Illustrating the impact of including future costs in economic evaluations: an application to end-stage renal disease care

There are strong theoretical arguments for including future costs for related and unrelated medical care and non-medical expenditures within economic evaluations. Nevertheless, there is limited data on how inclusion of such costs affects the cost effectiveness of medical interventions in practice. For a low-cost intervention that improves survival in end-stage renal disease (ESRD) patients, we sought to determine how the inclusion of future costs for related medical care (i.e. dialysis and transplantation) and for unrelated medical care and non-medical expenditure would affect the magnitude of the cost per QALY ratio. We performed a cost-utility analysis comparing hemodialysis using a synthetic dialyser (the current treatment of choice in Canada) with the historical gold-standard treatment (use of a cellulose dialyser). We contrasted the results of the analysis including and excluding various measures of future costs. While the inclusion of future costs for unrelated medical care and non-medical expenditures had a significant impact on the cost per QALY ratio, the size of the cost per QALY ratio was most sensitive to inclusion of future costs for related medical care. Our analysis shows that even relatively inexpensive interventions that extend survival of dialysis patients may not be cost-effective since, by extending survival, the extra outpatient dialysis costs that are incurred are large. Inclusion of such costs (which, in and of itself, is methodologically correct) in economic evaluations in this area may mitigate against the acceptance of interventions that are relatively inexpensive themselves but which improve patient survival.