BackgroundThis study aims to evaluate the association of metabolic syndrome (MetS) with the risk of all-cause mortality in elderly patients with acute respiratory distress syndrome (ARDS).MethodsElderly ARDS patients (≥ 65 years) enrolled from our hospital between January 2018 and July 2023 were divided into the MetS group or the non-MetS group. The outcomes were 28-day and 90-day all-cause mortality rates in the total population and two subgroups stratified by age (65–75 years and ≥ 75 years). Multivariate Cox regression was employed to assess the association of MetS with all-cause mortality, after controlling for potential cofounding factors.ResultsA total of 946 patients were divided into the MetS group (n = 410) or the non-MetS group (n = 536). The 28-day and 90-day all-cause mortality rates were significantly higher for MetS group compared to non-MetS group in the total population and two subgroups (all P < 0.01). Multivariate Cox regression indicated that MetS was significantly associated with a higher risk of 90-day all-cause mortality in the total population (HR = 1.62, 95% CI: 1.22–2.15; P < 0.01), and subgroups of patients aged 65–75 years (HR = 1.52, 95% CI: 1.04–2.21; P = 0.03) and ≥ 75 years (HR = 1.90, 95% CI: 1.23–2.94; P < 0.01). Moreover, with each MetS criterion added from 0 to 1 to 2, 3, and 4 of 4 criteria, both 28-day and 90-day all-cause mortality rates significantly increased (both P < 0.01).ConclusionMetS was associated with higher risks of 28-day and 90-day all-cause mortality in elderly patients with ARDS.