al., 2010; UN 2013), including in Ireland (e.g., Author, 2012; Cannon
et al., 2013). These disorders originate both independently and co-morbidly in youth (Jones,
2013; Pine et al., 1998), and are so-called due to the tendency for distress to be expressed
inwards (Cosgrove et al., 2011). There is a need for valid assessment measures that identify
emerging difficulties and subsequently enhance early intervention and prevention of mental
health difficulties in adolescence. It is also important that measures of internalising
disorders recognise the comorbidity of anxiety and depression (Mash & Hunsley, 2007).
Given the subjective nature of internalising disorders (Bernstein et al., 1996), self-report
measures are recommended as the first step in assessment (Law & Wolpert, 2013), and the
availability of multiple informant versions e.g. parent-report, in addition to self-report,
contributes to clinicians’ broader understanding of these difficulties (Southam-Gerow &
Chorpita, 2007).
Revised Child Anxiety and Depression Scale (RCADS)
The Revised Child Anxiety and Depression Scale (RCADS; Chorpita, 1998), for which
there are both self- and parent-report versions (Chorpita, 2003), was named the briefest
child and adolescent assessment measure aligned with the Diagnostic and Statistical Manual
(DSM) in a review by Southam-Gerow & Chorpita (2007), and has been deemed most
sensitive to clinical change in a review of four prominent measures (Wolpert, Cheng, &
Deighton, 2015). The clinical and research value of the RCADS is the measure’s ability to
differentiate between comorbid and independent aspects of internalising disorders (Mash &
Hunsley, 2007), and balance evidence-based assessment with real-world research demands
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(Ebesutani et al., 2012). As such, the RCADS has been recommended for use as a routine
outcome assessment measure in clinical settings in the UK (CORC, 2014).
The 47-item freely-available measure simultaneously assesses five subcategories of
anxiety: Generalised Anxiety Disorder (GAD), Separation Anxiety Disorder (SAD), Social
Phobia (SP), Panic Disorder (PD), Obsessive-Compulsive Disorder (OCD); as well as Major
Depressive Disorder (MDD). The measure generates total scores for each subscale, a Total
Anxiety score (GAD, SAD, SP, PD, OCD) and a Total Internalising score of all six subscales. Of
note, OCD has since been re-categorised in the DSM-V (APA, 2013) and excluded from the
anxiety disorders category. However, the most recent manual continues to recognise the
high comorbidity between OCD and anxiety disorders. Both share treatment approaches,
and it is therefore clinically useful to continue to assess OCD in line with anxiety disorders
(Ebesutani, Korathu-Larson, Nakamura, Higa-McMillan, & Chorpita, 2016).
A six-factor structure of the five anxiety and one depression subscales has been
supported with children and adolescents in Hawaiian school and clinical samples (Chorpita,
Yim, Moffitt, Umemoto, & Francis, 2000; Chorpita, Moffitt, & Gray, 2005), school samples in
Australia (deRoss, Gullone, & Chorpita, 2002), Denmark (Esbjørn, Somhovd, Turnstedt, &
Reinholdt-Dunne, 2012), and France (Bouvard, Denis, & Roulin, 2015), Southern American
Caucasian youth (Trent et al., 2013), and African-American youth (Brown et al., 2013; Trent
et al., 2013). The six-factor structure has also been supported for the RCADS-P in American
clinical (Ebesutani, Bernstein, Nakamura, Chorpita, & Weisz, 2010) and school samples
(Ebesutani et al., 2011), a Spanish cohort (Park, Ebesutani, Bose, & Chorpita, 2016), and
good fit was also observed in a Dutch sample for the five anxiety disorders (Mathyssek et al.,
2013).
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In contrast, Muris, Meesters, & Schouten (2002) did not support the six-factor
structure and thus developed a 25-item version of five five-item subscales excluding OCD.
However, Ebesutani et al. (2012) noted that the reliability and reduced content diversity of
the Total Anxiety subscale may have been jeopardised. As an alternative, Ebesutani et al.
