Objectives Evidence shows low-sodium potassium-rich salt substitutes (LSSS) are a potent strategy to reduce population blood pressure (BP) and chronic disease burden. We aimed to estimate the long-term health benefits, costs and cost-effectiveness of a government-led policy to gradually switch from regular salt to LSSS in Indonesia.

Methods We developed a Markov and lifetable simulation model to estimate the impact of using LSSS compared to current regular (100% sodium) salt on major BP-related diseases and health-adjusted life years (HALY). Data were sourced from the 2018 Indonesian Basic Health Research Survey (BP distribution), Total Diet Study (sodium intake), Global Burden of Disease 2019 study (disease epidemiology), meta-analyses (LSSS-BP relationship) and National Health Insurance – BPJS Kesehatan – (healthcare costs). Health outcomes, implementation costs, healthcare costs and incremental cost-effectiveness ratios (discounted at 3%) were simulated over 10 years and the remaining lifetime of the 2019 Indonesia population. Uncertainty analysis was done using Monte-Carlo simulations.

Results Over the first 10 years, compared to using regular salt, gradually switching to LSSS (10-year phase-in period towards current iodine fortification coverage levels) could avert 332,900 (95%UI: 296,700 – 364,800) incident cases and 25,900 (22,400 – 28,900) deaths from ischaemic heart disease, 406,900 (361,200 – 447,300) incident cases and 91,200 (74,800 – 105,000) deaths from haemorrhagic stroke, and 384,800 (325,200 – 438,000) incident cases and 35,200 (24,900 – 43,700) deaths from ischaemic stroke. This translated to 1.1 million HALYs gained in first 10 years and over 22 million HALYs gained over the lifetime. In the first 10 years, estimated implementation cost was USD 1.1 billion, with USD 3.4 billion in healthcare cost savings. Over both time horizons, LSSS were cost-saving in the main analysis and in multiple sensitivity analyses.

Conclusions Our modelling supports scaling the use of LSSS nationally as a cost-saving strategy to prevent substantial BP-related disease burden in Indonesia.