Psychometric properties of the Parenting Stress Index

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Journal of Intellectual Disability Research

doi: 10.1111/jir.12053

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Psychometric properties of the Parenting Stress Index with parents of children with autistic disorder L. A. Dardas1 & M. M. Ahmad2 1 Community Health Nursing Department, The University of Jordan/The Faculty of Nursing, Amman, Jordan 2 Clinical Nursing Department, The University of Jordan/The Faculty of Nursing, Amman, Jordan

Abstract Purpose The purpose of this study was to examine the psychometric properties and the theoretical structure of the Parenting Stress Index-short form (PSI-SF) with Jordanian parents of children with autistic disorder. Methods Using a cross-sectional design for data collection, the convenience sample of the study was composed of 184 Jordanian parents of children with autistic disorder. The factor structure for the PSI-SF was examined using confirmatory and exploratory factor analyses. Results We found that the modified three-factor model (30 items) fits the data significantly better than the 36-item model. The results showed that the 12 items of the Parental Distress sub-scale support the original scale structure. However, items in the Parent–Child Dysfunctional Interaction and Difficult Child sub-scales did not show stability in their structure. The results in this study showed that the PSI-SF in its 30-item model has endorsed the necessary validity of the scale with parents of children with autistic disorder. The study provides information on the effects of Arab culture on the validity of PSI-SF. Correspondence: Ms Latefa Ali Dardas, Community Health Nursing Department, The University of Jordan, Amman 11942, Jordan (e-mail: [email protected]).

© 2013 John Wiley & Sons Ltd, MENCAP & IASSID

Conclusion It is recommended to use the new factors structure of the PSI-SF with the 30 items in the studies that intend to examine the stress among parents with children with autistic disorder in the Arab world. Keywords Arabs, autistic disorder, confirmatory factor analysis, Parenting Stress Index, psychometrics

Introduction Stress is an inevitable aspect of human life that affects people differently (Lazarus & Folkman 1984). Parenting stress can be defined as an ‘aversive psychological reaction to the demands of being a parent’ (Deater-Deckard 1998, p. 315). According to Abidin (1995), parenting stress stems from a complex combination that has three sets of factors related to the child, the parent, and the child–parent interactions. Although some parenting stress is considered normal and functional for all parents (Crnic & Greenberg 1990; Deater-Deckard & Scarr 1996), research indicates that parents of children with chronic disabilities are at increased risk of experiencing elevated levels of stress. Indeed, it has been found that raising a child with chronic developmental disability is one of the most significant stressors for the parents (Weiss 1991; Koegel et al. 1992;

Journal of Intellectual Disability Research 2 L. A. Dardas & M. M. Ahmad • Psychometric properties of PSI-SF

Ericzon et al. 2005). Autistic disorder represents not only one of the most severe and pervasive chronic childhood disorders but also, the most complex in its developmental pattern [American Psychiatric Association (APA) 2000]. The disorder affects brain functions, specifically those areas that control social behaviours and communication skills. Thus, affected individuals are characterised by marked impairments in social interaction, delayed and/or stereotyped communication, and restricted or repetitive behaviours and interests (APA). Raising a child with autistic disorder has many inter-mutual influences on parents and their children. It has been found that the complexity and chronicity of autistic disorder can drain the parents’ energy and leave them exhausted, in despair and at risk for many psychosocial problems including elevated levels of stress (Sivberg 2002; Abbeduto et al. 2004; Seltzer et al. 2004). On the other hand, high levels of parental stress can adversely affect the children’s cognitive, language, behavioural and social development (McGlone et al. 2002; Anthony et al. 2005; Farver et al. 2006; Hart & Kelley 2006; Pesonen et al. 2008). What is known about the adverse impacts of autistic disorder on parental stress affirms the need to intervene early and consistently to provide support for those parents. In order to have confidence in the interventions proposed based on the parents’ level of stress, it is necessary to have a wellestablished, reliable and valid measure for parenting stress. One of the most commonly used measures is the Parenting Stress Index-Short Form (PSI-SF; Abidin 1995). The measure has three sub-scales, Parental Distress (PD); Parent–Child Dysfunctional Interaction (PCDI); and Difficult Child (DC) (Abidin). The PSI-SF is considered a valid and reliable measure when used with parents of typically developing children. Indeed, several studies have investigated the psychometric properties of the PSI-SF with parents of typically developing children. While some of these studies have revealed reasonably distinct factor structure for the measures with very good to excellent internal consistencies (e.g. Reitman et al. 2002), other studies failed to support the three-factor structure of the scale (e.g. Whiteside-Mansell et al. 2007; McKelvey et al. 2009). According to Farmer & Peterson (2012), © 2013 John Wiley & Sons Ltd, MENCAP & IASSID

