The impact of behaviour problems on caregiver stress in young people with autism spectrum disorders

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1 172 Journal of Intellectual Disability Research VOLUME 50 PART 3 pp MARCH 2006 doi: /j x Blackwell Science, LtdOxford, UKJIRJournal of Intellectual Disability Research Blackwell Publishing Ltd, Original ArticleProblem behaviour and caregiver stressl. Lecavalier et al. The impact of behaviour problems on caregiver stress in young people with autism spectrum disorders L. Lecavalier, S. Leone & J. Wiltz Nisonger Center and Department of Psychology, Ohio State University, Columbus, Ohio, USA Abstract Background The purpose of this study was to examine the correlates of caregiver stress in a large sample of young people with autism spectrum disorders (ASDs). Two main objectives were to: (1) disentangle the effects of behaviour problems and level of functioning on caregiver stress; and (2) measure the stability of behaviour problems and caregiver stress. Methods Parents or teachers of 293 young people with ASDs completed measures of stress, behaviour problems and social competence. Parents also completed an adaptive behaviour scale. Eighty-one young people were rated twice at a 1-year interval. Results Parents and teachers did not perfectly agree on the nature and severity of behaviour problems. However, both sets of ratings indicated that behaviour problems were strongly associated with stress. Conduct problems in particular were significant predictors of stress. Adaptive skills were not significantly associated with caregiver stress. Parental reports of behaviour problems and stress were quite stable over the 1-year interval, much more so than teacher Correspondence: Luc Lecavalier, Ohio State University, Nisonger Center, 305 McCampbell Hall, 1581 Dodd Drive, Columbus, OH, , USA ( lecavalier.1@osu.edu). reports. Parent ratings suggested that behaviour problems and stress exacerbated each other over time. This transactional model did not fit the teacher data. Conclusion Results of this study suggested that it is a specific group of externalized behaviours that are the most strongly associated with both parent and teacher stress. Results were discussed from methodological and conceptual perspectives. Keywords autism, behaviour problems, parent stress, pervasive developmental disorder, teacher stress, transactional model Introduction Caregivers of children with developmental disabilities face unique challenges. Families with children with developmental disabilities experience more negative psychological outcomes than families with typically developing children (Baker et al. 1997; Hauser-Cram et al. 2001). For instance, they experience additional financial burdens, more restrictions in social activities, and heightened parental stress. As a group, parents of children with autism seem to experience even more stress than parents of children with other disabilities (Donovan 1988; Dumas et al. 1991). Several studies have reported severity of

2 173 autistic symptomatology to be positively associated with parental stress (Bebko et al. 1987; Konstantareas & Homatidis 1989; Freeman et al. 1991; Szatmari et al. 1994; Kasari & Sigman 1997; Hastings & Johnson 2001). Investigators have defined the severity of autism by a number of different child characteristics such as hyperirritability, self-injurious behaviours, cognitive level, or the presence of seizures or dysmorphic features. In many such studies, severity of autism has been defined by the composite score on a parent or clinician-completed rating instrument, usually the Autism Behavior Checklist (ABC; Krug et al. 1980) or the Childhood Autism Rating Scale (CARS; Schopler et al. 1980). Scores on these instruments (and others) can be affected by the presence of behaviour problems and by the level of functioning of the child, thereby clouding the association between specific child characteristic and feelings of parental distress. For instance, the ABC contains items measuring temper tantrums, impulsivity, self-injurious behaviours and destructiveness. The CARS contains items measuring overactivity, fears and anxieties, and affective responses. Some authors have argued or reported that behaviour problems are the most important predictors of parental stress in children with disabilities. Baker and colleagues found this relationship to be true in young children with developmental delays (Baker et al. 2002, 2003). In their longitudinal study of 3-yearolds with and without disabilities, Baker et al. (2002) reported that when the influence of behaviour problems on parenting stress was accounted for, mental development explained no additional variance. Similarly, Orsmond et al. (2003) found evidence of a bidirectional relationship between aspects of mother s well-being and some types of behaviour problems of their children with intellectual disability (ID) (now adults; average age of 40 years). Individuals with autism spectrum disorders (ASDs) were not included in either longitudinal study. Behaviour problems are frequently reported in young people with ASDs (Tonge & Einfeld 2003; Gadow et al. 2004, 2005; Lecavalier 2005). Surprisingly, the relationship between behaviour problems and parental stress has received little attention in this population. The study by Hastings (2003) was the only one we located that actually included an instrument to measure behaviour problems that was intended for children with disabilities. In this study, teachers completed the Developmental Behaviour Checklist (DBC; Einfeld & Tonge 