(2012) retained the OCD subscale, reduced the anxiety subscales to five items each and
maintained the full MDD subscale. A two-factor anxiety/depression structure was
subsequently supported (Chorpita et al., 2005; Ebesutani et al., 2012; Ebesutani et al.,
2016). A five-factor model combining GAD and MDD (Ebesutani et al., 2010; 2011), a one-
factor Internalising Disorders model (Chorpita et al., 2005; deRoss et al., 2002), and
hierarchical models (Brown et al., 2013) have also been examined in previous research.
However, the six-factor model has been the most widely supported.
In terms of abbreviated versions, Park et al. (2016) examined the 25-item structure,
proposed by Ebesutani et al. (2012), with the Spanish RCADS-P but did not find consistent
support for its validity compared with the 47-item Spanish RCADS-P. Sandin, Chorot,
Valiente, & Chorpita (2010) provided support for a 30-item version in a Spanish population,
and Stevanovic et al. (2016) has demonstrated validity and a six-factor structure of a 37-
item version of the measure across ten ethnically and culturally diverse countries. The
measure did not perform well in an eleventh Philippines sample however, highlighting the
importance of examining the validity of assessment measures across cultures prior to
implementation. The authors note that there is a distinct lack of evidence for the RCADS in
an English speaking European population, yet nonetheless the RCADS has been
recommended for use in the UK (CORC, 2014).
In an Irish context, neither the RCADS nor RCADS-P have been extensively considered
as viable assessment measures. One study utilised the RCADS-25 in an Irish Child and
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Adolescent Mental Health Service (CAMHS) observing satisfactory reliability (Wynne, Doyle,
Kenny, Brosnan, & Sharry, 2016). However, the psychometric properties were not
investigated. The current research begins to address this gap in evidence by investigating
the psychometric properties of the original 47-item RCADS in a non-clinical Irish adolescent
sample.
It is also important to establish the measurement invariance of a scale to allow for
meaningful comparisons between various groups. For the RCADS, this involves assessing the
degree to which the measurement of depression and anxiety disorders is equivalent or
invariant across different subpopulations and groups. In order to make valid comparisons of
scores between groups, it is important that measurement equivalence is established. For
example, if the RCADS is measurement invariant across groups, individuals with similar
levels of the construct being measured (e.g., anxiety symptoms) will score similarly on each
item of the measure, and scoring metrics can therefore be considered equivalent across the
groups (Reise, Widaman & Pugh, 1993). Metric invariance can be assessed by examining
whether there are differences in scores of individual items across groups after controlling
for levels of the latent construct being measured.
The aim of this study was to conduct a metric invariance analysis to determine
whether RCADS scores, and subscale scores were equivalent between males and females,
and between those in Junior and Senior cycle. The first aim of the study was to examine the
factor structure of the RCADS using confirmatory item factor analysis (CFA for categorical
data) to establish a baseline model. The second aim was to test metric invariance in RCADS
items across both males and females, and across Junior and Senior school cycle (lower and
upper secondary school). Finally, the third aim was to examine reliability and validity of the
RCADS in a sample of Irish adolescents.
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Methods
Participants
Participants were 350 second-level students (186 female) aged 12-18 years
(M=14.97, SD=1.44). In Irish second-level schools, years 1-3 are known as Junior Cycle
(approximate age range 12-15 years) and Years 4-6 are known as Senior Cycle (approximate
age range 16-18 years). Junior and Senior Cycle were used as proxies for age. Students were
sampled from Junior Cycle years (Total=169; 1st=26; 2nd=133; 3rd=10) and Senior Cycle years
(Total=181; 4th/Transition Year=64; 5th=117) across four schools (one urban mixed sex, one
urban single sex, two rural mixed sex). Schools did not allow 6 th Year students to participate
due to final exams. The majority of students identified themselves as White (91.4%), 86% of
which identified as Irish (5.4% White not Irish, 3.4% Asian, 2.9% Other/half Irish, 1.4%
Black, .6% Eastern European, .3% Irish Traveller).