these mixed results could be attributed to the sample characteristics recruited for each study. In particular, they found the differences in the children’s ages as having a potential influence on parental stress ratings. Surprisingly, the PSI-SF scale has been used in many publications that targeted parents of children with autistic disorder. However, psychometric work on this measure has been conducted primarily with samples of healthy children. To date, only one study examined the psychometric properties of the PSI-SF in samples of parents of children with autistic disorder (Zaidman-Zait et al. 2010). In that study, several items in the PCDI and DC sub-scales showed poor functioning. The authors recommended additional research work to examine the factor structure of the PSI-SF in samples of parents of children with autistic disorder. Further, no investigations were made in the Arab world yet. Thus, two main reasons warrant conducting this study: First, two of the PSI-SF sub-scales (PCDI and DC) address the characteristics of children that may be stressful to their parents. However, the characteristics of children diagnosed with autistic disorder differ substantially from those with typical development. Consequently, assuming that the PSI-SF (which was assessed with normative samples) is valid across populations including those with pervasive chronic disabilities may lead to inappropriate explanations. The second reason for conducting this study relies in its population which was in part from the Arab world (Jordanian parents of children with autistic disorder). Arabs are united in a shared culture that is considered substantially different from their western counterparts (Retso 2002). The term culture can be defined as a shared set of traditions, belief systems, and behaviours shaped by history, religion, ethnic identity, language, and nationality (Griffith et al. 2003). Among Arabs, it is an extremely important responsibility to bring children up so that they will reflect well on the family. Arabs tend to give parents much of the credit for their children’s successes and much of the blame for their failures (Nydell 2005). In his review for the recent literature regarding the impact of Arab culture on mental illness and mental health, Fakhr El-Islam (2008) found that Arab cultural beliefs and practices have many influences in shaping the definition, perception, diagnosis, and


management of psychiatric disorders. Recognition of such diversities among cultures is necessary in order to design and conduct valid and reliable research, as well as accurate cross-cultural programs. No investigations regarding the psychometric properties of the PSI-SF have been made in the Arab world in samples of parents of children with developmental disabilities in general and autistic disorder in particular. The purpose of this study was to validate the PSI-SF with Jordanian parents of children with autistic disorder using exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) techniques.

Methods Participants The convenience sample of the study was composed of 184 parents of children with autistic disorder. Parents were included in the study if (1) they had a child under the age of 12 with a clinical diagnosis of autistic disorder made by board-certificated child psychiatrists using the Diagnostic and Statistical Manual of Mental Disorders DSM-IV-TR (fourth edition, text revision), and (2) they were able to read and write in Arabic. Parents were contacted through special education centres licensed to provide educational services for children with autistic disorder. The collection of the data was conducted by the first author over a period of 5 months (March to August 2012). Among the 184 participants, 62% (n = 114) were females (mothers). The mean age for the sample was 37 years (SD ⫾ 7.6) ranging from 21 to 69 years. About 97% (n = 178) of the participants were married. The mean income for the participants’ family was 498 Jordanian Dinar (1 JD = 1.4 US Dollar) ranging from 150 to 1500 JD. In relation to the number of children the participants had, 3.8% (n = 7) had one child, 24.5% (n = 45) had two children, 28.8% (n = 53) had three children, 21.2% (n = 39) had four children, 13.6% (n = 25) had five children, and 8.2% (n = 15) had 6–10 children. All of the participants had only one child diagnosed with autistic disorder. All of the children were clinically diagnosed with autistic disorder from board-certificated child psychiatrists using the DSM-IV criteria (American © 2013 John Wiley & Sons Ltd, MENCAP & IASSID

Psychiatric Association 2000). Only one centre adopted the multi-disciplinary diagnostic approach using two assessment tools, the DSM-IV and the Childhood Autism Rating Scale (CARS; Schopler et al. 1988). The criteria of the DSM-IV were used across the regions from which children were recruited as it is considered a standardised diagnostic procedure for autistic disorder in the country. About 84% (n = 155) of the children were males. The mean age for them was 6.3 years (⫾3) ranging from 2 to 12 years. The mean age for the children at which symptoms firstly appeared was 2 years (SD ⫾ 1) ranging from 6 months to 5 years. The mean age at which the children were medically diagnosed with autistic disorder was 3 years (SD ⫾ 1) ranging from 9 months to 6 years. This study has followed Nunnally & Bernstein’s (1994) guideline to determine the sample size when using factor analysis; a minimum of five cases per item are needed. The total number of items in the original PSI is 36, thus, the sample size should be at least 180.

