Adaptation and psychometric properties of the Self ...

Journal of Intellectual & Developmental Disability, 2013; Early Online: 1–5

BRIEF REPORT

Adaptation and psychometric properties of the Self-Efficacy/Social Support for Activity for persons with Intellectual Disability scale (SE/SS-AID) in a Spanish sample

J Intellect Dev Dis Downloaded from informahealthcare.com by 88.2.162.219 on 04/18/13 For personal use only.

ANTONIO IGNACIO CUESTA-VARGAS1, BERTA PAZ-LOURIDO2, MIYOUNG LEE3 & JANA J. PETERSON-BESSE4 1Department

of Physiotherapy, University of Malaga, Malaga, Spain, 2Department of Physiotherapy, University of the Balearic Islands, Mallorca, Spain, 3Kookmin University, Korea, and 4Institute for Human Development, University of Missouri–Kansas City, Kansas City, MO, USA

Abstract Background In this study we aimed to develop a Spanish version of the Self-Efficacy/Social Support Scales for Activity for persons with Intellectual Disability (SE/SS-AID). Method A cross-sectional study was carried out in a sample of 117 individuals with intellectual disability (ID). The SE/ SS-AID scales were translated into Spanish and their psychometric properties analysed. Results Confirmatory factor analysis showed acceptable fit (CFI ⫽ .94 for the SE-AID and .95 for the SS-AID), but RMSEA values outside of the optimal fit range (.28 and .15, respectively). Cronbach’s α was calculated for the SE-AID, SS-AID-family, SS-AID-staff, and SS-AID-peers scales, with results from .80 to .82. Conclusions The scales show acceptable validity and reliability evidence. Use of this instrument will allow researchers to gain more knowledge about how personal and social factors influence participation in physical activity in Spanish-speaking people with ID.

Keywords: intellectual disability, physical activity, self-efficacy, social support

Background Research indicates that individuals with intellectual disability (ID) participate in insufficient physical activity for many health benefits (Cuesta-Vargas, Paz-Lourido, & Rodríguez, 2011; Peterson et al., 2008), and have poor adherence to physical activity programs or sports (McGuire, Daly, & Smyth, 2007). Given this reality, there is a need for the development of theory-based interventions that promote physical activity in this population. The social cognitive theory (SCT) developed by Bandura (1986) has influenced research related to health behaviour and promotion of physical activity (Keller, Fleury, Gregor-Holt, & Thompson, 1999). Specifically, self-efficacy and social support have been two critical elements of SCT to physical activity research.

Self-efficacy perception is an important predictor of healthy behaviour and the self-management of chronic disease (Schwarzer & Renner, 2000). Selfefficacy has been correlated with people’s intention to practise physical activity, strategies to overcome a sedentary lifestyle, and maintenance of regular physical activity practice (Trost, Owen, Bauman, Sallis, & Brown, 2002). Studies have similarly indicated that self-efficacy correlates with physical activity among adults with ID and developmental disability (Peterson et al., 2008). Another important variable in physical activity studies based on SCT is social support. In the general population, research has indicated that social support has a critical influence on individual participation in physical activity (Trost et al., 2002;

Correspondence: Antonio Ignacio Cuesta-Vargas, Department of Physiotherapy, University of Malaga, Paseo de Martiricos S/N, 29071 Málaga, Spain. E-mail: [email protected] ISSN 1366-8250 print/ISSN 1469-9532 online © 2013 Australasian Society for Intellectual Disability, Inc. DOI: 10.3109/13668250.2013.784959


