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Sensitivity analyses

Posted by spjupmc on 25 Feb 2014 at 09:20 GMT

The paper uses a threshold analysis to determine the change in therapy costs that would be required to change the results of the study. It is shown that the costs of CBT and GET would need to increase by 45% and 22% respectively to reach the cost per QALY threshold of £30,000. In the analysis plan we said that we would assess cost-effectiveness for cost increases and decreases of 50%. The threshold analysis is arguably more useful than this but for the purposes of clarity we can confirm that because CBT and GET are not cost-effectiveness with therapy cost increases above 45% and 22% respectively then they are certainly not cost-effectiveness with therapy cost increase of 50%. APT was not cost-effective in the base case and so any increase in the costs of APT would reduce its cost-effectiveness further.

Conversely, therapy cost reductions of 50% would make APT cost-effective using the £30,000 threshold (because the threshold analysis shows this to happen at a reduction of 35%) but would make CBT and GET even more cost-effective.

The big assumption with all of this is that changing therapy costs does not impact on outcomes. We can not address that here but it is something worth exploring.

Competing interests declared: Author