Test-Retest Reliability and Validity of the Nutrition-Specific Quality of Life Questionnaire

Objective: The purpose of this study is to test the Nutrition-Specific Quality of Life (NSQOL) questionnaire for test-retest reliability and validity in a sample of patients on maintenance hemodialysis (MHD). Design and Methods: Test-retest reliability of the NSQOL questionnaire via two patient interviews and comparison of the NSQOL questionnaire to a comprehensive nutrition assessment performed by a registered dietitian nutritionist for validity testing. This study was conducted in one outpatient MHD center in Chicago, IL. Adults, aged 18 years or older, treated with MHD for at least six months prior to start of the study. A Spearman's correlation coefficient was used to determine test-retest reliability and a Cronbach's alpha was used to determine the internal consistency of the 2 NSQOL questionnaires. Validity testing was done by comparing the NSQOL questionnaire to the most recent comprehensive nutrition assessment. Results: The sample consisted of 17 men (63%) and 10 women (37%), with a mean age of 60 ± 13, who were mostly African American (63%) and Caucasian (26%). There was a significant correlation (P =. 001) between the initial NSQOL interview and repeat NSQOL interview in all questions except for question 14 (P =. 100). The NSQOL questionnaire was found to have excellent internal consistency with an α = 0.900. No significant relationship was found among total NSQOL score and age, dialysis vintage, albumin, or normalized protein catabolic rate; however, older participants had lower total NSQOL questionnaire scores. Although not statistically significant, there was variability between NSQOL questionnaire score and nutritional status. Conclusions: The NSQOL questionnaire was found to be reliable and had high internal consistency in this sample of patients receiving MHD. The NSQOL questionnaire may be beneficial for monitoring nutrition quality of life changes in-between nutrition assessment intervals.