2

A. I. Cuesta-Vargas et al.

Wendel-Vos, Droomers, Kremers, Brug, & van Lenthe, 2007). Research also indicates the importance of the social network for physical activity among individuals with ID (Heller, Ying, Rimmer, & Marks, 2002; Peterson et al., 2008; Temple & Walkley, 2007). Social support can come from different groups, such as family, friends, and others, through various types of support (e.g., emotional support, financial support, informational support, etc.). For people with ID, the literature describes social support received from three main supportive groups (family, professional caregivers and friends) as a factor that may contribute to participation in physical activity (Peterson et al., 2008). To study the relationship between physical activity intervention and outcomes, valid measures are needed. The Self-Efficacy/Social Support for Activity for persons with Intellectual Disability (SE/ SS-AID) scales were thus specifically developed to measure the effect of these correlates on physical activity participation for those with ID (Peterson, Peterson, Lowe, & Nothwehr, 2009). The validity and reliability evidence of these scales were further confirmed by Rasch modelling, an advanced statistical approach (Lee, Peterson, & Dixon, 2010). A Spanish version of the SE/SS-AID scales will have wide applicability, as Spanish is one of the five most spoken languages in the world (Organización de Naciones Unidas, 2000). Spain has 156,771 people with ID older than 6 years old, and over three quarters of those individuals have mild or moderate ID (Berjano, 2010), the group for whom the SE/SS-AID scales were developed. Research in the Spanish context also shows a need for increased health promotion intervention for this population; a study using the Short Form Health Survey (SF-36) in people with ID showed scores for the physical condition and physical functioning dimensions that were lower than for the general population in Spain (Mirón-Canelo, Alonso-Sardón, Serrano-López de las Hazas, & Sáenz-González, 2008). The aim of this study was (1) to carry out a crosscultural linguistic adaptation of the SE/SS-AID scales to Spanish, and (2) to provide evidence of the validity and reliability for the Spanish version of the scales.

Methods Spanish adaptation of the scales The SE/SS-AID scales were developed to measure the relationship between self-efficacy, social support, and physical activity participation for those with ID (Peterson et al., 2009). To provide factor structure

evidence for the Self-Efficacy (SE) and Social Support (SS) scales, the authors used confirmatory factor analysis methods (CFA). Results for 152 participants with mild to moderate ID demonstrated good fit for each of the scales, supporting the single-factor structure of each. Detailed study methods and results are described in Peterson et al. (2009) and Lee et al. (2010). This modified set of SE/SS-AID scales, composed of 23 questions, was employed in this study. The SE scale contained six items, with response options of “no,” “maybe,” and “yes.” Together, the three SS scales included 17 items, which were divided into three subcategories, including six family items, six staff items, and five peers items. The SS scales have response options of “no,” “yes – sometimes,” and “yes – a lot.” The aim of this process is to achieve a Spanish version of the English instrument that is conceptually equivalent in the target country/culture. That is, the instrument should be equally natural and acceptable in Spanish, and the psychometric properties of this application should not be different from the original language. Forward and backward translations were employed from English as follows: 1. Forward translation: two different translators from English to Spanish developed two independent translations of the original SE/SSAID scales. Both versions were compared and discussed, and differences were reconciled. 2. Back translation: an English linguist who had never seen the original document completed the translation of the Spanish document. 3. The two documents were compared to ensure both conceptual and semantic equivalence between the two texts. The scales were applied in practice to ensure that the adapted version retained its equivalence. Design In this study we employed a cross-sectional design. Once the translation and adaptation process was finished, as previously described, the scales were administered in mid 2010. The participants were individuals who took part in the Special Olympics, and all completed informed consent forms before data collection. This procedure was approved by the Institutional Review Board of the University of Málaga, Spain. A total of 117 adults with mild ID participated in this study.The sample was 35.6% female, and ages ranged from 18 to 45 years, with a mean and standard deviation of 33 ⫾ 13.1. All administrators were trained to administer the SE/SS-AID to persons with ID. The Spanish adaptations of the SE/SS-AID scales were


Brief Report: Spanish SE/SS-AID administered. In addition, body mass index (BMI) and waist circumference were measured the same day that the SE/SS-AID data were collected. Descriptive analysis was applied to calculate means (⫾ standard deviation) and medians (⫾ interquartile range) of demographic variables and the SE/SS-AID scales to summarise the variables measured and determine the level of SE and SS of participants. To determine the factor structure of the scales, CFA was employed. Although CFA was performed separately on each SS scale in the Peterson et al. (2009) study, the items were combined into one scale here for the purpose of the CFA. We satisfied the minimum of five participants-per-item ratio recommended by Kass and Tinsley (1979). For CFA, factor loadings of the variables were calculated and maximum likelihood estimation was employed to estimate model fit. The model fit indices included chi-square (χ2), the root mean square error of approximation (RMSEA), the comparative fit index (CFI), and the normed fit index (NFI). For RMSEA, values at or less than .08 reflect a close and reasonable fit (Hu & Bentler, 1999). The NFI and CFI vary along a continuum of 0 to 1 in which values at or greater than .90 are considered to be a satisfactory fit (McDonald & Marsh, 1990). Correlation coefficients were calculated to determine the association among the Spanish SE/SS-AID scales. Because SE and SS items used an ordinal scale, Spearman correlation was applied. To determine the internal consistency of the scale items, Cronbach’s α coefficients were calculated. To examine the stability reliability of the response to the scale, all participants completed the second response of the scale 1 week after the first data collection. Also, correlation coefficients (Rxx) were calculated to examine the relative stability reliability (test–retest). All statistical analyses were conducted using the Statistical Package for Social Science Version 15.0 for Windows and LISREL 8.80 (Jöreskog & Sörbom, 2007).

