Updated cost comparison of home care subcutaneous versus outpatient intravenous trastuzumab for HER2-positive breast cancer in Singapore

Background

Due to major changes in effective drug prices, we update the findings of our earlier cost-minimization analysis comparing home care subcutaneous (SC) trastuzumab with outpatient intravenous (IV) trastuzumab for HER2-positive breast cancer in Singapore. ¹

By the end of 2022, IV trastuzumab biosimilars accounted for 72% of total trastuzumab use across Singapore’s public institutions, according to the Agency for Care Effectiveness. ² Currently, only two biosimilars (Ogivri^® and Herzuma^®) are subsidized by the Standard Drug List (SDL) framework, while the originator Herceptin^® is no longer covered by any government subsidies (SDL or Medication Assistance Fund).

The previous economic evaluation utilized 2023 costs of trastuzumab originators for both IV and SC formulations. Notably, the cost of biosimilars is now less than 10% of the originator, representing a substantial change in drug costs that warrants re-evaluation.

Given that the goal of an economic evaluation is to generate evidence to support informed decision-making, we consider it our responsibility to update the analysis and disseminate the relevant findings.

This study aims to compare updated annual per-patient costs of home care with SC trastuzumab (originator) versus outpatient care with IV trastuzumab (biosimilar) in Singapore.

Methods

The reporting of this study conforms to the CHEERS guideline for economic evaluations (see Supplemental Appendix Table A). ³ The analytical approach followed the previously published methodology. ¹ Briefly, a model-based cost-minimization analysis using a micro-costing approach was conducted from a societal perspective to compare annual per-patient costs of home care SC trastuzumab and outpatient IV trastuzumab. The model included direct medical costs (drugs, consumables, manpower, and facility) and indirect costs due to productivity loss using the human capital approach. Probabilistic sensitivity analysis was performed using 1000 Monte Carlo iterations, and mean values with 95% uncertainty intervals (UIs) are reported. All costs are presented in 2024 Singapore dollars.

For this updated analysis, the IV trastuzumab drug cost was revised from Herceptin to the biosimilar Herzuma, while the SC formulation cost remained unchanged. Since only price data are available, a 5%–30% markup margin reported by the Ministry of Health ⁴ was applied to estimate procurement costs. Full details of all model parameters are provided in Supplemental Appendix Table B.

Results

Summarized in Table 1, the Monte Carlo simulation revealed that home-based care was considerably more expensive than outpatient care, with a 0% probability of being cost-saving. The overall annual per-patient cost was S$21,790 (95% UI: S$19,662–S$23,922) for home care versus S$6,949 (95% UI: S$5,347–S$10,782) for outpatient care, representing a 214% cost increase.

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Table 1.

Results of probabilistic sensitivity analysis.

Per patient per year	Total societal cost		Service delivery cost		Productivity loss
	Mean value, S$	95% UI	Mean value, S$	95% UI	Mean value, S$	95% UI
Outpatient IV	6,949	5,347–10,782	1,656	1,052–2,451	1,229	398–2,633
Home care SC	21,790	19,662–23,922	557	360–856	405	329–482
Difference	14,841	10,249–17,685	−1,099	−1,971 to −443	−824	−2,195 to 18
Percentage of difference	214%		−66%		−67%
Probability of being cost saving	0.00%		100%		97.5%

Service delivery includes consumables, infusion chair time, pharmacist time, and nurse time; productivity loss includes time spent on traveling due to treatment, and time spent on receiving treatment.

IV, intravenous; SC, subcutaneous; UI, uncertainty interval.

When service delivery costs were assessed separately, compared to outpatient care, the home-based model was cheaper by approximately S$1099 (66%) per patient, with 100% likelihood of being cost-saving. It also reduced productivity loss by approximately S$824 (67%) per patient annually, with a 97.5% probability of cost-savings.

