NICE conducted a single technology appraisal of dapagliflozin (FORXIGA®) for the treatment of type 2 diabetes. The economic evaluation included within the Bristol-Myers Squibb / AstraZeneca (BMS/AZ) submission to NICE was a patient level simulation. The model was constructed with an Excel spreadsheet front-end which tabulates data which are processed via:
- Excel formulas
- Visual Basic (VBA) functions and macros
- C++ programming code compiled into Dynamic Link Libraries (DLLs)
The DLL components of the economic model are bespoke pieces of software and were therefore not considered to fall within the list of standard software packages usually accepted by NICE.
Prior to the first Appraisal Committee, the Decision Support Unit was asked by NICE to examine the executable model submitted by BMS/AZ with the following aims:
- To establish whether the model functioned as described by the manufacturer
- To report any important aspects of the model that were not described in the manufacturer submission
- To examine whether the C++ code followed the steps described by the manufacturer and used the data described in the submission
- To validate whether the model produced the results described in the submission
Following the first Appraisal Committee meeting, an Appraisal Consultation Document (ACD) was issued by NICE and BMS/AZ submitted a response to the Dapagliflozin ACD which included revised economic models. The DSU was then asked by NICE to review the manufacturer’s written response to the ACD and the technical aspects of the revised economic model to determine whether the manufacturer had provided a satisfactory response to the concerns raised by the DSU in their review of the original economic models.
At the second Appraisal Committee meeting, the Committee concluded that it was unable to decide on the most plausible ICERs, or to make a recommendation on dapagliflozin, due to a number of unresolved issues, including uncertainty regarding the modelling of weight evolution within the BMS/AZ economic model.
Following the second committee meeting, NICE asked the DSU to further review the economic analysis provided in response to the Dapagliflozin ACD and to perform exploratory analyses, particularly in relation to how changes in weight are modelled over time for the different treatments.