2002) for 18 children with autism and scores were correlated with selfreport measures of maternal and paternal stress, anxiety and depression. Correlations between total DBC score and stress scores were 0.58 and 0.49 for mothers and fathers respectively. Teacher burnout was recently associated with behaviour problems in children with ID (Hastings & Brown 2002). In this study, which included some children with ASDs, child behaviour problems were associated with emotional exhaustion among 27 teachers and 28 teaching assistants who worked in special education schools. Interestingly, teacher stress in relation to children with ASDs has received virtually no attention in the literature despite that the most significant and universal teaching stressors are related to interactions with students (see Tellenback et al. 1983; Greene et al. 1997). Between 20% and 40% of educators report teaching to be highly stressful (Kyriacou & Sutcliffe 1978; Cockburn 1996). Although such evidence is based on research with general educators, one might expect teacher stress to be as prevalent (if not more so) for educators of children with ASDs. The purpose of the investigation reported here was to examine the correlates of caregiver stress in a large sample of children and adolescents with ASDs. Specifically, we were interested in disentangling the effects of level of functioning and behaviour problems on caregiver stress. We were interested in examining these relationships in both parents and teachers. We hypothesized that behaviour problems would be associated with caregiver stress, whereas level of functioning would not. Further, we hypothesized that this relationship would hold regardless of the level of functioning of the child or the type of rater (parent or teacher). To our knowledge, this is the first study to examine the relative contribution of behaviour problems on caregiver stress in an ASD population with both parent and teacher ratings. A second objective of the study was to examine the stability of behaviour problems and caregiver stress over time. This was accomplished by obtaining ratings on a sub-sample of children twice at a 12-month interval. As reported by Baker et al. (2003), we hypothesized that behaviour problems and caregiver stress would be stable across time. The repeated measurement would also allow us to examine a transac-

3 174 tional model of stress between caregiver and child behaviour, a less studied aspect in developmental disabilities. Simply put, a transactional model of stress stipulates that child and caregiver behaviours impact each other. We hypothesized that behaviour problems and stress would exacerbate each other over the 1-year period. Compared with most other studies of caregiver stress, three novel variations were introduced. First, level of functioning was measured with an adaptive behaviour scale. Whereas IQ tests provide estimates of optimal performance, adaptive behaviour measures are performance-based. Second, behaviour problems were measured with an instrument designed for young people with developmental disabilities, the Nisonger Child Behavior Rating Form (NCBRF; Aman et al. 1996; Tassé et al. 1996). The NCBRF has parent and teacher versions and contains two sub-scales that measure prosocial behaviours. Finally, given that parent characteristics have been found to be moderating factors in stress responses (e.g. Fong 1991; Hastings & Johnson 2001), we examined parent and teacher s familiarity with applied behaviour analysis (ABA) and ASDs. Method Participants The participants were the parents and teachers of 293 children and adolescents with ASDs. Two-hundred and forty-three young people with ASDs were boys (83%) and 272 were Caucasian (93%). The average age was 9.0 years (SD = 3.4; range 3 18) and 64% of the sample obtained composite scores on the Scales of Independent Behavior Revised (SIB-R, Bruininks et al. 1996) in the range of ID (i.e. at or below 70). Grade levels were as follows: 35% preschool or kindergarten; 24% grades 1 through 3; 13% grades 4 through 6; 8% grades 7 through 12; and 20% unspecified or none. The disabilities identified by the Individualized Education Plan (IEP) were as follows: 69% autism; 12% preschooler with a disability, 12% had another disability listed such as other health impaired or multiple disability, and 8% had this information missing. Eighty-six per cent of the parent ratings were provided by mothers. The average age of parents was 39.9 years (SD = 7.1) and 48% graduated from college. Ninety-three per cent of teacher ratings were provided by female respondents. The average age of teachers was 37.5 years (SD = 10.6) and the average teaching experience was 10.2 years (SD = 9.0). Fiftythree per cent of teachers had a Baccalaureate and 47% had a Master s degree. Ninety-two per cent of ratings were completed by primary or supporting instructors and 92% were completed by raters who knew the students they were rating for more than six months. Measures Parental Stress Index-Short Form The Parental Stress Index-Short Form (PSI-SF; Abidin 1995) is designed to identify potentially dysfunctional parent child systems. It is a direct derivative of the full length PSI and contains 36 items distributed among three sub-scales: Parental distress, Dysfunctional interaction, and Difficult child. Items are rated on a 5-point scale ranging from Strongly agree to Strongly disagree. The correlation between the 101- item PSI and the PSI-SF is 0.94 (Abidin 1995). In the current sample, alpha coefficients for the three sub-scales ranged from 0.82 