Methodological issues in assessing changes in costs pre- and post-medication switch: a schizophrenia study example

Faries, Nyhuis, Ascher-Svanum, Ascher-Svanum Haya

Description

Schizophrenia is a severe, chronic, and costly illness that adversely impacts patients' lives and health care payer budgets. Cost comparisons of treatment regimens are, therefore, important to health care payers and researchers. Pre-Post analyses ("mirror-image"), where outcomes prior to a medication switch are compared to outcomes post-switch, are commonly used in such research. However, medication changes often occur during a costly crisis event. Patients may relapse, be hospitalized, have a medication change, and then spend a period of time with intense use of costly resources (post-medication switch). While many advantages and disadvantages of Pre-Post methodology have been discussed, issues regarding the attributability of costs incurred around the time of medication switching have not been fully investigated. Methods Medical resource use data, including medications and acute-care services (hospitalizations, partial hospitalizations, emergency department) were collected for patients with schizophrenia who switched antipsychotics (n = 105) during a 1-year randomized, naturalistic, antipsychotic cost-effectiveness schizophrenia trial. Within-patient changes in total costs per day were computed during the pre- and post-medication change periods. In addition to the standard Pre-Post analysis comparing costs pre- and post-medication change, we investigated the sensitivity of results to varying assumptions regarding the attributability of acute care service costs occurring just after a medication switch that were likely due to initial medication failure. Results Fifty-six percent of all costs incurred during the first week on the newly initiated antipsychotic were likely due to treatment failure with the previous antipsychotic. Standard analyses suggested an average increase in cost-per-day for each patient of $2.40 after switching medications. However, sensitivity analyses removing costs incurred post-switch that were potentially due to the failure of the initial medication suggested decreases in costs in the range of $4.77 to $9.69 per day post-switch. Conclusion Pre-Post cost analyses are sensitive to the approach used to handle acute-service costs occurring just after a medication change. Given the importance of quality economic research on the cost of switching treatments, thorough sensitivity analyses should be performed to identify the impact of crisis events around the time of medication change.

Informations

• Publié par: biomed
• Publié le: 01 janvier 2009
• Nombre de lectures: 4
• Langue: English

Extrait

Cost Effectiveness and Resource Allocation

BioMedCentral

Open Access Research Methodological issues in assessing changes in costs pre and postmedication switch: a schizophrenia study example 1 12 Douglas E Faries*, Allen W Nyhuisand Haya AscherSvanum

1 2 Address: LillyUSA, LLC, Indianapolis, Indiana, USA andEli Lilly and Company, Indianapolis, Indiana, USA Email: Douglas E Faries*  [e-mail]; Allen W Nyhuis  [e-mail]; Haya AscherSvanum  [e-mail] * Corresponding author

Published: 27 May 2009Received: 7 September 2008 Accepted: 27 May 2009 Cost Effectiveness and Resource Allocation2009,7:11 doi:10.1186/14787547711 This article is available from: http://www.resourceallocation.com/content/7/1/11 © 2009 Faries et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract Background:Schizophrenia is a severe, chronic, and costly illness that adversely impacts patients' lives and health care payer budgets. Cost comparisons of treatment regimens are, therefore, important to health care payers and researchers. PrePost analyses ("mirrorimage"), where outcomes prior to a medication switch are compared to outcomes postswitch, are commonly used in such research. However, medication changes often occur during a costly crisis event. Patients may relapse, be hospitalized, have a medication change, and then spend a period of time with intense use of costly resources (postmedication switch). While many advantages and disadvantages of PrePost methodology have been discussed, issues regarding the attributability of costs incurred around the time of medication switching have not been fully investigated. Methods:Medical resource use data, including medications and acutecare services (hospitalizations, partial hospitalizations, emergency department) were collected for patients with schizophrenia who switched antipsychotics (n = 105) during a 1year randomized, naturalistic, antipsychotic costeffectiveness schizophrenia trial. Withinpatient changes in total costs per day were computed during the pre and postmedication change periods. In addition to the standard PrePost analysis comparing costs pre and postmedication change, we investigated the sensitivity of results to varying assumptions regarding the attributability of acute care service costs occurring just after a medication switch that were likely due to initial medication failure. Results:Fiftysix percent of all costs incurred during the first week on the newly initiated antipsychotic were likely due to treatment failure with the previous antipsychotic. Standard analyses suggested an average increase in costperday for each patient of $2.40 after switching medications. However, sensitivity analyses removing costs incurred postswitch that were potentially due to the failure of the initial medication suggested decreases in costs in the range of $4.77 to $9.69 per day postswitch. Conclusion:PrePost cost analyses are sensitive to the approach used to handle acuteservice costs occurring just after a medication change. Given the importance of quality economic research on the cost of switching treatments, thorough sensitivity analyses should be performed to identify the impact of crisis events around the time of medication change.

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