Top

Gepubliceerd in:

31-10-2023

Psychometric evaluation of the WHOQOL-BREF and its shorter versions for general Thai population: confirmatory factor analysis and Rasch analysis

Auteurs: Krittaphas Kangwanrattanakul, Christian U. Krägeloh

Gepubliceerd in: Quality of Life Research | Uitgave 2/2024

Abstract

Purpose

Rasch analysis was employed to validate the World Health Organization Quality of Life-BREF (WHOQOL-BREF) and its existing shorter versions in the general Thai population.

Methods

1200 respondents were randomly selected to complete the questionnaire. Confirmatory factor analysis (CFA) was employed to test the structure of the WHOQOL-BREF and its shorter versions with the random sub-sample of 900 respondents, while Rasch analysis was performed with a random sub-sample of 300 respondents.

Results

The CFA confirmed the factor structure of WHOQOL-BREF and its shorter versions. The Rasch analysis revealed that the WHOQOL-BREF, when a four-domain structure was tested using a subtest approach, achieved acceptable model fit to the Rasch model and met the expectations of unidimensionality with high reliability (PSI = 0.87). Individual domain models were also unidimensional, but reliability of the 3-item social domain was inadequate. While the 8-item EUROHIS-QOL-8 and 5-item WHOQOL-5 achieved an overall acceptable fit and met the expectations of unidimensionality, the reliability of the WHOQOL-5 was below the acceptable threshold (PSI = 0.66). Reliability of the EUROHIS-QOL-8 was satisfactory (PSI = 0.79).

Conclusions

The WHOQOL-BREF is a valid instrument for use in the Thai general population, both as a total score as well as individual subscales. Rasch analysis also supports the use of EUROHIS-QOL-8, but the WHOQOL-5 lacks good reliability. While the reliability of the EUROHIS-QOL-8 is sufficiently high for between-group analysis, the Thai WHOQOL-BREF total score can also be used for within-participant analyses. Rasch investigation with a more varied health conditions of general Thai samples or patient groups is encouraged for future studies.

vorige artikel Preference-based measures of health-related quality of life in Indigenous people: a systematic review

volgende artikel Alcohol consumption and health-related quality of life in regional, rural and metropolitan Australia: analysis of cross-sectional data from the Community Health and Rural/Regional Medicine (CHARM) study

Alleen toegankelijk voor geautoriseerde gebruikers

Remick, J. S., Kowalski, E., Samanta, S., Choi, S., Palmer, J. D., & Mishra, M. V. (2020). Health-related quality of life and patient-reported outcomes in radiation oncology clinical trials. Current Treatment Options in Oncology, 21(11), 87. https://doi.org/10.1007/s11864-020-00782-4CrossRefPubMed

Kaplan, R. M., & Hays, R. D. (2022). Health-related quality of life measurement in public health. Annual Review of Public Health, 43, 355–373. https://doi.org/10.1146/annurev-publhealth-052120-012811CrossRefPubMed

Aaronson, N., Alonso, J., Burnam, A., Lohr, K. N., Patrick, D. L., Perrin, E., et al. (2002). Assessing health status and quality-of-life instruments: Attributes and review criteria. Quality of Life Research, 11(3), 193–205. https://doi.org/10.1023/a:1015291021312CrossRefPubMed

Coons, S. J., Rao, S., Keininger, D. L., & Hays, R. D. (2000). A comparative review of generic quality-of-life instruments. Pharmacoeconomics, 17(1), 13–35. https://doi.org/10.2165/00019053-200017010-00002CrossRefPubMed

Romero, M., Vivas-Consuelo, D., & Alvis-Guzman, N. (2013). Is health related quality of life (HRQoL) a valid indicator for health systems evaluation? Springerplus, 2(1), 664. https://doi.org/10.1186/2193-1801-2-664CrossRefPubMedPubMedCentral

The WHOQOL Group. (1998). The World Health Organization quality of life assessment (WHOQOL): Development and general psychometric properties. Social Science & Medicine, 46(12), 1569–1585.CrossRef

Bowden, A., & Fox-Rushby, J. A. (2003). A systematic and critical review of the process of translation and adaptation of generic health-related quality of life measures in Africa, Asia, Eastern Europe, the Middle East, South Amercia. Social Science & Medicine, 57(7), 1289–1306. https://doi.org/10.1016/s0277-9536(02)00503-8CrossRef

Power, M., Harper, A., & Bullinger, M. (1999). The World Health Organization WHOQOL-100: Tests of the universality of quality of life in 15 different cultural groups worldwide. Health Psychology, 18(5), 495–505. https://doi.org/10.1037//0278-6133.18.5.495CrossRefPubMed

The WHOQOL Group. (1998). Development of the World Health Organization WHOQOL-BREF quality of life assessment. Psychological Medicine, 28(3), 551–558. https://doi.org/10.1017/s0033291798006667CrossRef

10.

