Genomic Testing in Australia: A Budget Impact Analysis Using Diffusion Modeling From a Healthcare System Perspective

Objectives: Genomic testing can shorten the diagnostic odyssey for people with rare diseases, yet clinical uptake has lagged funding policy in Australia. Therefore, we evaluated the 10-year budget impact of alternative implementation strategies for publicly funded genomic testing using national claims data and diffusion modeling. Methods: Monthly Medicare Benefits Schedule claims (1993–2025) were analyzed for chromosomal microarray analysis (CMA), Fragile X (FMR1) testing, and genomic tests across 7 rare-disease groups (syndromic and non-syndromic intellectual disability, neuromuscular, inherited cardiac, renal ciliopathies/tubulopathies, congenital hearing loss, mitochondrial). Logistic, Gompertz, and Bass diffusion functions and Seasonal Autoregressive Integrated Moving-Average models were fitted to uptake and used to forecast 2025 to 2034 volumes. Scenarios included status quo, broadened second-line eligibility, and first-line exome sequencing/genome sequencing (ES/GS) replacing CMA/FMR1 (60:40 ES:GS). Costs used were the 1 July 2024 Medicare Benefits Schedule fees; the results are in Australian (AUD) dollars. Results: Observed genomic testing volumes were below diffusion-implied trajectories. The 10-year cumulative spending was as follows: status quo AUD 1.1 million; broadened second-line AUD 7.5 million (incremental +6.4 million vs status quo); and first-line ES/GS AUD 6.2 million (incremental +5.1 million). In 2028, it was status quo AUD 0.23 million, second-line AUD 1.21 million, and first-line AUD 0.97 million. ES/GS achieved lower cumulative spend than the broadened second-line despite higher per-test fees, reflecting substitution from CMA/FMR1 and efficient diagnostic pathways. Conclusions: Indication-by-indication funding has yielded slower-than-expected uptake and likely under-budgeting. A first-line genomic testing pathway, aligned with CMA criteria, could better match clinical need while constraining spend versus expanding second-line eligibility. Harmonized eligibility and streamlined implementation would improve access and planning.