Costs and Outcomes in Hemodialysis and Hemodiafiltration

Abstract

Both survival and quality of life (QoL) are poor in patients on hemodialysis. Earlier studies have shown their QoL to be lower than in patients with for instance chronic heart failure, arthritis and metastatic colon cancer. Hemodialysis patients do not only face the symptoms of end-stage renal disease, but also the challenges of a demanding therapy. It is therefore important to explore determinants of QoL to ameliorate this outcome. Online hemodiafiltration might be such a determinant. It is a relatively new dialysis therapy that improves the clearance of middle molecular weight substances. It was hypothesized that due to this improved correction of the uremic environment, hemodiafiltration could decrease cardiovascular damage and thus cardiovascular morbidity and mortality as compared to low-flux hemodialysis. As resources in health care are scarce, there is an increasing demand that the surplus value of a new therapy is not only addressed by showing its effectiveness, but also by proving its cost-effectiveness. It was the aim of this thesis to evaluate both costs and outcomes in hemodialysis and hemodiafiltration. This thesis mainly included data of the Convective Transport Study (CONTRAST), a randomized controlled trial with 714 patients in 29 dialysis centers in the Netherlands, Norway and Canada. Patients were randomly assigned to either hemodiafiltration or hemodialysis. QoL was measured every year with a questionnaire, the Kidney Disease Quality of Life – Short Form (KDQOL-SF). This questionnaire combines the generic short-form 36 (SF-36) with kidney disease-specific QoL domains. Costs were analyzed using a societal perspective. Hemodialysis patients’ QoL improved over time. Physical domains however remained behind and these were especially poor. The physical composite score was one of the domains that differed in hemodialysis patients between dialysis centers. Current clinical performance targets in dialysis care showed no relation with patients’ QoL. Various parameters of protein-energy nutritional status did show a relation, but a composite score of this entity had no better prediction of outcome than its individual components. Hemodiafiltration had no effect on QoL or survival if compared to hemodialysis. An on-treatment analysis however suggested a positive effect of hemodiafiltration on survival in patients who reach a convection volume of more than 20.3 L per session. Even considering this fact, hemodiafiltration is not a cost-effective treatment. Although the additional cost of hemodiafiltration was relatively minor as compared to hemodialysis, it was not counterbalanced by a relevant gain in quality-adjusted life-years (QALY, a hypothetical year in optimal health). Physical QoL domains stayed behind in hemodialysis patients and its improvement should be a subject of future research. The variation in patients’ QoL between centers suggests room for improvement, which may be guided by the development of meaningful performance targets (e.g. on protein-energy nutritional status). Hemodiafiltration had no beneficial effect on survival or QoL. There may be a clinical advantage of hemodiafiltration as compared to hemodialysis in patients that attain >20.3L of convection volume, but still, hemodiafiltration is not cost-effective. Perhaps the surplus costs of hemodiafiltration can be reduced in the future; otherwise cost-effective alternatives for traditional in-center hemodialysis should be pursued.