to 0.89 and was 0.93 for the total score. According to normative data, 57.7% of parents in the current sample scored in the clinically significant range. Index of teaching stress The index of teaching stress (ITS; Greene et al. 1997) is designed to assess the level of teacher distress in relation to a specific child. It contains 90 items rated on a 5-point Likert scale ranging from Never distressing to Very distressing. Part A contains 47 items assessing the degree to which teachers find 47 behaviour problems stressful or frustrating. Part B contains 43 items assessing the impact of a particular student on the teaching process as well as the teachers selfefficacy, perceptions of support, and satisfaction from teaching. Only part B was completed in the current study. Example of items in this section include: This child does things that bother me a great deal, Having this student in my class is frustrating, and I do not enjoy teaching this child. The items of part B are distributed among four sub-scales: Self-doubt, Loss of satisfaction, Disrupts teaching, and Frustrating parent. In the current sample, alpha coefficients for

4 175 the four sub-scales ranged from 0.84 to 0.93 and was 0.96 for the total score. Nisonger Child Behavior Rating Form The NCBRF (Aman et al. 1996; Tassé et al. 1996) is a rating scale designed to assess social competence and behaviour problems in children and adolescents with developmental disabilities. There are parent and teacher versions of the instrument. Both versions are identical in terms of content, but have slightly different factor structures. The 10 social competence items are rated on a 4-point Likert scale ranging from Not true to Completely or always true and distributed on two sub-scales: Compliant/calm and Adaptive/social. The 66 problem behaviour items are also rated on a four-point Likert scale ranging from Did not occur or was not a problem to Occurred a lot or was a serious problem. There are 60 items from the parent version and 62 items from the teacher version that are distributed among six sub-scales: Conduct problem, Insecure/anxious, Hyperactive, Self-injury/stereotypic, Self-isolated/ritualistic, and Overly sensitive (parent version) or Irritable (teacher version). With the exception of the Overly sensitive/irritable subscales, both versions share very similar sub-scale content. The NCBRF has proven to have good construct validity in an ASD population; factor loadings and internal consistencies were acceptable for social competence and problem behaviour sub-scales of both parent and teacher forms (Lecavalier et al. 2004). Scales of Independent Behavior Revised The SIB-R (Bruininks et al. 1996) is a comprehensive measure of adaptive behaviour. It contains 14 subscales distributed into four areas: (1) motor skills; (2) social and communication skills; (3) personal living skills; and (4) community living skills. Each sub-scale has between 16 and 20 items ordered in ascending level of developmental difficulty and rated on a 4- point Likert scale ranging from Never or rarely even if asked (0) to Does very well always or almost always without being asked (3). The Broad independence score is a measure of overall adaptive behaviour or functional independence and is based on the average of the four different areas of adaptive behaviour. The SIB-R provides norms from early infancy to adulthood. In the current sample, internal consistencies for the 14 sub-scales ranged from 0.87 to 0.96 (average = 0.92). Familiarity with applied behaviour analysis and familiarity with autism spectrum disorders These two measures were developed in the context of a larger state evaluation project (Hammer & Lecavalier 2003). They contain six items each and measure familiarity, experience, and exposure to ABA and ASD. Items are rated on a 5-point Likert scale ranging from Strongly disagree to Strongly agree. Example of items include I am familiar with ABA and behaviour modification procedures (or ASD) and I have read a great deal on ABA/behaviour modification (or ASD). Scores were normally distributed and alpha coefficients varied between 0.84 and 0.88 for parent and teacher responses to both instruments. Procedure Data were collected in 37 school districts across Ohio over a 2-year period as part of larger state evaluation project (see Hammer & Lecavalier 2003; Lecavalier et al. 2004; Lecavalier 2005). The objective of this project was to identify variables associated with successful school models for students with ASDs. Data were collected from parents and teachers via questionnaires on classroom environments, school resources, and on several areas of student functioning. To be included in the current study, students needed to be aged between 3 and 18 years and receiving educational services for ASDs. They were not chosen on the basis of any demographic variables such as level of functioning, behaviour, or academic functioning. Rather, project coordinators from each district, consisting mostly of directors of special education programmes or school psychologists, selected between five and 20 students from their rosters, depending on the size of the school district. Investigators held eight regional meetings over the 2-year period with representatives of school district, parents and teachers to explain the purpose of the project and the completion of the different instruments. They also offered technical assistance in the completion of instruments. The SIB-R was completed as a checklist by parents only. It is designed to be administered in an interview

