Measurement properties of the Chinese Version of the Kidney Disease Quality of Life-Short Form (KDQOL-SF™) in end-stage renal disease patients with poor prognosis in Singapore

Abstract

Context: The Kidney Disease Quality of Life (KDQOL™) instrument is widely used to assess care of end-stage renal disease (ESRD) patients.

Objectives: This study aimed to demonstrate the measurement properties of the Chinese (simplified characters) version of the KDQOL-Short Form™ (KDQOL-SF™) in ethnic Chinese ESRD patients in Singapore.

Methods: Seventy-eight new ESRD patients, initially conservatively managed, were interviewed and followed-up; 31 later commenced dialysis. Quality of life (with the KDQOL-SF), Karnofsky Performance Status, and estimated glomerular filtration rate (eGFR) were assessed at 0, 3, 6, 9, 12, 18, and 24 months. Nonparametric statistics were used to assess correlation and changes.

Results: The patterns of descriptive summary and floor and ceiling effects were similar to those reported in the original English version. Most of the kidney disease-targeted scales and the generic scales of the KDQOL-SF demonstrated 1) criterion validity in terms of correlation with objectively measured and/or subjectively rated variables, 2) convergent/divergent validity in terms of correlation patterns between kidney disease-targeted and generic scales, and 3) responsiveness to change in terms of difference before and after dialysis, except for Work Status. Internal consistency reliability was satisfactory, but that for the Work Status scale was too low (alpha=0.32) and for two other kidney disease-targeted scales, Sexual Function and Dialysis Staff Encouragement, was too high (1.0).

Conclusion: Most of the scales in the Chinese version of the KDQOL-SF were valid and achieved internal consistency reliability, except for the Work Status scale. Also, the internal consistency reliability of two disease-targeted scales was too high, suggesting room for reduction of some items to reduce burden on respondents.