A Validity Study of the WHOQOL-BREF Assessment in Persons With Traumatic Spinal Cord Injury

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1 1890 A Validity Study of the WHOQOL-BREF Assessment in Persons With Traumatic Spinal Cord Injury Yuh Jang, OTR, MHE, Ching-Lin Hsieh, OTR, PhD, Yen-Ho Wang, MD, Yi-Hsuan Wu, BS ABSTRACT. Jang Y, Hsieh C-L, Wang Y-H, Wu Y-H. A validity study of the WHOQOL-BREF assessment in persons with traumatic spinal cord injury. Arch Phys Med Rehabil 2004;85: Objective: To examine the distribution of the scores, internal consistency, structure, and discriminant validity of the abbreviated version of the World Health Organization Quality of Life (WHOQOL-BREF) assessment in persons with traumatic spinal cord injury (SCI). Design: Validation study using multitrait analysis and known-groups methods. Setting: Community and hospital. Participants: Persons with SCI (N 111) and non-sci respondents (N 169). Interventions: Not applicable. Main Outcome Measure: The WHOQOL-BREF assessment. Results: The frequency distribution of the 4 domains of the WHOQOL-BREF assessment was nearly symmetric and showed no floor or ceiling effects. All domains showed good internal consistency (Cronbach range,.74.78), with the exception of the social relationships domain (.54). The 4-domain structure of the WHOQOL-BREF assessment was confirmed using multitrait analysis. The discriminant validity of the WHOQOL-BREF assessment in persons with SCI was satisfactory. Conclusions: The WHOQOL-BREF assessment is suitable for measuring QOL as perceived by a person with SCI. Key Words: Quality of life; Rehabilitation; Spinal cord injuries; Validity of results by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation ADVANCED METHODOLOGIES of medical management for persons with spinal cord injury (SCI) have resulted in the saving of lives, a reduction in the severity of the disability itself, and increased patient longevity. 1,2 Because increased life expectancy after SCI has been assured, it is now important to improve the quality of life (QOL) of persons with SCI, 2,3 and QOL has become a key outcome in determining the success of rehabilitation programs. 4-6 Thus, the measurement From the School of Occupational Therapy (Jang, Hsieh), College of Medicine (Wang), National Taiwan University; and Department of Physical Medicine and Rehabilitation, National Taiwan University Hospital, (Wang, Wu) Taipei, Taiwan. Supported by the National Science Council of the Republic of China (grant no. NSC B M47). No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit upon the author(s) or upon any organization with which the author(s) is/are associated. Reprint requests to Yen-Ho Wang, MD, Dept of Physical Medicine and Rehabilitation, National Taiwan University Hospital, No 7, Chung-Shan S Rd, Taipei 100, Taiwan, lukewang@ha.mc.ntu.edu.tw /04/ $30.00/0 doi: /j.apmr of QOL is of increasing importance in the field of rehabilitation. 4-6 A number of different approaches have been used to define and describe QOL in the SCI population. 4-6 Recently, Hallin et al 6 used a meta-analysis to compare 49 QOL studies on SCI carried out between 1966 and 1999, and showed that the variety of instruments and the diversity of their core content made comparison of the results difficult and the evaluations and conclusions unpredictable. Most instruments were condition-specific and used only by their developers. 6 The main problem in using a condition-specific instrument was that comparisons with the general population were impossible and information on cross-study or cross-cultural applicability was not available. 6 Other studies used a generic multi-item instrument to estimate the QOL, but the validity of these instruments has not been tested in an SCI population. 6 Hallin concluded that there is a need for instruments with high psychometric standards to measure QOL in persons with SCI. QOL can be viewed as a subjective and multidimensional concept that focuses on the self-perception of an individual s current state. There are many published methods for measuring QOL, but there is no consensus on the definition of QOL and the dimensions that should be included in QOL measurement The authors of most studies agree that QOL measures should include physical, psychologic, and social status. However, general QOL should evaluate all aspects of life, such as the safety of the environment in which people live and whether they feel they have adequate access to health care, transportation, and leisure opportunities. These factors, which are not considered in some QOL definitions and instruments, are important to persons with SCI. 4-6,11 The World Health Organization defined QOL as the person s perception of his/her position in life within the context of the culture and value systems in which he/she lives and in relation to his/her goals, expectations, standards, and concerns. It is a broad-ranging concept incorporating, in a complex way, the person s physical health, psychological state, level of independence, social relationships, personal beliefs, and relationship to salient features of the environment. 