The cost utility analysis of riluzole for the treatment of amyotrophic lateral sclerosis in the UK

This study reports the results of a long-term economic evaluation of riluzole in the treatment of amyotrophic lateral sclerosis (ALS) versus best supportive care in the United Kingdom. The aim was to assess the cost implications of the life extension offered by riluzole through cost utility analysis based on patient assessed utilities of different health states.

A Markov model was used to assess the cost-effectiveness of Rilutek with best supportive care. Transition possibilities and the distribution of patients by health states were taken from a cohort of 954 patients drawn from a large randomised, double blind, placebo-controlled, multicentre trial between 1992 and 1994 in the first 18 months and used to extrapolate the model to assess the long-term prolongation of life. Four distinct health states were used corresponding to mild, moderate, severe and terminal states. Costs associated with Rilutek included the acquisition cost and bi-monthly monitoring for raised ALT levels. Patient assessed utilities were collected by use of the standard gamble technique. 77 patients were entered into the study from two centres (King's, London and Preston) in the UK. Mean utilities for each of the health states was generated and, given that the data were skewed, a sensitivity analysis was undertaken with the median utility values.

The implications of life extension offered by riluzole versus best supportive care were assessed both in terms of life extension projected and quality adjusted survival using patient based utilities. Using the Markov model and the transitional probabilities the base case cost per life year gained was estimated at pound 14,370 and applying Standard Gamble utility scores, the base case cost per QALY was assessed as pound 20,904. The effect of discounting costs and benefits altered the cost effectiveness analysis to pound 17,760 per life year gained while a sensitivity analysis around median or mean scores for the utility weight resulted in a range of pound 19,020 to pound 25,794 per QALY gained. (C) 2001 Elsevier Science BY. All rights reserved.