Skip to main content
SpringerLink
Log in

Psychometric evaluation of the Schizophrenia Quality of Life Scale (SQLS) in English- and Chinese-speaking Asians in Singapore

  • Published:
Quality of Life Research Aims and scope Submit manuscript

Abstract

Objective

To assess the psychometric properties of the Schizophrenia Quality of Life Scale (SQLS) in Asians with schizophrenia in Singapore.

Methods

A consecutive sample of outpatients with schizophrenia completed the English or Chinese version of the SQLS and the Short-Form 36 Health Survey (SF-36) twice during two different clinic visits. The patients were also assessed for presence or absence of 22 psychiatric symptoms.

Results

About 202 patients (English-speaking: 140) participated in the study. Correlations between SQLS scales and other measures assessing similar constructs ranged from 0.46 to 0.69 (P < 0.001 for all). For SQLS psychosocial and symptoms/side effects scales, item-to-scale correlations were >0.4, Cronbach’s alpha and intra-class correlation coefficient values were close to or exceed 0.7, and Cohen’s effect size, standardized response mean, and Guyatt’s responsiveness index values approximated or exceeded 0.2 for both SQLS language versions; however, for the energy/motivation scale, item-to-scale correlations (range: 0.08–0.51), reliability (range: 0.46–0.66) and responsiveness (range: 0.04–0.08) statistics were not satisfactory for both SQLS versions.

Conclusions

The SQLS psychosocial and symptoms/side effects scales are valid, reliable and responsive in Singaporean patients with schizophrenia; the appropriateness of energy/motivation scale requires further investigation.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Similar content being viewed by others

References

  1. Saha, S., Chant, D., Welham, J., & McGrath, J. (2005). A systematic review of the prevalence of schizophrenia. PLoS Medicine, 2, e141.

    Google Scholar 

  2. Pinikahana, J., Happell, B., Hope, J., & Keks, N. A. (2002). Quality of life in schizophrenia: A review of the literature from 1995 to 2000. International Journal of Mental Health Nursing, 11, 103–111.

    Article  PubMed  Google Scholar 

  3. Bobes, J., Garcia-Portilla, P., Saiz, P. A., Bascaran, T., & Bousono, M. (2005). Quality of life measures in schizophrenia. European Psychiatry, 20(Suppl 3), 313–317.

    Article  Google Scholar 

  4. Hewitt, J. (2007). Critical evaluation of the use of research tools in evaluating quality of life for people with schizophrenia. International Journal of Mental Health Nursing, 16, 2–14.

    Article  PubMed  Google Scholar 

  5. Katschnig, H. (2000). Schizophrenia and quality of life. Acta Psychiatrica Scandinavica, 102, 33–37.

    Article  Google Scholar 

  6. Guyatt, G. H., Jaeschke, R., Feeny, D. H., & Patrick, D. L. (1996). Measurement in clinical trials: Choosing the right approach. In Spilker B. (Ed.), Quality of life and pharmacoeconomics in clinical trials (pp. 41–48). Philadelphia: Lippincott-Raven Publishers.

    Google Scholar 

  7. Osoba, D. (1998). Guidelines for measuring health-related quality of life in clinical trials. In Staquet M. J., Hays R. D., & Fayers P. M. (Eds.), Quality of life assessment in clinical trials methods and practice (pp. 19–35). Oxford: Oxford University Press.

    Google Scholar 

  8. Awad, A. G. (1992). Quality of life of schizophrenic patients on medications and implications for new drug trials. Hospital & Community Psychiatry, 43, 262–265.

    CAS  Google Scholar 

  9. Heinrichs, D. W., Hanlon, T. E., & Carpenter, W. T. Jr. (1984). The Quality of Life Scale: An instrument for rating the schizophrenic deficit syndrome. Schizophrenia Bulletin, 10, 388–398.

    PubMed  CAS  Google Scholar 

  10. Skantze, K., Malm, U., Dencker, S. J., May, P. R., & Corrigan, P. (1992). Comparison of quality of life with standard of living in schizophrenic out-patients. British Journal of Psychiatry, 161, 797–801.

    Article  PubMed  CAS  Google Scholar 

  11. Oliver, J., Huxley, P., Bridges, K., & Kaiser, W. (1996). Quality of life and mental health services. London: Routledge.

    Google Scholar 

  12. Lehman, A. F., Ward, N. C., & Linn, L. S. (1982). Chronic mental patients: The quality of life issue. American Journal of Psychiatry, 139, 1271–1276.

    PubMed  CAS  Google Scholar 

  13. Wilkinson, G., Hesdon, B., Wild, D., Cookson, R., Farina, C., & Sharma, V., et al. (2000). Self-report quality of life measure for people with schizophrenia: The SQLS. British Journal of Psychiatry, 177, 42–46.

    Article  PubMed  CAS  Google Scholar 

  14. Kaneda, Y., Imakura, A., Fujii, A., & Ohmori, T. (2002). Schizophrenia Quality of Life Scale: Validation of the Japanese version. Psychiatry Research, 113, 107–113.

    Article  PubMed  Google Scholar 

  15. Guillemin, F., Bombardier, C., & Beaton, D. (1993). Cross-cultural adaptation of health-related quality of life measures: Literature review and proposed guidelines. Journal of Clinical Epidemiology, 46, 1417–1432.

    Article  PubMed  CAS  Google Scholar 

  16. Ware, J. E., Snow, K. K., Kosinski, M., & Gandek, B. (1993). SF-36 health survey manual and interpretation guide. New York: New England Medical Center.