10(p28) This definition fits the theoretical QOL model in SCI rehabilitation and reflects the subjective perception of different aspects of life of the person with SCI. 11 A generic QOL instrument can be used in cross-cultural, cross-population, and cross-study comparisons. 7,8 The generic QOL instruments commonly used include the Sickness Impact Profile, Nottingham Health Profile, the Quality of Well-Being Scale, the Medical Outcomes Study 36-Item Short-Form Health Survey, the European Quality of Life Scale, and the World Health Organization Quality of Life (WHOQOL-100) assessment and its short version (WHOQOL-BREF). Of these generic QOL instruments, only the WHOQOL is based on a theoretical model, 7 developed by first establishing a definition of QOL, and then, in an international collaborative effort, defining the dimensions that should be included to measure QOL. 8,9,10,12 The WHOQOL-BREF assessment is being developed as a short version of the WHOQOL-100 for use in situations in which time is restricted or the burden on the respondent must

2 WHOQOL-BREF IN SCI, Jang 1891 be minimized and in large epidemiologic studies and clinical trials. 8,12 Using data collected for the WHOQOL-100 in preliminary field trial centers, items for the WHOQOL-BREF assessment were selected for their ability to explain a substantial proportion of the variance in their parent facet and domain. 8,12 The WHOQOL assessment tool was developed as a collaborative effort by field trial centers around the world working in their own national languages, including centers in China, Hong Kong, Taiwan, and the United States. 8,9,10,12 These field sites followed the same protocols and agreed through international consensus at each stage of the development process, making the tool useful in cross-cultural QOL comparisons. 8,9,10,12 On the basis of the results from the field trials, the WHOQOL-BREF assessment contains 4 domains of QOL: physical health, psychologic health, social relationships, and environment. 8,12,13 The WHOQOL-BREF assessment shows good to excellent internal consistency, test-retest reliability, discriminant validity, and construct validity in the healthy population and in different patient groups, but has not been tested on an SCI population. 8,12,13 When a generic QOL questionnaire is chosen for application to a specific population, such as persons with SCI, the tool should first be validated in this population. To the best of our knowledge, the validity of the WHOQOL-BREF assessment has not been examined in persons with traumatic SCI. Thus, the aim of this study was to investigate the item-response distribution, internal consistency, item-scale correlation structure, and discriminant validity of the WHOQOL-BREF assessment in persons with SCI. METHODS Subjects consisted of 2 groups, an SCI group and a non-sci group. Subjects selected met 2 eligibility criteria: being 18 years of age or older and being able to read. Subject Recruitment and Data Collection Procedures SCI group. Subjects with SCI were recruited from the National Taiwan University Hospital (NTUH). All had sustained traumatic SCI and had undergone rehabilitation at the NTUH between January 1989 and December The NTUH is among the major facilities providing rehabilitation services for persons with SCI throughout Taiwan. The demographic and QOL assessment data for the SCI subjects were collected between January and December We first tried to contact those subjects whose phone numbers and addresses were listed in the medical records to explain the purpose of the study and to make an appointment for a visit; those who could be contacted were asked if they would participate in the study. The questionnaire was administered in a standardized manner to those who agreed to take part by 3 research assistants at a location convenient for each subject (eg, hospital, follow-up clinic, home). If the subject was unable to write due to disability, the investigator held the questionnaire, the subject read the questions, and the investigator wrote down the subject s answers. In the SCI group, of the 233 persons who fulfilled the criteria for this study, 99 could not be contacted because of an incorrect address and phone number and 23 refused to take part in the study; this left 111 (48%) who were included in the study. As shown in table 1, there were no statistically significant differences between the responding and nonresponding groups in terms of age, education, and impairment type, but the responding group had a higher male/female ratio ( 2 test 7.52, P.006) and a shorter duration of injury ( 2 test 2.24, P.026). Table 1: Demographic Characteristics of the SCI and Non-SCI Subjects Category Non-SCI group. To assess the discriminant validity of the WHOQOL-BREF instrument, 169 non-sci subjects, reportedly free of any acute or chronic medical condition, were recruited from all 17 medical centers in Taiwan. 