Measures
Revised Child Anxiety and Depression Scale (RCADS)
The RCADS items are scored 0-3 (never – almost always) for GAD e.g. ‘I worry about
things’, SAD e.g. ‘I feel scared if I have to sleep on my own’, SP e.g. ‘I worry I might look
foolish’, PD e.g. ‘I suddenly become dizzy or faint when there is no reason for this’, OCD e.g. ‘I
have to do something in just the right way to stop bad things from happening to me ’, and
MDD e.g. ‘I feel worthless’. A scoring sheet available from Child First
(www.childfirst.ucla.edu) generates raw and T scores for each subscale, a Total Anxiety
Scale and a Total Internalising Scale. Standardised T scores are generated using gender and
US school grade. Grades were adapted to equivalent Irish second-level years (7 th Grade=1st
Year; 8th=2nd; 9th=3rd; 10th=4th; 11th=5th; 12th=6th). Higher scores indicate greater levels of
difficulty. The RCADS has previously demonstrated high reliability, and good internal
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consistency and convergent validity (Bouvard et al., 2015; Ebesutani et al., 2010; Esbjørn et
al., 2012).
Depression, Anxiety and Stress Scale Short Version (DASS-21)
The shortened version of the Depression, Anxiety and Stress Scale (Lovibond &
Lovibond, 1995) consists of 21 statements with three subscales relating to depression e.g. ‘I
felt that I had nothing to look forward to’, anxiety e.g. ‘I was worried about situations in
which I might panic and make a fool of myself’, and stress e.g. ‘I felt that I was rather
touchy’. Responses range from never to almost always (0-3). Higher scores indicate greater
distress. Previous research has illustrated the validity of the DASS-21 with adolescents
(Miller et al., 2015; Willemsen, Markey, Declercq, & Vanheule, 2011), including a national
study of Irish adolescents (Author, 2012). The DASS-21 Depression and Anxiety subscales
were used in the current study.
Procedure
Ethical approval was granted through the university with which the authors were
affiliated. Students completed questionnaires comprising questions relating to demographic
information, the RCADS self-report version, and the DASS-21 self-report version, in class or
year groups. Parent/guardian consent was sought, and parents/guardians were asked to
consider whether their child had experienced or was experiencing any mental health
difficulties and whether they would be able to participate in the research as a result of this
or any other factors e.g. learning disability. Students also provided consent prior to
participation.
Statistical Analyses
Five respondents were omitted for missing data greater than 20% (Ebesutani et al.,
2010). For remaining participants (N=345), the amount of missing data was low and ranged
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from .47%-3.76% (RCADS) and .21%-.84% (DASS-21). Missing data were treated as pairwise
missing which is the default when the weighted least squares (WLSMV) estimator is used
(Asparouhov & Muthén, 2010). Skewness and kurtosis were within the required ranges to
indicate data were normally distributed.
The latent structure of the 47-item RCADS was tested using confirmatory factor
analysis (CFA) for categorical data. Five alternative models identified from the literature
were specified and tested. Overall the aim of testing alternative models was to determine if
the internalising disorders assessed by the RCADS were better presented as six correlated
dimensions rather than five, two, or one dimensions, and if there was a hierarchical
structure (second-order factors) that explained the associations between the first-order
Depression and Anxiety dimensions. Model 1 is a correlated six factor model, of the six
RCADS subscales. Model 2 is a correlated five factor model, where GAD and MDD are
combined. Model 3 is a correlated two-factor model of Anxiety and MDD. Model 4 is a one-
factor model of Internalising Disorders. Model 5 tested that there was a hierarchical
structure for the RCADS items, whereby the six RCADS subscales of GAD, SAD, SP, PD, OCD
and MDD loaded onto an overall latent factor of internalising disorders.