5 176 format, but checklist administration is considered acceptable under certain circumstances (Bruininks et al. 1996). In addition to the regional meetings and technical support offered throughout, a summary sheet with instructions and examples was provided for accurate completion of the SIB-R. A doctoral level graduate student in psychology verified every completed SIB-R for anomalies in responding (e.g. not giving credit for skills that were obviously mastered such as crawling for an individual who walks, runs, and rides a bicycle). Separate packets for teachers and parents were mailed to the school. Project coordinators were instructed to send parent packets in the school bag of selected students. In all, 293 young people with ASDs were rated; 253 were rated by parents, 198 by teachers, and 158 by both informants. There were no statistical differences in terms of problem or prosocial behaviours, adaptive skills, gender distribution, or chronological age between the students who were rated by one or two different raters. A subset of children was rated twice at a 1-year interval by the same raters (50 by parents and 47 by teachers). These children were rated on the basis of the availability and willingness of the raters to participate. In order to decrease rater bias, only children with the same teacher were considered for the second set of ratings. Procedures, instruments and demographic characteristics of the students and raters were very much the same as those obtained for the total sample during the initial ratings. There were no statistical differences in terms of problem behaviours, social competence, adaptive skills, gender distribution or chronological age between the students who were rated once and those who were rated twice. Data analysis Adaptive behaviour raw scores were transformed to W scores for correlational analyses. The W scale is a special transformation of the Rasch ability scale and is centred on a value of 500, which has been set to approximate the average performance of a 10-year, 8- month old child. It is an equal interval measurement scale, making it better suited for correlational analyses (see Bruininks et al. 1996). Given the large number of correlations, one would expect to find significant associations on the basis of chance alone. In order to reduce the probability of type I error, only correlations with significance levels below 0.01 were considered meaningful. For interrater and test-retest data, paired-sample t- tests and intraclass correlation coefficient (ICC) were calculated. The ICC was estimated with a two-way mixed model and an absolute agreement. It is the single measure ICC that is reported. Parent and teacher agreement on the NCBRF was calculated at the sub-scale level on common items of both versions (both versions contain 85% common items). Analyses were not conducted on the sixth sub-scale (Overly sensitive for parents and Irritable for teachers) because fewer than 40% of the items were common to both versions. Data were analyzed with the Statistical Package for Social Sciences (SPSS) for Windows, version Results Parent and teacher agreement on the Nisonger Child Behavior Rating Form Cross-informant agreement was estimated on the 158 children who had been rated by both parents and teachers. The average time between ratings was 9.4 days (range 0 39; SD = 9.0). Table 1 shows means, SDs, t-values and ICCs for the seven NCBRF sub-scales and total score. There was no significant difference between parent and teacher ratings on any of the seven sub-scales. ICCs ranged from 0.16 to 0.57 (average value = 0.33) and was 0.28 for the total score. The only two correlations that were not significant at the P < 0.01 level were the Compliant/calm and Self-isolated/ritualistic sub-scale scores. Parent ratings Analyses were first conducted on parent characteristics in order to determine whether any of them were associated with stress. Parent s age, education level (college graduate or not) and familiarity with ABA and ASDs were not statistically associated with stress. Child s gender and chronological age were not associated with parental stress. Table 2 shows the correlations between the total stress score and subscale and total scores of the NCBRF and SIB-R. All eight NCBRF sub-scale scores were significantly associated with stress. All scores were statistically associated at the P < level, with the exception

6 177 Table 1 Means, SD s, t-values and ICCs for parent and teacher ratings on the NCBRF (n = 158) NCBRF sub-scales Parent Teacher t-value ICC Compliant/calm 7.2 (2.4) 7.9 (3.1) Adaptive/social 4.9 (2.1) 4.9 (2.5) * Conduct problem 7.8 (6.3) 7.7 (7.1) * Insecure/anxious 5.2 (6.1) 4.4 (5.1) * Hyperactive 10.2 (5.5) 9.4 (5.5) * SIB/stereotypy 2.6 (3.4) 2.6 (3.6) * Self-isolated/ritualistic 6.5 (4.5) 6.7 (4.7) Total behaviour problem 49.6 (25.0) 45.0 (26.0) * ICC, intraclass correlation coefficient; NCBRF, Nisonger Child Behavior Rating Form; SIB, Scales of Independent Behavior. *P < Table 2 Spearman ranked correlation coefficients between PSI-SF total score and NCBRF and SIB-R sub-scale and total scores (n = 253) NCBRF Compliant/calm -0.45** Adaptive/social -0.41** Conduct problem 0.40** Insecure/anxious 0.17* Hyperactive 0.29** SIB/stereotypy 0.28** Self-isolated/ritualistic 0.31** Overly sensitive 0.20* SIB-R Motor skills Social and communication skills -0.19* Personal living skills Community living skills Broad independence PSI-SF, Parental Stress Index-Short Form; NCBRF, Nisonger Child Behavior Rating Form; SIB-R, Scales of Independent Behavior Revised. *P < 0.01; **P < of the Insecure/anxious and Overly sensitive subscales that were associated at the P < 0.01 level. The strongest associations were found with the Compliant/calm and Conduct problem sub-scales, with correlations of and 0.40 respectively. The only adaptive behaviour domain that reached statistical significance was the Social and Communication Domain (r = -0.19; P < 0.01). In an effort to predict parental stress, we conducted a multiple hierarchical regression. In the first step we entered the SIB-R social and communication score, essentially making that score a covariate in the Table 3 Multiple regression predicting parental stress (n = 253) R R 2 Step 1: SIB-R social and communication Step 2: stepwise Compliant/calm Conduct problems Self-isolated/ritualistic SIB-R, Scales of Independent Behavior Revised. analysis. In the second step, all significant NCBRF sub-scales at the P < level were entered in a stepwise fashion. Table 3 shows the results of this regression model. Step 1 (SIB-R score) only accounted for 4% of the variance. The Compliant/ calm, Conduct problems, and Self-isolated/ritualistic sub-scales accounted for an additional 26% of the variance. Turning to the stability of behaviour problems and parental stress, Table 4 shows means, SDs, t-values and ICCs for sub-scale and total scores of the NCBRF and PSI-SF. The only statistical difference in ratings from 1 year to the next was observed on the Adaptive/social sub-scale of the NCBRF with a slight increase in scores at the 12-month follow-up. The ICCs for the eight NCBRF sub-scales varied between 0.63 and 0.89 (average of 0.81) and was 0.82 for the total score. The ICCs for the three PSI-SF sub-scales ranged from 0.63 to 0.81 (average of 0.75) and was 0.79 for the total score. Finally, we conducted two sets of hierarchical multiple regressions to examine the mutual impact that

7 178 Table 4 Means, SD s, t-values and ICCs for parent ratings of problem behaviour and stress (n = 50) Year 1 Year 2 t-value ICC NCBRF Compliant/calm 8.9 (2.8) 9.3 (2.9) ** Adaptive/social 4.7 (2.2) 5.4 (2.2) 2.84* 0.63** Conduct problem 10.4 (7.8) 11.2 (9.1) ** Insecure/anxious 5.7 (6.2) 6.2 (6.8) ** Hyperactive 10.5 (6.1) 10.6 (6.0) ** SIB/stereotypy 2.3 (3.0) 2.4 (3.3) ** Self-isolated/ritualistic 6.3 (4.1) 6.2 (3.9) ** Overly sensitive 4.7 (3.2) 5.0 (3.3) ** Total behaviour problem 44.4 (25.9) 46.6 (28.1) ** PSI-SF Parental distress 29.4 (9.7) 28.8 (8.9) ** Dysfunctional interaction 28.5 (7.6) 29.0 (6.9) ** Difficult child 37.1 (9.0) 36.6 (8.9) ** Total stress 95.0 (22.9) 94.4 (21.0) ** ICC, intraclass correlation coefficient; NCBRF, Nisonger Child Behavior Rating Form; SIB, Scales of Independent Behavior; PSI-SF, Parental Stress Index-Short Form. *P < 0.01; **P < behaviour problems and stress had on each other. In the first multiple regression, the dependent variable was the total stress score at time 2. Step 1 consisted of entering the total stress score at time 1. Step 2 consisted of entering the total problem behaviour score at time 1 as well as changes in behaviour problem scores from time 1 to time 2. The model explained 72% of the variance. Step 1 accounted for 63% of the variance while step 2 accounted for an additional 9% of the variance [(F-value change (2, 46) = 7.89; P = )]. Thus, although stress scores were stable over the 12-month period, the child s initial behaviour problems and change in behaviour problems accounted for additional variance. In other words, behaviour problems exacerbated stress over the 1-year period. In the second multiple regression, the dependent variable was the total problem behaviour score at time 2. Step 1 consisted of entering the total problem behaviour score at time 1. The second step consisted of entering the total stress score at time 1 and changes in stress scores from time 1 to time 2. This model explained 72% of the variance. The first step accounted for 68% of the variance and the second step accounted for an additional 4% of variance [(F-value change (2, 46) = 3.47; P = 0.04)]. Therefore, although behaviour problems were stable over the 1-year period, the initial stress levels and change in stress levels accounted for additional variance. In other words, stress exacerbated behaviour problems. Teacher ratings Analyses were first conducted on teacher characteristics in order to determine whether any of them were associated with stress. The teacher s age, years of experience, education level (Baccalaureate or Master s), length of time they knew the student, and familiarity with ABA were not associated with stress levels. However, familiarity with ASDs was negatively associated with the total stress score (r = -0.25; P < 0.001). Child s gender was not associated with stress, but, unlike with parent ratings, their chronological age was (r = 0.23; P = 0.001). Table 5 shows the correlations between total stress score and sub-scale and total scores of the NCBRF and SIB-R. The only NCBRF sub-scale that was not associated with stress was the Insecure/anxious subscale; all other scores reached statistical significance at the P < level. As with the parent ratings, the strongest correlations were found with the Compliant/calm and Conduct problems sub-scales, with coefficients of and 0.53 respectively. None of

