Cost-effectiveness comparison of tizanidine and baclofen in the management of spasticity

Baclofen and tizanidine are both used for the treatment of muscle spasticity of spinal origin. Their effectiveness, cost and adverse-effect profiles differ. This paper sets out to estimate the cost effectiveness of each drug, and the impact of changing from baclofen to tizanidine. A simplified but realistic model of physician behaviour and patient response was developed as a decision tree and populated with data derived from the available published clinical comparative trials. We considered patients with spasticity caused by multiple sclerosis or spinal cord injury. The outcome measure used was 'cost per successfully treated day' (STD). Costs were estimated from the perspective of the UK National Health Service at 2000 values. Expected cost for a cohort of 100 patients over 1 year was estimated to be pound 181 545 with baclofen and pound 211 930 with tizanidine. The estimated number of STDs was 20,192 with tizanidine and 17,289 with baclofen. The overall cost effectiveness of managing spasticity using baclofen and tizanidine was very similar ( pound 10.50 and pound 10.49 per STD respectively). The incremental cost effectiveness (ICE) of using tinzanidine as an alternative to baclofen for first-line treatment was pound 10.47 per STD. Sensitivity analysis found the model to be robust to changes in key parameters Drug cost should not be a determining factor in making this treatment choice, as the cost effectiveness ratios are similar for both products.