Each model was specified and estimated using Mplus 7.1 (Muthén & Muthén, 2013)
using the robust weighted least squares estimator (WLSMV) based on the polychoric
correlation matrix of latent continuous response variables. The WLSMV estimator is the
most appropriate estimator of ordinal indicators in a CFA for categorical data (Brown, 2006).
The WLSMV estimator has been shown to produce correct parameter estimates, standard
errors and test statistics (Flora & Curran, 2004). The error variances were uncorrelated for
all models. Goodness of fit for each model was assessed with a range of fit indices including
the relative Chi-square (chi-square/df) (relative χ2; Tabachnick & Fidell, 2007), the
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Comparative Fit Index (CFI; Bentler, 1990), the Tucker-Lewis Index (TLI; Tucker & Lewis,
1973), the Root Mean Square Error of Approximation (RMSEA; Browne & Cudek, 1993) and
RMSEA 90% Confidence Intervals, and Weighted Root Mean Square Residual (WRMR;
Muthén & Muthén, 2013). Values indicating acceptable model fit are .90 or above for CFI
and TLI, while values up to .08 for RMSEA indicate reasonable errors of approximation, with
values up to .05 indicate close model fit (Jöreskog & Sörbom, 1993). Chi-square tests are
sensitive to larger sample sizes (Hooper, Coughlan, & Mullen, 2008), therefore the relative
chi-square (chi-square/df) was used as an index of fit, with values less than 2 indicating a
good model fir (Ullman, 2001). It is therefore recommended that Chi-square tests should
not be taken as the sole model indicator of model fit and that the various fit indices should
also be examined (Schermelleh-Engel, Moosbrugger, & Müller, 2003), as per the current
study.
To assess differences, if any, for gender and age, Multiple Indicators Multiple Causes
(MIMIC) models were conducted to determine gender-based or age-based metric invariance
(Holland & Warner, 1993), i.e. differences in item scores across groups while controlling for
an overall latent variable, was present. To investigate this, MIMIC models test 1) the
relationships between items and factors (i.e. the baseline measurement model), 2) factors
and the group variable (i.e. structural regression coefficients), and 3) items and the group
variable (i.e. the direct effect). If different scores on the observed variables emerge between
groups who share the same underlying latent variable, metric invariance is established
(Haroz, Ybarra, & Eaton, 2014). After establishing the baseline model, latent variables are
regressed on variables representing the groups under investigation, with significant
regression coefficients indicating significant mean differences between groups (i.e. Male/
Female, Junior/Senior cycle) at the latent variable level. Modification Indices (MI) for the
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direct paths from the group variable to the RCADS measure are inspected to determine the
presence of DIF. Modification indices (MI) identify paths that if added to the model would
significantly improve model fit by reducing the chi-square by 5 or more. In a sequential
manner, the path with the largest MI was included in the model and the model was re-
estimated. This process continued until there were no MIs greater than 5. It is important to
rule out DIF and establish measurement invariance, as it can lead to incorrectly detected
group differences and prevent the use of assessment measures across certain populations
(Borsboom, 2006; Teresi & Fleishman, 2007).
Next, convergent validity was examined using Pearson’s r correlations between
RCADS and DASS-21 Depression and Anxiety subscales. To examine divergent validity,
significant differences between the correlations were examined using Fisher’s z-tests, as it
was expected that the correlations would be moderate given the comorbidity of anxiety and
depression. To assess reliability, internal consistency was established using Cronbach’s
alpha. Item-total correlations were also examined, with .30 taken as the cut-off for
adequate item-total correlation values (Nunnally & Bernstein, 1994).