13 This nationwide study was conducted during 1997 by the WHOQOL Taiwan group. 13 The demographic characteristics of the SCI and non-sci subjects are presented in table 1. There were statistically significant differences in gender ( 2 test 37.11, P.001), educational level ( 2 test 37.26, P.001), and employment status ( 2 test 63.05, P.001) between the groups, but no statistically significant difference for age. Measurements A self-administered questionnaire, including demographic and injury-related information and the WHOQOL-BREF assessment, was used and took about 30 minutes to complete. The demographic and injury-related variables consisted of age (in years), gender, highest educational level currently achieved (3 levels: junior high or below, high school, college or above), time after injury (in years), and impairment type (tetraplegia or paraplegia). The WHOQOL-BREF assessment is a self-reported questionnaire that contains 26 items, and each item represents 1 facet. The facets are defined as those aspects of life that are considered to have contributed to a person s QOL. Among those 26 items, 24 of them make up the 4 domains of physical health (7 items), psychologic health (6 items), social relationships (3 items), and environment (8 items), whereas the other 2 items measure overall QOL and general health. 8,12 Respondents rated the intensity, frequency, or evaluation of the selected attributes of QOL during the previous 2 weeks on a 5-point Likert-response scale. The translation process used by the WHOQOL Taiwan group to develop a linguistically and culturally appropriate version for use in Taiwan has been revised and is reported elsewhere. 13,14 Statistical Analysis Statistical analysis was performed using the SPSS, version 11.0, a for Windows. For statistical analysis, the WHOQOL-BREF assessment was first summarized to a 4-domain construct (physical health, psychologic health, social relationships, environment) accord- SCI Nonresponders (n 122) Responders (n 111) Non-SCI (n 169) Gender (male/female) 89/33 97/14 87/82 Mean age SD (y) Education Junior high or below High school College or above Employed Mean time after injury SD (y) Type of impairment Complete tetraplegia Incomplete tetraplegia Complete paraplegia Incomplete paraplegia Abbreviation: SD, standard deviation.

3 1892 WHOQOL-BREF IN SCI, Jang ing to the guidelines for the WHOQOL-BREF. 8 All domain scores were calculated by taking the mean score for all items included in each domain and multiplying by a factor of 4. 8 The score for each domain therefore ranged from 4 to 20, with a higher score indicating better QOL. Missing values were replaced with the appropriate mean score for the domain to which the item belonged, following the scoring guidelines used in the development of the WHOQOL-BREF assessment. 8 Overall QOL and general health facets are not included in the WHO- QOL-BREF domain structure, but were analyzed as part of the WHOQOL-BREF instrument in this and other studies. 8,12 Score range and distributions. The percentage of subjects with missing replies for each item and the response distributions at the domain and item level were calculated. These frequency analyses were used to evaluate the difficulty of completion and to identify problematic items. The frequency of the lowest score for an item (1) or a domain (4) was considered as the floor and the frequency of the highest score for an item (5) or a domain (20) as the ceiling. The floor or ceiling effect represented the percentage of subjects achieving the lowest or highest scores possible, respectively. Floor and ceiling effects exceeding 20% of sample size were considered to be significant. 15 Internal consistency. The Cronbach coefficient 16 was used to examine the internal consistency of the domains in the WHOQOL-BREF assessment. This coefficient estimates the reliability of an instrument according to the extent to which items are internally consistent, taking into consideration the number of items in the instrument. 