8 179 the correlations between the total stress score and the SIB-R reached statistical significance. In an effort to predict teacher stress, we conducted a multiple hierarchical regression. In the first step, familiarity with ASDs and age of the student were Table 5 Spearman ranked correlation coefficients between ITS total score and NCBRF and SIB-R sub-scale and total scores (n = 198) NCBRF Compliant/calm -0.45** Adaptive/social -0.27** Conduct problem 0.53** Insecure/anxious 0.08 Hyperactive 0.34** SIB/stereotypy 0.33** Self-isolated/ritualistic 0.35** Irritable 0.44** SIB-R Motor skills Social and communication skills Personal living skills Community living skills Broad independence ITS, index of teaching stress; NCBRF, Nisonger Child Behavior Rating Form; SIB, Scales of Independent Behavior; SIB-R, Scales of Independent Behavior Revised. **P < entered. In the second step, all NCBRF sub-scales that were significantly associated with stress at the P < level were entered in a stepwise fashion. As can be seen in Table 6, step 1 accounted for 9% of the variance and step 2 accounted for an additional 34% of variance. The Conduct problems, Irritable, and Self-isolated/ritualistic sub-scales were retained in the second step. Turning to the stability of behaviour problems and teacher stress, Table 7 shows means, SDs, t-values and ICCs for sub-scale and total scores on the NCBRF and ITS. None of the t-values reached statistical significance. The ICCs for the eight NCBRF sub-scales varied between 0.54 and 0.70 (average of Table 6 Multiple regression predicting teacher stress (n = 198) R R 2 Step 1: age, familiarity ASD Step 2: stepwise Conduct problems Irritable Self-isolated/ritualistic ASD, autism spectrum disorder. Table 7 Means, SD s, t-values and ICCs for teacher ratings of problem behaviour and stress (n = 47) Year 1 Year 2 t-value ICC NCBRF Compliant/calm 8.6 (2.6) 8.5 (3.0) ** Adaptive/social 7.1 (3.0) 7.2 (3.0) ** Conduct problem 5.4 (5.4) 5.4 (5.1) ** Insecure/anxious 5.0 (5.7) 6.1 (5.3) ** Hyperactive 6.7 (3.9) 7.6 (5.2) ** SIB/stereotypy 3.5 (3.7) 4.0 (4.2) ** Self-isolated/ritualistic 6.4 (3.9) 7.3 (4.9) ** Irritable 5.3 (4.1) 5.4 (4.7) ** Total behaviour problem 35.8 (17.3) 39.2 (22.4) ** ITS Self-doubt 27.4 (7.3) 29.2 (9.9) * Loss of satisfaction 18.6 (5.4) 20.0 (6.4) Disrupts teaching 11.8 (3.9) 11.8 (5.0) ** Frustrating parent 8.5 (3.4) 9.3 (3.7) ** Total stress 35.8 (17.3) 39.2 (22.4) * ICC, intraclass correlation coefficient; NCBRF, Nisonger Child Behavior Rating Form; SIB, Scales of Independent Behavior; ITS, index of teaching stress. *P < 0.01; **P <

9 ) and was 0.68 for the total score. The ICCs for the four ITS sub-scales ranged from 0.25 to 0.67 (average of 0.44) and was 0.37 for the total score. Finally, two sets of multiple hierarchical regressions were conducted to examine the mutual impact that behaviour problems and teacher stress had on each other. These analyses were conducted in the same manner that the parent ratings were analyzed. In this case, only 21% of the variance was accounted for by the first model (where stress scores at time 2 were the dependent variable) and 54% of the variance was accounted for by the second model (where problem behaviour scores at time 2 were the dependent variable). Furthermore, stress and problem behaviours scores at time 2 did not contribute any additional variance in their respective models. In other words, there was no evidence that behaviour problems exacerbated teacher stress when prior levels of stress were accounted for, nor was there evidence that stress exacerbated problem behaviours when prior levels of behaviour problems were controlled for. Discussion Parent and teacher ratings clearly indicated that behaviour problems were more associated with stress than any other child or caregiver characteristic measured. Thus, our first hypothesis was supported. Cohen (1988) suggested that correlations of 0.1 represent small effects, 0.3 moderate effects, and 0.5 large effects. According to these guidelines, most parent and teacher NCBRF sub-scales were correlated with stress with moderate to large effect sizes. Smaller, but significant effects were found for parent and teacher ratings on the Insecure/anxious sub-scale and parent ratings on the Overly sensitive sub-scale. Conduct problems and lack of prosocial behaviours were the most strongly associated with caregiver stress. These sub-scales are quite similar in that they both refer to disruptive and rule-breaking behaviours. For instance, the items Defiant, Disobedient, and Physically attacks people are found on both versions of the Conduct problems sub-scale and the items Accepts redirection, Follows rules, and Resisted provocation, was tolerant are found on both versions of the Compliant/calm sub-scale. The bulk of explained variance in both multiple regressions was also associated with these disruptive and rule-breaking behaviours. The Irritable sub-scale was also retained in the regression model for teachers. Examples of items on this sub-scale include Easily frustrated, Explosive and Temper tantrums. Of note is the fact that these items were associated with the Conduct problems sub-scale in the Lecavalier et al. (2004) factor analysis of the NCBRF. Although the majority of variance in the multiple regressions was explained with disruptive and rulebreaking behaviours, the Self-isolated/ritualistic subscale was part of the final regression model. Items from this sub-scale common to both versions include Shy, Rituals, Isolates-self, and Odd repetitive behaviours and could be viewed as core features of autism. The fact that these sub-scales were retained in the stepwise regression means that they contributed unique variance. The fact that they were retained last means that they contributed much less variance than the other sub-scales. These findings refine the few studies on parental