Results
Confirmatory Factor Analysis for Categorical Data
As shown in Table 1, the original six-factor model yielded good model fit in the
current sample, χ2(1019)=1563.95, p<.01, demonstrating excellent CFI=.96, TLI=.96,
RMSEA=.034 (90% CI .035-.043) and adequate WRMR=1.09 and a relative chi-square value
of 1.534 indicating a good model. Figure 1 displays the path diagram with standardised
factor loadings, and standard error variances for each item in brackets. The second-order
model originally investigated by Brown et al. (2013) was also supported in the current
sample, χ2(1028)=1566.47, demonstrating similarly good fit to the original model with equal
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CFI, TLI, RMSEA and 90% CI values, and similarly adequate WRMR=1.10, and a relative chi-
square value of 1.524 indicating a good model. Good fit for the second order model is
unsurprising given the high correlations between the RCADS subscales, confirming the
presence of a latent factor of internalizing disorders. Nonetheless, the original six-factor
model was considered to be a more parsimonious solution. Poorer model fit was observed
for the five, two, and one-factor models when compared with the six-factor and second-
order models (Table 1).
MIMIC
To investigate metric invariance, MIMIC models were employed where the latent
variables were regressed firstly on the gender variable (Male/Female) and secondly on the
school cycle variable (Junior/Senior Cycle) to examine the direct effects. For gender, this
model made little difference to the overall fit, χ2(1060)=1641.51, CFI=.96, TLI=.95,
RMSEA=.04 (90% CI=.036; .044), WRMR=1.13, and chi-square/df ratio =1.55. However,
inspection of the modification indices revealed that direct effects from the gender variable
to five items would improve the model fit if freely estimated. Each direct effect was added
sequentially to determine if there were significant differences, while controlling for any
difference in the overall level of the latent factor between males and females. The final
model, with direct effects from the gender variable to five items, was χ2(1055)=1592.21,
CFI=.96, TLI=.96, RMSEA=.04 (90% CI=.035; .042), WRMR=1.10, chi-square/df ratio =1.51 and
provided a better fit. The factor loadings for the baseline and metric invariance corrected
models are presented in Table 2. The regression coefficients for the structural effects of
gender on the latent factors and the five non-invariant items are presented in Table 3. These
findings indicate that females reported significantly higher levels of GAD, SP, SAD, OCD, PD,
and MDD, than males. The largest effect was for MDD, with females having a mean
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score .69 of a standard deviation higher than males, followed by GAD and SAD with a mean
score of .55 of a standard deviation above the mean. The direct effects from the gender
variable to all five items were statistically significant, while statistically controlling for the
latent variables in the model. This indicated that females scored significantly higher on
feelings of worry when someone may be angry with them (RCADS8; SP), feeling scared to
take a test (RCADS7; SP), and fear of being at home alone (RCADS5; SAD). Males were
significantly more likely to endorse feeling nervous going to school (RCADS18; SAD) and
feeling that nothing is much fun anymore (RCADS6; MDD). The effect sizes were small, and
indicated that the mean difference between males and females on the items ranged
between .48 to .67 of a standard deviation.
The latent variables were also regressed on a variable representing school cycle
(Junior/Senior Cycle) as a proxy for age to examine the direct effects. This model made little
difference to overall fit, χ2(1060)=1631.87, CFI=.96, TLI=.96, RMSEA=.04 (90% CI=.036; .04),
WRMR=1.09, chi-square/df ratio= 1.54. However, inspection of the modification indices
revealed that direct effects from the school cycle variable to three items would improve the
model fit if freely estimated. Similar to gender, each direct effect was added sequentially to
determine if there was significant metric invariance, while controlling for any difference in
the overall level of the latent factor between groups. The fit of these models are presented
in Table 1. The final DIF corrected model was χ2(1057)=1604.01, CFI=.96, TLI=.96,
RMSEA=.039 (90% CI=.035; .04), WRMR=1.08, chi-square/df ratio =1.52, which provided a
better fit. The factor loadings for the baseline and DIF corrected models are presented in
Table 2.
