BackgroundThe United Nations Sustainable Development Goals (SDGs) target 3.4 aims to reduce premature mortality attributable to non-communicable diseases (NCDs) by one-third of their 2015 levels by 2030. Although meeting this target leads to longevity, survivors may suffer from long-term disability caused by NCDs. This paper quantifies the potential gains in health-adjusted life expectancy for people aged 30-70 years (HALE[30-70)) by examining the reductions in disability in addition to premature mortality. Additionally, we also assessed the feasibility of meeting the SDGs target 3.4.MethodsWe extracted data from the Global Burden of Disease Study 2019 for all NCDs and four major NCDs (cancers, cardiovascular diseases, chronic respiratory diseases, and diabetes mellitus) in 188 countries from 1990 to 2019. Bayesian age-period-cohort models were used to predict possible premature mortality in 2030. The life table was used to estimate the unconditional probability of death and HALE[30-70). Estimates of the potential gains in HALE[30-70) were based on three alternative future scenarios: a) eliminating all premature deaths and disability from a specific cause, b) meeting SDGs target 3.4, and survivors' disability is eliminated, and c) meeting SDGs target 3.4, but survivors remain disabled for the rest of their lives.ResultsIn 2030, the unconditional probability of premature mortality for four major NCDs in most countries remained at more than two-thirds of the 2015 baseline. In all scenarios, the high-income group has the greatest potential gains in HALE[30-70), above the global average of HALE[30-70). In scenario A, the potential gains in HALE[30-70) of reducing premature mortality for four major NCDs are significantly lower than those for all NCDs (range of difference for all income groups: 2.88 - 3.27 years). In scenarios B and C, the potential gains of HALE[30-70) in reducing premature mortality for all NCDs and the four major NCDs are similar (scenario B: 0.14 - 0.22, scenario C: 0.05 - 0.19). In scenarios A and B, countries from the high-income group have the greatest potential gains in HALE[30-70) from cancer intervention, whilst countries from the other income groups result in a greater possible HALE[30-70) gains from cardiovascular diseases control. In scenario C, countries from each income group have the largest potential gains in HALE[30-70) from diabetes reduction and chronic respiratory diseases prevention.ConclusionsAchieving SDGs target 3.4 remains challenging for most countries. The elimination of disability among the population who benefit from the target could lead to a sizable improvement in HALE[30-70). Reducing premature death and disability at once and attaching equal importance to each to in line with the WHO goal of "leaving no one behind".