Effect of comorbidity on treatment of anxious children and adolescents: results from a large ...

25 Pages·2012·0.5 MB·English

Macquarie University ResearchOnline

This is the author version of an article published as:

Rapee, R. M., Lyneham, H. J., Hudson, J. L., Kangas, M., Wuthrich, V. M., and
Schniering, C. A. (2013). Effect of comorbidity on treatment of anxious children and
adolescents: results from a large, combined sample. Journal of the American
Academy of Child & Adolescent Psychiatry, Vol. 52, Issue 1, p. 47-56.

Access to the published version: http://doi.org/10.1016/j.jaac.2012.10.002

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Journal of the American Academy of Child & Adolescent Psychiatry, Vol. 52, Issue 1,
2013, DOI: 10.1016/j.jaac.2012.10.002.
*Title Page including all author information
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The effect of comorbidity on treatment of anxious children and adolescents: Results from a large,
combined sample

Ronald M. Rapee, PhD
Heidi J. Lyneham, PhD
Jennifer L. Hudson, PhD
Maria Kangas, PhD
Viviana M. Wuthrich, PhD
Carolyn A. Schniering, PhD

Centre for Emotional Health, Macquarie University, Sydney

Correspondence to:
Ron Rapee
Centre for Emotional Health
Department of Psychology
Macquarie University
Sydney. NSW. 2109. Australia
[email protected]