The regression coefficients for the structural effects of school cycle on the latent
factors and the three items identified as demonstrating DIF; feeling scared away from home
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(RCADS46), worrying at night (RCADS45), and responding to stressors with feelings in the
stomach (RCADS3) are presented in Table 3. These findings indicate that Senior Cycle
students reported significantly higher levels of GAD, SP, OCD, and MDD, while those in the
Junior Cycle reported significantly higher levels of SAD and PD. The largest effect was for
SAD and PD, with Junior Cycle students having a mean score of .19 of a standard deviation
higher than those in Senior Cycle. The other effects were small, with estimates ranging
between .02 to .13. Further, the direct effects from the school cycle variable to items
RCADS46, RCADS45, and RCADS3 were statistically significant. This indicated that Junior
Cycle students scored significantly higher on feeling scared away from home, while Senior
Cycle students were more likely to endorse higher rates of stomach sensations when
experiencing problems while statistically controlling for the latent variables in the model.
The effect sizes were small, ranging from .35 to .63.
Validity
Correlations, all of which were significant, between the RCADS subscales, and the
RCADS and DASS-21 Depression and Anxiety are displayed in Table 4. All RCADS subscale
correlations were significant, indicating the high level of comorbidity of anxiety and
depression and the possibility of a latent internalizing disorders factor. To establish validity,
correlations between the RCADS and DASS-21 were examined. The RCADS MDD subscale
(r=.79) and Total Internalising factor (r=.73) were most strongly correlated with the DASS-21
Depression subscale compared to the DASS-21 Anxiety subscale. The RCADS PD subscale
(r=.72) and Total Anxiety subscale (r=.71) were most strongly correlated with the DASS
Anxiety subscale. The Total Internalising overall scale was also strongly correlated with the
DASS-21 Anxiety subscale (r=.72). The strong correlation reported between the Panic
Disorder subscale and the DASS-21 Anxiety subscale is understandable considering that
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many of the DASS-21 anxiety items reflect the construct of panic e.g. ’’I felt I was close to
panic’’. These results provide evidence of convergent validity for the RCADS, and further
highlight the comorbidity of anxiety and depression as indicated by the strong correlations
for the RCADS Total Internalising scores with both DASS-21 subscales.
Significant correlations between the RCADS and the DASS-21 subscales were also
shown by gender, and by Junior versus Senior Cycle as a proxy for age. The correlations
between the six RCADS subscales and the DASS Depression and Anxiety subscales were
higher for the Junior Cycle than for the Senior Cycle, landing primarily between r=.59 and
r=.81 for Junior Cycle, and between r=.39 and r=.76 for the Senior cycle. Correlations were
also higher for females than males, landing primarily between r=.49 and r=.83 for females,
and r=.32 and r=.63 for males.
Furthermore, divergent validity was partially supported for the total sample (Table
4). Of the RCADS anxiety scales, the highest correlations with the DASS-21 Anxiety subscale
were for PD (r=.72), and Total Anxiety (r=.71), with all three correlating lower with the DASS-
21 Depression subscale. The difference for the PD subscale was significant suggesting
divergent validity. SAD and OCD correlations were moderately higher for the DASS-21
Anxiety subscale than the DASS-21 Depression subscale, while the GAD and OCD
correlations were moderately higher with the DASS-21 Depression subscale. The highest
correlations for the MDD (r=.79) and Total Internalising (r=.73) were with the DASS-21
Depression subscale. Both correlated relatively highly with the DASS-21 Anxiety subscale,
however the difference for the MDD subscale was significant thus indicating divergent
validity. As previously noted, the strong correlations across the anxiety and depression
constructs are unsurprising given the comorbidity of both.
Internal Consistency
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Internal consistency for the RCADS subscales ranged from adequate to excellent,
α=.60 to .96 (Table 5). When examined by gender and age, differences in alpha-levels were
not substantial. Of note, alpha for the SAD subscale was higher for the Junior than the
Senior cycle. Separation anxiety is more prevalent in children and younger adolescents
(Copeland, Angold, Shanahan, & Costello, 2014), hence this may explain why the subscale
may have performed better with the younger adolescents in the current study. The PD
subscale showed a lower reliability for males than females, which may suggest that these
items are more salient for females than males and support existing findings on gender
differences in panic disorders, which are more prevalent amongst females (McLean,
Asnaani, Litz, & Hofmann, 2011). Corrected item-total correlations are displayed in Table 6,
with no items emerging below the cut-off of .30 for each subscale.