Gholami, A., Araghi, M. T., Shamsabadi, F., Bayat, M., Dabirkhani, F., Moradpour, F., et al. (2016). Application of the World Health Organization Quality of Life Instrument, Short Form (WHOQOL-BREF) to patients with cataract. Epidemiology and Health, 38, e2016005. https://doi.org/10.4178/epih.e2016005CrossRefPubMedPubMedCentral

11.

Taylor, W. J., Myers, J., Simpson, R. T., McPherson, K. M., & Weatherall, M. (2004). Quality of life of people with rheumatoid arthritis as measured by the World Health Organization Quality of Life Instrument, short form (WHOQOL-BREF): Score distributions and psychometric properties. Arthritis and Rheumatism, 51(3), 350–357. https://doi.org/10.1002/art.20398CrossRefPubMed

12.

Iqbal, M. S., Kassab, Y. W., Al-Saikhan, F. I., Almalki, Z. S., Haseeb, A., Iqbal, M. Z., et al. (2020). Assessing quality of life using WHOQOL-BREF: A cross-sectional insight among patients on warfarin in Malaysia. Saudi Pharmaceutical Journal, 28(8), 936–942. https://doi.org/10.1016/j.jsps.2020.06.014CrossRefPubMedPubMedCentral

13.

Schmidt, S., Mühlan, H., & Power, M. (2006). The EUROHIS-QOL 8-item index: Psychometric results of a cross-cultural field study. European Journal of Public Health, 16(4), 420–428. https://doi.org/10.1093/eurpub/cki155CrossRefPubMed

14.

Geyh, S., Fellinghauer, B. A., Kirchberger, I., & Post, M. W. (2010). Cross-cultural validity of four quality of life scales in persons with spinal cord injury. Health and Quality of Life Outcomes, 8, 94. https://doi.org/10.1186/1477-7525-8-94CrossRefPubMedPubMedCentral

15.

Skevington, S. M., Lotfy, M., & O’Connell, K. A. (2004). The World Health Organization’s WHOQOL-BREF quality of life assessment: psychometric properties and results of the international field trial: A report from the WHOQOL group. Quality of Life Research, 13(2), 299–310. https://doi.org/10.1023/b:Qure.0000018486.91360.00CrossRefPubMed

16.

Sakthong, P., Schommer, J. C., Gross, C. R., Sakulbumrungsil, R., & Prasithsirikul, W. (2007). Psychometric properties of WHOQOL-BREF-THAI in patients with HIV/AIDS. Journal of the Medical Association of Thailand, 90(11), 2449–2460.PubMed

17.

Abdullah Bandar, N. F., Jani, R., & Karim, M. A. (2014). Psychometric properties of the WHOQOL-BREF questionnaire among disabled students in Malaysian higher learning institutions. Applied Research in Quality of Life, 9(3), 469–478. https://doi.org/10.1007/s11482-013-9244-8CrossRef

18.

Yoshitake, N., Sun, Y., Sugawara, M., Matsumoto, S., Sakai, A., Takaoka, J., et al. (2015). The psychometric properties of the WHOQOL-BREF in Japanese couples. Health Psychology Open, 2(2). https://doi.org/10.1177/2055102915598089CrossRefPubMedPubMedCentral

19.

Rosén, H., Ahlström, G., & Lexén, A. (2020). Psychometric properties of the WHOQOL-BREF among next of kin to older persons in nursing homes. Health and Quality of Life Outcomes, 18(1), 103. https://doi.org/10.1186/s12955-020-01345-9CrossRefPubMedPubMedCentral

20.

Chang, K.-C., Wang, J.-D., Tang, H.-P., Cheng, C.-M., & Lin, C.-Y. (2014). Psychometric evaluation, using Rasch analysis, of the WHOQOL-BREF in heroin-dependent people undergoing methadone maintenance treatment: Further item validation. Health and Quality of Life Outcomes, 12(1), 148. https://doi.org/10.1186/s12955-014-0148-6CrossRefPubMedPubMedCentral

21.

