Measuring kidney disease-related loss in samples of predialysis and dialysis patients: validating the kidney disease loss scale

Background and objectives: Kidney disease-related loss is clinically significant in patients with ESRD and is related to depression and quality of life. The Kidney Disease Loss Scale (KDLS) was recently developed for long-term dialysis patients as a means of studying loss and applying it to clinical practice; however, its validity and usability in the other developmental stages of ESRD - predialysis and early dialysis - remain unknown. This study examined the validity and reliability of the KDLS in the long-term dialysis, early dialysis, and predialysis populations. Design, setting, participants, & measurements: Four groups of participants were recruited from four large university teaching hospitals in the Sydney metropolitan area. Participants were long-term dialysis (n = 151), early dialysis (n = 163), and predialysis (n = 111) patients. An additional independent group of dialysis (n = 50) patients were recruited to measure the test-retest reliability. Multisample confirmatory factor analysis and correlational analysis were used. Results: Results demonstrated good internal consistency and test-retest reliability for KDLS. Multisample confirmatory factor analysis indicated that the factor structure of KDLS was invariant across samples and thus supported its construct validity. The convergent and discriminant validities of KDLS were supported by its correlations with scales that measure health-related quality of life, depression, and positive affect in the expected directions and magnitudes. The KDLS was sensitive to the developmental stages of ESRD. Conclusions: These findings demonstrated that the concept of loss exists in dialysis patients. The KDLS is a reliable measure of loss in ESRD and valid in the developmental stages of ESRD.