Discussion
With the aim of establishing the psychometric properties of scores from the 47-item
RCADS in a previously unexamined sample of Irish adolescents, the current study provided
further cross-cultural validation of the six-factor structure of the measure in an English
speaking European sample. The second-order model also demonstrated fit indices similar to
the six-factor model thus indicating the presence of a hierarchical latent ‘internalising
disorders’ factor, which explains the comorbidity and subsequent high correlations between
anxiety and depression as assessed by the RCADS. However, the RCADS is utilised in clinical
settings such as Child and Adolescent Mental Health Services (CAMHS) in the UK (CORC,
2014), for the purposes of diagnosis and formulation of specific anxiety and depressive
disorders among adolescents, with a significant value being the ability to detect six disorders
independently using a single measure (Mash & Hunsley, 2007). As such, the original six-
factor structure was deemed to be the most parsimonious and clinically useful model in the
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current study, which is the first to support this model in an English speaking, European
population. Reliability and convergent validity were also established, and there was
evidence for divergent validity for the MDD and Panic Disorder subscales.
In order to determine whether the RCADS was invariant across gender and age,
whereby school cycle was used as a proxy, metric invariance was investigated. For gender,
five of 47 items showed DIF between males and females. Females reported being more
likely to worry when someone was angry (RCADS8), to be scared to take a test (RCADS7),
and to be afraid to be at home alone (RCADS5), while males reported being more likely to
have trouble going to school in the morning as a result of being nervous or afraid
(RCADS18), and that nothing was much fun anymore (RCADS6). While females overall tend
to report greater levels of anxiety and depression, more nuanced gender-based differences
have been observed within disorders (McLean & Anderson, 2009). In terms of anxiety,
females have greater tendencies to worry (McLean & Anderson, 2009) while Bennett,
Ambrosini, Kudes, Metz, & Rabinovich (2005) observed within-disorder differences in levels
of depression among adolescent males and females. The authors reported that females
experienced greater levels of guilt, concentration problems, difficulty working, etc., while
males experienced higher levels of clinical anhedonia, i.e. inability to feel pleasure or fun in
day-to-day activities. Males also tend to exhibit behavioural reactions to anxiety and
depression (Brownhill, Willhelm, Barclay, & Schmied, 2005), which may contribute to the
greater levels of trouble going to school and higher rates of apathy towards enjoyment of
activities as reported by males in the current study.
Differences between Junior and Senior school cycles were also observed. Younger
adolescents in the Junior Cycle reported being more likely to feel afraid staying away from
home overnight (RCADS46), and older adolescents in the Senior Cycle reported being more
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likely to worry at night (RCADS45) and to experience feelings in the stomach in response to
stressors (RCADS3). Trends in anxiety disorders differ across age groups with Separation
Anxiety Disorder being most prevalent amongst children and younger adolescents, and
subsequently decreasing in mid-adolescence while rates of other disorders including Panic
Disorder increase (Copeland et al., 2014). These studies may explain these specific age
differences in anxiety symptoms and why fear of staying away from home was most
prevalent in Junior Cycle, and the Panic Disorder item of experiencing feelings in the
stomach in response to stressors was more reported in Senior Cycle.
The divergent validity of the RCADS was only preliminarily supported in the current
study. All anxiety and depression subscales for both the RCADS and DASS-21 were at least
moderately correlated, with high correlations observed between anxiety and depression
subscale due to the comorbidity of anxiety and depression. The correlations between MDD
and the DASS-21 Depression subscale, and PD and the DASS-21 Anxiety subscale, were
determined to be significantly higher than MDD and the DASS-21 Anxiety subscale, and PD
and the DASS-21 Depression subscale, using Fisher z-tests for investigating differences in
correlations. These findings indicate that the MDD and PD subscales in the current study
successfully detected their individual latent construct best. The performance of the MDD
subscale is unexpected. The PD subscale may have performed best in the current study
given that the DASS-21 was used as the comparative measure as the anxiety items of the
DASS-21 are more aligned with the construct of panic, e.g. ‘’I was aware of the action of my
heart in the absence of physical exertion (e.g., sense of heart rate increase, heart missing a
beat).’’ These findings further emphasise the clinical value of the RCADS as a measure able
to detect individual anxiety disorders (Mash & Hunsley, 2007).