3

Table 1. Median and interquartile scores of the Spanish version of the SE/SS-AID scales Percentiles

SE_AID SS_AID_family SS_AID_staff SS_AID_peers

M

SD

Mdn

25

50

75

7.21 7.77 10.89 8.42

3.82 3.87 2.51 2.51

7.00 8.00 12.00 10.00

4.00 6.00 11.00 6.75

7.00 8.00 12.00 10.00

12.00 12.00 12.00 10.00

df ⫽ 9, p ⬍ .000, for three SS-AID scales and SE-AID, respectively, indicating there was residual variance that still remained to be explained. This result was expected given that the χ2 test is highly sensitive, and even small differences in model fit are statistically significant (Hu & Bentler, 1999). Most of the other fit indices were satisfactory: NFI ⫽ .94 and CFI ⫽ .95 for the combined SS-AID scales, NFI ⫽ .90 and CFI ⫽ .91 for the SE-AID, and the factor loadings of all of the variables were ⬎ .50, indicating acceptable construct validity. The error of approximation was an exception, as this statistic did not indicate optimal fit (RMSEA ⫽ .15 for the combined SS-AID scales and RMSEA ⫽ .29 for the SE-AID). The relationships between the constructs of the Spanish version of the SE/SS-AID scales had low relationships, showing the orthogonality of the scales. SS-AID staff demonstrated significant relationships with SE-AID (r ⫽ .21) and SS-AID family (r ⫽ .37). In addition, the domains of SS-AID peers showed significant relationships with SS-AID family (r ⫽ .39), and SS-AID staff (r ⫽ .37). Cronbach’s α for the SE-AID and SS-AID family, SS-AID staff, and SS-AID peers scales was .82, .83, .81, and .80, respectively. The stability reliability from the correlation coefficients between test and retest were relatively high, Rxx’⫽ .99 for SS-AID family, .96 for SS-AID staff, .91 for SS-AID peers, and .77 for SE-AID. Descriptive analysis results for each item (mean and standard deviation) and Cronbach’s α if item is deleted for the Spanish version of the SE/ SS-AID scales are shown in Table 2.

Results To ensure content validity, forward and backward translations were conducted by two translators and reviewed by experts. The participants were 56.3% male with 35.6% reporting ⬎3 hours/week of sport practice. BMI of the participants was 29.02 ⫾ 5.0, and mean waist circumference was 94.07 ⫾ 13.1 cm. The mean, median, and interquartile scores for each scale are shown in Table 1. The χ2 test for the four-factor model was significant, χ2 ⫽ 422.20, df ⫽ 116, p ⬍ .000 and χ2 ⫽ 85.40,

Discussion The findings of our research using the translated and adapted version of the scales show that the most psychometric properties of this version are good. The fit indices associated with the CFA models were satisfactory for the SE-AID scale and the combined SS-AID scale; however, the error of approximation was an exception, as this statistic did not indicate optimal fit (RMSEA ⫽ .15 for the combined SS-AID scales and RMSEA ⫽ .29 for the

4

A. I. Cuesta-Vargas et al.


Table 2. Test–retest items, means, and standard deviations for the Spanish version of the SE/SS-AID scales