stress in autism that have taken problem behaviours into consideration. For instance, Hastings (2003) reported associations between parent stress and total DBC scores based on teacher ratings. Other studies only measured specific problem behaviours such as physical aggression, self-injurious behaviour and restlessness (Konstantareas & Homatidis 1989; Freeman et al. 1991). The similarity of correlations across parent and teacher ratings is notable given that different stress measures were used and that both versions of the NCBRF have slightly different factor structures. This occurred even though raters did not perfectly agree on the nature and severity of behaviour problems. In other words, parents and teachers agreed that certain behaviour problems were more stressful than others even though they didn t necessarily agree on the absolute presence and severity of these behaviours. According to Cichetti (1994), the level of clinical significance for interrater reliability is poor when the ICC is below 0.4; fair when it is between 0.4 and 0.59; good when it is between 0.60 and 0.74; and excellent when it is above Only the Insecure/ anxious and SIB/stereotypy sub-scales had ICCs above 0.4. The fact that the t-values were not statistically significant indicates random disagreement between raters rather than a systematic tendency for one rater to provide ratings in one direction. These results are similar to those reported by Tassé & Lecavalier (2000) with the same instrument on a

10 181 sample of children with ID. They are also similar to the average correlation reported in Achenbach et al. (1987) meta-analysis of cross-informant agreement. The less than perfect agreement should not be misinterpreted as a lack of validity. Instead, it can be explained by several factors, including differential patterns of medication use, different baseline effects and different environments. Our second hypothesis was supported for parents only. Indeed, parent reports of behaviour problems and stress were quite stable over the 12-month period. Stability was indicated by very high ICCs and only one change in group averages. The data also suggested that behaviour problems and stress exacerbated each other, which is similar to the findings reported by Baker et al. (2003) in young children with and without developmental delays. Teacher ratings revealed a different pattern, however. The ICCs for the eight NCBRF sub-scales, though indicative of stability, were not as high as those obtained for parent ratings. A major difference between parent and teacher results lay in the stability of stress scores. Unlike parents, the ICCs for ITS sub-scales and total scores ranged from poor to fair according to the guidelines proposed by Cichetti (1994) and there was no evidence to support a transactional model of stress. It should be noted that despite the large sample size, the teacher analyses were based on a smaller sample which increases the probability of Type II errors because of diminished power. However, there are several lines of reasoning to support the results that we obtained. For instance, unlike parents, teachers only spend a finite number of hours with the children. Furthermore, there might have been more changes in the school environment than at home (e.g. different students or aides in the classroom at follow-up). Finally, as a group, teachers probably have more training, resources and experience with children with ASDs and behaviour problems than parents. There was indeed a small but significant correlation between self-reported familiarity with ASDs and stress in teachers that was not observed in parents. This possible training benefit for teachers agrees with the assertion of Jennett et al. (2003) that teachers may benefit from knowledge of autism treatment philosophy. These findings can refine multivariate models of caregiver stress. Most studies of parental stress have been conducted with an ABCX model of stress, where X is stress, the outcome variable, and A represents child characteristics (the stressors) that are moderated by B parental resources such as socioeconomic status or social network and C cognitions such as belief systems and coping styles. The results of this study suggest that the child characteristics most strongly associated with both parent and teacher stress may be a specific group of externalized behaviours. These findings are encouraging in that externalized behaviour problems of this sort are amenable to behavioural and pharmacological interventions. Finally, a word on methodological strengths and limitations of the study. One strength was the large and heterogeneous sample of raters and young people with ASDs. They were non-referred children with a variety of ASDs and they were recruited from a range of urban and rural areas across a large catchment area. Unfortunately, the cost of this larger sample size was a loss of diagnostic specificity. Without evaluating every child individually, it is impossible to confirm with certainty who met the diagnostic criteria for Autistic Disorder, Asperger s Disorder, or a Pervasive Development Disorder (PDD) not otherwise specified. However, given the context of the study, we do feel confident that all participants had some type of ASD (school districts in Ohio have been reluctant to offer educational services without a psychiatric diagnosis). The choice of instruments to assess child characteristics is also worth discussing. The NCBRF was developed for people with developmental disabilities, validated on a population with ASDs, and contains prosocial behaviours. Adaptive behaviour measures like the SIB-R provide an estimate of the behaviours a person actually engages in instead of providing an estimate of their intellectual potential. A great number of studies have shown that many young people with developmental disabilities possess adaptive skills below their intellectual abilities (e.g. see Zigler & Bennett-Gates 1999). Thus, the use of an adaptive behaviour scale might better approximate level of functioning in relation to the types of burden typically felt by caregivers. The choice of stress measures could be viewed as a strength or a weakness. It is a strength in that both measures were aimed at measuring stress felt towards a specific child. On the other hand, it is impossible to know to what extent other sources might have

