Validation of an instrument for measuring satisfaction of patients undergoing hemodialysis

BACKGROUND: Patients’ satisfaction is an indicator of the quality of healthcare services. Its measurement involves developing and validating complex instruments. The purpose of this study was to validate a scale for measuring hemodialysis patients’ satisfaction with the provided care, the Scale for Evaluation of Hemodialysis Patient’s Satisfaction with Service provided at a Chronic Kidney Disease Unit (or ESUR-HD, its acronym in Spanish). METHODS: The instrument was applied to 370 patients undergoing hemodialysis for undertaking exploratory and confirmatory analyses, internal consistency assessment, and Rasch analysis. In order to assure test-retest reliability, the instrument was applied once again to 54 patients after 2 days. Convergent validity was assessed by estimating correlation coefficients based on the results of 2 instruments (ESUR-HD and SDIALOR) simultaneously applied in 70 patients. Sensitivity to change was assessed in 40 patients by comparing the scale scores before and after an intervention consisting of improved care conditions. RESULTS: In the 44 items of the scale a 9-factor structure was found (1: Facilities and organization of the service. 2: Care provided by the attending nurses and/or nursing assistants. 3: Attention to psychological and administrative issues. 4: Contact and social work personnel. 5: Medical attention and care. 6: Nutritional attention and care. 7: Medications supply and quality. 8: Features of the admission process. 9: Attention and care provided by head nurses). Chronbach alpha for the scale was 0.96. Lin’s concordance correlation for the whole scale was 0.85. Although statistically different from 0, low correlation values with dimensions from another scale measuring the same attribute were found. The scale could detect construct changes through increased scores in specific dimensions following an intervention aimed at enhancing satisfaction. Rasch analysis located improperly fit items and suggested reducing items measurement levels. Despite the effect encountered, Rasch analysis showed the scale might not capture variability in upper attribute levels. CONCLUSION: The ESUR-HD scale measures hemodialysis patients’ satisfaction in one dimension with 9 domains. Validity and reliability are adequate. The instrument may detect changes in the construct. Subsequent versions of the scale should include new items allowing improved discrimination amongst high satisfaction levels. TRIAL REGISTRATION: 10.1186/ISRCTN45318400. April 05, 2017