Assessing the validity of the ICECAP-A capability measure for adults with depression

Paul Mark Mitchell,Angelo Iezzi,Willem Kuyken,Hareth Al-Janabi,Joanna Coast,Jeff Richardson,Sarah Byford

doi:10.1186/s12888-017-1211-8

Abstract

BackgroundEffectiveness and cost-effectiveness are increasingly important considerations in determining which mental health services are funded. Questions have been raised concerning the validity of generic health status instruments used in economic evaluation for assessing mental health problems such as depression; measuring capability wellbeing offers a possible alternative. The aim of this study is to assess the validity of the ICECAP-A capability instrument for individuals with depression.MethodsHypotheses were developed using concept mapping. Validity tests and multivariable regression analysis were applied to data from a cross-sectional dataset to assess the performance of ICECAP-A in individuals who reported having a primary condition of depression. The ICECAP-A was collected alongside instruments used to measure: 1. depression using the depression scale of the Depression, Anxiety and Stress Scale (DASS-D of DASS-21); 2. mental health using the Kessler Psychological Distress Scale (K10); 3. generic health status using a common measure collected for use in economic evaluations, the five level version of EQ-5D (EQ-5D-5L).ResultsHypothesised associations between the ICECAP-A (items and index scores) and depression constructs were fully supported in statistical tests. In the multivariable analysis, instruments designed specifically to measure depression and mental health explained a greater proportion of the variation in ICECAP-A than the EQ-5D-5L.ConclusionThe ICECAP-A instrument appears to be suitable for assessing outcome in adults with depression for resource allocation purposes. Further research is required on its responsiveness and use in economic evaluation. Using a capability perspective when assessing cost-effectiveness could potentially re-orientate resource provision across physical and mental health care services.

Highlights

Effectiveness and cost-effectiveness are increasingly important considerations in determining which mental health services are funded
Recent findings show health related quality of life (HRQoL) measures fare better in patients with depression compared to other mental health groups such as patients with bipolar disorder and schizophrenia, there is an acknowledgement of the restricted coverage of themes important to all mental health patients in the most commonly used HRQoL measures: EQ-5D and SF-6D [7]
The ability to use quality-adjusted life years (QALYs) to compare across very different health situations has meant that it has retained its position of prominence, in particular QALYs using EQ-5D [18]

Summary

Introduction

Effectiveness and cost-effectiveness are increasingly important considerations in determining which mental health services are funded. These include worries about the impact on equity of using QALY maximisation as the objective for economic evaluation [8,9,10] and concerns about whether QALYs are fully able to capture broader patient value from health care [11,12,13,14] This latter topic has received particular focus in the past decade with unease about a sole reliance of just health related aspects of quality of life, emanating from a number of different research groups [15,16,17]. A recent study into the methods for assessing cost-effectiveness by NICE found that the current standard approach leads to a negative impact on QALYs forgone in a number of areas including forgone gains from mental health services [19]

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