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Economic projection model assumptions and parameters

For the purposes of modelling, we delineate three principal themes of assumptions:
i) The prevalence of DM and prediabetes within the Scheme’s participants:
We assume that there is a homogeneous prevalence of diabetes, prediabetes, and
complications amongst the Scheme’s participants.
We assume that all individuals within the target age range will take part in each of the
prescribed interventions and will not withdraw from the programme once they enrol.
ii) The onset of complications due to DM:
We assume that complication onset is homogenous throughout the target population and
principally influenced by years of DM history.
iii) The follow-up treatment provided to the Scheme’s participants:

We assume that all participants diagnosed with DM will receive care within either the
public or private sector moving forward and that any differences in prices billed to patients
for services between the sectors are negligible.

In building these assumptions into the economic projections model, we aim to define the
parameters through which we expect future savings and benefits to both patients and the
health system (Appendix N).

i. BIA parameters
To assess the impact of the Scheme in different variations, the BIA was conducted using
three scenarios: a baseline scenario modelling expected expenditures assuming that the
health system maintains its status quo and no population-wide programmes for screening or
risk management are implemented (Base Scenario); a modified scenario showcasing
expected expenditures if a screening and basic follow-up care programme is implemented
(Scenario 1); a third scenario projecting expenditures if a screening programme is
implemented in conjunction with a comprehensive management programme (RAMP-DM)
(Scenario 2) (Table 4.9).

We calculated our costs and cost-savings using a 30-year horizon with a closed prospective
cohort, wherein individuals maintain participation within the Scheme, except in the event of
death, throughout the time horizon.

Parameters for the model include the prevalence of the different stages of DM, flow
parameters to simulate progression and regression of illness, rates of complications and
expected costs, mortality rates and costs, and costs due to screening and intervention (see
Box 4.8 for definitions). The shifts in each of the above listed rates are explored in greater
detail in Appendix O.

All costs are expressed as before discounting, per the guidelines presented in the 2012 Task
Force for International Society for Pharmacoeconomics and Outcomes Research Health
Sciences Policy Council to determine new best practices for BIAs (Sullivan et al., 2014).

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