Measures The PSI-SF is a 36-item self-reported questionnaire designed to measure stress associated with parenting among parents of children younger than 12 years of age (Abidin 1995). The measure has three subscales, each consisting of 12 items: PD; PCDI; and DC (Abidin). The PD sub-scale measures parents’ perceptions of their own behaviour including perceived competence, marital conflict, views of social support, and life restrictions because of the parenting demands, (e.g. ‘I feel trapped by my responsibilities as a parent’). The PCDI sub-scale measures the parents’ view of expectations and interactions with their child, (e.g. ‘My child rarely does things for me that make me feel good’). The DC sub-scale measures the parents’ perceptions of their child’s temperament, demandingness, and compliance, (e.g. ‘My child makes more demands on me than most children’) (Abidin). The PSI-SF also has a reliability scale (Defensive Responding) consisting of seven items from the PD scale. Respondents scoring less than a raw score of 10 is thought to signify either that parents are minimising parenting stress, that they are more competent than the average parent and unusually


sanguine, or that they do not care enough about the child to feel stressed by the difficult behaviour (Abidin). In this study, the mean score for the defensive responding reliability scale was 23 (⫾5.7) indicating valid results for subsequent analysis. The items of the scale range from 1 (strongly disagree) to 5 (strongly agree) and has a 5th grade reading level. The expected time to complete the questionnaire was between 10 and 15 min. Raw scores above 33 on the PD and DC sub-scales and above 27 on the PCDI sub-scale are considered clinically elevated. Raw total scores above 90 indicates clinically significant high level of stress scores (Abidin 1995). Test–retest reliability coefficients of the total stress score have been reported to be 0.84, for the PD sub-scale 0.85, for the PCDI sub-scale 0.68 and for the DC 0.78. For the internal consistency of the PSI-SF, reports for total stress have been 0.91, for PD 0.87, for PCDI 0.80 and for the DC sub-scale 0.85 (Abidin 1995).

Ethical considerations Ethical approval was granted by the academic research committee at the deanship of the academic research in the University of Jordan. The purpose, methods, risks, and benefits of the study were explained to the participants before they decided to participate. The participants were assured that their participation is completely voluntary. Confidentiality of the data obtained were assured by assigning an identification number (ID) to the participants, attaching the ID number rather than other identifiers to the actual data, and restricting access to identifying information.

Factor analysis Researchers used EFA to summarise data by grouping together variables that are intercorrelated. Whereas CFA necessitates the estimation and specification of one or more hypothesised models of factors structure, each of which proposes a set of latent variables (factors) to account for covariance among a set of observed variables. Moreover, there is a principal difference between EFA and CFA; in EFA there is no priori restrictions placed on the pattern of relationships between the observed measures and the latent © 2013 John Wiley & Sons Ltd, MENCAP & IASSID

variables; while in CFA, the researcher must specify in advance a number of key aspects of the factor model such as the number of factors and factor loadings (Brown 2006). In this study, CFA was used to evaluate the validity of the PSI among parents of children with autistic disorder by assigning the items to their respective factors according to theoretical expectations (Arbuckle 2012). However, CFA may follow an EFA and both techniques are considered complementary to each other (Munro 2005).

Results Regarding the total scores among the three stress sub-scales, the highest score was for PD sub-scale (40.29 out of 60); whereas the lowest score was for PCDI (37.70). The highest score among the 36 items was ‘ My child makes more demands on me than most children’ (4.41 out of 5) under the DC sub-scale. Table 1 presents the participants score means and standard deviations for each item in the 36-item scale. The EFA was performed using the Statistical Package for Social Sciences (IBM Corporation 2012). A principal components analysis with Varimax rotation for the parents of children with autistic disorder was performed with the 36 items in the original PSI scale and with the modified 30 items. Determining the number of factors to be extracted depends on how strongly and cleanly the variables load on the factors (Munro 2005). The variable loads strongly on a particular factor if loading ⱖ0.40, and is considered clean if the absolute difference between the loading is more than 0.20 (Nunnally & Bernstein 1994). Accordingly, nonclean and or low loading items were deleted from the model (PCDI: 19, 22, 24; DC: 31, 32, 33), and two items (PCDI: 18, 21) were re-allocated to DC sub-scale to fit the theoretical meaning and loading criteria. The modified model ended with 30 items. Table 2 shows the loading of the 30 items on the three factors and the accounted cumulative variance with entire sample was 50.36%. Yet, the accounted cumulative variance with the 36 items was only 41.71%. The Kaiser–Meyer–Oklin (KMO) is a measure that provides an approach to comparing the


Table 1 Means and standard deviations (SDs) for the 36 items of the Parenting Stress Index

Item #

Item label

Mean

SD

pd1 pd2 pd3 pd4 pd5 pd6 pd7 pd8 pd9 pd10 pd11 pd12

I often have the feeling that I cannot handle things very well I find myself giving up more of my life to meet my child’s needs than I ever expected I feel trapped by my responsibilities as a parent. Since having my child I have been unable to try new and different things Since having my child I feel that I am almost never able to do things that I like to do I am unhappy with the last purchase of clothing I made for myself There are quite a few things that bother me about my life Having a child has caused more problems than I expected in my relationship with my spouse I feel alone and without friends When I go to a party I usually expect not to enjoy myself I am not as interested in people as I used to be I don’t enjoy things as I used to. Total score for Parental Distress sub-scale