17
A significant strength of the current research is the novel contribution the findings
make to the existing literature and clinical use of the RCADS, given that the measure is
recommended for use in clinical settings in the UK despite the lack of evidence regarding the
psychometric properties of the RCADS in an English speaking European population. In
addition, the study employed novel statistical methods for investigating the RCADS as a
four-point response scale using WLSMV to compare models, and MIMIC to investigate
differential item functioning to determine metric invariance. A limited number of previous
RCADS studies (e.g. Ebesutani et al., 2011) have done so, with none focusing specifically on
the youth-report RCADS across gender and age. The data handling techniques employed in
the current were an added strength given that alternative methods, such as maximum
likelihood estimation, can produce incorrect standard errors, reduce the strength of the
relationship between variables and result in potential pseudo-factors (Brown, 2006).
It would be of value for the RCADS subscales to be examined against anxiety-only
and depression-only measures e.g. SCARED (Hale, Raajimakers, Muris, & Meeus, 2005), BDI-
II (Beck, Steer, & Brown, 1996), to explore the divergent validity of the measure in terms of
these comorbid constructs further, given the inability of the DASS-21 to detect differences
between anxiety disorders. In addition, examining the RCADS with unrelated constructs e.g.
externalising difficulties (Chorpita et al., 2005) would also be beneficial. To further
investigate the clinical value of the RCADS, future research should examine the criterion-
related validity of the measure in terms of predictive and concurrent validity for variables
such as wellbeing, suicidality, substance use, etc., as this is an under-examined area of the
RCADS. In addition, the timeframe of the current study did not allow for test-retest
reliability to be examined with this population, and this should be examined in further
18
research given that the RCADS is utilised as an outcome tracking measure in the UK National
Health Service and elsewhere.
Sampling issues were a further limitation of the current research. The sample lacked
6th Year students due to exam restrictions. Although school type was varied, national
representativeness was not established, schools varied in terms of socio-economic
catchment areas, and differences for students from varying ethnic and cultural backgrounds
were not considered. The RCADS has previously demonstrated validity and reliability across
ethnic samples (Kösters, Chinapaw, Zwaanswijk, van der Wal, & Koot, 2015; Stevanovic et
al., 2016; Trent et al., 2013). Given that minority ethnic and cultural groups often experience
increased risk of mental health difficulties and disparities in healthcare (Alegria, Green,
McLaughlin, & Loder, 2015; O’Neill & Lowry, 2014), it is important to identify suitable
measures to detect distress in such populations. The current research provides a basis from
which further studies in an Irish context can be conducted e.g. with multi-ethnic samples,
with clinical samples, and validation of the RCADS-P. Shortened versions of the RCADS (e.g.
Ebesuanti et al., 2012; Sandin et al., 2010) should also be considered, given the need for
brief assessment measures in mental health care.
Ultimately, the validity of the RCADS as an assessment measure of internalising
disorders had not been established in an English speaking population prior to the current
study, despite recommendations for use of the RCADS in the UK (Law & Wolpert, 2013). The
current study was the first to establish the psychometric properties of the 47-item, six-
factor structure of the RCADS in a non-clinical Irish adolescent sample, providing evidence to
support the clinical utility of the measure in an English speaking, European population.
Despite the current findings revealing differences in some items on the RCADS, it should be
noted that these effects were small. Future research is warranted to establish whether
19
gender and age differences in certain items are consistent across a range of adolescent
samples.
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