16 Cronbach values greater than 0.7 were considered acceptable for internal consistency. 17 Domain Structure of the WHOQOL-BREF Assessment for Persons With SCI The Multitrait Analysis Program (MAP) was used to confirm the existing 4-domain structure of the WHOQOL- BREF developed by the WHOQOL group. 8 Multitrait analysis is a method for evaluating the assumptions underlying the construction of a summated ratings scale from a set of questionnaire items MAP analyses were performed to identify any items (or facets) that were more highly associated with another domain than with its own predicted domain or highly associated with both. The MAP method has been used in the field to confirm that the pattern of the correlations corresponds to expectations. 17 It is an effective method in identifying items that have been assigned to the scale with which they are most strongly correlated and with which they are only weakly associated. 17 This analysis has been used in previous WHOQOL work. 9,12,20,21 Using this method, correlations (Pearson r) between the 24 items and the 4 domains were explored to confirm the existing facet-domain structure identified by the WHOQOL group. 8 Discriminant Validity Discriminant validity tests are used to examine differences between different groups completing the same instrument. 17 For our purposes, the ability of the domain scores to discriminate between the SCI and non-sci groups was tested by comparing the mean scores in the 2 groups, using t tests. Because of the significant differences in gender, education, and employment status between the groups, the impact of these sociodemographic variables on the QOL scores (dependent variable) of subjects in both groups was assessed through a hierarchical multiple regression in which these sociodemographic variables were entered together as a block, followed by the group variable (SCI group, non-sci group) as the independent variable. Table 2: Internal Consistency (Cronbach coefficient) of the WHOQOL-BREF Assessment in Persons With SCI (n 111) Domain and Facet Floor Effect, n (%) RESULTS Ceiling Effect, n (%) Missing Replies (%) Overall QOL facet 6 (5.4) 1 (0.9) 0 General health facet 10 (9.0) 2 (1.8) 0 Physical health domain.75 0 (0.0) 1 (0.9) Pain and discomfort 13 (11.7) 11 (9.9) 0 Dependence on medication 8 (7.2) 18 (16.2) 0 Energy and fatigue 8 (7.2) 6 (5.4) 0 Mobility 33 (29.7) 6 (5.4) 0.9 Sleep and rest 11 (9.9) 6 (5.4) 0 Activities of daily living 19 (17.1) 3 (2.7) 0 Work capacity 19 (17.1) 6 (5.4) 0 Psychologic health domain.74 0 (0.0) 1 (0.9) Positive feelings 23 (20.7) 4 (3.6) 0 Spirituality/personal beliefs 12 (10.8) 12 (10.8) 0 Thinking, memory, and concentration 10 (9.0) 7 (6.3) 0 Bodily images and appearance 7 (6.3) 11 (9.9) 0.9 Self-esteem 6 (5.4) 3 (2.7) 0.9 Negative feelings 8 (7.2) 6 (5.4) 0 Social relationships domain.54 0 (0.0) 0 (0.0) Personal relationships 3 (2.7) 5 (4.5) 0 Sexual activity 20 (18.0) 2 (1.8) 7.0 Social support 2 (1.8) 8 (7.2) 0 Environment domain.78 0 (0.0) 0 (0.0) 0 Physical safety and security 8 (7.2) 3 (2.7) 0 Physical environment 8 (7.2) 9 (8.1) 0 Financial resources 16 (14.4) 7 (6.3) 0 Opportunities for acquiring new information and skills 6 (5.4) 10 (9.0) 0 Participation and opportunities for leisure 21 (18.9) 4 (3.6) 0 Home environment 6 (5.4) 7 (6.3) 0 Health and social care 3 (2.7) 9 (8.1) 0 Transport 6 (5.4) 5 (4.5) 0 Distribution of WHOQOL-BREF Assessment Scores For the entire SCI sample, the mean scores standard deviation (SD) were (median, 12.0) on the physical health domain, (median, 12.0) on the psychologic health domain, (median, 13.3) on the social relationships domain, and (median, 12.0) on the environment domain. The scores spanned virtually the entire range and the median was close to the mean, indicating that the distribution of these domain scores were nearly symmetric. As shown in table 2, the percentage of lowest and highest scores for all WHOQOL-BREF items was, in general, below 20%, the 2 exceptions being a floor effect seen for the mobility

