A comparison of four different approaches to measuring health utility in depressed patients

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RESEARCH

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A comparison of four different approaches to measuring health utility in depressed patients Nicholas Turner1*, John Campbell2, Tim J Peters3, Nicola Wiles1 and Sandra Hollinghurst4

Abstract Background: A variety of instruments are used to measure health related quality of life. Few data exist on the performance and agreement of different instruments in a depressed population. The aim of this study was to investigate agreement between, and suitability of, the EQ-5D-3L, EQ-5D Visual Analogue Scale (EQ-5D VAS), SF-6D and SF-12 new algorithm for measuring health utility in depressed patients. Methods: The intraclass correlation coefficient (ICC) and Bland and Altman approaches were used to assess agreement. Instrument sensitivity was analysed by: (1) plotting utility scores for the instruments against one another; (2) correlating utility scores and depressive symptoms (Beck Depression Inventory (BDI)); and (3) using Tukey’s procedure. Receiver Operating Characteristic (ROC) analysis assessed instrument responsiveness to change. Acceptability was assessed by comparing instrument completion rates. Results: The overall ICC was 0.57. Bland and Altman plots showed wide limits of agreement for each pair wise comparison, except between the SF-6D and SF-12 new algorithm. Plots of utility scores displayed ’ceiling effects’ in the EQ-5D-3L index and ’floor effects’ in the SF-6D and SF-12 new algorithm. All instruments showed a negative monotonic relationship with BDI, but the EQ-5D-3L index and EQ-5D VAS could not differentiate between depression severity sub-groups. The SF-based instruments were better able to detect changes in health state over time. There was no difference in completion rates of the four instruments. Conclusions: There was a lack of agreement between utility scores generated by the different instruments. According to the criteria of sensitivity, responsiveness and acceptability that we applied, the SF-6D and SF-12 may be more suitable for the measurement of health related utility in a depressed population than the EQ-5D-3L, which is the instrument currently recommended by NICE. Keywords: Depression, EQ-5D, SF-6D, Health related utility, QALYs

Background The National Institute for Health and Care Excellence (NICE) guidance on the management of depression identifies several priorities including accurate case recognition, optimal use of medication and effective delivery of psychological therapies [1]. This guidance highlights the need to identify cost-effective interventions and the use of cost per quality adjusted life years (QALYs) for this purpose. Measuring health related quality of life (HRQoL) to construct QALYs can be conducted in a number of ways, including

* Correspondence: [email protected] 1 Centre for Mental Health, Addiction and Suicide Research, School of Social and Community Medicine, University of Bristol, Oakfield House, Canynge Hall, 39 Whatley Road, Bristol BS8 2PS, UK Full list of author information is available at the end of the article

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