SE_AID_1 SE_AID_2 SE_AID_3 SE_AID_4 SE_AID_5 SE_AID_6 SS_AID_FAMILY_1 SS_AID_FAMILY_2 SS_AID_FAMILY_3 SS_AID_FAMILY_4 SS_AID_FAMILY_5 SS_AID_FAMILY_6 SS_AID_STAFF_1 SS_AID_STAFF_2 SS_AID_STAFF_3 SS_AID_STAFF_4 SS_AID_STAFF_5 SS_AID_STAFF_6 SS_AID_PEERS_1 SS_AID_PEERS_2 SS_AID_PEERS_3 SS_AID_PEERS_4 SS_AID_PEERS_5

M

SD

1.84 1.47 1.20 1.12 1.03 1.00 1.74 .94 1.03 1.12 1.56 1.65 1.68 1.73 1.89 1.93 1.89 1.78 1.67 1.67 1.71 1.61 1.91

.873 .869 .832 .876 .921 .923 .754 .91 .912 .934 .801 .901 .674 .654 .787 .98 .543 .657 .754 .782 .754 .814 .742

SE-AID). It may be that the specific sample in this study may have affected factor structure and little increase of error does not necessarily mean that the structure of the scale is poor. It is difficult to directly compare fit of the SS-AID scale with the English version since the study by Peterson and colleagues (2009) performed a separate CFA model for SS from each referent group. However, both studies did show evidence for overall satisfactory fit. In future research, applying the Rasch model will enable researchers to compare endorsements of each SE and SS item between the English and Spanish versions. As found in previous validation studies of the English scales (Lee et al., 2010; Peterson et al., 2009), the test–retest reliability of the Spanish version SE/SS-AID scales was also promising. In fact, the internal consistency and test–retest reliability of the Spanish SE/SS-AID scales were higher than in the study by Peterson and colleagues. Cronbach’s α for the SE-AID and each SS-AID scale were satisfactory, ⬎ .8 in the current study (vs. .7– .74, which were barely adequate in the previous study by Peterson et al., 2009) and test–retest of Rxx ⫽ .98 for combined SS-AID and .77 for SEAID (compared to .76 – .79 and .49 in the Peterson et al., 2009, study, respectively). Important differences in participants and study settings could account for the higher levels in the current study. The participants from the current study were recruited during Special Olympics

events, and the participants in the English study were recruited through the agency that provided them with supported living services. This study had a few important limitations that should be noted. Whereas test–retest reliability of the scale for the instrument was good, the interrater reliability was not assessed. Because the participants were recruited during a Special Olympics event, the participants were interested in participating in physical activity in some manner and this could be expected to reduce the variance in the self-efficacy and social support for physical activity across the sample compared to another group. As such, the representativeness of our sample in this study could be quite limited. The cross-cultural adaptation of the SS/SE-AID scales resulted in a Spanish version that shows good psychometric properties. In addition, the use of this instrument in further research and policy formation regarding physical activity and health promotion in people with ID in the Spanish context is promising. In the future, this can be used to develop appropriate strategies to increase people with ID’s participation in physical activity toward a healthier lifestyle. Although this study specifically performs a crossvalidation of the scales within a sample from Spain, replication of the validation and reliability procedures in other Spanish-speaking samples could extend the utility of these scales. We expect that Spanish scales could be useful for populations in the United States and in other countries with substantial Spanishspeaking populations.

Author note At the time the research was conducted, the fourth author, Jana J. Peterson-Besse, was affiliated with the Institute for Human Development, University of Missouri–Kansas City, Kansas City, MO, USA, and is now currently at the Department of Public Health, Pacific University, Forest Grove, OR, USA. This research was partially funded by the Oficina de Transferencia de Resultados de Investigacion de la Universidad de Málaga (OTRI-UMA (ref. 806/423505, cod 00334).

Acknowledgements The authors would like to thank all participants and collaborating staff who took part in the research. Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.