4 WHOQOL-BREF IN SCI, Jang 1893 Table 3: Domain Structure of the WHOQOL-BREF Assessment for Persons With SCI Using the MAP Program (n 111) Facet Physical Health Psychologic Health Social Relationships Environment Overall QOL General health Physical health domain Pain and discomfort Dependence on medication Energy and fatigue Mobility Sleep and rest Activities of daily living Work capacity Psychologic health domain Positive feelings Spirituality/personal beliefs Thinking, memory, and concentration Bodily images and appearance Self-esteem Negative feelings Social relationships domain Personal relationships Sexual activity Social support Environment domain Physical safety and security Physical environment Financial resources Opportunities for acquiring new information and skills Participation and opportunities for leisure Home environment Health and social care Transport facet (29.7%) and for the positive feeling facet (20.7%). Despite this, the percentage of the highest and lowest scores for each of the 4 domains was very low (range, 0% 0.9%). Although the percentage of missing replies for most items was below 0.9%, it was quite high (7.0%) for the sexual activity facet, as expected from previous studies. 14,22,23 Acceptable internal consistency (Cronbach, 0.7) was found for all WHOQOL-BREF domains, with the exception of the social relationships domain, for which the coefficient was.54 (table 2). Domain Structure of the WHOQOL-BREF for Persons With SCI Table 3 presents the results of the multitrait analysis showing correlations between the WHOQOL-BREF facets and domains. As expected, all facets showed the highest correlation with the domain to which they were originally assigned by the WHOQOL group. Ten items showed moderate correlations (.50) with domains other than their intended domain. Three of these items mobility, activities of daily living (ADLs), and work capacity were from the physical health domain and correlated moderately with the psychologic health domain; mobility and ADLs also correlated moderately with the environment domain. Moderate correlations were also seen for the positive feelings and self-esteem items (psychologic health domain) with the physical health domain, the personal relationships item (social relationships domain) with the psychologic health domain, the physical safety and security item (environment domain) with the physical health and psychologic health domains, the opportunities for acquiring new information and skills item (environment domain) with the psychologic health domain, and the participation and opportunities for leisure and transport items (environment domain) with the physical health domain. However, no item for the SCI group correlated more strongly with any other domain than with its own domain, confirming that the 4-domain structure of the WHOQOL- BREF assessment could be applied to persons with SCI. Discriminant Validity Table 4 presents the results of the discriminant validity analysis by t test. Significant mean differences were found between the non-sci and SCI groups for each domain, and the overall QOL and general health facets. Table 4 also shows that Table 4: Discriminant Validity of the WHOQOL-BREF Assessment by t Test Facet and Domain Non-SCI (n 169) SCI (n 111) t P Overall QOL facet General health facet Physical health Psychologic health Social relationships Environment NOTE. Values are mean SD.

5 1894 WHOQOL-BREF IN SCI, Jang discriminant validity was best demonstrated in the physical health domain, followed by the psychologic, social, and environmental domains. The scores of physical, psychologic, social, and the overall QOL and general health facets were influenced by the SCI and non-sci group, but not for the environment domain (t.86, P.389), after controlling for gender, education, and employment status. These results generally supported the discriminant validity of the WHOQOL- BREF assessment in persons with SCI. DISCUSSION This is the first study to examine the validity of the WHO- QOL-BREF assessment in persons with traumatic SCI. Generally, the results supported the validity of the WHOQOL-BREF assessment for the SCI population, and showed a nearly symmetric distribution of domain scores and an acceptable validity; however, a few modifications, discussed below, are needed. Distribution of WHO-BREF Assessment Scores No floor or ceiling effect was seen for the overall QOL and general health facets and the 4 domains. However, the mobility and positive feeling facets showed significant floor effects. The reason for this might be that most SCI subjects have limitations of mobility and low expectations for the future. The percentage of missing replies to item 21 ( How satisfied are you with your sex life? ) was a little high (7.0%) compared with those for other items. This was not the only phenomenon in our study. In fact, 13% of a nationwide sample of 1068 subjects (both healthy and ill) in Taiwan did not answer this question 13 ;in addition, in studies in the United Kingdom and the Netherlands, respectively, 19% of patients with cancer and 12% to 22% of patients with chronic liver disease did not answer this item, whereas the percentage of missing replies to other items was less than 5%. 