Keywords: anxiety disorders, treatment, comorbidity, mood disorders, externalizing
Words: Abstract - 252; Text - 5120; Figures - 0; Tables - 3
Acknowledgements:
The research reported in this paper was supported by a variety of granting bodies including: National
Health & Medical Research Council; Australian Research Council; Australian Rotary Health.
Running head: Comorbidity and treatment for child anxiety
*Blinded Manuscript - <B>No Author Information</B>
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2 The effect of comorbidity on treatment of anxious children and adolescents: Results from a large,
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combined sample
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Keywords: anxiety disorders, treatment, comorbidity, mood disorders, externalizing
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Words: Abstract - 252; Text - 5120; Figures - 0; Tables - 3
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17 Running head: Comorbidity and treatment for child anxiety
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2 Abstract
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Objective: The purpose of the current study was to evaluate the influence of comorbid disorders on
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both the degree of change and the end-point of skills-based treatment for anxious young people.
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10 Method: Data on 780 children aged 7-17 years was compiled from a variety of samples within one
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clinic. All children had a primary anxiety disorder and engaged in a manualized, 10-session, skills-
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based treatment program. Outcome was determined according to diagnostic status as well as
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17 continuous symptom measures. Analyses compared results between four groups: no comorbidity,
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comorbid anxiety disorders, comorbid externalising disorders, comorbid mood disorders. All
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22 analyses were intent-to-treat.
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25 Results: Children with comorbid depression were the least likely to be free of their primary anxiety
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diagnosis at the end of treatment and follow-up. According to both child and maternal reports,
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30 symptoms of anxiety reduced similarly over time in all groups, but children with comorbid mood
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32 disorders scored significantly highest at all time points. When examining effects of anxiety treatment
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on comorbid disorders, comorbid mood disorders but not externalizing disorders reduced
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37 significantly over time.
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40 Conclusions: The existence of comorbid disorders does not appear to affect the rate or extent of
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response to skills-based treatment for child anxiety. However, comorbidity has a marked influence
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45 on the end point of treatment. Children with non-anxiety comorbidity, and especially with comorbid
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mood disorders demonstrate greater severity at outset and remain worse following treatment. On
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the positive side, treatment for anxiety disorders also appears to reduce comorbid mood disorders,
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52 although it has less effect on comorbid externalising disorders.
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3 Within current nosological systems for child and adolescent anxiety disorders, comorbidity is
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the rule 1. Up to 80% of young people who meet criteria for a primary anxiety disorder diagnosis,
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8 meet criteria for one or more additional diagnoses, especially among clinical populations. The most
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10 common comorbid disorders are other anxiety disorders, but comorbid mood and externalising
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disorders are also often identified 2. High levels of additional disorders are associated with all of the
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15 anxiety disorders in young people and patterns of comorbidity do not appear to differ markedly
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between anxiety disorders.
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A key consideration, both clinically and theoretically, is whether the existence or type of
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23 comorbid conditions affect the response of anxious young people to intervention. Childhood anxiety
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25 disorders can be treated with good success using medication or skills-based programs 1. Among the
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latter, around 50-60% of children are free of their presenting anxiety disorder immediately after
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30 treatment, increasing to around 65% at follow-up 3. Although several treatment studies have
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examined predictors of response within post-hoc analyses, these have generally failed to identify
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35 consistent predictors, with the most consistent identified influence being parent psychopathology 1.
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37 However, the small samples, strong overall treatment response, and post-hoc analyses have meant
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that identification of predictors of response to psychological treatment for child anxiety has not yet
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45 Clinically there is a common assumption that existence of comorbid disorders complicates
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treatment and reduces treatment efficacy. Within the realm of child anxiety, several studies have
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50 empirically examined this issue e.g., 4, 5-9. In one of the first studies, Kendall and colleagues compared
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52 response to treatment among 173 children aged 8-13 years with primary anxiety disorders 7. The
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sample was divided into three groups for analyses: those with only a single (anxiety) disorder, those
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57 with two or more anxiety disorders and those with comorbid externalising disorders. No significant
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differences were identified between groups on treatment response. A similar study of children aged
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7 to 16 years with primary anxiety disorders, used the same group breakdown and also failed to
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following treatment or 12 months later 9. In a comprehensive review of the extant literature,
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7 Ollendick and colleagues concluded that the existence of comorbid conditions does not appear to
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9 influence the response to treatment for children with primary anxiety disorders 10.
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Despite these conclusions, three studies have interpreted their results differently. In one of
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15 the earlier studies, data from 106 anxious children combined from two treatment trials were
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17 dichotomized to reflect treatment success vs treatment failure 11. The two groups did not differ in
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the presence of any comorbid disorder, nor in the presence of comorbid externalising disorders, but
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22 five of seven children with comorbid depression were treatment failures. This prompted the authors
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to conclude that comorbid depression could specifically undermine intervention for child anxiety.
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27 The conclusion was further supported by the higher scores among treatment failures on the Child
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29 Depression Inventory, although these scores did not predict response to treatment as reflected in
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change on the clinician's rating of diagnostic severity. A small study of young people specifically with
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34 OCD (N=40) similarly demonstrated fewer treatment responders among those with non-anxiety
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36 comorbidity (5 of 9) relative to those without comorbidity (18 of 19) 12. More recently, an
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examination of response to treatment among 124 children aged 8-12 years demonstrated worse
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41 outcomes among those with comorbid disorders than among those with only a single anxiety
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43 disorder 13. Importantly, this effect was apparent when treatment response was determined via
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46 diagnosis-free rates or clinically significant change (end-point determinants) but not when response
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48 was assessed through reliable change (a measure of change over time).
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A somewhat different but related issue is whether a treatment program aimed at anxiety
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54 disorders can influence comorbid conditions. Several studies have shown that treatment for one
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56 anxiety disorder can reduce other anxiety disorders 4, 5, 7. This is hardly surprising given the overlap
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between anxiety disorders and the fact that many anxiety treatment programs are generic. A more
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interesting question is whether treatment for anxiety reduces non-anxiety comorbidity. Few studies
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treatment for anxiety, but the reduction in oppositional disorder at the end of treatment did not
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7 reach significance. Similarly, only 32% of externalising disorders had remitted at the end of
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9 treatment for anxiety in another report from this group, although 68% had remitted 7 years later 8.