Stucki, G., Daltroy, L., Katz, J. N., Johannesson, M., & Liang, M. H. (1996). Interpretation of change scores in ordinal clinical scales and health status measures: The whole may not equal the sum of the parts. Journal of Clinical Epidemiology, 49(7), 711–717. https://doi.org/10.1016/0895-4356(96)00016-9CrossRefPubMed

22.

Medvedev, O. N., & Krägeloh, C. U. (2022). Rasch measurement model. In O. N. Medvedev, C. U. Krägeloh, R. J. Siegert, & N. N. Singh (Eds.), Handbook of assessment in mindfulness research (pp. 1–18). Springer.CrossRef

23.

Wang, W. C., Yao, G., Tsai, Y. J., Wang, J. D., & Hsieh, C. L. (2006). Validating, improving reliability, and estimating correlation of the four subscales in the WHOQOL-BREF using multidimensional Rasch analysis. Quality of Life Research, 15(4), 607–620. https://doi.org/10.1007/s11136-005-4365-7CrossRefPubMed

24.

Uddin, M. N., & Islam, F. M. A. (2019). Psychometric evaluation of an interview-administered version of the WHOQOL-BREF questionnaire for use in a cross-sectional study of a rural district in Bangladesh: An application of Rasch analysis. BMC Health Services Research, 19(1), 216. https://doi.org/10.1186/s12913-019-4026-0CrossRefPubMedPubMedCentral

25.

Fan, X., & Sun, S. (2013). Item response theory. In T. Teo (Ed.), Handbook of quantitative methods for educational research (pp. 45–67). SensePublishers.CrossRef

26.

Krägeloh, C. U., Kersten, P., Rex Billington, D., Hsu, P. H., Shepherd, D., Landon, J., et al. (2013). Validation of the WHOQOL-BREF quality of life questionnaire for general use in New Zealand: Confirmatory factor analysis and Rasch analysis. Quality of Life Research, 22(6), 1451–1457. https://doi.org/10.1007/s11136-012-0265-9CrossRefPubMed

27.

Lin, C.-Y., Hwang, J.-S., Wang, W.-C., Lai, W.-W., Su, W.-C., Wu, T.-Y., et al. (2019). Psychometric evaluation of the WHOQOL-BREF, Taiwan version, across five kinds of Taiwanese cancer survivors: Rasch analysis and confirmatory factor analysis. Journal of the Formosan Medical Association, 118, 215–222. https://doi.org/10.1016/j.jfma.2018.03.018CrossRefPubMed

28.

Liang, W. M., Chang, C. H., Yeh, Y. C., Shy, H. Y., Chen, H. W., & Lin, M. R. (2009). Psychometric evaluation of the WHOQOL-BREF in community-dwelling older people in Taiwan using Rasch analysis. Quality of Life Research, 18(5), 605–618. https://doi.org/10.1007/s11136-009-9471-5CrossRefPubMed

29.

Department of Mental Health. Quality of life indicators of the World Health Organization Thai version (WHOQOL-bref-Thai). Retrived Feb 24 2022, from https://www.dmh.go.th/test/whoqol/

30.

Phungrassami, T., Katikarn, R., Watanaarepornchai, S., & Sangtawan, D. (2004). Quality of life assessment in radiotherapy patients by WHOQOL-BREF-THAI: A feasibility study. Journal of the Medical Association of Thailand, 87(12), 1459–1465.PubMed

31.

Sakthong, P., Sonsa-Ardjit, N., Sukarnjanaset, P., & Munpan, W. (2015). Psychometric properties of the EQ-5D-5L in Thai patients with chronic diseases. Quality of Life Research, 24(12), 3015–3022. https://doi.org/10.1007/s11136-11015-11038-zCrossRefPubMed

32.

Kangwanrattanakul, K., & Parmontree, P. (2020). Psychometric properties comparison between EQ-5D-5L and EQ-5D-3L in the general Thai population. Quality of Life Research, 29(12), 3407–3417. https://doi.org/10.1007/s11136-020-02595-2CrossRefPubMed

33.

Mahatnirundkul, S. (1998). Comparison of the WHOQOL-100 and the WHOQOL-BREF (26 items). Journal of Mental Health of Thailand, 5, 4–15.