3.53 4.11 3.65 3.34 3.38 3.25 3.66 2.63 2.42 3.47 3.34 3.51 40.29

1.08 1.03 1.23 1.31 1.25 1.34 1.13 1.43 1.25 1.28 1.31 1.26 10.47

pcdi13 pcdi14 pcdi15 pcdi16 pcdi17 pcdi18 pcdi19 pcdi20 pcdi21 pcdi22 pcdi23 pcdi24

My child rarely does things for me that make me feel good Most times I feel that my child likes me and wants to be close to me My child smiles at me much less than I expected When I do things for my child, I get the feeling that my efforts are not appreciated very much When playing, my child doesn’t often giggle or laugh. My child doesn’t seem to learn as much as most children My child is not able to do as much as I expected. My child doesn’t seem to smile as much as most children. It takes a long time and it is really hard for my child to get used to new things I feel that I am: (being a parent) I expected to have closer and warmer feelings for my child than I do and this bothers me Sometimes my child does things that bother me just to be mean Total score for Parent–Child Dysfunctional Interaction sub-scale

3.36 1.87

1.18 1.12

3.14 2.82 4.23 3.86 3.47 3.40 2.25 3.02 3.35 37.70

1.20 1.20 1.01 0.99 1.32 1.22 1.03 1.30 1.25 8.73

dc25 dc26 dc27 dc28 dc29 dc30 dc31 dc32 dc33 dc34 dc35 dc36

There are some things my child does that really bother me a lot. My child generally wakes up in a bad mood I feel that my child is very moody and easily upset My child does a few things that bother me a great deal My child reacts very strongly when something happens that my child doesn’t like My child gets upset easily over the smallest thing My child’s sleeping and eating schedule was much harder to establish than I expected. I have found that getting my child to do something is: Think carefully and count the number of things which your child does that bothers you. My child turned out to be more of a problem than I expected. My child makes more demands on me than most children. My child seems to cry more often than most children Total score for Difficult Child sub-scale

4.23 2.74 3.58 3.88 3.87 3.16 3.04 2.08 2.22 3.16 4.41 3.59 39.95

0.78 1.27 1.14 1.00 1.02 1.19 1.36 0.90 1.30 1.29 0.80 1.22 7.58

zero-order correlations to the partial correlations between pairs of variables (Munro 2005). The KMO in EFA in the study model is 0.89; Kaiser (1974) stated that if KMO is greater than 0.50 it is acceptable. The closer the KMO to one, the better the correlations between pairs of variables that can be explained by the other variables (Norusis 1998). Bartlett’s Test of Sphericity evaluates all factors together and each factor separately against a © 2013 John Wiley & Sons Ltd, MENCAP & IASSID

hypothesis stating that there are no factors (Tabachnick & Fidell 2001). The Bartlett’s Test in this study is significant (P < 0.001), indicating that enough shared variance is present. The modified structural model for the PSI scale in this study is identified by three interrelated constructs. The Cronbach’s alphas for the 30-item three-factors model of PSI in the current study were equal or higher than the 36-item (Table 3).


Table 2 Exploratory factor analysis of the Parenting Stress Index Scale with the total sample (n = 184)

Principal components with varimax rotation

Item #

Parental Distress

Difficult Child

Parent–Child Dysfunctional Interaction

pd4 pd12 pd5 pd6 pd11 pd9 pd10 pd3 pd7 pd2 pd1 pd8 dc27 dc28 dc36 dc30 dc25 dc18 dc21 dc34 dc29 dc26 dc35 pcdi15 pcdi23 pcdi20 pcdi16 pcdi17 pcdi14 pcdi13 % variance† Cumulative variance

0.80 0.79 0.78 0.77 0.75 0.70 0.67 0.66 0.61 0.53 0.47 0.46 0.15 0.22 0.23 0.17 0.35 * * 0.37 0.27 * 0.14 * 0.16 * 0.15 0.13 0.15 0.31 20.57 20.57

* 0.21 0.16 * 0.14 * 0.28 0.24 0.25 0.23 0.30 * 0.69 0.68 0.67 0.65 0.64 0.62 0.58 0.57 0.56 0.54 0.53 0.13 0.16 0.23 0.27 0.15 * 0.27 16.25 36.81

0.11 0.13 * 0.23 * 0.10 * * 0.21 * 0.24 0.28 0.22 0.12 * 0.25 * 0.31 0.21 0.10 * 0.32 0.19 0.83 0.76 0.73 0.71 0.66 0.65 0.45 13.55 50.36

* Item loading of