Journal of Intellectual Disability Research 125
doi: 10.1111/j.1365-2788.2007.00978.x
volume 52 part 2 pp 125–131 february 2008
Mental health problems in children with intellectual disability: use of the Strengths and Difficulties Questionnaire S. Kaptein,1 D. E. M. C. Jansen,1 A. G. C. Vogels2 & S. A. Reijneveld1,2 1 University Medical Center Groningen, University of Groningen, Department of Health Sciences, The Netherlands 2 TNO – Quality of Life, The Netherlands
Abstract Background The assessment of mental health problems in children with intellectual disability (ID) mostly occurs by filling out long questionnaires that are not always validated for children without ID. The aim of this study is to assess the differences in mental health problems between children with ID and without ID, using a short questionnaire, the Strengths and Difficulties Questionnaire (SDQ). Methods We studied 260 children (6–12 years) selected from special education schools for trainable children (response: 57%). Parents completed the extended Dutch version of the SDQ, questions on background characteristics and on the care provided. A non-ID control group of 707 children (response: 87%) was included to compare mental health problems. Results In total, 60.9% of children with ID had an elevated score on the SDQ, compared with 9.8% of children without ID. Only 45% of the children with ID and an elevated SDQ score had visited a
Correspondence: Dr. D. E. M. C. Jansen, University Medical Center Groningen, University of Groningen, Department of Health Sciences, PO Box 196, Groningen, 9700 AD, Groningen, the Netherlands (e-mail:
[email protected]).
healthcare professional for these problems in the last 6 months. Discussion The SDQ or an adapted version could contribute to the early identification of mental health problems in children with ID. Further research is needed to confirm the validity of the SDQ when used in a sample of children with ID. Keywords children, intellectual disability, mental health problems, Strengths and Difficulties Questionnaire
Introduction People with intellectual disability (ID) are more at risk for health problems than people without ID (Van Schrojenstein Lantman-de Valk et al. 2000; Jansen et al. 2004). Both the prevalence of physical disorders (Van Schrojenstein Lantman-de Valk et al. 1997) and of mental health problems (Holland & Koot 1998) is higher in people with ID than in people without ID. In many cases these mental health problems in people with ID are already present at a young age: estimates of the prevalence of mental health problems in children with ID range from 30% to 60%. The wide prevalence range is, among other things, a result of differentiation in the definition of mental health problems and the
© 2007 The Authors. Journal Compilation © 2007 Blackwell Publishing Ltd
volume 52 part 2 february 2008
Journal of Intellectual Disability Research 126 S. Kaptein et al. • Mental health problems in children with ID
use of different instruments to assess these problems (Einfeld & Tonge 1996b; Linna et al. 1999; Dekker et al. 2002). Two often used instruments for the assessment of mental health problems in children with ID are the Developmental Behaviour Checklist (DBC) and the Child Behaviour Checklist (CBCL) (Einfeld & Tonge 1995; Dekker et al. 2002; Buelow et al. 2003; Koskentausta et al. 2004). The DBC is a 96-item multiple-choice questionnaire administered by parents or teachers that describes emotional and behavioural disturbance in young people with ID (Einfeld & Tonge 1995). The CBCL is a questionnaire consisting of 113 descriptive items that provides a parental report of the extent of a child’s behavioural problems and social competencies. Although both questionnaires have achieved wide acceptance, both the DBC and the CBCL are long questionnaires with 96 and 113 items, respectively. Recently, a short form of the DBC is developed (the DBC-P24). However, this short form is not intended as an instrument for estimating any subscores (Taffe et al. 2007). Next to it, the DBC is not designed for use in young people without ID. Another widely used questionnaire for detecting mental health problems in children is the Strengths and Difficulties Questionnaire (SDQ). The SDQ consists of 25 items subdivided into five scales: emotional symptoms, conduct problems, inattention-hyperactivity, peer problems and prosocial behaviour (Goodman 1997). In several studies, the psychometric properties of the SDQ and the CBCL are compared (Goodman & Scott 1999; Klasen et al. 2000; Van Widenfelt et al. 2003). These studies showed that the SDQ and the CBCL are equally valid for most clinical and research purposes, but that at the same time the SDQ and CBCL also differ in several respects. First of all, certain items of the SDQ are phrased positively in order to increase the questionnaire’s acceptability to respondents. Conversely, comparable items of the CBCL include only negative items (Goodman & Scott 1999). Another difference concerns the SDQ’s impact supplement providing an estimate of burden, which is a part of the diagnostic criteria in child and adolescent psychiatry. It is probable that a combination of symptom and impact scores will be the best indicator of caseness as was the case for the British version of the SDQ
(Obel et al. 2004). One of the most obvious differences, however, lies in the length of the questionnaires. The SDQ has 25 items whereas the CBCL consists of 118 items. Evidently, the advantage of a short questionnaire is that the filling out is less burdensome for the participants to complete. According to Vostanis (2006), there has been almost no research with the SDQ among children with ID. The only evidence comes from a secondary analysis of a national survey of the mental health of 4172 children and adolescents between 5 and 15 years in the UK by Emerson (Emerson 2005; Vostanis 2006). However, in that survey it was unclear whether children had or had not an ID. As a result, Emerson had to combine survey items to identify children who were likely to have ID. In this way, eventually 124 children were operationally defined as having ID. The results of the study of Emerson shows that de SDQ appears to be a very useful measure of mental health problems of children and adolescents with ID. The results also illustrate that children with ID report greater difficulties than their non-ID peers on all subscales except for prosocial behaviour (Emerson 2005). The aim of this study is to investigate whether previous differences between children with and without ID in emotional and behavioural problems, using more time consuming measures, can also be found using a short questionnaire, the SDQ.