34.

Taboonpong, S., Suttharangsee, W., & Chailangka, P. (2001). Evaluating psychometric properties of WHO quality of life questionnaire in Thai elderly. Journal of Gerontolology & Geriatric Medicine, 2, 6–12.

35.

Li, K., Kay, N. S., & Nokkaew, N. (2009). The performance of the World Health Organization’s WHOQOL-BREF in assessing the quality of life of thai college students. Social Indicators Research, 90(3), 489–501. https://doi.org/10.1007/s11205-008-9272-1CrossRef

36.

Leung, Y.-Y., Png, M.-E., Conaghan, P., & Tennant, A. (2014). A systematic literature review on the application of Rasch analysis in musculoskeletal disease—A special interest group report of OMERACT 11. The Journal of Rheumatology, 41(1), 159–164. https://doi.org/10.3899/jrheum.130814CrossRefPubMed

37.

Norquist, J. M., Fitzpatrick, R., Dawson, J., & Jenkinson, C. (2004). Comparing alternative Rasch-based methods vs raw scores in measuring change in health. Medical Care, 42(1 Suppl), I25-36. https://doi.org/10.1097/01.mlr.0000103530.13056.88CrossRefPubMed

38.

Demir, S. (2022). Comparison of normality tests in terms of sample sizes under different skewness and kurtosis coefficients. International Journal of Assessment Tools in Education, 9, 397–409. https://doi.org/10.21449/ijate.1101295CrossRef

39.

Terwee, C. B., Bot, S. D., de Boer, M. R., van der Windt, D. A., Knol, D. L., Dekker, J., et al. (2007). Quality criteria were proposed for measurement properties of health status questionnaires. Journal of Clinical Epidemiology, 60(1), 34–42. https://doi.org/10.1016/j.jclinepi.2006.1003.1012CrossRefPubMed

40.

Jöreskog, K. G. (1990). New developments in LISREL: Analysis of ordinal variables using polychoric correlations and weighted least squares. Quality and Quantity, 24(4), 387–404. https://doi.org/10.1007/BF00152012CrossRef

41.

Flora, D. B., & Curran, P. J. (2004). An empirical evaluation of alternative methods of estimation for confirmatory factor analysis with ordinal data. Psychological Methods, 9(4), 466–491. https://doi.org/10.1037/1082-989x.9.4.466CrossRefPubMedPubMedCentral

42.

Hu, L. T., & Bentler, P. M. (1999). Cutoff criteria for fit indexes in covariance structure analysis: Conventional criteria versus new alternatives. Structural Equation Modeling, 6(1), 1–55. https://doi.org/10.1080/10705519909540118CrossRef

43.

Linacre, J. (1994). Sample size and item calibration stability. Rasch Measurements Transactions, 7(328), 44.

44.

Tennant, A., & Conaghan, P. G. (2007). The Rasch measurement model in rheumatology: What is it and why use it? When should it be applied, and what should one look for in a Rasch paper? Arthritis and Rheumatism, 57(8), 1358–1362. https://doi.org/10.1002/art.23108CrossRefPubMed

45.

Pallant, J. F., & Tennant, A. (2007). An introduction to the Rasch measurement model: An example using the Hospital Anxiety and Depression Scale (HADS). British Journal of Clinical Psychology, 46(Pt 1), 1–18. https://doi.org/10.1348/014466506x96931CrossRefPubMed

46.

Smith, E. V., Jr. (2002). Detecting and evaluating the impact of multidimensionality using item fit statistics and principal component analysis of residuals. Journal of Applied Measurement, 3(2), 205–231.PubMed

47.

Lundgren-Nilsson, Å., Jonsdottir, I. H., Ahlborg, G., Jr., & Tennant, A. (2013). Construct validity of the Psychological General Well Being Index (PGWBI) in a sample of patients undergoing treatment for stress-related exhaustion: A Rasch analysis. Health and Quality of Life Outcomes, 11, 2. https://doi.org/10.1186/1477-7525-11-2CrossRefPubMedPubMedCentral

48.

Mansolf, M., & Reise, S. P. (2017). When and why the second-order and bifactor models are distinguishable. Intelligence, 61, 120–129. https://doi.org/10.1016/j.intell.2017.01.012CrossRef

49.