    Google Scholar 

  17. Ware, J. E., Kosinski, M., & Dewey, J. E. (2000). How to score version 2 of the SF-36 Health Survey. Lincoln: QualityMetric Inc.

    Google Scholar 

  18. Thumboo, J., Fong, K. Y., Machin, D., Chan, S. P., Leong, K. H., & Feng, P. H., et al. (2001). A community-based study of scaling assumptions and construct validity of the English (UK) and Chinese (HK) SF-36 in Singapore. Quality of Life Research, 10, 175–188.

    Article  PubMed  CAS  Google Scholar 

  19. Wilkinson, G., Wild, D., Fitzpatrick, R., Jenkinson, C., & Hesdon, B. (1999). User manual for the SQLS. Headington: Oxford Outcomes.

    Google Scholar 

  20. Browne, S., Roe, M., Lane, A., Gervin, M., Morris, M., & Kinsella, A., et al. (1996). Quality of life in schizophrenia: Relationship to sociodemographic factors, symptomatology and tardive dyskinesia. Acta Psychiatrica Scandinavica, 94, 118–124.

    Article  PubMed  CAS  Google Scholar 

  21. Meltzer, H. Y., Burnett, S., Bastani, B., & Ramirez, L. F. (1990). Effects of six months of clozapine treatment on the quality of life of chronic schizophrenic patients. Hospital & Community Psychiatry, 41, 892–897.

    CAS  Google Scholar 

  22. Juniper, E. F., Gordon, H. G., & Roman, J. (1996). How to develop and validate a new health-related quality of life instrument. In Spilker B. (Ed.), Quality of life and pharmacoeconomics in clinical trials (pp. 49–56). Philadelphia: Lippincott-Raven Publishers.

    Google Scholar 

  23. Fayers, P. M., & Machin, D. (2000). Quality of life: Assessment, analysis and interpretation. Chichester: John Wiley & Sons.

    Google Scholar 

  24. Hays, R. D., Anderson, R. T., & Revicki, D. (1998). Assessing reliability and validity of measurement in clinical trials. In Staquet M. J., Hays R. D., & Fayers P. M. (Eds.), Quality of Life assessssment in clinical trials methods and practice (pp. 169–182). Oxford: Oxford University Press.

    Google Scholar 

  25. Cohen, J. (1988). Statistical power analysis for the behavioral sciences (2nd ed.). Hillsdale: Lawrence Earlbaum Associates.

    Google Scholar 

  26. Deyo, R. A., Diehr, P., & Patrick, D. L. (1991). Reproducibility and responsiveness of health status measures. Statistics and strategies for evaluation. Controlled Clinical Trials, 12, 142S–158S.

    Article  PubMed  CAS  Google Scholar 

  27. Guyatt, G., Walter, S., & Norman, G. (1987). Measuring change over time: Assessing the usefulness of evaluative instruments. Journal of Chronic Diseases, 40, 171–178.

    Article  PubMed  CAS  Google Scholar 

  28. Schunemann, H. J., & Guyatt, G. H. (2005). Commentary—goodbye M(C)ID! Hello MID, where do you come from? Health Services Research, 40, 593–597.

    Article  PubMed  Google Scholar 

  29. Kay, S. R., Fiszbein, A., & Opler, L. A. (1987). The positive and negative syndrome scale (PANSS) for schizophrenia. Schizophrenia Bulletin, 13, 261–276.

    PubMed  CAS  Google Scholar 

  30. Overall, J. E., & Gorham, D. R. (1962). The brief psychiatric rating scale. Psychological Reports, 10, 799–812.

    Article  Google Scholar 

  31. Peto, V., Jenkinson, C., & Fitzpatrick, R. (2001). Determining minimally important differences for the PDQ-39 Parkinson’s disease questionnaire. Age Ageing, 30, 299–302.

    Article  PubMed  CAS  Google Scholar 

  32. Walters, S. J., & Brazier, J. E. (2003). What is the relationship between the minimally important difference and health state utility values? The case of the SF-6D. Health Quality of Life and Outcomes, 1, 4.

Download references

Author information

Authors and Affiliations

  1. Department of Community, Occupational and Family Medicine & Centre for Health Services Research, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore

    Nan Luo

  2. School of Human Development and Social Services, SIM University, Singapore, Singapore

    Boon-Kheng Seng

  3. Program for Assessment of Technology in Health, Department of Clinical Epidemiology and Biostatistics, McMaster University, Ontario, Canada

    Feng Xie

  4. Discipline of Pharmacy & Experimental Pharmacology, School of Biomedical Sciences, University of Newcastle, Callaghan, Australia

    Shu-Chuen Li

  5. Department of Rheumatology and Immunology, Singapore General Hospital, Singapore, Singapore

    Julian Thumboo

  6. Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore

    Julian Thumboo

Authors
  1. Nan Luo
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Boon-Kheng Seng
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Feng Xie
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Shu-Chuen Li
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. Julian Thumboo
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to Nan Luo.

Rights and permissions

Reprints and permissions

About this article

Cite this article

Luo, N., Seng, BK., Xie, F. et al. Psychometric evaluation of the Schizophrenia Quality of Life Scale (SQLS) in English- and Chinese-speaking Asians in Singapore. Qual Life Res 17, 115–122 (2008). https://doi.org/10.1007/s11136-007-9278-1

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s11136-007-9278-1

Keywords

Search

Navigation