Projecting direct medical costs and productivity benefits of improving access to advanced therapy for rheumatoid arthritis: a projection modelling study

Figures & data

Figure 1. Model Schematic. Module (1) projected the size of the target population and divided them by their treatment status. Module (2) calculated the average direct medical cost and productivity loss per patient. Multiplying the number of patients projected by module (1) and per patient average cost and loss by module (2) gave the total cost and benefits for a specific scenario.

Figure 2. Six sub-modules within the direct medical cost calculation.

Table 1. Input values used in the model for the population size projection.

Model inputs	Values	Source
Adult (≥18 years) population, 2021	23,498,434	Department of Statistic Malaysia
Population growth rate (annual)	0.6%
Prevalence (annual) proportion of RA	0.23%	NIAR 2009–2019
Proportion with moderate-to-severe disease	56.1%
Proportion unresponsive and/or intolerant to conventional synthetic DMARD among the moderate-to-severe RA cases	50.0%
Proportion with AT access at baseline (Year 2019)	2.7%	MARBLE 2009–2019

Table 2. Projected patient number and the breakdown by at access status under the status quo scenario.

Target population	2020	2021	2022	2023	2024
Total	10,764	10,828	10,893	10,959	11,024
Without AT access	10,473	10,536	10,599	10,663	10,727
With AT access	291	292	294	296	298

Table 3. Projected patient number with at access under three access improvement scenarios. Yoy = year-on-year.

Access Improvement scenario	2020	2021	2022	2023	2024
Scenario (1) 15% yoy increase	334	380	426	473	521
Scenario (2) 20% yoy increase	349	409	471	533	595
Scenario (3) 25% yoy increase	363	439	515	592	670

Table 4. Projected total and subcategory direct medical costs under the status quo scenario.

	2020	2021	2022	2023	2024	Percentage
Total direct medical cost (MYR, million)	162.0	163.3	164.0	165.0	166.0	100%
Subcategory costs (MYR, million)
Drug cost	38.8	39.0	39.2	39.5	39.7	23.9%
Health service utilization	117.3	118.0	118.7	119.4	120.1	72.3%
Non-pharmacological management	1.9	1.9	1.9	1.9	1.9	1.1%
RA related surgical intervention	2.0	2.0	2.00	2.0	2.0	1.2%
RA related CV sequalae	0.7	0.7	0.7	0.7	0.7	0.4%
Adverse events	1.2	1.2	1.2	1.2	1.2	0.7%

Note: total might not add up to 100% due to rounding.

Table 5. Projected 5-year total differential direct medical cost in between the status quo scenario vs. the three access improvement scenarios.

	Status quo vs.
	15% access improvement	20% access improvement	25% access improvement
5-year total direct medical cost (MYR, million)	+19.0	+25.4	+31.7
Subcategory cost (MYR, million)
Drug cost	+22.9	+30.5	+38.1
Health service utilization	− 3.7	− 4.9	− 6.1
Non-pharmacological management	− 0.2	− 0.2	− 0.2
RA related surgical intervention	− 0.1	− 0.1	− 0.1
RA related CV sequalae	0	0	0
Adverse events	0	0	0

Table 6. Projected 5-year differential productivity cost in between the status quo scenario vs. the three access improvement scenarios.

	Status quo vs.
	15% access improvement	20% access improvement	25% access improvement
5-year differential productivity cost (MYR, million)	− 1.9	− 2.5	− 3.2

Table 7. Projected 5-year differential drug cost under different at utilization mixes scenarios (20% improvement scenario used).

	5-year cumulative differential drug cost (MYR, thousand)
	With % of anticipated tsDMARD price adjustment
Examined scenario	0%	−10%	−15%	−20%
Scenario (1) 10% of bDMARD use move to tsDMARD	+453	+190	+58	−73
Scenario (2) 10% of tsDMARD use move to bDMARD	−120	−50	−15	+19

Note: + means incremental cost; - means decremental cost.

Figure 3. Results of the one-way sensitivity analysis using a 20% range in both directions.