Methods Participants and procedure Data were obtained by using a two-stage sample procedure. The primary sampling cluster concerned all primary special education schools for trainable children in the provinces of Groningen and Drenthe. This primary sample was stratified by the moment of receiving a routine visit by the child healthcare physician. Next, all schools who received a routine visit within the next three moments (n = 7) were asked to participate in the study (response 100%). As the name suggests, the visits of the child healthcare physicians were routine and basically without specific reason on that particular moment. Since the chance of receiving a routine visit within the next 3 months was equally for all
© 2007 The Authors. Journal Compilation © 2007 Blackwell Publishing Ltd
volume 52 part 2 february 2008
Journal of Intellectual Disability Research 127 S. Kaptein et al. • Mental health problems in children with ID
schools, the sample can be considered as random, leading to valid population estimates. In the Netherlands the special education schools for trainable children (children with a mild or moderate ID) are attended by children with an IQ < 60 or an IQ of 60–70 and additional difficulties ( Wallander et al. 2006). All parents of children aged 6–12 years attending one of these schools (n = 457) were asked to fill out a questionnaire. If parents did not return the questionnaire, they were sent a reminder. Of the 457 approached parents, 262 participated (57%) (of which two were excluded because their child exceeded the age range). A control group was included to compare problems in behaviour, emotions and relationships in children with ID to those without ID. This non-ID sample was obtained from a previous study that used a two-step sampling procedure. In the first step, a national sample from nine of the 41 Dutch Preventive Child Healthcare (PCH) Services was taken. In the second step, each Service provided a sample of children aged 7–12 years who were invited for routine well-child examinations (Vogels et al. 2005; Reijneveld et al. 2006). The Dutch PCH services provide routine health examinations for the entire population which offers an ideal setting for the early detection of psychosocial problems among children (Brugman et al. 2001; Reijneveld et al. 2004). Next these PCH-services gathered data of children aged 7–12 years old. Thirty-five child health professionals participated in this study. In total, 814 parents and their children were asked to participate in this study, 10% refused to participate and 3% did not return the questionnaire, resulting in a response of 711 children (87%) (Vogels et al. 2005).
respondent thinks the young person has a problem, and if so, enquires further about chronicity, distress, social impairment, and burden for others. Several studies have shown the good reliability and validity of the SDQ in a non-ID population (Goodman & Scott 1999; Smedje et al. 1999; Koskelainen et al. 2000; Goodman 2001; Muris et al. 2003; Van Widenfelt et al. 2003). For the purposes of this study we used the cut-off scores provided by Vogels et al. (2005) for use in Dutch PCH. Regarding care provided parents were asked which healthcare professional their child had visited in the last 6 months because of problems with behaviour, emotions or relationships. Questions on background characteristics concerned sex and date of birth of the child, living situation and severity of the ID.
Analysis First, Cronbach’s Alphas of the (sub)scales were computed for children with ID and without ID. Subsequently, we assessed differences in problems regarding behaviour, emotions and relationships in girls and boys with ID, using independent sample T-tests. Next, we compared differences in these problems between children with and without ID. We computed Cohen’s d effect sizes and performed T-tests. Effect sizes
