# Prevention of rheumatic heart disease in New Zealand: High-dose subcutaneous benzathine penicillin is cost-saving compared with traditional intramuscular injections

## TL;DR

Using high-dose subcutaneous penicillin injections instead of traditional intramuscular injections halves treatment costs and improves adherence in children with rheumatic fever.

## Contribution

Demonstrates that subcutaneous penicillin injections are more cost-effective and improve adherence compared to traditional methods.

## Key findings

- Subcutaneous penicillin injections nearly halve 12-month treatment costs for children with rheumatic fever.
- Cost-savings are greatest in younger children and with high adherence.
- Subcutaneous injections reduce nurse time, travel, and caregiver burden.

## Abstract

•Subcutaneous injection of penicillin nearly halves 12-month treatment costs for 10-year-old children with rheumatic fever compared with intramuscular benzathine penicillin G.•Cost-savings are greatest in younger children and when adherence is high.•Subcutaneous injection of penicillin may improve adherence, reduce school absences, and prevent disease progression.•Less frequent injections reduce nurse time, travel, and caregiver burden.

Subcutaneous injection of penicillin nearly halves 12-month treatment costs for 10-year-old children with rheumatic fever compared with intramuscular benzathine penicillin G.

Cost-savings are greatest in younger children and when adherence is high.

Subcutaneous injection of penicillin may improve adherence, reduce school absences, and prevent disease progression.

Less frequent injections reduce nurse time, travel, and caregiver burden.

Acute rheumatic fever is a preventable condition that can lead to chronic illness and early death. Standard prevention with 4-weekly intramuscular (IM) benzathine penicillin G (BPG) injections for ≥10 years may be associated with poor adherence. High-dose 10-weekly subcutaneous penicillin injections (SCIP) may improve adherence by reducing injection frequency. Since 2025, SCIP has been included in the repository of standard operating procedures in lower North Island hospitals in New Zealand (NZ). We compare the costs of delivering a full course of secondary prophylaxis using SCIP vs IM BPG injections in NZ children with a first acute rheumatic fever presentation and no/mild carditis.

Treatment administration costs and productivity losses from SCIP vs IM BPG were modeled using real-world survey data on time off school and work. Starting age of secondary prophylaxis, adherence, and administration site over the treatment period were varied. Costs are in 2024 NZ$, discounted at 3.5%.

SCIP reduced 12-month costs by nearly half to NZ$ 1629 for a 10-year-old child. Over a full course, SCIP consistently offered societal cost-savings, especially in younger children and higher adherence scenarios.

Prevention using SCIP is cost-saving to NZ society. Increased adherence to SCIP may contribute to longer, healthier lives for those diagnosed with rheumatic fever.