Brief Report: Spanish SE/SS-AID


References Bandura, A. (1986). Social foundations of thought and action: A social cognitive theory. Englewood Cliffs, NJ: Prentice Hall. Berjano, G. E. (2010). Discapacidad intelectual y envejecimiento: un problema social del s.XXI [Intellectual Disabilities and ageing: A social problem in the XXI century]. Madrid, Spain: FEAPS. Cuesta-Vargas, A. I., Paz-Lourido, B., & Rodríguez, A. (2011). Physical fitness profile in adults with intellectual disabilities: Differences between levels of sport practice. Research in Developmental Disabilities, 32, 788–794. doi:10.1016/j.ridd.2010.10.023 Heller, T.,Ying, G.-S., Rimmer, J. H., & Marks, B. A. (2002). Determinants of exercise in adults with cerebral palsy. Public Health Nursing, 19, 223–231. doi:10.1046/j.0737-1209.2002.19311.x Hu, L., & Bentler, P. M. (1999). Cutoff criteria for fit indexes in covariance structure analysis: Conventional criteria versus new alternatives. Structural Equation Modeling, 6, 1–55. doi:10.1080/ 10705519909540118 Jöreskog, K. G., & Sörbom, D. (2007). LISREL 8.80. Chicago, IL: Scientific Software International, Inc. Kass, R. A., & Tinsley, H. E. A. (1979). Factor analysis. Journal of Leisure Research, 11, 120–138. Keller, C., Fleury, J., Gregor-Holt, N., & Thompson, T. (1999). Predictive ability of social cognitive theory in exercise research: An integrated literature review. The Online Journal of Knowledge Synthesis for Nursing, E6, 19–31. doi:10.1111/j. 1524-475X.1999.00019.x Lee, M., Peterson, J. J., & Dixon, A. (2010). Rasch calibration of physical activity self-efficacy and social support scale for persons with intellectual disabilities. Research in Developmental Disabilities, 31, 903–913. doi:10.1016/j.ridd.2010.02.010 McDonald, R. P., & Marsh, H. W. (1990). Choosing a multivariate model: Noncentrality and goodness of fit. Psychological Bulletin, 107, 247–255. doi:10.1037/0033-2909.107.2.247 McGuire, B. E., Daly, P., & Smyth, F. (2007). Lifestyle and health behaviours of adults with an intellectual disability. Journal of Intellectual Disability Research, 51, 497–510. doi:10.1111/j. 1365-2788.2006.00915.x

5

Mirón Canelo, J. A., Alonso Sardón, M., Serrano López de las Hazas, A., & Sáenz González, M. C. (2008). Calidad de vida relacionada con la salud en personas con discapacidad intelectual en España [Health-related quality of life among people with intellectual disabilities in Spain]. Revista Panamericana de Salud Pública, 24, 336–344. doi:10.1590/ S1020-49892008001100006 Organización de Naciones Unidas ONU. (2000). Países de habla hispana promueven uso del español en la ONU [Spanish countries promote Spanish language in UN]. Retrieved August 9, 2010, from http://www.un.org/spanish/News Peterson, J. J., Lowe, J. B., Peterson, N. A., Nothwehr, F. K., Janz, K. F., & Lobas, J. G. (2008). Paths to leisure physical activity among adults with intellectual disabilities: Self-efficacy and social support. American Journal of Health Promotion, 23, 35–42. doi:10.4278/ajhp.07061153 Peterson, J. J., Peterson, N. A., Lowe, J. B., & Nothwehr, F. K. (2009). Promoting leisure physical activity participation among adults with intellectual disabilities: Validation of selfefficacy and social support scales. Journal of Applied Research in Intellectual Disabilities, 22, 487–497. doi:10.1111/j. 1468-3148.2009.00500.x Schwarzer, R., & Renner, B. (2000). Social-cognitive predictors of health behavior: Action self-efficacy and coping self-efficacy. Health Psychology, 19, 487–495. doi:10.1037/0278-6133. 19.5.487 Temple, V. A., & Walkley, J. W. (2007). Perspectives of constraining and enabling factors for health-promoting physical activity by adults with intellectual disability. Journal of Intellectual & Developmental Disability, 32, 28–38. doi:10.1080/13668250701194034 Trost, S. G., Owen, N., Bauman, A. E., Sallis, J. F., & Brown, W. (2002). Correlates of adults’ participation in physical activity: Review and update. Medicine & Science in Sports & Exercise, 34, 1996–2001. doi:10.1097/00005768-200212000-00020 Wendel-Vos, W., Droomers, M., Kremers, S., Brug, J., & van Lenthe, F. (2007). Potential environmental determinants of physical activity in adults: A systematic review. Obesity Reviews, 8, 425–440. doi:10.1111/j.1467-789X.2007.00370.x