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Several trials assessing treatment for childhood PTSD have shown small to moderate effect size
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14 reductions in symptoms of depression and externalising, but almost none have assessed comorbid
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16 diagnoses 14.
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In summary, the majority of research that has examined the effect of comorbidity on
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22 response to treatment by evaluating change across time on continuous measures has failed to
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indicate that comorbid conditions significantly reduce treatment efficacy for anxiety in young
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27 people. In contrast, a few studies that have determined treatment endpoints in a categorical manner
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anxiety comorbidity might affect the final point reached within treatment. Few studies have
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34 examined effects of anxiety treatments on non-anxiety comorbid conditions, but effects on
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externalising disorders do not appear to be as extensive as they are for anxiety disorders. At present,
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the research into these vital clinical issues is affected by key limitations. First, very few studies have
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41 examined treatment response according to both change and endpoint. Further, sample sizes have
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not been large in the context of demonstrating moderation effects. The numbers of children in most
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46 studies who demonstrated non-anxiety comorbidity have been particularly small, ranging from as
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48 few as 9 up to a maximum of 44. The small samples have not allowed more detailed evaluation of
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the influence of comorbid mood disorders versus externalising disorders. The restriction among
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53 some samples to children aged 14 years or less also limits the number of participants with comorbid
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The current study examined data from children treated in our specialist anxiety unit over the
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2 past decade, allowing examination of a large sample of anxious children and adolescents. Treatment
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over this time utilized a consistent package and was aimed at children and adolescents aged from 7
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7 to 17 years. The large sample allowed us to separately examine children with comorbid mood
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disorders and comorbid externalizing disorders.
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19 Participants
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Eligible participants for the study comprised a total of 866 children and adolescents aged
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from 7 to 17 years (plus their parents) who were treated using a standard structured treatment
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27 program at the xxx between 2000 and 2011. Approximately 64% of the children participated in
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29 randomized clinical trials e.g., 15, 16 while the remainder were treated in ongoing clinical services
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32 between trials. In both cases, assessment processes were consistent and all treatment was
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Children were included in the current study if they met Diagnostic and Statistical Manual of
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40 Mental Disorders, 4th ed. DSM-IV; 18 criteria for a diagnosis of any anxiety disorder as their primary
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42 (most interfering) disorder. Exclusions were generally kept to a minimum to maximize external
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validity and primarily reflected conditions requiring urgent assistance (such as severe suicidal
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47 ideation or chronic school refusal) or conditions that might be disruptive to groups (such as
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unmedicated ADHD, severe oppositional defiant disorder across more than one setting, or moderate
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intellectual disability). Diagnoses were assigned based on structured interview (described below).
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54 For the purposes of the current study children were excluded from analyses if they met criteria for a
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comorbid disorder other than anxiety, mood, or externalising (n=86) (primarily learning disorders,
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59 Asperger's Disorder, or sleep disorders). This left a total of 780 participants (372 girls, 408 boys,
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mean age 10.7 years, s.d. = 2.6 years) who met criteria for the following principal diagnoses:
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specific phobia (6.9%), obsessive compulsive disorder (6.6%), other anxiety (2%).
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8 The sample was divided into four groups based on comorbidity. Because many children had
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mood disorders was too small for meaningful analysis, an hierarchical system was used as follows: 1)
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15 no comorbid disorders (N = 76; 9.7%); 2) comorbid anxiety disorders only (N = 426; 54.6%), 3)
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comorbid externalizing disorders (most of these children also had comorbid anxiety disorders) (N =
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134; 17.2%), and comorbid mood disorders (most of these children also had comorbid anxiety and
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22 28 (19%) had comorbid externalising disorders1) (N = 144; 18.5%). Demographic comparison
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between the groups is presented in Table 1.
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Measures
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31 Diagnoses: Diagnoses were assigned by graduate students in clinical psychology or qualified clinical
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psychologists following structured interview with the Anxiety Disorders Interview Schedule for DSM-
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IV, Parent and Child versions 19. Interviewers received training to criterion and research from our
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38 clinic overlapping with the current sample has demonstrated inter-rater agreement of kappa = 1.00
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for an overall diagnosis of anxiety disorder, and ranging from .68 to .93 across the major anxiety
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43 disorders 20. Diagnoses and clinician-rated severity of each diagnosis (CSR; on a scale of 0 to 8) were
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45 based on composite parent and child report. A CSR of four or more indicated that diagnostic criteria
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were met at a clinically interfering level. The interview was repeated at post-treatment and follow-
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50 up, allowing both the absence of diagnosis and CSR to be reported as outcomes.
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53 Anxiety symptoms: To measure symptoms of anxiety, children completed the Spence Children’s
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Anxiety Scale SCAS: 21 and their parents completed the parallel parent version SCASp: 22. These
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58 measures contain 38 anxiety items that all load on a single higher order scale, with a range from 0 to
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114. Internal consistency (alpha = .92) and 6-month retest reliability (alpha = .60) for both total
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reports from mothers are presented in the current paper.
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8 Negative thinking: Children completed the Children’s Automatic Thoughts Scale CATS: 23, a measure
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10 of children’s negative thoughts and beliefs. The measure contains four subscales, social threat (alpha
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= .85), physical threat (alpha = .92), failure and loss (alpha = .92), and hostility (alpha = .85). The
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15 measure also has good retest reliability over 3 months (alphas = .68-.77) and the various subscales
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each discriminate between relevant forms of child psychopathology (Schniering & Rapee, 2002). For
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the current study total scores were used to provide a measure of general negative thinking. This has
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22 a total of 40 items with a range from 0 to 160.
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Externalizing symptoms: Across the decade, two different measures of externalizing symptoms were
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used in our Centre at different times. Approximately 24% of mothers completed the parent report
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30 form of the Child Behavior Checklist CBCL: 24. This widely used measure of child psychopathology
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provides subscales for internalising and externalising symptoms. Given our more specific measure of
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35 anxiety (described above), only the externalising subscale is reported in the current study. The
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Questionnaire SDQ: 25. This measure provides a briefer but very similar measure to the CBCL and
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42 produces several subscales. To produce a measure of externalising symptoms for the current study,
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we combined the conduct problems, hyperactivity, and peer problems subscales. Children's scores
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on the externalizing scales of the CBCL or SDQ were standardised across the sample and across time
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49 points (thereby allowing examination of changes across time) and results for the standard score are
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reported.
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Treatment
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