Review of Models Used in Economic Analyses of New

Authors: Carl V Asche Stephen E Hippler Dean T Eurich

Publish Date: 2013/12/20

Volume: 32, Issue: 1, Pages: 15-27

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Abstract

Economic models are considered to be important as they help evaluate the longterm impact of diabetes treatment To date it appears that no article has reviewed and critically appraised the costeffectiveness models developed to evaluate new oral treatments glucagonlike peptide1 GLP1 receptor agonists and dipeptidyl peptidase4 DPP4 inhibitors for type 2 diabetes mellitus T2DMThis study aimed to provide insight into the utilization of costeffectiveness modelling methods The focus of our study was aimed at the applicability of these models particularly around the major assumptions related to the clinical parameters glycated haemoglobin A1c systolic blood pressure SBP lipids and weight used in the models and subsequent clinical outcomesMEDLINE and EMBASE were searched from 1 January 2004 to 14 February 2013 in order to identify published costeffectiveness evaluations for the treatment of T2DM by new oral treatments GLP1 receptor agonists and DPP4 inhibitors Once identified the articles were reviewed and grouped together according to the type of model The following data were captured for each study comparators country evaluation and key cost drivers time horizon perspective discounting rates currency/year costeffectiveness threshold sensitivity analysis and costeffectiveness analysis curvesA total of 15 studies were identified in our review Nearly all of the models utilized a health care payer perspective and provided a lifetime horizon The CORE Diabetes Model UK Prospective Diabetes Study UKPDS Outcomes Model Cardiff Diabetes Model Centers for Disease Control and Prevention CDC Diabetes CostEffectiveness Group Model and Diabetes Mellitus Model were cited With the exception of two studies all of the studies made significant assumptions surrounding the impact of GLP1 receptor agonists or DPP4 inhibitors on clinical parameters and subsequent short and longterm outcomes Moreover often the differences in the clinical parameters were relatively small eg 1 or 2 mmHg in blood pressure and would not be considered by many as clinically important Yet the impact of these small clinical changes often resulted in large lifetime changes in health outcomes in the models In particular many studies assumed that changes in weight associated with the therapies would equate to improved outcomes despite limited evidence for this assumption Although the new oral treatments were regarded as cost effective in most studies based upon the studies reviewed the validity of these projections particularly for the longer time frames is questionable Indeed although most of these studies have been conducted in the last 5 years recent trial evidence has already questioned the validity of most of these studiesIt is clear that a number of changes are required in the evaluation of diabetes therapies First and foremost the basic models need to be updated to include contemporary important clinical trial data assessing hard clinical outcomes in patients with diabetes Second there should be less emphasis on 40year or lifetime costs and consequences of the therapies and a greater focus on shortterm 5year and intermediateterm 10year outcomes Practice is continually evolving and the probability that these models would provide any valid predictions beyond 10 years is remote Third all modellers should immediately remove the basic assumption that small clinically inconsequential changes in A1c SBP lipids and weight result in major clinical improvements in patients Future models should aim to include all relevant treatment outcomes whether these relate to effects on underlying diabetes and its complications or to short or longterm side effects of treatment We need to explore why costsaving interventions could benefit further from adding patient characteristics which may be able to better predict the use of lowercost alternatives Moreover the vast array of different clinical cost and utility data used in the different models reviewed makes it apparent that a uniform methodology should be developed for diabetes economic models In this manner future models could be run using the same data which would allow for more acceptable comparability between studiesThe authors Carl Victor Asche Stephen Hippler and Dean Eurich declare that they have no conflicts in preparing this manuscript All of the authors contributed to the research by reviewing articles interpreting findings and formulating discussion of the results and the drawing of conclusions Carl Victor Asche serves as the overall guarantor

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