The impact on health system expenditure in Australia and OECD countries from accelerated NCD mortality decline through prevention or treatment strategies to achieve Sustainable Development Goal Target 3.4

Background: It is unclear what the relative impacts of prevention or treatment of NCDs are on future health system expenditure. First, we estimated expenditure in Australia for prevention vs treatment pathways to achieve SDG target 3.4. Second, we applied the method to 34 other OECD countries. Methods: We used GBD data to estimate average annual percentage changes in disease incidence, remission, and CFRs from 1990-2021, and projected to 2030 to estimate business-as-usual (BAU) reductions in NCD mortality risk (40q30). For countries not on track to meet SDG3.4 under BAU, we modelled two intervention scenarios commencing in 2022 to achieve SDG3.4: (1) prevention via accelerated incidence reduction; (2) treatment via accelerated increases in remission and decreases in CFRs. Australian disease expenditure data were input into a PMSLT model to estimate expenditure changes from 2022 to 2040. Assuming similar expenditure patterns, the method was applied across OECD countries. Findings: In Australia, current trends project a 25% reduction in 40q30 by 2030, short of the 33.3% SDG3.4 target. Achieving this requires a 2.53 percentage point (pp) annual acceleration in incidence decline (prevention) or 1.56pp acceleration in CFR reduction and remission increase (treatment). Prevention reduces disease expenditure by 0.72%-3.17% by 2030 and 2040; treatment initially increase expenditure by 0.16%, before reducing it by 0.98%. A treatment scenario reducing only CFRs increased expenditure initially; increasing remission alone achieved savings similar to prevention. Only Sweden, Ireland, and South Korea were on track to meet SDG3.4. Other OECD countries showed similar expenditure impacts to Australia. Interpretation: Whether reducing NCD mortality saves money depends on pathway taken (prevention or treatment). Care is needed when linking NCD mortality reduction to health system savings.