Improving the model for the uk ms disease modifying treatment risk sharing scheme analysis: a new natural history dataset.
Palace J., Bregenzer T., Tremlett H., Duddy M., Boggild M., Zhu F., Oger J., Dobson C.
Although in 2002 the National Institute for Clinical Excellence, in 2002, concluded that the disease modifying treatments (DMTs) for MS-interferon-b and glatiramer acetate-were not cost effective over the short-term, it was recognised that longer-term benefits were possible. The 'UK risk sharing scheme' was initiated in order to deliver these drug cost-effectively by monitoring a cohort of MS patients over a 10 year period after starting a DMT, and if necessary adjusting the cost to meet a 20 year target of £36,000 per Quality Adjusted Life Year. The first (2 year) analysis,(1) used a natural history dataset from London, Ontario, Canada as the comparator cohort to estimate the transition probabilities. However, the model proved too susceptible to change in the sensitivity analysis, mainly related to the artificial 'smoothing' of key disability-related (Expanded Disability Status Scale (EDSS)) data which prevented scores from being recorded as improving. Thus the scientific advisory committee advised that an alternative data set should be sought where the actual EDSS scores were accessible. It was agreed that access to the dataset to allow validation of different models was important and that the original Discrete Markov model used would be compared to a Continuous Model to allow potential covariates and out of window EDSS scores to be used.