Skevington, S. M., Rowland, C., Panagioti, M., Bower, P., & Krägeloh, C. (2021). Enhancing the multi-dimensional assessment of quality of life: Introducing the WHOQOL-Combi. Quality of Life Research, 30(3), 891–903. https://doi.org/10.1007/s11136-020-02661-9CrossRefPubMed

50.

Medvedev, O. N., Siegert, R. J., Kersten, P., & Krägeloh, C. U. (2016). Rasch analysis of the Kentucky inventory of mindfulness skills. Mindfulness, 7(2), 466–478. https://doi.org/10.1007/s12671-015-0475-7CrossRef

51.

Maritz, R., Tennant, A., Fellinghauer, C., Stucki, G., & Prodinger, B. (2019). The functional independence measure 18-item version can be reported as a unidimensional interval-scaled metric: Internal construct validity revisited. Journal of Rehabilitation Medicine, 51(3), 193–200. https://doi.org/10.2340/16501977-2525CrossRefPubMed

52.

Tennant, A., & Pallant, J. (2007). DIF matters: A practical approach to test if differential item functioning makes a difference. Rasch Measurement Transactions, 20, 1082–1084.

53.

Andrich, D., & Hagquist, C. (2015). Real and artificial differential item functioning in polytomous items. Educational and Psychological Measurement, 75(2), 185–207. https://doi.org/10.1177/0013164414534258CrossRefPubMed

54.

Romanoski, J., & Douglas, G. (2002). Test scores, measurement, and the use of analysis of variance: An historical overview. Journal of Applied Measurement, 3(3), 232–242.PubMed

55.

Andrich, D., Sheridan, B., & Luo, G. (2009). RUMM 2030 (Beta Version for Windows) Perth. RUMM Laboratory Pty Ltd.

56.

Li, K., Kay, N. S., & Nokkaew, N. (2009). The performance of the World Health Organization’s WHOQOL-BREF in assessing the quality of life of Thai college students. Social Indicators Research, 90(3), 489–501. https://doi.org/10.1007/s11205-008-9272-1CrossRef

57.

Rocha, N. S., & Fleck, M. P. (2009). Validity of the Brazilian version of WHOQOL-BREF in depressed patients using Rasch modelling. Revista de Saude Publica, 43(1), 147–153. https://doi.org/10.1590/s0034-89102009000100019CrossRefPubMed

58.

Chang, C. C., Wu, T. H., Chen, C. Y., Wang, J. D., & Lin, C. Y. (2014). Psychometric evaluation of the internalized stigma of mental illness scale for patients with mental illnesses: Measurement invariance across time. PLoS ONE, 9(6), e98767. https://doi.org/10.1371/journal.pone.0098767ADSCrossRefPubMedPubMedCentral

59.

Podsakoff, P. M., MacKenzie, S. B., Lee, J. Y., & Podsakoff, N. P. (2003). Common method biases in behavioral research: A critical review of the literature and recommended remedies. Journal of Applied Psychology, 88(5), 879–903. https://doi.org/10.1037/0021-9010.88.5.879CrossRefPubMed

60.

Gu, H., Wen, Z., & Fan, X. (2015). The impact of wording effect on reliability and validity of the Core Self-Evaluation Scale (CSES): A bi-factor perspective. Personality and Individual Differences, 83, 142–147. https://doi.org/10.1016/j.paid.2015.04.006CrossRef

61.

Krägeloh, C. U., Billington, R., Hsu, P. H., & Landon, J. (2015). What New Zealanders find important to their quality of life: Comparisons with international WHOQOL data from 14 other countries. Australian and New Zealand Journal of Public Health, 39(4), 384–388. https://doi.org/10.1111/1753-6405.12350CrossRefPubMed

62.

Balalla, S. K., Medvedev, O. N., Siegert, R. J., & Krägeloh, C. U. (2019). Validation of the WHOQOL-BREF and shorter versions using Rasch analysis in traumatic brain injury and orthopedic populations. Archives of Physical Medicine and Rehabilitation, 100(10), 1853–1862. https://doi.org/10.1016/j.apmr.2019.05.029CrossRefPubMed

63.