11 182 influenced the ratings. The PSI and ITS do not include stresses associated with other life events or life roles. They can only be interpreted as an indication of the stress level derived from the caregiver s interaction with the child. The total stress score was chosen as a variable because it represents the overall level of parenting stress an individual is experiencing and is a combination of stress reported in the areas of parental distress, stresses derived from parent s interactions with the child, and stresses that result from the child s characteristics (Abidin 1995). There is some overlap between the Difficult child sub-scale of the PSI and behaviour problems. In the current sample, the average absolute correlation between the Difficult child and NCBRF sub-scales was 0.40, indicating that variables shared 16% variance. Related to the issue of shared measurement variance is the fact that our relationships only held when the same raters completed all the instruments. Our relationships did not hold up when parent ratings of behaviour problems were correlated with teacher ratings of stress (and vice versa). Along the same lines, the observed relationships were obtained with a sample composed predominantly of female informants. The results might not hold for male informants; some studies have reported that fathers report stress differently from mothers (e.g. see Hastings 2003). Additional research is needed on the fathers and male educators stress. Additional studies are needed to replicate and extend the results presented here. One natural extension is to examine the role of the severity of the core features of ASDs on caregiver stress. Both regression models suggested that some core symptoms might actually contribute to the stress reported by caregivers. Additional research on teacher stress in relation to students with ASDs is also needed. These special educators might be at even greater risk than their peers because of the very nature of the core features of ASDs, the high prevalence of behaviour problems, and because learning is especially challenging. It is important to identify factors which reduce caregiver stress, particularly those factors that are amenable to manipulation. Acknowledgements This research was supported in part by funding from the Ohio Department of Education. The authors wish to thank the project coordinators, teachers and parents for their cooperation. They also wish to thank Martha Tzou, Brighton Hammer, and Kim DiSilvio for their assistance with data management. References Abidin R. R. (1995) Parenting Stress Index Professional Manual, 3rd edn. Psychological Assessment Ressources, Inc., Odessa, FL. Achenbach T. M., McConaughy S. H. & Howell C. T. (1987) Child/adolescent behavioral and emotional problems: implications of cross informant correlations for situational specificity. Psychological Bulletin 101, Aman M. G., Tassé M. J., Rojahn J. & Hammer D. (1996) The Nisonger CBRF: a child behavior rating form for children with developmental disabilities. Research in Developmental Disabilities 17, Baker B. L., Blacher J., Crnic K. A. & Edlebrock C. (2002) Behavior problems and parenting stress in families of three-year-old children with and without developmental delays. American Journal on Mental Retardation 107, Baker B. L., Blacher J., Kopp C. B. & Kraemer B. (1997) Parenting children with mental retardation. International Review of Research in Mental Retardation 20, Baker B. L., McIntyre L. L., Blacher J., Crnic K., Edlebrock C. & Low C. (2003) Pre-school children with and without developmental delay: behavior problems and parenting stress over time. Journal of Intellectual Disability Research 47, Bebko J. M., Konstantareas M. M. & Springer J. (1987) Parent and professional evaluations of stress associated with characteristics of autism. Journal of Autism and Developmental Disorders 17, Bruininks R. H., Woodcock R. W., Weatherman R. F. & Hill B. K. (1996) Scales of Independent Behavior Revised: Manual. Riverside Publishing Company, Boston, MA. Cichetti D. V. (1994) Guidelines, criteria, and rule of thumb for evaluating normed and standardized assessment instruments in psychology. Psychological Assessment 6, Cockburn A. D. (1996) Primary teachers knowledge and acquisition of stress relieving strategies. British Journal of Educational Psychology 66, Cohen J. (1988) Statistical Power Analysis for the Behavioral Sciences, 2nd edn. Erlbaum, Hillsdale, NJ. Donovan A. M. (1988) Family stress and ways of coping with adolescent who have handicaps: maternal perceptions. American Journal on Mental Retardation 92, Dumas J. E., Wolf L. C., Fisman S. N. & Culligan A. (1991) Parenting stress, child behavior problems, and dysphoria

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