22,23 This might reflect the fact that many people found this question intrusive. The wording of this question might need to be changed to improve the applicability of the WHOQOL-BREF assessment. Despite the minor problems above, overall, the utility of the WHOQOL-BREF assessment was demonstrated. Internal Consistency The WHOQOL-BREF assessment showed internal consistency in 3 domains, but not the social relationships domain (.55). Alpha values are generally lower for domains containing very few items. 17 Because the social relationships domain calculation is based only on 3 items, whereas those for the other domains are based on 6 to 8 items, this lower value was not unexpected. Similar results were found in a crosscultural study, where value for the social relationships domain in different field sites ranged from.51 to.77, while values in other domains were greater than Structure of the WHOQOL-BREF Assessment The theoretical constructs that underpinned the development of the WHOQOL-BREF assessment were the 4 domains of physical health, psychologic health, social relationships, and environment. 8 In our study, multitrait analysis of the relationship between WHOQOL-BREF facets and related domains confirmed the original WHOQOL-BREF structure developed by the WHOQOL-BREF group. Although 10 items also had moderate correlations with domains other than their intended domain, these results might be influenced by the specific characteristics of SCI. Severe physical disability means that persons with SCI have difficulties with mobility and transportation and in performing ADLs, work, and leisure. Difficulty in participation might affect a person s perception of his/her physical health, psychologic health, and even the environment. 23 Positive feelings and self-esteem might influence the person s feelings of physical health. 1,3 Despite this, no item correlated more strongly with another domain than with its own domain. In general, the 4-domain structure of the WHOQOL-BREF was confirmed. Discriminant Validity The WHOQOL-BREF assessment was able to differentiate between the SCI and the non-sci groups in the physical health, psychologic health, and social relationships domains, but not the environment domain, after controlling for age, gender, education, and employment status. Although a strength of the WHOQOL-BREF assessment is that it includes the social relationships and environment domains, which are not always included in other assessments, the discriminant power of these domains did not seem to be as good. In the study by Skevington et al, 12 although the total sample demonstrated good discriminant validity in all domains, if we examine the results carefully, we can see that several field trial centers were unable to differentiate between sick and healthy respondents, especially in the environment domain. This raises the question of whether additional items should be added to increase the discriminant power for the environment domain. This is especially relevant in persons with SCI, who have severe physical disabilities and are very sensitive to the environment in which they live. 11,24 Study Limitations The size of the sample and the response rate in our study were lower than expected, because contact had been lost with many of the persons with SCI, due to nonnotification of a change of address. In addition, data were mainly collected in 1 hospital and therefore cannot be generalized to persons with traumatic SCI in other hospitals. Although this study provides preliminary support for use of the WHOQOL-BREF assessment in persons with SCI, we did not examine the test-retest reliability, concurrent validity in comparison to other relevant measurements, or responsiveness of the WHOQOL-BREF assessment. Further longitudinal studies testing the responsiveness and replicating the validity and reliability in a larger sample are needed. CONCLUSIONS This study describes the initial testing of the WHOQOL- BREF assessment in persons with SCI. The WHOQOL-BREF assessment is based on a cross-cultural concept and available in most of the world s major languages; thus, it is suitable for use in multinational collaborative research. The WHOQOL-BREF assessment encompasses domains and facets that are integral to the assessment of QOL. However, the WHOQOL-BREF assessment needs more work on the test-retest reliability, concurrent validity, as well as responsiveness, which is the ability of a scale to detect changes. This validity study suggests that the WHOQOL-BREF assessment can be used to measure QOL as perceived by a person with SCI. References 1. Trieschmann RB. Spinal cord injuries: psychological, social, and vocational rehabilitation. 2nd ed. New York: Demos; DeVivo MJ, Shewchuk RM, Stover SL, Black KJ, Go BK. 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