Pires, A. C., Fleck, M. P., Power, M., & da Rocha, N. S. (2018). Psychometric properties of the EUROHIS-QOL 8-item index (WHOQOL-8) in a Brazilian sample. Brazilian Journal of Psychiatry, 40(3), 249–255. https://doi.org/10.1590/1516-4446-2017-2297CrossRefPubMedPubMedCentral

64.

da Rocha, N. S., Power, M. J., Bushnell, D. M., & Fleck, M. P. (2012). The EUROHIS-QOL 8-item index: Comparative psychometric properties to its parent WHOQOL-BREF. Value Health, 15(3), 449–457. https://doi.org/10.1016/j.jval.2011.11.035CrossRefPubMed

65.

Snell, D. L., Siegert, R. J., Surgenor, L. J., Dunn, J. A., & Hooper, G. J. (2016). Evaluating quality of life outcomes following joint replacement: Psychometric evaluation of a short form of the WHOQOL-Bref. Quality of Life Research, 25(1), 51–61. https://doi.org/10.1007/s11136-015-1044-1CrossRefPubMed

66.

Kleinman, A., Eisenberg, L., & Good, B. (1978). Culture, illness, and care: Clinical lessons from anthropologic and cross-cultural research. Annals of Internal Medicine, 88(2), 251–258. https://doi.org/10.7326/0003-4819-88-2-251CrossRefPubMed

Titel: Psychometric evaluation of the WHOQOL-BREF and its shorter versions for general Thai population: confirmatory factor analysis and Rasch analysis
Auteurs: Krittaphas Kangwanrattanakul
Christian U. Krägeloh
Publicatiedatum: 31-10-2023
Uitgeverij: Springer International Publishing
Gepubliceerd in: Quality of Life Research / Uitgave 2/2024
Print ISSN: 0962-9343
Elektronisch ISSN: 1573-2649
DOI: https://doi.org/10.1007/s11136-023-03521-y

Andere artikelen Uitgave 2/2024

Personal and perceived stigma in relation to diverse domains of quality of life among patients with major depressive disorder having residual symptoms: a hospital-based cross-sectional study in Thailand

Home care and quality of life among community-dwelling dependent older adults in Israel: a multiple mediator model

Alcohol consumption and health-related quality of life in regional, rural and metropolitan Australia: analysis of cross-sectional data from the Community Health and Rural/Regional Medicine (CHARM) study

Open Access

Quality of life of the Canadian population using the VR-12: population norms for health utility values, summary component scores and domain scores

Open Access

Mapping the 12-item World Health Organization disability assessment schedule 2.0 (WHODAS 2.0) onto the assessment of quality of life (AQoL)-4D utilities

Open Access

Bohn Stafleu van Loghum

Psychometric evaluation of the WHOQOL-BREF and its shorter versions for general Thai population: confirmatory factor analysis and Rasch analysis

Abstract

Purpose

Methods

Results

Conclusions

Andere artikelen Uitgave 2/2024

Personal and perceived stigma in relation to diverse domains of quality of life among patients with major depressive disorder having residual symptoms: a hospital-based cross-sectional study in Thailand

Home care and quality of life among community-dwelling dependent older adults in Israel: a multiple mediator model

Alcohol consumption and health-related quality of life in regional, rural and metropolitan Australia: analysis of cross-sectional data from the Community Health and Rural/Regional Medicine (CHARM) study

Quality of life of the Canadian population using the VR-12: population norms for health utility values, summary component scores and domain scores

Mapping the 12-item World Health Organization disability assessment schedule 2.0 (WHODAS 2.0) onto the assessment of quality of life (AQoL)-4D utilities

Mood assessments of family caregivers of patients with severe brain injury in China

Bohn Stafleu van Loghum

Deel dit onderdeel of sectie (kopieer de link)

Abstract

Purpose

Methods

Results

Conclusions

Log in om toegang te krijgen

Personal and perceived stigma in relation to diverse domains of quality of life among patients with major depressive disorder having residual symptoms: a hospital-based cross-sectional study in Thailand

Home care and quality of life among community-dwelling dependent older adults in Israel: a multiple mediator model

Alcohol consumption and health-related quality of life in regional, rural and metropolitan Australia: analysis of cross-sectional data from the Community Health and Rural/Regional Medicine (CHARM) study

Quality of life of the Canadian population using the VR-12: population norms for health utility values, summary component scores and domain scores

Mapping the 12-item World Health Organization disability assessment schedule 2.0 (WHODAS 2.0) onto the assessment of quality of life (AQoL)-4D utilities

Mood assessments of family caregivers of patients with severe brain injury in China