A COMPARISON OF EVALUATIVE INDEXES OF QUALITY-OF-LIFE AND COGNITIVE FUNCTION IN HEMODIALYSIS-PATIENTS

In the setting of end-stage renal disease, the reproducibility and responsiveness of three health-related quality-of-life instruments were evaluated. The Time Trade Off instrument (TTO) is a generic instrument used to evaluate the utility of a health state. The Hemodialysis Quality-of-Life questionnaire (HQL) is a disease-specific instrument. A series of function-specific tests evaluated neurocognitive function. The TTO and HQL instruments are patient centric in that patient values define the health status while the neurocognitive function tests reflect the values of healthcare professionals. Forty-seven chronic hemodialysis patients participated. Those with adequate dialysis, defined as a Kt/V (a measure of small solute removal during hemodialysis) above 1.0 were maintained at that level for two administrations of the three instruments separated by six to eight weeks. The test-retest intraclass correlation coefficient exceeded 0.90 for all five domains of the HQL questionnaire and exceeded 0.70 for nine neurocognitive function tests. Patients with inadequate dialysis (Kt/V < 0.8) had Kt/V increased to above 1.0. The TTO was not responsive. For the HQL questionnaire, an item was considered responsive if a 1-point improvement, on a 7-point Likert type scale, occurred significantly more often among those with an improvement in hemodialysis treatment compared to those without improvement. Only one item had such a change and therefore the HQL cannot be considered responsive. For the neurocognitive function tests, the ratio of change score for patients with an improvement in hemodialysis treatment to the standard deviation of change score among stable patients was used to define responsiveness. A ratio > 0.5 was considered as indicative of responsiveness. This did not occur more often among those with improved dialysis than among those with stable hemodialysis treatment.