A detailed cost breakdown is illustrated in Table 2. The annual drug cost was the primary cost driver, with home-based SC trastuzumab (S$20,829) far exceeding outpatient IV trastuzumab (S$4,065). Although the home-based strategy generated savings on consumables (S$225), chair time (S$1016), pharmacist time (S$242), patient traveling time (S$337), and treatment duration (S$487), these were partially offset by an additional cost for nurse activities (S$384).

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Table 2.

Cost breakdown from results of probabilistic sensitivity analysis.

Costing categories	Outpatient IV, S$ (95% UI)	Home care SC, S$ (95% UI)	Mean difference, S$ (95% UI)
Drug	4,065(3312–7,596)	20,829(18,702–22,932)	+16,764(12,510–19,267)
Consumables	252(216–288)	27(18–36)	−225(−270 to −180)
Infusion chair time	1,016(465–1,807)	NA	−1,016(−1,807 to −465)
Pharmacist time	242(99–455)	NA	−242(−455 to −99)
Total nurse time	146(63–265)	530(334–833)	+384(182–674)
Preparing for cannulation	146(63–265)	NA	NA
Drug preparation for SC injection	NA	125(12–358)	NA
SC injection	NA	49(8–128)	NA
Travel between house visits	NA	356(252–473)	NA
Absenteeism due to travel	337 (51–941)	NA	−337(−941 to −51)
Absenteeism due to treatment	892 (191–2,195)	405 (329–482)	−487(−1,784 to 222)

IV, intravenous; NA, not applicable; SC, subcutaneous; UI, uncertainty interval.

Discussion

Economic evaluations can be sensitive to cost data. Changes in pricing have led to substantial shifts in market share between originator and biosimilar trastuzumab, resulting in significantly different drug costs that warrant re-assessment. This updated analysis reaffirms that drug cost is the key driver of overall expenditure in trastuzumab delivery. As drug prices can fluctuate markedly over time, we separately assessed the costs of service delivery (manpower, facility, and consumables) and productivity loss. The results are consistent with our previous analysis, indicating that home-based care is less costly than outpatient care in these components. They also align with systematic reviews highlighting the increasing contribution of indirect costs, including productivity loss and time burden associated with the current landscape.^5,6 This supports our decision to separately examine service delivery and productivity costs when comparing home-based and outpatient treatment models. However, when biosimilar IV formulations are considered, the total cost of home-based SC administrations becomes substantially higher than that of outpatient IV administration. Under current policy and market conditions, home care SC trastuzumab is unlikely to be cost-saving from a societal perspective, and this contradicts the previous finding. ¹

Wong et al. ⁷ similarly reported that home-based cancer drug delivery is structurally cost-inefficient, largely because it could serve only one patient at a time and cannot be scaled up effectively. By contrast, a community-based model led by the National University Cancer Institute Singapore, in which selected low-risk treatments are delivered in a dedicated space within existing primary care clinics, achieved similar goals of improving patient experience (98.6% satisfaction rate) and reducing hospital workload (~10%), while remaining financially sustainable. This suggests that the community-based model may offer a more viable balance between patient experience and system-level efficiency than home-based care. However, there remains scope for further research to identify specific patient populations who may be appropriately and safely managed within home-based cancer treatment models. Moreover, future studies should explore the factors that contribute to the cost-effectiveness of such home-based care in comparison to conventional outpatient services. This could help improve how patients are selected for home treatment and guide decisions about using healthcare resources more efficiently.

Beyond drug pricing, the treatment landscape for HER2-positive early breast cancer is also evolving through optimization of trastuzumab dosing and delivery strategies. Recent evidence suggests that alternative dosing approaches can substantially reduce patient out-of-pocket costs and treatment burden without compromising clinical intent, highlighting the growing importance of indirect costs and service delivery considerations in economic evaluations. ⁸ Together, this underscores the importance of timely economic evaluations whenever treatment costs, subsidy structures, or care delivery models evolve.

Conclusion

Under current drug prices and subsidy policies, IV trastuzumab administered in the outpatient clinic remains the cost-saving option compared with SC trastuzumab administered at the patient’s home, from a societal perspective.

Supplemental Material