Measurement invariance of the kidney disease and quality of life instrument (KDQOL-SF) across Veterans and non-Veterans

Abstract

BackgroundStudies have demonstrated that perceived health-related quality of life (HRQOL) of patients receiving hemodialysis is significantly impaired. Since HRQOL outcome data are often used to compare groups to determine health care effectiveness it is imperative that measures of HRQOL are valid. However, valid HRQOL comparisons between groups can only be made if instrument invariance is demonstrated. The Kidney Disease Quality of Life-Short Form (KDQOL-SF) is a widely used HRQOL measure for patients with chronic kidney disease (CKD) however, it has not been validated in the Veteran population. Therefore, the purpose of this study was to examine the measurement invariance of the KDQOL-SF across Veterans and non-Veterans with CKD.MethodsData for this study were from two large prospective observational studies of patients receiving hemodialysis: 1) Veteran End-Stage Renal Disease Study (VETERAN) (N = 314) and 2) Dialysis Outcomes and Practice Patterns Study (DOPPS) (N = 3,300). Health-related quality of life was measured with the KDQOL-SF, which consists of the SF-36 and the Kidney Disease Component Summary (KDCS). Single-group confirmatory factor analysis was used to evaluate the goodness-of-fit of the hypothesized measurement model for responses to the subscales of the KDCS and SF-36 instruments when analyzed together; and given acceptable goodness-of-fit in each group, multigroup CFA was used to compare the structure of this factor model in the two samples. Pattern of factor loadings (configural invariance), the magnitude of factor loadings (metric invariance), and the magnitude of item intercepts (scalar invariance) were assessed as well as the degree to which factors have the same variances, covariances, and means across groups (structural invariance).ResultsCFA demonstrated that the hypothesized two-factor model (KDCS and SF-36) fit the data of both the Veteran and DOPPS samples well, supporting configural invariance. Multigroup CFA results concerning metric and scalar invariance suggested partial strict invariance for the SF-36, but only weak invariance for the KDCS. Structural invariance was not supported.ConclusionsResults suggest that Veterans may interpret the KDQOL-SF differently than non-Veterans. Further evaluation of measurement invariance of the KDQOL-SF between Veterans and non-Veterans is needed using large, randomly selected samples before comparisons between these two groups using the KDQOL-SF can be done reliably.

Dimensions of Oppositional Defiant Disorder in Young Children: Model Comparisons, Gender and Longitudinal Invariance

“…Strong invariance (Meredith 1993) is present if a model shows configural, metric, and scalar invariance. We chose not to assess invariance in item unique error variances and in factor variances-covariances because such analyses: (a) were not essential for meaningful between-and within-group comparisons of levels of ODD (Bontempo and Hofer 2007;Saban et al 2010); and (b) would have unnecessarily increased the number of statistical tests we conducted, thereby requiring an even stricter Bonferroni adjustment that would predispose the results of null-hypothesis inferential testing toward invariance.…”

“…Factorial invariance concerns the degree to which the items used to measure a construct have the same meaning and measure the construct in the same way across different groups of respondents (Brown 2006;Saban et al 2010). When invariance is not present, there is the possibility of construct bias in which the meaning of a construct differs across those groups or longitudinally (Kline 2011).…”

Fatores associados à qualidade de vida de pacientes renais crônicos em hemodiálise

“…This instrument assesses the overall quality of life and integrates specific data, which provides a comprehensive analysis. (9)(10)(11) This research enables the identification of the actual deficits related to the health of patients, and the determination of which of these cause greater impact on quality of life. (10) For the final score of the KDQOL-SF, data on each dimension were converted to a scale of 0 to 100.…”

Rationale and design of a patient-centered medical home intervention for patients with end-stage renal disease on hemodialysis

“…Using our primary outcome measure, Kidney Disease Quality of Life (KDQOL), we note that typical ESRD patients score about 48.6 points on the KDQOL scale (SD ≈ 11.3). 2,4,29,30 With a goal to raise this figure by 10% to 53.5, which can be clinically meaningful, we calculated power based on a comparison of KDQOL score after 12 months of exposure to the intervention to baseline score (or score at entry for those who entered later). Using SAS macro GEESIZE version 3.1, 26 under a Gaussian GEE model for repeated measures, 77 patients total are required to test this hypothesis with power 0.80 at the alpha = 0.05 two-sided level of significance.…”