Psychometric properties of the world health organization disability assessment schedule II -12 Item (WHODAS II) in trauma patients
Introduction
Trauma as a leading causes of death in worldwide, causing about 16000 deaths each day. Moreover it is the main cause of disability of active population in developing countries [1]. The global burden associated with trauma is 12% [2]. According to the first national study of disease in Iran, from the total number of 21572 disability-adjusted life year (DALYs) due to all disease and injuries, 28% were related to traumas [3]. Currently, there are about one billion people suffering from disability around the world. Most of these people live in low- or middle-income countries. A great deal of disabilities is related to traffic accidents, falls, burns, violence, and assaults. In some countries, one quarter of all disabilities are caused by traumas [4].
Based on World Health Organization (WHO) definition “Disabilities is an umbrella term, covering impairments, activity limitations, and participation restrictions. Impairment is a problem in body function or structure; activity limitation is a difficulty encountered by an individual in executing a task or action; while a participation restriction is a problem experienced by individual in involvement in life situations. Thus disability is a complex phenomenon, reflecting an interaction between features of a person's body and features of the society in which he or she lives” [5].
There are different instruments for measuring disability. One of the most comprehensive disability assessment instruments is the World Health Organization Disability Assessment Schedule II (WHODAS II). The WHODAS II is a multi-dimensional instrument developed by the Epidemiology branch of the World Health Organization. This schedule has 36 items in six domains including understanding and participation, getting around, self-care, getting along with people, life activities, and participation in society. Based on the International Classification of Function, Disability and Health (ICF), these six domains fall into two main domains of activity limitation (including the domains of understanding and participation, getting around, and self-care) and participation (encompassing the domains of getting along with people, life activities, and participation in society) [6]. The WHODAS II has been developed for assessing problems associated with chronic diseases, mental disorders, traumas, and drug abuse [7]. This schedule has been translated into sixteen languages in fourteen countries and has been reported to have an acceptable validity and reliability [6] with a six-factor structure [7]. The only study which dealt with evaluating the psychometric properties of the 36-item WHODAS II among trauma patients was conducted by Wolf et al. (2012) on 63 patients with spinal cord injury. They reported that the schedule could differentiate between patients’ disability and work force status in three domains of getting around, self-care, and life activities. Moreover, they reported Cronbach's alpha values of 0.61–0.97 and an acceptable convergent validity for the schedule [8].
The short-form 12-item version of the WHODAS II was also developed for evaluating routine health outcomes in epidemiologic studies [6]. The completion of this schedule took about five minutes through either phone or clinical interviewing [9]. Given its simplicity, the 12-item WHODAS II is preferred over its 36-item version [6]. Studies conducted in different countries have reported acceptable internal consistency, construct validity and discriminate validity and also one-factor structure for the 12-item WHODAS II [6], [10], [11], [12], [13], [14].
Previous studies have evaluated the psychometric properties of the WHODAS II among patients with musculoskeletal disorders [15], [16], [17], chronic diseases [7], [16], cancer [7], hearing impairments [18], mental disorders [7], [15], and spinal cord injuries [19]. However, to the best of our knowledge, the psychometric properties and the factor structure of this schedule have not yet been evaluated among trauma patients. Moreover, this schedule has been neither translated into Persian nor validated for being used in the Iranian context yet. The aim of this study was to assess the psychometric properties of the Persian version of the 12-item WHODAS II among trauma patients.
Section snippets
Study population
In this methodological study 220 trauma patients hospitalized in Shahid Beheshti Hospital, the only trauma center (Level III) in Kashan city were studied during 2013–2014. Kashan is located in central part of Iran with 400,000 populations and high rate of trauma. The inclusion criteria were: age 15–65 year, hospitalization for more than 24 h due to trauma, absent of any mental and physical disability before injury and consent to participating in this study. Patients who were not available during
Findings
The mean of participants’ ages was 34.7 ± 14.5 years. Most of the participants were male patients (84.1%) and employed (61.4%), had Iranian nationality (89.1%), had secondary or tertiary degrees (38.8%), and resided in urban areas (80.9%). Traumas were mainly blunt (89.5%) and had been induced by road accidents (76.8%). Most of the patients had multiple injuries (77.7%). The means of patients’ ISS and GSC were 12.7 ± 9.1 and 13.8 ± 2.3, respectively (Table 1).
Discussion
To the best of our knowledge, this was the first study which evaluated the psychometric properties of the Persian version of the 12-item WHODAS II. Study findings revealed that the Persian 12-item WHODAS II has an acceptable validity.
The Cronbach's alpha of the WHODAS II was 0.91. A Cronbach's alpha of 0.7 or greater shows the acceptable reliability of a scale [21]. Accordingly, the reliability of the Persian 12-item WHODAS II is high. Luciano et al. (2010) and Tazaki et al. (2014) also
Conflict of interests
The authors declare that they have no competing interests.
Authors’ contributions
Masoumeh Abedzadeh- Kalahroudi carried out the data collection, and drafted the manuscript. Ebrahim razi participated in the design of the study, coordination and helped to draft the manuscript. Mojtaba Sehat performed the statistical analysis and its interpretation. Mohsen Asadi-Lari participated in the study design and made critical revision to the paper. All authors read and approved the final manuscript.
Acknowledgements
This study was a part of Ph.D dissertation supported by deputy of research, Kashan University of Medical Sciences, Kashan, Iran (Grant no: 9303). We also express our thanks to staff of Trauma Research Center and Shahid Beheshti Hospital for their co operation.
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