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The Cost-Effectiveness of the Improving Access to Psychological Therapies (IAPT) Programme in Severe Mental Illness: A Decision Analytical Model Using Routine Data

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Original languageEnglish
Pages (from-to)873-883
Number of pages11
JournalCommunity Mental Health Journal
Issue number5
Early online date8 Mar 2019
Accepted/In press1 Mar 2019
E-pub ahead of print8 Mar 2019
Published1 Jul 2019

King's Authors


This is the first site level economic evaluation of the Improving Access to Psychological Therapies programme for severe mental illness (IAPT-SMI) that is funded by NHS England. It also aims to illustrate the challenges involved in evaluations based on routine data with low internal validity. Six IAPT-SMI pilot sites treated 1 of 2 clinical groups: (i) psychosis or bipolar disorder; (ii) personality disorder. A decision analytical model nested in a before-after framework- the same patients 12 months after treatment versus 12 months before treatment—was used to compare the cost-effectiveness of IAPT-SMI with treatment as usual (TAU). IAPT-SMI appears to be more costly overall but save non-psychological treatment costs. There is evidence it may improve function and lower incidence of harmful behaviour. However, there is a need for evaluations with a more conventional study design that measure a more comprehensive array of resource use and clinical outcomes.

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